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We evaluated blood and fecal biomarkers as indicators of severity in symptomatic patients with confirmed Clostridium difficile infection (CDI). Recruitment included patients with CDI based on clinical symptoms and supporting laboratory findings. Disease severity was defined by physician's assessment and blood and fecal biomarkers were measured. Toxigenic culture done using spore enrichment and toxin B detected by tissue culture were done as confirmatory tests. Polymerase chain reaction (PCR) ribotyping was performed on each isolate. There were 98 patients recruited, with 85 (87%) confirmed cases of toxigenic CDI (21 severe, 57 moderate, and seven mild), of which 68 (80%) were also stool toxin-positive. Elevated lactoferrin (p = 0.01), increased white blood cell (WBC) count (p = 0.08), and low serum albumin (p = 0.03) were all associated with the more severe cases of CDI. Ribotype 027 infection accounted for 71% of severe cases (p < 0.01) and patients with stool toxin had significantly higher lactoferrin levels and WBC counts (p < 0.05). Our findings show that elevated fecal lactoferrin, along with increased WBC count and low serum albumin, were associated with more severe CDI. In addition, patients infected with ribotype 027 and those with stool toxin had significantly higher fecal lactoferrin and WBC counts.

Purpose: The performance of a rapid test for methicillin-resistant Staphylococcus aureus (MRSA) in a large community hospital was investigated., Methods: A prospective observational study was conducted to evaluate an immunochromatographic assay (Alere PBP2a Culture Colony Test, Alere Scarborough, Inc.) for rapid differentiation of MRSA and methicillin-susceptible S. aureus (MSSA) strains using isolates cultured overnight on common laboratory media. S. aureus isolates cultured for 12-24 hours were tested with the assay, which detects penicillin-binding protein 2a (PBP2a) and provides results in six minutes. The test results were compared with data from standard overnight antimicrobial susceptibility testing to determine the assay's sensitivity and specificity. Changes in therapy associated with use of the rapid assay were evaluated., Results: Over an 11-month period, 661 inpatient isolates from mostly nonhematologic sites were tested. There were six false-negative results, indicating assay sensitivity of 98.4%, with no false positives (specificity of 100%). Eight invalid test results were documented. During designated evaluation periods, a total of 169 patient cases involving PBP2a testing were reviewed by the hospital's antimicrobial stewardship pharmacist. In 63 of those cases (37%), changes in therapy were implemented on the day of test result posting. Interventions often involved switching patients from inappropriate to appropriate MRSA therapy or optimizing MRSA- or MSSA-targeted therapy., Conclusion: An assay for quickly differentiating between MRSA and MSSA was highly sensitive, highly specific, and inexpensive in actual hospital use and led to rapid prescription of appropriate antistaphylococcal therapy 24-48 hours after culture specimens were collected.

The ability of the rapid BinaxNOW Staphylococcus aureus (BNSA) immunochromatographic test (Alere Scarborough, Inc., ME) to accurately differentiate S. aureus from coagulase-negative staphylococci (CoNS) and other Gram-positive cocci (GPC) directly from VersaTREK blood culture bottles was evaluated. A total of 319 positive patient blood culture bottles with GPC seen in clusters with Gram staining were tested using the BNSA test and a direct tube coagulase test (DTCT). The BNSA test was accurate for the detection and differentiation of S. aureus from CoNS and other GPC within 30 min from the time of blood culture positivity and demonstrated a test sensitivity and specificity of 95.8% and 99.6%, respectively. BNSA test results were faxed to the antimicrobial stewardship pharmacist by noon each day in order to evaluate empirical antimicrobial therapy and facilitate more rapid changes or modifications if necessary. Same-day reporting of BNSA test results in conjunction with an antimicrobial stewardship program was more impactful in improving treatment for inpatients with documented S. aureus bacteremia than in reducing empirical vancomycin use in inpatients with CoNS during the first 24 h following reporting.

One hundred and seven group B Streptococcus (GBS) isolates and 344 group A Streptococcus (GAS) isolates were collected between 2005 and 2009 from 2 area hospitals and studied for resistance to erythromycin (ERY) and clindamycin (CLI) and the presence of the erm(T) macrolide resistance gene. The erm(T) gene was found in 5 (8%) of 61 erythromycin nonsusceptible GBS isolates and in 22 (55%) of 40 erythromycin nonsusceptible GAS isolates. The erm(T) gene in all 27 GBS/GAS erm(T) gene-positive isolates was located on a plasmid. Three erm(T) gene-positive plasmids were DNA sequenced. Two plasmids (1 each from GBS and GAS isolates) were both 4967 bp in size, contained the erm(T) gene, and differed by only 2 base pairs, suggesting interspecies horizontal transfer of the erm(T) gene containing plasmid. The third (GBS) plasmid was 6825 bp in size and contained GBSi1, a group II bacterial intron, as well as the erm(T) gene. Pulsed-field gel electrophoresis of all 27 erm(T) gene containing isolates and a selection of erm(T) gene-negative isolates indicated possible clonal expansion among erm(T) gene containing GAS isolates, but not among the 5 erm(T) gene-positive GBS isolates., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Spectra MRSA agar (Remel, Lenexa, KS), a novel chromogenic medium originally developed to detect methicillin-resistant Staphylococcus aureus (MRSA) from nasal swabs, was evaluated in this multicenter study for the detection of MRSA from positive blood cultures exhibiting Gram-positive cocci upon initial Gram staining.

Two strains of Raoultella planticola and one of Raoultella ornithinolytica showing carbapenem resistance were recovered from patients hospitalized in New Jersey and Ohio. All patients had received previous antimicrobial treatment, including carbapenems. These strains harbored bla(KPC-2) and bla(KPC-3). Carbapenemase genes were embedded in isoforms of Tn4401 and were plasmidic and chromosomal in location.

Among 48 erythromycin-resistant group D streptococci (GDS), 36 had the erm(T) resistance gene. erm(T) was also found in 4 of 31 erythromycin-resistant Enterococcus faecium isolates. This is the first report of the erm(T) gene in U.S. GDS isolates and the first report of the erm(T) gene in enterococci.

Background: Acinetobacter baumannii is a gram-negative, coccobacillus found in water and is a significant nosocomial pathogen in hospitals. This report chronicles the appearance in June 2003 of a multidrug-resistant A baumannii (MDR-AB) strain, its dissemination, and interventions used to control it in an acute care hospital (ACH) and long-term acute care facility (LTAC)., Methods: Molecular typing using pulsed-field gel electrophoresis (PFGE) showed that 88 of 99 strains (89%) gave an identical banding designated as clone A. Eight additional isolates were variants of clone A, and 3 isolates were unrelated., Results: A baumannii was isolated from 229 patients between January 2003 and December 2004. Of these patients, 151 (66%) were colonized/infected with MDR-AB. Most isolates were resistant to antibiotics except for imipenem and ampicillin/sulbactam. Isolates included 108 (72%) in the respiratory tract, 32 (21%) in wounds, 6 (4%) in blood, and 5 (3%) in urine. Most isolates were found in the LTAC (70 isolates), ICU step-down (27 isolates), and ICU (26 isolates)., Conclusion: This epidemiologic history illustrates (1) epidemic clonal spread, (2) target populations, (3) variable monthly prevalence, and (4) intervention outcomes. With intervention, the number of new isolates in the ACH decreased by dedicating an infection control professional to critical care, daily surveillance, isolation of positive MDR-AB patients, universal gloving, and routinely reporting results.

We report here on the activity of tigecycline and comparators against multidrug-resistant (resistant to >or=3 antimicrobial classes; MDR) Enterobacteriaceae from the USA collected between January 2004 and January 2006 as part of the Tigecycline Evaluation and Surveillance Trial (TEST). Nationally, 131 (5.9%) Escherichia coli, 174 (10.1%) Klebsiella pneumoniae, 4 (1.2%) Klebsiella oxytoca, 24 (4.9%) Enterobacter aerogenes, 126 (9.5%) Enterobacter cloacae and 20 (2.6%) Serratia marcescens isolates were MDR. Four isolates (two K. pneumoniae and two E. cloacae) were resistant to nine antimicrobials. Tigecycline performed well against MDR E. coli (MIC(90) 0.5 microg/mL, 0% resistant) and K. pneumoniae (MIC(90) 4 microg/mL, 9.2% resistant). A MIC(90) of 8 microg/mL was reported for tigecycline against the other MDR organisms studied here, notably lower than those of most comparators.

Five inducibly clindamycin (CLI)-resistant group B Streptococcus (GBS) isolates, all negative for erm(A) and erm(B) genes, were found to contain erm(T), a gene previously reported in erythromycin-resistant animal isolates of Lactobacillus spp. and human isolates of Streptococcus bovis. One additional GBS isolate, constitutively resistant to CLI, was also positive for the erm(T) gene in addition to erm(B). To our knowledge, this is the 1st report of erm(T) in GBS, the 2nd bacterial species from humans in which the erm(T) gene has been identified, and the 3rd erm gene to be found in GBS.

The emergence of macrolide- and lincosamide-resistant Streptococcus pneumoniae is a worldwide concern. Of particular interest is the increasing prevalence of erythromycin and clindamycin-resistant isolates containing both erm(B) and mef genes. This study determined the prevalence of erythromycin and clindamycin resistance in 596 clinical S. pneumoniae isolates from 2 adult tertiary care hospitals over a 4-year period (2001-2004). Erythromycin resistance increased from 24% to 34%, but S. pneumoniae isolates resistant to clindamycin as well as to erythromycin increased from 3% in 2001 to 15.5% in 2004 (5-fold increase). Among erythromycin-resistant isolates, those also resistant to clindamycin (MLS(B) phenotype) increased 3-fold (12.8-45%). Of forty-one erythromycin/clindamycin-resistant S. pneumoniae isolates tested, 29 (71%) contained both erm(B) and mef(E) genes. Pulsed-field gel electrophoresis performed on 28 erm(B) + mef(E) positive isolates identified 2 predominant and possibly related clones, which made up 64% of the isolates.

In vitro susceptibility testing on 200 Streptococcus agalactiae strains isolated during a 4-year period from vaginal/rectal specimens demonstrated a very high resistance rate for both erythromycin (54%) and clindamycin (33%). Methylase genes erm(B) and erm(TR) and efflux genes mef(E) and mef(A) were detected. Pulsed-field gel electrophoresis showed evidence of both clonal spread and multiclonal dissemination of resistant strains. All but 3 of 200 isolates were susceptible to telithromycin.

During 2001, occurrences of extended-spectrum beta-lactamase (ESBL)-producing Klebsiella pneumoniae isolates were detected in a single medical center (Hospital A) from the SENTRY Antimicrobial Surveillance Program that became endemic in long-term acute care areas and in the intensive care unit in 2002-2003. Between 2001 and 2003, 123 patients were infected or colonized with ESBL-positive K. pneumoniae. Resistance profiles were determined by reference broth microdilution methods, and automated ribotyping and pulsed-field gel electrophoresis (PFGE) were performed. The ESBL-positive K. pneumoniae isolates were resistant to aztreonam, ceftazidime, aminoglycosides, and trimethoprim/sulfamethoxazole and susceptible to ciprofloxacin and tetracycline. In 1997, 1998, and 2000, 9 ESBL-producing K. pneumoniae strains from 2 New York City hospitals shared the same antibiograms and ribotype (204.2) as the strains from Hospital A. PFGE patterns divided Hospital A isolates into 2 subtypes (A and A1) and 3 New York City strains were similar to the Hospital A isolates (A2, A3, and A4). Isoelectric focusing studies of 1 New York City isolate (A4) revealed pIs at 5.4, 7.7, and 8.2. PCR and sequencing results from 1 strain of each Hospital A and 1 New York PFGE pattern determined that TEM-1 and SHV-5 (ESBL) were present in all strains. In addition, 2 New York isolates from 1998 (A3 and A4) also had an OXA-2 enzyme. ESBL-producing K. pneumoniae isolates with ribotype 204.2 from SENTRY Program sites have been recognized in New York only since 1997 and in Hospital A beginning in 2001. The similarities of the antibiogram and epidemiological patterns suggest that these isolates have persisted over time and may have evolved into different but genetically related endemic ESBL-positive K. pneumoniae clones that have the ability to cause sustained epidemic outbreaks in US medical centers.

We describe 4 patients infected with levofloxacin-resistant pneumococci after therapy for community-acquired pneumonia (CAP). The 4 patients had 15 episodes of CAP; Streptococcus pneumoniae was isolated from blood or sputum samples obtained during 14 of the episodes. The underlying medical condition was Bruton agammaglobulinemia in 3 patients and chronic lymphoid leukemia in the other. The initial episode of CAP in each patient was due to a levofloxacin-susceptible strain. One of 4 reinfections and 5 of 6 relapses were due to levofloxacin-resistant strains. All of these strains had amino acid substitutions in the quinolone-resistance-determining region of the genes parC and gyrA. The time between episodes of pneumonia varied from 1 to 4 months. In immunocompromised patients with suspected or proven pneumococcal infection, it may be prudent not to use fluoroquinolone monotherapy empirically when the patient has a history of fluoroquinolone therapy in at least the past 4 months.

We describe a patient with community-acquired pneumonia due to Legionella pneumophila serogroup 6. This patient was found to have bronchoalveolar carcinoma of the lung by means of cytologic testing in 1 of 2 bronchoalveolar lavage samples, but no lesions were visible on bronchoscopy. Despite intravenous administration of azithromycin to the patient, repeat culture and polymerase chain reaction showed persistence of Legionella; the isolates remained susceptible to azithromycin. The patient did not respond to 14 doses of daily intravenously administered azithromycin. The poor outcome may have been partially due to the suspected underlying lung malignancy, as shown by cytologic examination, and by a delay in seeking medical attention.

Fluoroquinolone resistance in Moraxella catarrhalis isolates has been quite rare. This report presents a case history of a 22-year-old man with compromised immune status and severe pneumonia caused by M. catarrhalis. The organism was markedly resistant (MICs, 1.5- > 32 micrograms/mL) to several marketed fluoroquinolones including the agent (levofloxacin) used for concurrent and prior therapy. The emergence of this problematic strain seems related to chronic exposure of the patient to compounds in the class and poor patient compliance to prescribed medications. The strain was not clonally related to other M. catarrhalis strains isolated in the same hospital during early 1998. This second documented case of a fluoroquinolone-resistant M. catarrhalis clinical isolate presents a warning that resistances can emerge in at-risk patients, and that surveillance systems (SENTRY) will be necessary to monitor for unusual organisms and spread of resistance phenotypes among commonly isolated respiratory tract pathogens.

Over the past decade the incidence of necrotizing fasciitis due to group A streptococci has increased. Appropriate management of this life-threatening infection requires rapid recognition, immediate antibiotic therapy, and expeditious surgical debridement or excision.

Streptococcus pyogenes causes a variety of diseases ranging from mild pharyngitis to severe toxic shock syndrome (TSS) and acute rheumatic fever. Since 1987 there has been a resurgence of severe group A streptococcus infections including TSS, necrotizing fasciitis, and myositis. Using molecular and serotyping procedures, we recently studied two clusters of group A streptococcus disease that occurred within separate family units. The first cluster involved two family members (one with TSS and one with necrotizing fasciitis) and three health care workers who attended one of the index patients. The second cluster included a mother (with necrotizing fasciitis of the hand) and her three children. Group A streptococci isolated from individuals within both cluster groups were serotype M3;T3/13/B3264, and pulsed field gel electrophoresis revealed that all isolates except one had identical fingerprints of Sma I-digested chromosomal DNA. The findings demonstrate the potential for spread of serious group A streptococcus disease among individuals and the need for barrier protection when health care workers are exposed to secretions from infected individuals.

A rapid (2.5 h) direct enzyme immunoassay (EIA) for Clostridium difficile toxin A was developed for clinical use. Specimen centrifugation and filtration were not required. The EIA detected toxin A levels in patient stool as low as 20 pg (2 ng/ml of stool). The test was 5,000 times more sensitive for toxin A than it was for toxin B and did not react with a panel of other bacterial species with the exception of one highly toxigenic strain of Clostridium sordellii. The EIA was compared with the cytotoxin assay, culture of toxigenic C. difficile (toxigenic culture), and latex agglutination by using 313 fresh stool specimens submitted from patients with suspected C. difficile-associated disease. Results read visually and with a plate reader were similar. Sixty-two specimens were positive by one or more tests, but only 22 (35%) were positive by all four laboratory methods. The EIA was 84.1% sensitive and 98.9% specific when it was compared with the cytotoxin assay. The use of toxigenic culture to referee discrepant results (EIA versus cytotoxin assay) showed the EIA sensitivity and specificity to be 95.1 and 99.3%, respectively, with respect to other laboratory methods. Patient charts were reviewed for antibiotic-associated diarrhea on 108 specimens, including all those that were positive by at least one test method. Of 34 patients determined to have C. difficile-associated disease, 29 (85.3%) were positive by EIA, 32 (94.1%) were positive by the cytotoxin assay, 27 (79.4%) were positive by toxigenic culture, and 20 (58.8%) were positive by latex agglutination. Seven patients with antibiotic-associated diarrhea had a positive latex result, but results were negative by EIA, the cytotoxin assay, and toxigenic culture. The EIA demonstrated high specificity and good sensitivity for C. difficile-associated disease cases. The test can be used alone or in combination with the cytotoxin assay or toxigenic culture to provide rapid and sensitive results.

Seven commonly used antimicrobial susceptibility testing methods were used to test the susceptibility of 150 isolates of Pseudomonas aeruginosa against gentamicin, tobramycin, amikacin, carbenicillin, and piperacillin. Results were compared with respect to the susceptibility characteristics of the population of isolates as defined by each method. Conventional methods included agar disk diffusion and agar dilution, carried out in accordance with current recommendations of the National Committee for Clinical Laboratory Standards, as well as broth microdilution testing with cation-supplemented Mueller-Hinton broth (CSMHB). Methods in which instrumentation was used for result determination included the Autobac I, Avantage, Sensititre Autoreader (using a breakpoint panel at 18 h of incubation), and Vitek (AMS-240, using the GNS susceptibility card). When necessary for comparison, MIC data were converted to categorical interpretations (susceptible, intermediate, and resistant). With respect to gentamicin, no significant differences were noted among the results of disk diffusion, broth microdilution, Sensititre Auto breakpoint, or Vitek methods which characterized 60 to 67% of isolates as susceptible, 16 to 22% as intermediate, and 13 to 17% as resistant. In contrast, agar dilution, Autobac, and Avantage, although yielding gentamicin results similar to those of one another, were each significantly different in result reporting from the other four methods above for gentamicin results, and they characterized the Pseudomonas population largely as susceptible (88 to 97%), with 0 to 6% intermediate and only 3% to 6% resistant. More isolates were characterized as being resistant to gentamicin in the Avantage test if an assay broth supplemented with increased amounts of calcium was used. Cation impregnation of Autobac disks did not appreciably change Autobac results. The geometric mean MIC of gentamicin was 4 micrograms/ml lower in the agar dilution method than in the CSMHB microdilution method, despite monitoring of the agar for cation content through performance disk diffusion testing with P. aeruginosa ATCC 27853. Tobramycin activity was greater than gentamicin activity, and susceptibility to tobramycin ranged from 89 to 97%, with few statistically significant differences noted among the seven methods studied. Differences in MIC distribution and geometric mean MIC between agar dilution and CSMHB microdilution testing were minimal and suggested less of a cation influence on tobramycin than gentamicin results. Although amikacin was also more active than gentamicin (83 to 99% of isolates were susceptible), differences in the amikacin results among methods tended to reflect the same trends in reporting as seen with gentamicin testing, with the exception that results of Avantage testing were similar to those of disk diffusion, CSMHB microdilution, Sensititre, and Vitek. A difference in geometric mean MIC of 5 micrograms/ml between CSMHB testing and agar dilution testing suggested the influence of divalent cations on amikacin results. Few highly significant differences were noted among methods when isolates were tested against carbenicillin and piperacillin, except that Avantage piperacillin results (66% susceptible) and Autobac piperacillin results (98% susceptible) were noticeably different from the percent piperacillin susceptibility (range, 85 to 92%) measured by the other methods. Method-dependent variability among aminoglycoside susceptibility results, particularly when testing gentamicin, prevents meaningful comparison of Pseudomonas susceptibility trends among hospitals when different methods are used and promotes confusion and frustration among clinical microbiologists and clinicians owing to the uncertainties of clinical meaning of these data.

The Abbott MS-2 system (Abbott Laboratories, Diagnostic Division, Irving, Tex.), equipped with updated bacterial identification software (version 03.02), was used to perform both direct identification and susceptibility tests on gram-negative bacilli from positive BACTEC blood culture bottles. Ninety-eight of 101 Enterobacteriaceae strains, one strain of Acinetobacter calcoaceticus, and two strains of Pseudomonas aeruginosa were correctly identified by following a direct inoculation procedure. One Enterobacter sakazakii isolate was misidentified as Enterobacter cloacae. Ninety-seven percent of 936 direct susceptibility results were identical to the results obtained by using the standard MS-2 susceptibility procedure. Only five tests yielded a sensitive-direct and a resistant-standard MS-2 susceptibility result.

Quantitative cytological and chemical methods have been developed to study the intracellular iodophilic polysaccharide (IPS) content of two strains of Streptococcus mutans. The cytological method uses a periodic acid-chlorite treatment of thin sections to increase the affinity of IPS for uranyl and lead salts. This results in the IPS appearing as individual electron-dense granules which can be counted for quantitative studies. As a basis for these quantitative studies, IPS was measured chemically by dissolving whole cells with hot KOH and quantitating spectrophotometrically the amount of iodine-polysaccharide complex formed.

The in vitro activity of netilmicin was compared to gentamicin, tobramycin and amikacin against 461 strains of glucose fermenting and nonfermenting bacteria. The minimum inhibitory concentrations of netilmicin, gentamicin and tobramycin against the majority of Enterobacteriaceae, Staphylococcus and Streptococcus were quite similar. Gentamicin, however, was approximately fourfold more active against strains of S. marcescens. Amikacin was the most effect antibiotic against strains of fermenting and nonfermenting bacilli resistant to at least one aminoglycoside. Many gentamicin-resistant species of nonfermenting bacilli, however, remain highly resistant to all four aminoglycosides tested.

The continued synthesis of deoxyribonucleic acid, protein, cell wall peptidoglycan and intracellular iodophilic polysaccharide (IPS) by Streptococcus mutans strain FA-1 after several treatments intended to inhibit protein synthesis was studied. Exponential-phase cultures were: (i) simultaneously deprived of two required amino acids (cystine and leucine) that are not present in the cell wall peptidoglycan of this species; (ii) depreived of required amino acids (lysine or glutamate plus glutamine ) that are present in both peptidoglycan and protein; or (iii) treated with tetracycline. Each of these three types of treatment was accompanied by a different pattern of unbalanced growth. The patterns of unbalanced growth that accompanied treatments (i) or (ii) differed substantially from the patterns observed previously for Streptococcus faecalis ATCC 9790, a noncariogenic organism that does not contain IPS. In contrast to S. faecalis 9790, S. mutans FA-1 failed to accumulate peptidoglycan and thicken its wall when deprived of non-wall amino acids. Instead, S. mutans FA-1 continued to accumulate IPS to levels substantially higher than those found in exponential-phase cells. Again, in contrast to S. faecalis, S. mutans FA-1 failed to autolyze upon deprivation of essential precursors of wall peptidoglycan. Under conditions of lysine of glutamate/glutamine deprivation, S. mutans FA-1 continued to accumulate IPS to very high levels. Treatment with tetracycline did result in peptidoglycan accumulation and wall thickening in a manner very similar to that observed previously for inhibition of protein synthesis in S. faecalis. Realtively little IPS synthesis continued after tetracycline treatment. Accumulation of IPS appeared to occur when both ribonucleic acid and peptidoglycan synthesis were severely inhibited. The observations are discussed in terms of the survival of cariogenic organisms in the oral environment.

The recently updated MS-2 Bacterial Identification system software (Abbott Laboratories, Diagnostic Division, Irving, Tex.) was compared with the original MS-2 Bacterial Identification software and the API 20E, using 968 strains of Enterobacteriaceae. The updated MS-2 software correctly identified 94.4% of the isolates tested. API 20E and the original MS-2 software correctly identified 91 and 85.3% of the strains, respectively. MS-2 responses were considered to be equivocal (needing additional tests for verification) if the percent likelihood values were less than 80%. The percentage of equivocal responses was reduced from 6.5% with the original software to 2.2% with the updated software, and the percentage of incorrect identifications was reduced from 8.2 to 3.4% with the original and updated software, respectively. Organisms belonging to 25 taxonomic groups were tested. Direct comparison of the two MS-2 programs showed that the updated MS-2 software increased the identification accuracy of Salmonella spp., Enterobacter cloacae, Providencia stuartii, Escherichia coli, Shigella spp., Klebsiella pneumoniae, Serratia marcescens, Proteus mirabilis, and Acinetobacter calcoaceticus. A decrease in accuracy was seen with Citrobacter freundii, Hafnia alvei, Enterobacter agglomerans, and Yersinia pseudotuberculosis when the updated software was used. The remaining 12 taxonomic groups were not affected by the software changes. The updated MS-2 software appears to significantly improve the identification accuracy of the MS-2 Bacterial Identification system.

A rapid Spot-CAMP test was evaluated for its ability to accurately identify colonies of Streptococcus agalactiae (Lancefield Group B) growing on primary sheep blood agar plates. The test uses a beta-lysin-containing filtrate, which is prepared from a broth culture of Staphylococcus aureus. A drop of beta-lysin filtrate is applied adjacent to a suspected group B Streptococcus (GBS) colony and the plate is incubated and then examined for a zone of synergistic hemolysis. The Spot-CAMP test demonstrated 100% correlation with both a Standard CAMP procedure and Lancefield serogrouping. The rapid Spot-CAMP test was easy to perform and inexpensive, and could presumptively identify within 30 minutes colonies of GBS growing on primary isolation plates.

The Rapid Identification Method (RIM) Escherichia coli Kit (Austin Biologicals Laboratories Inc., Austin, TX) was evaluated as a means to rapidly differentiate at reduced cost clinical isolates of Escherichia coli from other members of the Enterobacteriaceae. A group of 408 gram-negative rods that were isolated on primary isolation plates were tested with the use of both the kit and complete bacterial identification. The RIM E. coli Kit identified 92.5% (272 of 294) of the E. coli isolates. Only 1 of 114 non-E. coli isolates was misidentified as E. coli (positive predictive value equal to 99.6). Although the RIM E. coli Kit was sufficiently rapid (less than one hour), any supply cost savings would depend upon the proportion of true E. coli in the group of organisms tested. Savings derived from the lower cost of using the RIM E. coli Kit would be reduced by the extra cost of screening non-E. coli isolates, which would then have to be completely identified.

The in vitro inhibitory activity of rosamicin and erythromycin against 283 strains of nonfermenting, gram-negative bacilli was determined by using a broth dilution procedure. Rosamicin demonstrated greater activity than erythromycin against most strains tested. A number of species demonstrated significantly lower minimum inhibitory concentrations to rosamicin and would fall within the therapeutic range of the drug based on current pharmacological data.

Antimicrobial elution disks containing amoxicillin-clavulanic acid (Augmentin), cefotetan, ciprofloxacin, or norfloxacin were tested in the Avantage automated susceptibility test system. Performance was compared against an agar diffusion procedure in a three-site collaborative study. Results of 1,500 comparison with amoxicillin-clavulanic acid showed a full accord (agreement of both systems) of 93.6% and an essential accord (agreement excluding minor discrepancies) of 97.6%. Results for cefotetan showed a full accord of 95.1% and an essential accord of 98.3% by the two methods. Results for both ciprofloxacin and norfloxacin were in full accord for more than 98% of tests with gram-negative bacilli and staphylococci, but tests with enterococci gave 38 and 26.1% minor discrepancies (the result of one method was resistant or susceptible and the result of the other method was intermediate), respectively. The results indicated that the Avantage test system is accurate and reliable and provides appropriate determination of bacterial susceptibility with the four antibiotics tested.

The amount of intracellular, iodophilic, glycogen-like polysaccharide (IPS) present in cells of two strains of Streptococcus mutans at various stages of growth in a chemically defined medium was determined by quantitative electron microscopy. The results obtained were then compared with the chemically determined, iodophilic polysaccharide content of cultures. The ultrastructural method used determined the fraction of area of central longitudinal sections of individual cells occupied by stained granules, and was therefore capable of determining amounts of polysaccharide in cells starved of glucose. Although the results of the two methods showed very good quantitative correlation, the ultrastructural method allowed study of glycogen synthesis on a cellular basis, and detected some heterogeneity in amounts of IPS stored by individual cells. The ultrastructural method also permits the detection of much smaller amounts of stored IPS than does the chemical method.

In this multicenter study, 621 sets of blood culture specimens were drawn from 280 patients who were suspected of being septic and who were receiving antimicrobial therapy. Equal volumes of each specimen were inoculated into BACTEC 6B and 16B media. The 16B medium contained adsorbent and cationic resins for neutralizing the effects of the drugs. Of the 621 sets drawn, there were 72 positive cultures in 16B and 52 positive cultures in 6B. In 23 cases the organism was detected only in the 16B medium, and in 3 cases the organism was detected in 6B only. The remaining 49 positives were detected in both culture bottles. In 13 of these 49 cultures, detection in 16B was made between 1 and 5 days earlier than in 6B, whereas 3 of 49 specimens were detected 1 day earlier in 6B; the remaining 33 cultures became positive at approximately the same time in both media. There were a total of 43 patients with positive cultures in this study. Of these patients, 28 had sepsis detected in both the 16B and 6B media. The 6B medium alone detected an additional three cases of sepsis, and the 16B resin medium alone identified 12 additional cases. Supplementary culturing of samples from patients receiving antimicrobial therapy significantly increased the number of positive cultures and positive patients, as well as significantly shortening the time to positivity in these cultures.