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Aim: This study compared several traditional culture-based media and chairside cultural assays for ability to recover mutans streptococci (MS) from pure cultures and from saliva samples. Methods and Results: When pure cultures were used with traditional culture-based media, mitis-salivarius bacitracin (MSB) agar demonstrated less support for bacterial recovery than trypticase-yeast extract-cysteine sucrose-bacitracin (TYCSB) agar and the modified medium of Ritz (HLR-S). One species of MS, Streptococcus ferus (c), was not recovered on MSB medium. Chairside cultural tests displayed considerable disparity between tests in recovering bacteria from pure cultures. On the glass adherence assay (Mucount®), S. ferus was not detected and Streptococcus criceti was not detected on the dipslide assay (Cariescreen SM®) or on the plastic adherence assay (Dentocult SM Strip mutans®). The frequency of isolation of pure strains of bacteria other than MS was common. From saliva samples, the frequency of isolation of MS on HLR-S and TYCSB media and the glass adherence assay was 91–97%. The frequency of isolation on MSB medium and on the dip-slide and plastic adherence assays was significantly decreased (37, 47 and 69%, respectively). Recovery scores varied considerably among the culture methods studied and tended to be highest on the HLR-S medium and on the glass adherence assay. Conclusions: Growth and recovery profiles of pure bacterial cultures and of saliva samples for the MS varied according to different media. Significance and Impact of the Study: Caution should be exercised in comparing results between studies that employ different cultural methods for MS enumeration. [ABSTRACT FROM AUTHOR]

Aims: To investigate the use of mannitol salt agar (MSA) supplemented with acriflavine for selective growth and quantification of Staphylococcus aureus from flushed dairy manure wastewater (FDMW). Methods and Results: Minimal inhibitory concentrations of acriflavine in MSA were determined by comparing the growth of S. aureus subsp. aureus (ATCC 33591) and Staphylococcus epidermidis (ATCC 155) in pure culture. Acriflavine concentrations of 1·3, 1·4 and 1·5 mg l−1 reduced CFU of S. epidermidis by 43%, 55% and 87%, respectively, while CFU of S. aureus subsp. aureus were only reduced by 15%, 20% and 26% at the respective concentrations of acriflavine. MSA supplemented with 1·5 mg l−1 acriflavine was tested for selective growth of indigenous S. aureus from three grab samples of FDMW. Acriflavine concentrations of 1·5 mg l−1 reduced background flora without significantly reducing ( P < 0·05) indigenous S. aureus counts. Conclusions: Acriflavine-supplemented MSA provides an effective media for selective growth and quantification of indigenous S. aureus from FDMW in the presence of high levels of background microflora. Significance and Impact of the Study: S. aureus is implicated for mastitis infections in dairy cows. Therefore, a reliable means for monitoring and detecting the organism in FDMW provides a tool for measuring the effectiveness of treatment for reducing S. aureus levels and implementing flushwater recycling without affecting herd health. [ABSTRACT FROM AUTHOR]

Fifty-six species in the Trichocomaceae were recovered from bark of trees and shrubs from hot arid and temperate regions, and following one fire in a temperate region of Australia. Fungi were recovered from dry bark after incubation for up to 1 h at up to 105°C. Fourteen species also regenerated on agar after their conidia were heated for 1 h at 105°C. Anamorphic species were commonly recovered and widespread. Teleomorphic species were only recovered after heating the bark. In addition, anamorphic fungi were recovered from one plant species following a natural fire. The results support the view that both anamorphic and teleomorphic fungi may tolerate extreme temperatures in their environment while dry. [ABSTRACT FROM AUTHOR]

The ascomycete Sclerotinia sclerotiorum is a plant pathogen with a very broad host range. In order to identify and characterize genes involved in S. sclerotiorum infection of Brassica napus (canola), expressed sequence tags (ESTs) were examined from libraries prepared from three tissues: complex appressorium (infection cushions), mycelia grown on agar and lesions formed on leaves of B. napus. A high proportion of genes (68%) had not been previously reported for S. sclerotiorum in public gene or EST databases. The types of novel genes identified in the infection cushion library highlights the functional specificity of these structures and similarities to appressoria in other fungal pathogens. Quantitative real-time PCR was used to analyse tissue specificity and timing of transcription of genes with best matches to MAS3 (appressoria-associated protein from Magnaporthe grisea), cellobiohydrolase I, oxaloacetate acetylhydrolase, metallothionein, pisatin demethylase, and an unknown gene with orthologs in fungal pathogens but not in saprophytic fungi. [ABSTRACT FROM AUTHOR]

Campylobacter jejuni is a leading cause of gastroenteritis in humans. Campylobacter jejuni produces extracellular polysaccharides that have been characterized structurally and shown to be independent of lipopolysaccharides. Furthermore, it has been suggested that these C. jejuni polysaccharides are capsular in nature, although their lipid anchor has not been identified. In this report, the occurrence of a lipid-linked capsular-like polysaccharide in C. jejuni is conclusively shown, and the lipid anchor identified as dipalmitoyl-glycerophosphate. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the accuracy of cefoxitin disc diffusion as a prediction of oxacillin resistance in coagulase-negative staphylococci (CoNS), and also to compare genotypic and phenotypic methods for detecting this resistance property. A total of 151 clinical CoNS isolates were tested by PCR for the presence of the mecA gene (gold standard method). The isolate susceptibilities were determined by the disc diffusion method with oxacillin (1 μg) and cefoxitin (30 μg) and by the agar dilution method for cefoxitin and oxacillin. Although none of the techniques showed 100% sensitivity and 100% specificity, the cefoxitin disc diffusion and oxacillin agar dilution were the best methods for detecting resistance to oxacillin among CoNS as these methods produced the best negative and positive predictive values. A combination of methods can be used routinely to identify resistance to oxacillin in CoNS. [ABSTRACT FROM AUTHOR]

The article evaluates the Sanita-kun coliforms, a dehydrated medium sheet for coliform detection. It consists of a transparent cover film, an adhesive sheet, a layer of nonwoven fabric and a water-soluble compound film. 26 food types belonging to nine food categories was used for validating the medium sheet. The sheet can be used to provide an alternative method to coliform count agar.

Aims: To evaluate the suitability of Colilert-18 in detecting Escherichia coli and total coliforms in tropical freshwater samples. Methods and Results: Target organisms were isolated from yellow-fluorescent and yellow wells of Colilert-18/Quanti-Tray using m-TEC agar and m-ENDO LES agar respectively. All the selected isolates were first identified based on their fatty acid methyl ester profile. Isolates showing contradictory results to that of the Colilert-18 procedure were re-identified using API 20E strips. A total of 357 isolates, 177 from yellow-fluorescent wells and 180 from yellow wells, were identified. Conclusions: The false-positive and -negative rates for E. coli detection using Colilert-18 were 36·4% and 11%, respectively, while for coliform detection the false-positive rate was 10·3%. Significance and Impact of the Study: The high false-positive rate of Colilert-18, tempers its value for E. coli detection when used for tropical freshwater samples. [ABSTRACT FROM AUTHOR]

Aims: Use of an electronic nose (zNoseTM) to discriminate between volatile organic molecules delivered during bacterial/fungal growth on agar and in broth media. Methods and Results: Cultures of bacteria ( Klebsiella pneumoniae, Pseudomonas aeruginosa, Escherichia coli) and yeasts (two Candida albicans strains) were grown on agar and in broth media and incubated for 24 h at 37°C. Headspace samples from microbial cultures were analysed by the zNoseTM, a fast gas chromatography-surface acoustic wave detector. Olfactory images of volatile production patterns were observed to be different for the various species tested after 24 h. Moreover, some strains (two K. pneumoniae, two C. albicans) did not show changes in volatile production patterns within our species. Conclusions: Our experiments demonstrate that the electronic nose system can recognize volatile production patterns of pathogens at species level. Significance and Impact of the Study: Our results, although preliminary, promise exciting challenges for microbial diagnostics. [ABSTRACT FROM AUTHOR]

Background Candida auris is commonly detected in human ear secretions. However, C. auris occasionally causes bloodstream infections even in immunocompetent patients resulting in poor prognosis. It was speculated that C. auris growth within the blood might be regulated by proteins in the bloodstream. Thus, in this study, the potential role of blood proteins in the regulation of C. auris growth was investigated. Methods Five Candida species (C. albicans, C. auris, C. glabrata, C. parapsilosis, and C. tropicalis) were incubated overnight. Colony suspensions for each species were prepared and adjusted to OD 1.0 at absorbance 0.1. Then, human serum albumin (HSA) and bovine serum albumin (BSA) were diluted (2.5 g/dL–0.002 g/dL) and mixed with the suspensions. Mixed samples were adjusted to 100 μL and incubated on MHA plates at 35°C for 2 days. Then, 50 μL of the combined sample was extracted and streaked onto Yeast extract-Peptone-Dextrose (YPD) agar. The remaining 50 μL sample was analyzed using an XTT assay. Further testing was then conducted on the effects of a specific blood protein albumin on Candida. Thereby, C. albicans and C. auris were cultured following the procedure above and stained with Annexin V and PI. Results The growth of C. auris mixed with a high albumin concentration (2.5~0.15 g/dL) was regulated compared with that of other Candida species (P < 0.01) (Figures 1 and 2); however, the growth of C. auris mixed with a lower albumin concentration was similar to that of other species. The wash-out study showed that C. auris growth and survival in the high albumin concentration was not different than that of other species. Conclusion HSA and BSA regulated C. auris growth which led to increased necrosis of C. auris. Conversely, growth of the other Candida species was not regulated. Therefore, albumin might be involved in the growth and necrosis of C. auris. As the highest concentration at which albumin regulated C. auris growth was similar to that found in human serum, it is possible that serum albumin might help prevent C. auris from entering the bloodstream via the ear or skin. Disclosures All authors: No reported disclosures. [ABSTRACT FROM AUTHOR]

Background Pulmonary mucormycosis, a life-threatening infection of immunocompromised individuals, can have a 95% mortality rate, even with treatment. Intravenous (IV) liposomal amphotericin B (AmBisomeâ, AmBi) is used to treat the infection, but rapid growth of the pathogen can limit the drug's effectiveness. In the present study we investigated whether nebulized (nebz) AmBi could improve treatment outcome using a neutropenic murine model of pulmonary mucormycosis. Methods Rhizopus oryzae (ATCC MYA4621) was grown on Potato Dextrose Agar for 3–7 days, followed by spore harvesting, and determination of spore viability. Male ICR mice were immunosuppressed with 200 mg/kg of cyclophosphamide d-2, d0, d+2, d+4, and d0 challenged intranasally with 1 × 106 spores. In Study 1, mice (n = 16 mice/gp) were given AmBi at 7.5 or 10 mg/kg IV for 6 days, or nebz AmBi for 20 minutes (1.33 mg/mL AmBi in reservoir) for 4 days. In Study 2, 16 mice/gp were given AmBi at 15 mg/kg IV for 6 days or nebz AmBi for 7 days. PBS was the control. Lungs and kidneys were collected d+6 to determine drug concentration by a bioassay (n = 7–8 mice/gp) and morbidity (n = 8 mice/gp) monitored to d+21. Results In Study 1, survival was significantly better with nebz AmBi for 4 days (50%) or 10 mg/kg IV AmBi (33%) vs. 7.5 mg/kg IV AmBi (0%) (P < 0.003). In Study 2 with 13% survival in the PBS mice, 7 days of nebz AmBi produced 100% survival and 15 mg/kg IV AmBi gave 83% survival (P < 0.02 vs. PBS), underscoring the need for more intensive treatments. In Study 2, we also observed that average lung drug levels with nebz AmBi were significantly lower (3 μg/g lung) than with 15mg/kg AmBi IV (19 μg/g lung) (P = 0.003), even though both treatments were comparably effective. Kidney drug levels with 15 mg/kg AmBi IV were 13 μg/g and in comparison, nebz AmBi produced no detectable drug. Conclusion Daily nebulization of AmBi for one week or a high dose of IV AmBi at 15 mg/kg for 6 days protected the mice from severe pulmonary mucormycosis caused by R. oryzae , delivering effective drug levels to the lungs. The IV treatment yielded elevated levels of drug in the kidneys, while nebulization with AmBi produced no detectable drug in the kidneys. This indicated that nebz AmBi would be a less nephrotoxic, but still very effective route for drug delivery. Disclosures All authors: No reported disclosures. [ABSTRACT FROM AUTHOR]

Background Enterobacteriaceae is the main pathogens of UTI. It is important to be aware the local epidemiological data for an appropriate initial treatment. Resistance to antimicrobial agents has increased, especially to first-choice antibiotics in the treatment of cystitis. Our objective is to asses the antimicrobial susceptibility profile from uropathogens isolated in community and evaluated the dissemination of extended-spectrum ß lactamase (ESBL), in E. coli and K. pneumoniae in south of Brazil. Methods From June 2016 to June 2017, all urine samples collected in the Basic Health Units and Emergency Departments were sent to a Central Laboratory. Identification and susceptibility tests were performed on the VITEK® 2 (bioMérieux, France) system. Clinical Laboratory Standards Institute (CLSI) breakpoints were used for the interpretation of susceptibility. Positive cultures were defined as those demonstrating ≥105 CFU / mL (colony-forming units). The presence of ESBL was also subjected to the Chrom ID BLEE® agar plate test (bioMérieux- Marcyl'Etoile, France). PCR technique uses specific primers for genes bla TEM and bla SHV. Detection of the bla CTX-M genes was performed by multiplex PCR. Results A total of 56,555 microbiologic tests were performed, 8189 were positive. Women were responsible for 89.4%, and 10% were pregnant. Table 1 shows uropathogens isolated. Graphic 1 shows antimicrobial susceptibility. Extended-spectrum ß lactamase production was present in 6.7% (n = 489). People older than 60 years had ESBL more frequent (P < 0.05) as well as being pregnant is not related to ESBL (P < 0.05). Table 2 shows the distribution of the bla genotypes. Table 3: Distribution of blaCTX-M. Among bla CTX-M1 genotype, bla CTX-M15 was the most frequent. Conclusion In this study, the most frequent uropathogen isolated was E. coli followed by K. pneumoniae. Cotrimoxazol had high rates of resistance and nitrofurantoin the lowest. Quinolone resistance is more than 10%. Sensitivity to aminoglycosides and carbapenems remains high.We found relevant frequency of ESBL, CTX-M-1-group most commonly found. Among CTX-M-1, bla CTX-M15 was the most isolated. Disclosures All authors: No reported disclosures. [ABSTRACT FROM AUTHOR]

Background Environmental contamination in outpatient clinics is poorly understood. Methods We performed a microbiological analysis of surfaces in wound and pulmonary outpatient clinics at a tertiary care center. Cultures were obtained with pre-moistened cellulose sponges from three locations (Exam bed/chair, patient chair, physician area/chair) before and after clinic days. Sponges were combined with 1% Tween20-PBS and mixed in the Seward Stomacher. The homogenate was centrifuged and all but 5 mL of the supernatant was discarded. Samples were plated on Sheep's blood agar and selective media for S. aureus, Enterococcus spp. and Gram-negative bacteria. CFU was determined by counting the number of colonies on each plate and using dilution calculations to calculate the CFU of the original ~5 mL homogenate. The total sample areas in the wound and pulmonary clinic were 12,735 cm2 and 16,400 cm2, respectively. Results A total of 300 samples were obtained over 90-days. Median total room CFU was 7,918 (IQR 2,939–18,855) (Figure 1). Median CFU for the examination area, patient area and physician areas were 2090 (537–10508), 1524 (573–4605) and 960 (371–2183), respectively (Figure 2). The proportions of samples positive for S. aureus, Enterococcus spp. and Gram-negative bacteria were 5.0, 3.3 and 7.7%, respectively (Table 1). In general, median total CFU increased during the clinic day (median CFU before the clinic day 6883 (2937–14983) vs. median after clinic day=10351 (3484–21263) (Figure 3). Environmental bioburden was higher in the wound clinic than the pulmonary clinic (median 18206 CFU [IQR 10048–25037) vs. 3764 [IQR 1452–6671], P < 0.001) (Figure 1). The average number of patients seen in the wound clinic per clinic day was greater than the pulmonary clinic (3.8 vs. 2.2, P < 0.001). Conclusion Outpatient clinic rooms were contaminated with clinically important pathogens. Contamination varied by environmental location and increased as the clinic day progressed. Higher contamination was seen in the wound clinic possibly due to higher patient volume vs. increased environmental contamination that occurs while giving wound care. Wound care clinics may need to focus on more detailed cleaning to reduce environmental contamination and the risk of pathogen transmission in at-risk patients. Disclosures All authors: No reported disclosures. [ABSTRACT FROM AUTHOR]

Background Carbapenem-resistant Gram-negative bacteria are important nosocomial pathogens, and therapeutic options are often limited. Methods Clinical isolates were gathered during a surveillance study in 2017 involving 7 hospitals in Brooklyn, NY. Isolates underwent susceptibility testing using the agar dilution method; for the combination of imipenem-relebactam and ceftolozane-tazobactam, the concentrations of relebactam and tazobactam were fixed at 4 µg/mL. Breakpoints were defined according to CLSI criteria; for imipenem-relebactam, the breakpoint of imipenem was utilized. Isolates were screened by PCR for common carbapenemases. Results Overall susceptibility patterns are given in the Table. Of 1805 isolates of E. coli (including 4 with bla KPC), 100% were susceptible to imipenem and imipenem-relebactam. Of 503 isolates of K. pneumoniae (including 19 isolates with bla KPC), all were susceptible to imipenem-relebactam. Of 171 isolates of Enterobacter spp. (including 3 with bla KPC), 100% were susceptible to imipenem-relebactam. Of 260 isolates of P. aeruginosa , 96% were susceptible to imipenem-relebactam and nearly all to ceftolozane-tazobactam. Against A. baumannii , the activity of imipenem-relebactam was the same as imipenem and the ceftolozane-tazobactam MIC was ≤ 4 µg/mL in 65% of isolates. Conclusion Imipenem-relebactam possesses promising activity against multidrug-resistant Enterobacteriaceae endemic to New York City. Ceftolozane-tazobactam demonstrated excellent activity against P. aeruginosa , including isolates resistant to carbapenems. Disclosures All authors: No reported disclosures. [ABSTRACT FROM AUTHOR]

Background Vancomycin-resistant Enterococcus (VRE) infection is frequently associated with immunocompromised and critically ill patients. VRE carriers are at increased risk for infection due to VRE colonization and they pose a risk as a transmission source. VRE infection and Clostridium difficile infection (CDI) share common risk factors, including disruption of the intestinal microbiome. Thus, therapeutic approaches that decolonize VRE would be valuable. Herein, we report on stool VRE clearance in a cohort analysis from a Phase 2 open-label study of RBX2660, standardized microbiota-based drug, for recurrent CDI. Methods This prospective, multicenter, open-label Phase 2 study enrolled subjects with recurrent CDI. Participants received up to 2 doses of RBX2660 delivered via enema with doses 7 days apart. Patients were requested to voluntarily submit stool samples at baseline and at 7, 30 and 60 days, 6, 12, and 24 months after the last administration of RBX2660. Stool samples were tested for VRE using bile esculin azide agar with 6 µg/mL vancomycin and gram staining. Vancomycin resistance was confirmed via blood agar and etest. Results Stool samples were available for 143 patients. Twenty-one patients were VRE-positive at the first test (baseline or 7 day). Of the 19 VRE-positive patients that provided additional samples at later timepoints, 18 (94.7%) converted to negative as of the last available follow-up (30 or 60 days and 6, 12, or 24 months). The remaining patient remained positive at all follow-ups. Conclusion This cohort analysis of VRE-positive patients within an rCDI population provides additional support that microbiota-based formulations, such as RBX2660, may have additional benefit beyond reducing the recurrence of CDI. Additional study is needed to confirm the role of microbiome restoration on VRE clearance. Disclosures All authors: No reported disclosures [ABSTRACT FROM AUTHOR]

Background Rapid blood culture diagnostics increase cost and have unclear benefit for patients with Gram-negative bacilli (GNB) bloodstream infections (BSIs). We conducted a multicenter, prospective randomized controlled trial (RAPIDS-GN), comparing outcomes of patients with GNB BSI who had blood culture testing with standard of care (SOC) culture and antibiotic susceptibility testing (AST) vs. rapid organism identification (ID) and phenotypic AST using the Accelerate Pheno System (AXDX). Methods Subjects with blood culture Gram stain showing GNB were randomized to receive SOC testing with antimicrobial stewardship review (AS) or AXDX plus SOC testing with AS, at two academic medical centers between October 2017 and October 2018. SOC testing included rapid MALDI-TOF mass spectrometry ID and agar dilution or broth microdilution AST. In a modified intention to treat analysis, subjects were excluded if: Gram stain was erroneous, culture was positive during off-hours, blood culture in the prior week had GNB, they were deceased/on comfort care, or admitted to a nonparticipating hospital. The primary outcome was time to first antibiotic modification within 72 hours after randomization. Subjects without antibiotic modifications were assigned a time of 72 hours. No censoring was observed. T-tests and Wilcoxon rank-sum tests were used for statistical analyses. Results Of 500 randomized subjects, 448 were included (226 SOC, 222 AXDX). Groups did not differ in baseline characteristics (Table 1). Median (IQR) hours to first antibiotic modification was faster in the AXDX vs. SOC group [8.6 (2.6, 27.6) vs. 14.9 (3.3, 41.1)], P = 0.02 (Figure 1). Median (IQR) hours to first Gram-negative antibiotic modification (including escalation and de-escalation) was faster in the AXDX than SOC group [17.4 (4.9, 72) vs. 42.1 (10.1, 72)], P < 0.001 (Figure 2). Groups did not differ in clinical outcomes (Table 2). Mean (S.D.) time to results was faster for AXDX than SOC for organism ID [2.7 (1.2) h vs. 15.6 (20.3) h, P < 0.001] and AST [13 (55.7) h vs. 54.6 (45.5) h, P < 0.001]. Conclusion In the largest trial to evaluate the clinical impact of a blood culture diagnostic for GNB BSI, we found that rapid organism ID and phenotypic AST led to faster changes in antibiotic therapy for Gram-negative bacteremia. Disclosures Ritu Banerjee, MD, PhD, Accelerate Diagnostics: Grant/Research Support; BioFire: Research Grant; Biomerieux: Research Grant; Roche: Research Grant Robin Patel, MD, ASM and IDSA: Other Financial or Material Support, Travel reimbursement, editor's stipends; CD Diagnostics, Merck, Hutchison Biofilm Medical Solutions, Accelerate Diagnostics, ContraFect, TenNor Therapeutics Limited, Shionogi: Grant/Research Support; Curetis, Specific Technologies, NextGen Diagnostics, PathoQuest, Qvella: Consultant; NBME, Up-to-Date, the Infectious Diseases Board Review Course: Honorarium recipient, Other Financial or Material Support; Patent on Bordetella pertussis/parapertussis PCR issued, a patent on a device/method for sonication with royalties paid by Samsung to Mayo Clinic, and a patent on an anti-biofilm substance issued: Other Financial or Material Support, Patents. [ABSTRACT FROM AUTHOR]

Background Ventriculoperitoneal (VP) shunt is one of the commonest procedures in neurosurgical practice. A significant problem encountered in shunt procedures is infection, with infection rate ranging from 2 to 27%, often with poor outcome. The objectives of the study were to retrospectively evaluate the infection rate associated with central nervous system (CNS) shunts, assess the frequency of the pathogens as well as their antibiotic sensitivity pattern to aim at suitable prophylaxis. Methods Materials and Methods. Retrospective study conducted in the Microbiology Department, SGPGI, Lucknow from December 2017 to August 2018. A total of 168 CSF samples were received with a suspected shunt infection. Samples were analyzed by wet mount, India ink, gram stain and inoculated on blood agar and MacConkey agar. Identification and AST were done by MALDI- TOF system (VITEK-MS) and Vitek 2.0 automated sensitivity system. Results During the study period, 37/168(22.02%) CSF were positive by culture. Most frequently isolated pathogen was Acinetobacter baumannii 20/37(54.05%), followed by Staphylococcus aureus 06/37 (16.20%), Enterococcus faecalis 04/37(10.81%) coagulase negative staphylococci- CONS 04/37(10.81%), Klebsiella pneumoniae 2/37 (5.40%)and Escherichia coli 1/37(2.70%). 100% of A. baumannii and E. coli strains were found to be XDR and carbapenem-resistant showing susceptibility to minocycline and colistin only. All strains of K.pneumoniae were MDR. 66.7% S.aureus were MRSA and showed 100% resistance to fluoroquinolone. A similar pattern was seen in CONS. 25% of Enterococci were found to be vancomycin resistant. Conclusion Discussion and Conclusion. The antibiotic sensitivity pattern suggests aminoglycosides, colistin and vancomycin to be a better choice of antibiotics either prophylactically/therapeutically, which may result in effective sterilization of the CSF. Infections following VP shunt procedure are secondary to catheter blockage complicating the results of surgery and are associated with high morbidity and mortality rates. Disclosures All authors: No reported disclosures. [ABSTRACT FROM AUTHOR]

Background Antibiotic resistance is a global health crisis. While persistent drug discovery of novel antibiotics has previously been relied upon to thwart resistance, evolution inevitably perseveres. While genes conferring antibiotic resistance have previously been characterized, it is unclear how varying genetic contexts can change the antibiotic resistance phenotype a given gene confers. Methods The DH10B strain of E. coli was transformed with a blaADC-7 plasmid. In 12 evolutionary replicates, the modified E. coli strain and a clinical strain of A. baumannii containing the same resistance gene were passaged daily for 10 days on cefepime gradient agar plates with gradually increasing concentrations of cefepime. MICs of cefepime and a diverse set of 15 other drugs were determined for the parental strains and after the final passage passage. MIC of cefepime after intermediary passages were determined for select replicates. Lastly the blaADC-7 gene after the final passage was sequenced. Results At the end of 10 passages, collateral sensitivity in A. baumannii was observed to tigecycline and fosfomycin in 5 and 6 replicates respectively, out of 12 total. 4 out of 12 E. coli replicates displayed collateral sensitivity to minocycline (Figure 1). In the third E. coli replicate, Sanger sequencing revealed a novel S286R mutation in blaADC-7 appearing in passage seven which preceded a several log fold increase in the MIC of cefepime (Figures 2 and 3). No additional mutations were found in the other evolutionary replicates. Conclusion Patterns of resistance varied among antibiotics of the same class, (e.g. tetracyclines, fourth-generation cephalosporins) in both E. coli and A. baumannii ; however, A. baumannii expressed less widespread collateral resistance than E. coli. A previously undiscovered S286R mutation in blaADC-7 coincided with a pronounced increased in resistance to cefepime. Further studies are required to determine whether this mutation gives rise to a structural change in the protein product. Given that no other mutations were found, resistance to cefepime and subsequent collateral resistance to other antibiotics may have developed due to epigenetic changes or mutations outside the blaADC-7 genes. Indeed, future experiments with whole-genome sequencing may reveal such changes. Disclosures All authors: No reported disclosures. [ABSTRACT FROM AUTHOR]

Background CRE are globally important pathogens associated with significant morbidity and mortality. The problem of carrying CRE may continue to create a problem in discharged cases in the community. Saccharomyces boulardii sachet therapy (SBST) is reported to cause decolonization in several MDR bacteria carriers. Herein, it is aimed to present the decolonizing rates of rectal CRE colonized cases after SBST treatment. Methods The study period was August 2018–March 2019. Inclusion criteria were: (i) age >18, (ii) receiving Saccharomyces boulardii 250 mg sachets q12h for 7 days, (iii) being proven CRE carrier on rectal swab culture (RSC) up to 5 days period before SBST. The first repeated RSC was performed 3–5 days after the end of SBST. Data were retrieved from the hospital electronic database. Cases with three consecutive weekly performed negative RSC were considered to be decolonized. RSC were processed according to CDC protocol; briefly, the swab was inoculated into 10 mL of trypticase soy broth (bioMérieux Inc. Marcy-l'Étoile, France) with the addition of one 10-μg ertapenem disk (Oxoid, Altrincham, UK) and incubated at 35°C for 18–20 h. The next day, after vortexing, 100 μL of the inoculum was subcultured (8) onto chromID CARBA agar plates (bioMérieux) and incubated at 35°C for 18–20 h. Suspected CRE colonies on chromID CARBA (blue/green to blue/gray in color) were identified by the VITEK MS system (bioMérieux). Susceptibility testing of the isolates was performed with the VITEK 2 system (bioMérieux). Isolates were tested for their resistance phenotypes to imipenem, ertapenem, and meropenem by E-test (bioMérieux). The results were interpreted according to the EUCAST criteria. Results Fifteen cases [2 women, mean age 60.6 ± 18.3 (min. 18–max. 83)] fulfilled the inclusion criteria. All had a history of carbapenem usage. Five cases (33%) had three consequent negative RSC after SBST and were considered to be decolonized. Twelve cases were receiving concomitant antibiotic during SBST (10 carbapenem based regimens). Three cases who received no concomitant antibiotic were decolonized. Conclusion SBST may be a promising tool for decolonizing CRE carriers. These data need to be validated in larger cohorts preferably via randomized-controlled trials. Disclosures All authors: No reported disclosures. [ABSTRACT FROM AUTHOR]

Background Nosocomial infections due to CR-PA are associated with significant morbidity and mortality, and knowledge of epidemiology and underlying mechanisms of antimicrobial resistance is critical to addressing this threat. Recently, we identified a CR-PA of sequence type (ST) 309 resistant to all available β-lactams due to acquired β-lactamases as a potential emerging clone. To assess the evolving landscape of resistance in CR-PA we performed a cross-sectional survey of historical and contemporary isolates utilizing phenotypic testing and whole-genome sequencing (WGS). Methods Historical CR-PA isolates (n = 61, collected from 1999 to 2015) and contemporary isolates (n = 110, collected from 2017 to 2018) from a large urban hospital network in Houston, TX were tested for susceptibility to meropenem, aztreonam (ATM), ceftolozane/tazobactam (C/T), and ceftazidime/avibactam (CZA) using E-test on Mueller–Hinton (MH) agar. WGS for all isolates was performed on a MiSeq platform (Illumina). Data analysis was performed using a custom analysis pipeline, including Tseemann MLST tool, Resfinder, and Abricate using the CARD database. Results The prevalence of resistance across all β-lactams tested increased in contemporary strains as compared with that of historical strains (Figure 1). Among important contemporary antipseudomonal antibiotics C/T, ATM, and CZA, resistance increased from 0%, 22%, and 5% to 15%, 44%, and 16%, respectively (Figure 1). WGS revealed that ST235 was the most common sequence type, followed by ST111 in the historical collection (Figure 2). In contrast, a larger degree of genetic diversity was found in contemporary isolates, with the emergence of multidrug-resistant clones such as ST308 (2%) and ST309 (3%). Resistance to C/T was associated with acquired β-lactamases in 88% (14/16) of isolates, including VIM-2, GES-19/GES-26, VEB-1, NMD-1, and OXA enzymes. Conclusion Resistance to newer agents C/T and CZA markedly increased in contemporary CR-PA strains. While the epidemic clones ST235 and ST111 were the most frequent STs, ST308 and 309 have emerged among contemporary MDR isolates. Most concerning was the association of C/T resistance and the acquisition of β-lactamases, due to the potential for further dissemination. Disclosures All authors: No reported disclosures. [ABSTRACT FROM AUTHOR]

Background Cutibacterium acnes (C. acnes) is a common shoulder periprosthetic joint infection (PJI). Blue light (BL) is effectively used in the dermatologic clinical setting against acne vulgaris caused by C. acnes. Photodynamic therapy (PDT) is the use of light source and photosensitizer (PS) to enhance antimicrobial activity. We studied the effect of PDT using BL and PS in vitro on shoulder PJI isolates of C. acnes. Methods 19 strains were grown in thioglycollate medium and diluted in sterile normal saline (NS) to a turbidity of 0.5 McFarland standard; OD600 of 0.1 to 0.15. 250 µL with PS added were placed in 96-well plates at 37ºC, exposed to BL (415 nm) placed 1 cm above for 0 to 60 minutes at 15-minute intervals. Susceptibility to BL alone, and BL with PSs such as riboflavin (R, Vit B2), fluorescein (F) or demeclocycline (tetracycline antibiotic, "D") were studied. After serial 10-fold dilution with NS, 3 µL of each well were spotted onto Brucella Blood Agar plates and incubated anaerobically for 48 hours. Eradication was defined as below the limit of detection. Definitions include Sensitive (S) if 3-log decrease in bacterial density or eradication at any time point, Weakly Sensitive (WS) with 1- to 3-log decrease and Resistant (R) with no decrease. Results Based on BL alone, (n = 19). 68% strains were S, 32% were resistant. BL+ R (10 μg/mL) effect in 25% (n = 3) and exerted a protective effect against 33% (n = 4). BL+ F (1 μg/mL) potentiated in 67%. BL+ D (0.1–1.5 μg/mL) in 83% of strains tested. The most resistant strain was eradicated using BL + D at an increased concentration of demeclocycline (2.5 μg/mL). Conclusion F and D enhanced the potential for eradication compared with BL exposure alone. R was a photo-protectant to BL for select strains. Prior studies have hypothesized endogenous intracellular porphyrins excited by BL causing energy transfer and production of highly cytotoxic reactive oxygen species causing bacterial death. Future clinical research evaluating the use of preoperative PS and surgical site exposure to BL as a preventative PJI strategy are needed. Our research shows that BL with the addition of PS significantly reduces the bacterial burden of clinically relevant PJI shoulder isolates of C. acnes in an in vitro model. Disclosures All authors: No reported disclosures. [ABSTRACT FROM AUTHOR]

Background Biofilms of Trichosporon asahii are known to resist the effects of antifungal drugs, but the study of their susceptibility to various abiotic stresses remains sparse. This study was thus undertaken to compare the level of in vitro resistance of T. asahii biofilm and planktonic cells to various stress factors. Methods In this study, one T. asahii clinical isolate identified by amplifying IGS1 sequencing and one reference strain (NCCPF940033) were used. Biofilm and planktonic cells of T. asahii were exposed to increasing concentrations of NaCl (0.5–6 M) and d -sorbitol (3–13 M) for inducing osmotic stress; H2O2 (5–50 mM), menadione sodium bisulfate (0.048–100 mM) and ox bile (1–12%) for oxidative stress; PH 1 to 13 for PH stress; congo red (600–10,000 µg/mL) for cell wall stress; CuSO4·5H2O/ZnSO4/FeSO4 (1.25–2,560 mM) and MgSO4 (250–3,000 mM) for metal stress. The biomass and metabolic activity of biofilms were quantitatively determined by crystal violet method and XTT reduction assay, respectively. Further, spot assay of serially diluted (10–1 to 10–6) planktonic cells was performed on agar plates containing stress and non-stress control to determine relative percentage growth of strains. Results Biofilm cells of both the strains exhibited significantly higher (ANOVA) stress resistance than planktonic cells and on an average showed at least 100 times more resistant to stresses than planktonic cells [Minimum Biofilm Eradication Concentration (MBEC) vs. Minimum Inhibitory Concentration (MIC)]; H202 >50 mM vs. 10 mM, Ox bile >12% vs. 2%, Menadione >100 mM vs. 0.39 mM, Zn/Fe/Cu >2,560 mM vs. 10 mM, Mg >3,000 mM vs. 1,000 mM, NaCl >6 M vs. 1.5 M, d -sorbitol >13 M vs. 5 M and Congo red >10,000 µg/mL vs. 800 µg/mL. Besides optimal PH 5–10, extreme acidic and alkaline PH led to complete inhibition of viable planktonic cells. Highest biomass reduction (77.2%) and highest viability inhibition (69%) of biofilm were observed at PH 3 and 13, respectively. Menadione reduced 86.9% biomass and 89.3% viability which accounted the highest biofilm inhibition. Conclusion This is the first report on comparing the susceptibility of planktonic and biofilm T. asahii cells to various stress factors. The increased resistance of T. asahii biofilm may serve as a survival advantage against the host adversity. Disclosures All authors: No reported disclosures. [ABSTRACT FROM AUTHOR]

Background The majority of bacterial BSIs are believed to stem from a single, clonal organism. We hypothesized that most CRK BSIs are caused by genetically diverse, clonal strains that exhibit different phenotypes. Methods Blood cultures (BCs) that were positive for CRK from each of 10 patients (patients) were streaked onto agar plates, and 100 individual colonies were chosen for Illumina whole-genome sequencing. Strains from 3 patients were tested for in vitro phenotypes and virulence in mice. Results Patients had BSIs due to ST258 K. pneumoniae (Kp; 6), non-ST258 Kp (3), and K. michiganensis (Km; 1). 5 patients were infected with strains that differed by core genome single nucleotide polymorphism phylogeny (2–5 unique genotypes/patient) [figure]. 6 patients were infected with strains that differed by gene or plasmid content, and/or gene deletions [table]. Differences in individual patients encompassed antibiotic resistance and putative virulence genes (including mixtures of blaKPC+ and blaKPC– strains, and various capsular (CPS) and porin mutant strains). In total, BSIs in 8 of 10 patients were caused by a genotypically diverse population. In each of 3 patients, genotypically diverse ST258 Kp strains demonstrated significant differences in antibiotic susceptibility, CPS content, mucoviscosity, adherence, resistance to serum killing, and mortality rates and tissue burdens during BSIs of mice. ST258 strains from a pt with and without a KPC-bearing IncFIA plasmid differed in β-lactam susceptibility, but were equally virulent. Progressive loss of CPS in ST258 strains from another patient enhanced serum killing and adherence, and attenuated virulence. Using PCR markers to test 96 colonies per positive BC bottle, we demonstrated that strains selected by the clinical micro lab accounted for 2% to 98% of a population in different patients. Conclusion CRK causing BSIs in most patients demonstrated remarkable genotypic diversity, which impacted antibiotic susceptibility, virulence and other phenotypes. Differences were not recognized during hospitalization since clinical labs select single, morphologically distinct colonies for evaluation. Studies are needed to understand the clinical implications of our findings, diversity during other BSIs, and whether clinical lab practices need revision. Disclosures All authors: No reported disclosures. [ABSTRACT FROM AUTHOR]

Background Agr is a key regulator that controls expression of secreted exoproteins and surface protein in Staphylococcus aureus. It has been reported that mixed status of two different phenotypes including agr functional and nonfunctional subpopulations can coexist in vitro and in vivo. However, data on the natural course and clinical implication of the mixed agr status is limited. We thus investigated the frequency and characteristics of the mixed agr in clinical settings. Methods We evaluated isogenic paired MRSA isolates collected from patients with persistent S. aureus bacteremia (SAB) between October 2010 and April 2016, and then prospectively performed surveillance for the presence of mixed agr function in MRSA isolates from patients with SAB between May 2016 and December 2017. The mixed agr status was evaluated by single colony evaluation on sheep blood agar plate containing RN4220 supernatant (β-hemolysin) (Figure 1). Cross-streaking with RN4220 and RNAIII measurement were performed to confirm the agr functionality of each of hemolytic and non-hemolytic colonies, separately. The expression levels of RNAIII, hla , and saeS / saeR were measured by real-time reverse transcription polymerase chain reaction. Results A total of 161 first blood isolates were collected during study period, and 6 isolates (4%) displayed mixed phenotype by single colony test. The mixed hemolytic pattern was observed in 5 out of 52 ST72 isolates (10%) and 1 out of 82 ST5 isolates (1%) (Figure 1). No difference was found in the genotypes between hemolytic and non-hemolytic colonies from each isolate. Of the 6 isolates, three lost mixed hemolytic features in the follow-up blood cultures (Table 1). One ST72 and one ST5 isolate showed agr mixed pattern determined by different RNAIII levels, but remaining four ST72 isolates had mixed hemolytic pattern due to different expression of hla correlated with saeS / saeR expression (Figure 2). Conclusion The mixture of agr function status among the clinical blood isolates of MRSA was rarely observed and isolates displaying heterogeneous hemolytic phenotype were largely due to differential expression of α-hemolysin. Further investigation is needed to unveil the clinical significance of mixture of different hemolytic phenotypes. Disclosures All authors: No reported disclosures. [ABSTRACT FROM AUTHOR]

Background Clostridioides difficile is an organism acquired not only in healthcare settings but also in community settings. For the past several years our hospital has performed screening tests to detect asymptomatic carriage of C. difficile. We now aim to better understand the ribotypes and degree of diversity among these C. difficile strains obtained in a systematic screening. Methods This study was performed at a 600 bed teaching affiliated hospital in Milwaukee, WI, where surveillance testing is performed in selected units upon admission and weekly thereafter using nucleic acid amplification test (NAAT; Xpert® C. difficile ; Cepheid, Sunnyvale, CA). Screening tests are obtained regardless of symptoms. NAAT positive samples underwent anaerobic cultures in C. difficile selective broth (CCMB-TAL) for 24–48 hr and then to Brucella blood agar plates (BA) for 48–72 hr to confirm C. difficile presence. PCR-ribotyping was performed as previously described by Stubbs et al. with minor modifications. The results were compared with a database containing >3,000 clinical isolates including C. difficile reference strains from the Cardiff ribotype collection. Results A total of 104 strains belonging to 93 unique patients were processed. Patients had a mean age of 60 years (range: 18 - 89) and 49% were females. Most patients were hospitalized in the hematology oncology units (55.7%) or in the solid-organ transplant step down unit (9.6%). A total of 25 different ribotypes were identified. The most common ribotype was 014/020 (23; 22%), followed by ribotype 56 (13; 12.5%), 106 (12; 11.5%), 027 (11; 10.5%), 002 (6; 5.7%), and 078/126 (5; 4.81). Regarding the timing of admission, 70 strains were obtained within 4 days from hospital admission and the remaining 34 were obtained afterwards. Both groups had ribotype 014/020 as the most frequently detected ribotype but 027 were the second most commonly detected at the time of admission (table). A total of 7 patients had more than one stool sample processed and 5 of them had discordant ribotypes at different time points. Conclusion Systematic screening tests for C. difficile carriage in a single center showed a large heterogeneity of ribotypes with the majority not being 027. Additionally, most patients tested more than once carried different ribotypes. Disclosures All authors: No reported disclosures. [ABSTRACT FROM AUTHOR]

Background The more rapidly a pathogen can be identified in cases of sepsis, the more swiftly targeted therapy can be commenced. We aimed to evaluate the accuracy and clinical utility of a method for rapid microorganism identification from blood and sterile site fluid enrichment cultures using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) in a high-throughput regional microbiology laboratory. Methods A drop of blood or fluid from cultures flagging positive was inoculated onto chocolate agar and incubated until MALDI-TOF MS analysis 5–6 hours later. Results obtained with conventional overnight incubation were used as controls. The number of isolates reliably and correctly identified, and recommendations for changes to clinical management were recorded. A pilot study was undertaken to demonstrate feasibility using a cut-off score of ≥2.0, following which the method was integrated into the laboratory workflow using a cut-off score of ≥1.7 (identification to genus level) because patient management can often be altered with this degree of accuracy. Results In the pilot study, 154/210 blood cultures (73.3%) were reliably identified (score ≥2.0) and, of these, 151 (98.1%) were correctly identified. The operational study included 144 blood cultures and 14 sterile site fluid enrichment cultures. 121 (76.6%) were reliably identified (score ≥1.7) and, of these, 117 (96.7%) were correctly identified. Four isolates (2.5%) were yeasts, 104 (65.8%) were Gram-positive bacteria and 50 (31.6%) were Gram-negative bacteria. 78 of the 104 bacteria (75.0%) were correctly identified. The median score for Gram-positives was 1.89 (IQR 0.36). For Gram-negatives, 47 of the 50 isolates (94.0%) were correctly identified. The median score for Gram-negatives was 2.29 (IQR 0.14). No yeasts were reliably identified. Recommendations for changes to clinical management were made for seven (3.8%) and nine patients (6.0%) in the pilot study and operational study, respectively. The method was easily integrated into the laboratory workflow and did not require additional staff. Conclusion We build on previous work by providing a simple method for rapid micro-organism identification which allows easy integration into a busy laboratory, and which improves clinical management. Disclosures All authors: No reported disclosures. [ABSTRACT FROM AUTHOR]

Background Bare Below the Elbows (BBE) is an approach to healthcare worker (HCW) attire that limits patient contact with contaminated HCW clothing. While supported by biological plausibility, the practice is controversial. Critics cite limited evidence that bare skin is less contaminated in comparison to sleeved garments such as white coats. This study is a comparison of the flora and bioburden between BBE and sleeved HCW. Methods HCW on 2 progressive care units were asked to allow swab sampling of their dominant wrist/forearm (Figure 1). Non-clinicians were excluded. Hand hygiene was not performed prior to sampling. HCW agreeing to participate completed informed consent, and a survey regarding bathing and laundering. Swabs were inoculated into TSA broths, and incubated for 24 hours at 37°C. Bioburden was estimated using McFarland standard optical densities by 2 independent blinded evaluators. The broth was streaked on blood agar and MacConkey plates. Colonies consistent with possible Staphylococcus spp. were tested with latex agglutination, and positive isolates were plated on CHROMagar™ MSSA/MRSA. Fisher's exact/Wilcoxon rank-sum tests were used to compare the categorical/numerical data between BBE and sleeved providers using SAS version 9.4. Results Sixty-three HCW participated; 30 were BBE and 33 sleeved. A comparison of the 2 groups is shown in Table 1. The majority of bacterial growth was morphologically consistent with skin flora; no Gram-negative rods grew. The bioburden estimates and presence of Staphylococcus aureus were not different between the groups (P = 0.099 and 0.325, respectively). Surveys indicated that BBE providers were more likely to be working in freshly laundered garments (P < 0.0001); this was true for all BBE providers except 2 HCW on shift >24 hours. Three sleeved individuals could not remember when they last laundered the garment in which they were providing clinical care. Conclusion HCW laundering practices remain suboptimal, particularly among sleeved HCW. The potential impact of hand hygiene on comparative bioburden between sleeved and BBE HCWs remains unknown and is the focus of future investigations. Disclosures All Authors: No reported Disclosures. [ABSTRACT FROM AUTHOR]

Background Aerococcus urinae is frequently identified by MALDI-TOF in urinary specimens. It is generally susceptible to β-lactams, but its susceptibility pattern to fluoroquinolones (FQ) remains unpredictable. The goal of this study was to evaluate the performance of the gradient diffusion method (Etest®) to determine FQ susceptibility compared with broth microdilution (BMD) and agar dilution (AD). Methods Prospectively collected isolates of A. urinae from urinary tract specimens originating from 5 hospitals in Quebec city and Montreal were identified by MALDI-TOF (Vitek-MS). All isolates were tested using BMD according to CLSI guidelines, and also with Etest® strips on MH agar w/ 5% sheep blood. Isolates showing trailing, insufficient growth or discordance between both methods were further tested by agar dilution (MH agar w/5% horse blood + β-NAD) according to EUCAST guidelines. Breakpoints were interpreted using CLSI M45-A3. Combined results of BMD and AD were then compared with Etest. Results Of the 207 isolates of A. urinae tested, 37 showed trailing (17,8%) and 19 (9,2%) insufficient growth with the BMD method and were retested using AD. Moreover, 38 isolates (ciprofloxacin) and 13 isolates (levofloxacin) showed either lack of categorical or essential agreement between Etest and BMD and were also retested using AD to arbitrate discrepancies. Susceptibility profiles combining BMD and AD are presented in Table 1. As suggested in EUCAST guidelines, readings were much clearer and growth was better with AD compared with BMD. The categorical agreement of the Etest® with BMD+AD was 95% for ciprofloxacin and 97% for levofloxacin. Essential agreement was 95% for ciprofloxacin and 97% for levofloxacin. No very major errors were identified. Two major errors were identified for levofloxacin (1,2%) and one for ciprofloxacin (0.6%). Conclusion Gradient diffusion method using Etest® strips on MH agar w/ sheep blood is a valid method to determine susceptibility to FQ for urinary tract isolates. As a reference method, AD provides clearer endpoints and better growth than BMD for FQ susceptibility testing. Disclosures All authors: No reported disclosures. [ABSTRACT FROM AUTHOR]

Aims: The aim of this study was to evaluate the performance of chromogenic agars, Agar Listeria according to Ottaviani and Agosti (ALOA) and Rapid L. mono agar, compared with Oxford agar for the enumeration and detection of Listeria species in food. Methods and Results: A total of 170 food samples were examined using the three plating media. Listeria species were isolated from 63 samples. In contrast to Oxford agar, detection of Listeria colonies on chromogenic media was as good after 24 h of incubation of plates as after 48 h. While there was no significant difference in recovery of Listeria monocytogenes on the three media, recovery of other Listeria species was significantly poorer on Rapid L. mono agar compared with Oxford and ALOA agars. Recovery of species other than L. monocytogenes was significantly improved by including a secondary enrichment stage in the detection method. Conclusions: Using chromogenic agars, presumptive identification of L. monocytogenes is possible after 24 h, compared with 3–4 days using Oxford agar. However, the poor detection of species other than L. monocytogenes on Rapid L. mono agar is a disadvantage of this medium. Significance and Impact of the Study: This study provides new information regarding the isolation of Listeria species other than L. monocytogenes from food using chromogenic plating media. This is important, as non-pathogenic Listeria species act as markers for the likelihood of presence of L. monocytogenes and allow preventive action to be taken to avoid its presence. [ABSTRACT FROM AUTHOR]

A comparison of several media , i.e., potato dextrose agar with olive oil (Oil-PDA), modified Dixon agar (mDIX) and variations of Leeming and Notman agar (LNA) for the isolation and growth of Malassezia and Candida species was examined. Since LNA supported the highest growth of Malassezia species its key components, i.e., ox bile, glycerol monostearate, glycerol and Tween 60, were added to CHROMagar Candida. All 7 species of Malassezia grew well on this modified medium (LN-CHROM) after incubation for 4&ThickSpace;days at 30°C and development was equal to that observed on LNA. Colonies on LN-CHROM were smooth and from pink to dark purple in color. Furthermore, the use of LN-CHROM did not alter the colony characteristics of Candida species as compared to that found on CHROMagar Candida. The results of the present investigation indicate that the use of LN-CHROM would make possible the simultaneous isolation and identification of Malassezia and Candida species. [ABSTRACT FROM AUTHOR]

In this study, we describe a simple method for the identification of Candida albicans in clinical samples. A total of 383 clinical isolates of Candida species were streaked onto chocolate agar and incubated for 48 h at 37°C in the presence of an atmosphere of 6% CO 2 . All 208 of the C. albicans isolates tested, developed an easy to identify filamentous colony morphology. Of 175 other Candida species tested, 172 (98.3%) were distinguishable from C. albicans by their smooth colony morphology. Three isolates (1.7%) exhibited weak filamentation after prolonged incubation. Although not a routine medium in medical mycology a significant advantage of using chocolate agar lies in its use in clinical bacteriology laboratories for the isolation of fastidious bacteria. Implementation of the proposed method is applicable across a range of specimen types, thus allowing the direct identification of C. albicans in clinical samples. This simple method may allow a quicker entry into directed treatment. [ABSTRACT FROM AUTHOR]

Aims: To investigate the inhibitory and lethal effects of triclosan against several micro-organisms at different stages of their phase of population growth. Methods and Results: Triclosan minimum inhibitory concentrations against several test organisms were determined in broth and agar using standard protocols. The bisphenol effect on bacterial population growth kinetics was studied using the Bioscreen C microbial growth analyser. Finally, the efficacy of triclosan on phases of bacterial growth was determined using a standard suspension test. The duration of the lag phase for all micro-organisms tested was increased by bisphenol in a concentration-dependent manner. The population growth kinetics of the micro-organisms was also altered after biocide exposure. At higher concentrations, triclosan was bactericidal regardless of their phase of population growth, although population in stationary phase and particularly, washed suspensions, were more resilient to the lethality of triclosan. This lethal activity was concentration and contact time dependent, and in some instances, bactericidal activity of bisphenol was observed within 15 s. Conclusions: Low concentrations of triclosan affected the growth of several bacteria, while higher concentrations were bactericidal regardless of the bacterial phase of population growth. Significance and Impact of the Study: Here, we presented clear evidence that the interaction of triclosan with the bacterial cell is complex and its lethality cannot be explained solely by the inhibition of metabolic pathways such as the enoyl acyl-reductase. However, the inhibition of such pathways cannot be ruled out as part of the lethal mechanism of the bisphenol at a low bactericidal concentration. [ABSTRACT FROM AUTHOR]

Aims: The aims of this study were; (i) to provide thermal inactivation data for Staphylococcus aureus; (ii) to examine the kinetics, including decimal reduction times ( D-value) and rate constants ( k), that describe the thermal inactivation of Staph. aureus and to compare two different methods of calculating D-values and (iii) to determine whether or not chilled storage would toughen these microorganisms resulting in increased thermotolerance. Methods and Results: Isolates of Staph. aureus recovered from domestic refrigerators were grown in shaken culture for 8 h at 37°C, recovered and washed by centrifugation and combined to form a cocktail of five strains. Samples from this cocktail were (a) heat treated at 50, 55 and 60°C or (b) held under simulated domestic refrigeration conditions for 72 h and then heat treated as above. The numbers of Staph. aureus in heat treated and chill held, heat treated samples were enumerated by direct selective plating onto Baird Parker Agar (BPA) and recovery plating on Tryptone Soya Agar (TSA) subsequently overlaid with BPA. D-values were obtained using two different methods both of which may be used when the thermal inactivation follows first order kinetics. In the first method D-values are obtained by plotting the Log10 of the surviving cells against time and using the equation D = −1/slope. The second method uses the rate constant ( k) which is obtained from the slope of a plot of ln N/ N0 vs time and D is obtained using the equation D = 2·303 k−1. D50, D55 and D60 values ranged from 94·3 to 127·9 min, 13 to 21·7 min and 4·8 to 6·5 min. Prechilling did not enhance thermal resistance. The method of calculation did not affect the D-values obtained because the thermal inactivation of S taph. aureus in this study followed first order kinetics with r2 values of 0·91–0·99. Conclusions: The thermal inactivation of Staph. aureus in tryptone soya broth (TSB) follows first order kinetics and in general chilling of these bacteria does not increase the resistance to thermal destruction during subsequent thermal processes such as cooking. Significance and Impact of the Study: This study provides much needed data on the thermal resistance of Staph. aureus and validates chilling as a food storage activity which does not cause toughening of the microorganisms to subsequent cooking. However, the data generated strongly suggests that Staph. aureus is more thermotolerant than Listeria monocytogenes and should be used as the target microorganism in designing mild thermal treatments for food, in which case the current recommendations for pasteurization (70°C for 2 min, minimum) should be revised. [ABSTRACT FROM AUTHOR]

Aim: To develop a new isolation medium with higher recovery rates of Alicyclobacillus spp. Methods and Results: SK agar was developed with optimized incubation temperature, pH, acidulant, Tween 80 concentration and divalent cation addition. Results indicate that detection of Alicyclobacillus spp. by SK agar was significantly higher ( P > 0·05) than those obtained by K agar, orange serum agar, and potato dextrose agar. Conclusions: Current media used for Alicyclobacillus spp. isolation still resulted in high numbers of false negative products. The sensitivity of SK agar to Alicyclobacillus spp. allows detection of low numbers of Alicyclobacillus spp. and also provides a more higher isolation results compared with currently used media. Significance and Impact of the Study: SK agar will be useful to the fruit juice industry to obtain more accurate numbers of contaminant Alicyclobacillus spp. With this media, false negative samples can be reduced, and the likelihood of exported products being rejected can be greatly reduced. [ABSTRACT FROM AUTHOR]

Aims: To examine whether water activity ( aw) in combination with low concentration of fungicides can be used to effectively control Aspergillus niger van Tieghem growth in cultural medium, the Sabouraud dextrose agar (SDA). The data would be used as baseline information for reducing A. niger contamination in insect artificial diets. Methods and Results: Aspergillus niger was isolated from an insect artificial diet. Four concentration levels (i.e. 0, 1, 10 and 20 μmol) of two fungicides (i.e. amphotericin B and itraconazole) were tested against A. niger under four aw levels (i.e. 0·994, 0·961, 0·921 and 0·859) adjusted by including 0, 12·5, 25 and 38% of glycerol in the medium mixture. Aspergillus niger growth was significantly reduced at low fungicide concentration (1 μmol), and at reduced aw. The spore germination was prevented with either higher fungicide concentration (>10 μmol), or low aw in the medium ( aw < 0·921). The two ecological determinants (fungicides and aw) showed a significant impact on A. niger survival in the medium ( P < 0·0001). Itraconazole is more effective than amphotericin B in controlling A. niger contamination in the agar medium. Conclusion: Adjustment of aw (with 12·5% of glycerol) in combination with 1 μmol of itraconazole can effectively prevent A. niger growth in the SDA cultural medium. Significance and Impact of the Study: Aspergillus niger contaminations have frequently affected the quality of insects produced from mass rearing facilities. Low aw in combination with low fungicide concentration has the potential to become one of the most cost-effective management strategies to prevent A. niger contamination in insect artificial diets. The effect of fungicides and low aw in artificial diets on insect biology needs to be further examined. [ABSTRACT FROM AUTHOR]

Aims: To investigate the physicochemical surface properties, such as cellular surface charge, hydrophobicity and electron donor/acceptor potential of a selection of Shiga toxigenic Escherichia coli (STEC) isolates grown in broth and agar culture. Methods and Results: Cellular surface charge was determined using zeta potential measurements. Hydrophobicity of the isolates was determined using bacterial adhesion to hydrocarbons assay, hydrophobic interaction chromatography and contact angle measurements. Microbial adhesion to solvents was used to determine the electron donor/acceptor characteristics. No differences of surface charge measurements were found between broth and agar grown cultures. Isolates belonging to serogroup O157 and serotypes O26:H11 and O111:H- were significantly ( P < 0·05) less negatively charged than other STEC serotypes tested. All strains were hydrophilic with most methods and demonstrated a lower hydrophobicity in agar culture compared with broth culture. All strains demonstrated a strong microbial adhesion to chloroform indicating that STEC possess an electron donor and basic character. A relationship between serogroup O157 and other STEC serotypes was apparent using principal-component analysis (PCA). Conclusions: Combining the results for physicochemical properties using PCA differentiated between strains belonging to the O157 serogroup and other STEC/non-STEC strains. PCA found similar results for broth and agar grown cultures. Significance and Impact of the Study: Particular serotypes of STEC possess similar physicochemical properties which may play a role in their pathogenicity or potential attachment to various surfaces. [ABSTRACT FROM AUTHOR]

Aims: To determine the possibility of using guar gum, a colloidal polysaccharide, as a cheap alternative to agar for gelling microbial culture media. Methods and Results: As illustrative examples, 12 fungi and 11 bacteria were cultured on media solidified with either guar gum or agar. All fungi and bacteria exhibited normal growth and differentiation on the media gelled with guar gum. Microscopic examination of the fungi and bacteria grown on agar or guar gum gelled media did not reveal any structural differences. However, growth of most of the fungi was better on guar gum media than agar, and correspondingly, sporulation was also more advanced on the former. Bacterial enumeration studies carried out for Serratia sp. and Pseudomonas sp. by serial dilution and pour-plate method yielded similar counts on both agar and guar gum. Likewise, a selective medium, succinate medium used for growth of Pseudomonas sp. did not support growth of Bacillus sp. when inoculated along with Pseudomonas on both agar or guar gum supplemented medium. Conclusions: Guar gum, a galactomannan, which is 50 times cheaper than Difco-bacto agar, can be used as a gelling agent in place of agar in microbial culture media. Significance and Impact of the Study: As the media gelled with guar gum do not melt at temperature as high as 70°C, these can be used for isolation and maintenance of thermophiles. [ABSTRACT FROM AUTHOR]

To identify the region in which a root perceives a decrease in the ambient water potential and changes its elongation rate, we applied two agar blocks (1 ⊗ 1 ⊗ 1 mm³) with low water potential bilaterally to primary roots of maize (Zea mays) at various positions along the root. When agar blocks with a water potential of -1.60 MPa (-1.60-MPa blocks) or lower were attached to a root tip, the rate of elongation decreased. This decrease did not result from any changes in the water status of elongating cells and was not reversed when the -1.60-MPa blocks were replaced by -0.03-MPa blocks. The rate decreased slightly and was unaffected, respectively, when 1.60-MPa blocks were applied to the so-called decelerating region of the elongating zone and the mature region. However, the rate decreased markedly and did not recover for several hours at least when such blocks were attached to the accelerating region. In this case, the turgor pressure of the elongating cells decreased immediately after the application of the blocks and recovered thereafter. The decrease in elongation rate caused by 1.60-MPa blocks applied to the root tip was unaffected by additional -0.03-MPa blocks applied to the accelerating region and vice versa. We concluded that a significant reduction in root growth could be induced by water stress at the root tip, as well as in the accelerating region of the elongating zone, and that transmission of some signal from these regions to the decelerating region might contribute to the suppression of cell elongation in the elongation region. [ABSTRACT FROM AUTHOR]

Evaluates the Rapid'L.Mono agar chromogenic medium for identification and differentiation of Listeria monocytogenes from other species of Listeria by a simple color change reaction. Differentiation based on specific detection of phosphatidylinositol phospholipase C activity and inability of Listeria monocyto genes to metabolize xylose; Comparison with the detection principles of standard method agars; Validation with surimi, mixed salad, brie and processed deli turkey; Sensitivity and specificity for the medium.

The performance of denaturing gradient gel electrophoresis (DGGE) for analysing yeasts associated with wine grapes was compared with cultural isolation on malt extract agar (MEA). After optimisation of PCR and electrophoretic conditions, the lower limit of yeast detection by PCR-DGGE was 102 cfu ml-1, although this value was affected by culture age and the relative populations of the species in mixed culture. In mixed yeast populations, PCR-DGGE detected species present at 10–100-fold less than other species but not when the ratio exceeded 100-fold. Aureobasidium pullulans was the main species isolated from immature, mature, and both damaged and undamaged grapes. It was not detected by PCR-DGGE when present at populations less than 103 cfu g-1. When approaching maturity, damaged grapes gave a predominance of Metschnikowia and Hanseniaspora species (105–107 cfu g-1), all detectable using PCR-DGGE. However, various species of Rhodotorula, Rhodosporidium and Cryptococcus were not detected by this method, even when populations were as high as 104 cfu g-1. PCR –DGGE was less sensitive than culture on MEA for determining the yeast ecology of grapes and could not reliably detect species present at populations less than 104 cfu g-1. However, this method detected a greater diversity of species than agar plating. [Copyright &y& Elsevier]

a.h. rickard, p. gilbert and p.s. handley. 2004. To characterize the expression of coaggregation between Blastomonas natatoria 2.1 and Micrococcus luteus 2·13 following growth in liquid culture, on agar and in an artificial biofilm matrix composed of poloxamer hydrogel. The ability of B. natatoria 2·1 and M. luteus 2·13 to coaggregate with one another was assessed following growth in liquid culture as colonies on agar or within a poloxamer hydrogel matrix. In all these environments a cycle of gain and loss of coaggregation occurred when the two cell types were aged simultaneously, with optimum expression occurring in early stationary phase. Blastomonas natatoria 2·1 cells only coaggregated maximally after entry into stationary phase. Conversely, M. luteus 2·13 cells only coaggregated in exponential phase and early stationary phase and coaggregation ability was lost in late stationary phase. Maximal coaggregation therefore only occurred between the two strains if both were in early stationary phase, when the surface properties of the two cell types were optimal for coaggregation. In addition to occurring between cells grown in liquid culture, coaggregation between aquatic bacteria occurs after growth as a biofilm on agar and in an artificial biofilm matrix in poloxamer. Under all conditions, the B. natatoria 2·1 coaggregation adhesin and complementary receptor on M. luteus 2·13 were only expressed simultaneously during early stationary phase. [ABSTRACT FROM AUTHOR]

l.h. travassos, m.n. pinheiro, f.s. coelho, j.l.m. sampaio, v.l.c. merquior and e.a. marques. 2004. To investigate phenotypic aspects including biotyping, drug susceptibility and production of extracellular enzymes and genetic diversity of Stenotrophomonas maltophilia clinical strains obtained from seven hospitals in Rio de Janeiro, Brazil. Thirty-nine S. maltophilia strains were investigated by biotying, susceptibility testing, extracellular enzymes detection and by randomly amplified polymorphic DNA (RAPD)-PCR. Biotyping distinguished 13 biotypes among 39, and one of them was prevalent. The majority of the strains produced DNase, gelatinase and haemolysin. Protease, lipases and phospholipase C activities were observed in highly variable amounts. None of the strains was elastase producer. The percentage of full susceptibility, by agar dilution, was 100, 94·8, 81·6 and 26·3% for trimethoprim/sulphametoxazole, ticarcillin/clavulanate, ciprofloxacin and ceftazidime, respectively. Thirty-three RAPD-PCR profiles were obtained suggesting multiple sources of acquisition. The results pointed out the necessity of monitoring S. maltophilia especially in critical hospital wards, to assure effective control measures. Despite of the genetic diversity among the strains, in two situations it was observed indistinguishable RAPD-PCR profiles among strains isolated from different patients who had been hospitalized in the same hospital ward, suggesting the possibility of nosocomial transmission that until now has been rarely related. [ABSTRACT FROM AUTHOR]

Studies the thermostability of β-Agarase from the novel marine isolate, JAMB-A94 by researchers from Japan. Success of the researchers in cloning and sequencing agaA gene from the marine bacterium JAMB-A94; Calculation of the molecular mass of the protein encoded from the agaA gene; Presence of agarose and agaropectins in the cell walls of some red algae.

m. baserisalehi, n. bahador, s.k. augustine, a.y. al-mahdi and b.p. kapadnis. 2004. To design a special device which can be used with nonselective blood-free nutrient agar without enrichment for detection of campylobacters from water. The Kapadnis–Baseri device (KB device) was designed and evaluated in comparison with the conventional method (C method) for detection of Campylobacter spp. from river water samples. The results indicated that the recovery of Campylobacter spp. by KB device was relatively more than by C method. To date, the methods for recovery of campylobacters are time consuming and involve use of special culture media, which is cost ineffective. The KB device is designed based on two important characters of Campylobacter, viz. motility and activity at low temperature. With this device we isolated Campylobacter spp. from river water on nonselective media without enrichment. Thus this device is as effective as the use of antibiotic media for the isolation of campylobacters. The KB device will be useful for isolation of Campylobacter spp. from water and other environmental samples, which is less time consuming and inexpensive. Besides, this device allows isolation of antibiotic sensitive campylobacters. [ABSTRACT FROM AUTHOR]

We improved genetic transformation of the thermophilic cyanobacterium, Thermosynechococcus elongatus BP-1, by combining electroporation with a top agar method. Transformation was also improved when a disruptant of a putative type I restriction endonuclease (tll2230) was used as recipient cells. In particular, some constructs, with which wild type has never been transformed, were successfully integrated into the tll2230-disruptant. Single-crossover recombination was detected more frequently than the double-crossover recombination. In accordance with the presence of all the homologs of pil genes in Synechocystis sp. PCC 6803, we found that T. elongatus is naturally transformable with exogenous DNA. [ABSTRACT FROM AUTHOR]

Eight white-rot fungal strains were screened for biodecolourisation of eight dyes commercially employed in various industries. Decolourisation of Poly R 478 was used as a standard to ascertain the dye-decolourisation potential of various fungi. All the fungi tested significantly decolourised Poly R 478 on solid agar medium. When tested in a nitrogen-limited broth medium, Dichomitus squalens, Irpex flavus, Phlebia spp. and Polyporus sanguineus were better industrial dye decolourisers than Phanerochaete chrysosporium. [ABSTRACT FROM AUTHOR]

A fungal contaminant on an agar plate containing colonies of Xanthophyllomyces dendrorhous markedly increased carotenoid production by yeast colonies near to the fungal growth. Spent-culture filtrate from growth of the fungus in yeast–malt medium also stimulated carotenoid production by X. dendrorhous. Four X. dendrorhous strains including the wild-type UCD 67-385 (ATCC 24230), AF-1 (albino mutant, ATCC 96816), Yan-1 (β-carotene mutant, ATCC 96815) and CAX (astaxanthin overproducer mutant) exposed to fungal concentrate extract enhanced astaxanthin up to approximately 40% per unit dry cell weight in the wild-type strain and in CAX. Interestingly, the fungal extract restored astaxanthin biosynthesis in non-astaxanthin-producing mutants previously isolated in our laboratory, including the albino and the β-carotene mutant. The fungus was identified as Epicoccum nigrum by morphology of sporulating cultures, and the identity confirmed by genetic characterization including rDNA sequencing analysis of the large-subunit (LSU), the internal transcribed spacer, and the D1/D2 region of the LSU. These E. nigrum rDNA sequences were deposited in GenBank under accesssion numbers AF338443, AY093413 and AY093414. Systematic rDNA homology alignments were performed to identify fungi related to E. nigrum. Stimulation of carotenogenesis by E. nigrum and potentially other fungi could provide a novel method to enhance astaxanthin formation in industrial fermentations of X. dendrorhous and Phaffia rhodozyma. [Copyright &y& Elsevier]

The filamentous fungus Fusarium oxysporum is a soil-borne facultative parasite that causes economically important losses in a wide variety of crops. F. oxysporum exhibits filamentous growth on agar media and undergoes asexual development producing three kinds of spores: microconidia, macroconidia, and chlamydospores. Ellipsoidal microconidia and falcate macroconidia are formed from phialides by basipetal division; globose chlamydospores with thick walls are formed acrogenously from hyphae or by the modification of hyphal cells. Here we describe rensa, a conidiation mutant of F. oxysporum, obtained by restrictionenzyme-mediated integration mutagenesis. Molecular analysis of rensa identified the affected gene, REN1, which encodes a protein with similarity to MedA of Aspergillus nidulans and Acr1 of Magnaporthe grisea. MedA and Acr1 are presumed transcription regulators involved in conidiogenesis in these fungi. The rensa mutant and REN1-targeted strains lack normal conidiophores and phialides and form rod-shaped, conidium-like cells directly from hyphae by acropetal division. These mutants, however, exhibit normal vegetative growth and chlamydospore formation. Nuclear localization of Ren1 was verified using strains expressing the Ren1-green fluorescent protein fusions. These data strongly suggest that REN1 encodes a transcription regulator required for the correct differentiation of conidiogenesis cells for development of microconidia and macroconidia in F. oxysporum. [ABSTRACT FROM AUTHOR]

Background: Chlorinated organic chemicals, such as polychlorinated biphenyls (PCB), hexachlorobenzene (HCB), dichlorodiphenyl trichloroethane (DDT), and dichlorodiphenyl dichloroethene (DDE, the most stable daughter compound of DDT) are persistent lipophilic compounds found in a large portion of the general population. To explore the hypothesis that environmental exposure to these compounds is associated with altered DNA integrity in human sperm, a study of 212 male partners of a sub-fertile couple who presented to the Massachusetts General Hospital Andrology Laboratory was conducted.Methods: The neutral single cell microgel electrophoresis assay (comet assay) was used to assess DNA integrity in sperm. VisComet image analysis software was used to measure total comet length, the proportion of DNA present in the comet tail, and tail distributed moment, an integrated measure of length and intensity.Results: In the regression analyses, there were no statistically significant consistent associations between the comet assay parameters and any of the individual PCB congeners, sum of PCB, or p,p'-DDE.Conclusion: These results suggest that there are not strong relationships between adult levels of these chlorinated organic compounds and sperm DNA damage as measured by the comet assay. [ABSTRACT FROM AUTHOR]

Objectives: The aim of this study was to evaluate the combined effects of antibiotic combinations by agar incorporation inhibitory tests and by time-kill tests on seven geographically and epidemiologically distinct isolates of multidrug-resistant Pseudomonas aeruginosa. All seven strains were resistant to piperacillin, meropenem, ceftazidime, cefoperazone-sulbactam, aztreonam, amikacin and ciprofloxacin. Methods: Strains were distinguished by pulsed-field gel electrophoresis after DNA extraction and restriction with SpeI. MICs of the seven antibiotics listed above were determined by agar dilution. The effect of combinations of these agents was determined by agar incorporation tests and by time-kill studies. Results: Among the two-drug combinations, the combination aztreonam and amikacin was the most effective, inhibiting proliferation in five of the seven strains. Among the three-drug combinations, the combinations of piperacillin, ceftazidime and amikacin, and that of ceftazidime, aztreonam and amikacin were the most effective, inhibiting proliferation in all seven strains. In the killing tests, the three-drug combination of ceftazidime, aztreonam and amikacin was the most effective. This three-drug combination had bacteriostatic effects on all seven strains 2, 4, 6 and 24 h after drug addition, synergic effects on 2-3 strains and bactericidal effects on 1-2 strains after 4, 6 and 24 h. Conclusions: The three-drug combination of ceftazidime, aztreonam and amikacin may be effective against P. aeruginosa resistant to all commonly used antipseudomonal drugs, and deserves further study. [ABSTRACT FROM AUTHOR]