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Introduction: In cystic fibrosis, the Pseudomonas aeruginosa cells grow inside the thick mucus layer. In spite of being an obligate aerobe, P. aeruginosa is able to grow in a limited oxygen environment. Bacterial cells could be suddenly exposed to high oxygen levels due to the movements of the mucus mass. The aim of study was to determine the impact of a previous anaerobic incubation on the antimicrobial susceptibility of P. aeruginosa strains isolated from patients with cystic fibrosis., Materials and Methods: Four P. aeruginosa strains were used in this study (ATCC 23389 and 3 clinical isolates). The disk diffusion method was used to determine the antimicrobial susceptibility., Results: The anaerobic pre-incubation produced changes on the susceptibility in all studied strains. All susceptible strains after an aerobic incubation remained susceptible after an anaerobic incubation except one clinical strain, which became resistant to betalactams. The response was strain-dependent and the most significant increase in susceptibility was observed in two of the three clinical isolates when ciprofloxacin was used., Conclusions: The antimicrobial susceptibility of P. aeruginosa strains varies after their exposure to anaerobic conditions. Treatments promoting mucus fluidization could contribute to increase the antimicrobial efficacy.

Standardized broth dilution methods are cumbersome for routine use in a clinical laboratory to study antifungal yeast susceptibility. Recently, the CLSI has standardized a disk diffusion method faster and more suitable to study fluconazole and voriconazole susceptibility. The objectives of the present study were to determine: a) the suitability of the Neo-Sensitabs tablets to study fluconazole susceptibility; b) whether Mueller-Hinton agar with methylene blue (MHAG-AM) could be used in the E-test method; and c) the interaction of the methylene blue with RPMI medium. A total of 84 blood stream yeast isolates were used (25 C. albicans, 7 C. parapsilosis, 10 C. tropicalis, 12 C. glabrata, 7 C. krusei, 4 C. lusitaniae and 19 C. neoformans). The methylene blue makes sharper inhibition zones both in MHAG-AM and RPMI media. With fluconazole Neo-Sensitabs tablets, the lowest percentage of very major errors was found in MHAG-AM and the greatest in RPMIG. In both diffusion methods and culture media, the very major errors were found in C. albicans, C. tropicalis (only with Neo-Sensitabs) and C. glabrata. The percentage of fluconazole-resistant strains was lower in the media that contained glucose (2%). Neo-Sensitabs tablets are a reliable alternative to the dilution methods to detect fluconazole susceptibility. In the case of resistance, more studies are required; nevertheless, inhibition zone > or =17 mm should be applied to define fluconazole resistance.

In order to standardize and evaluate a disk diffusion method with visual reading to detect in vitro fluconazole susceptibility of yeast, 1193 clinical isolates were tested. These included 584 Candida albicans, 196 Candida parapsilosis, 200 Candida tropicalis, 113 Candida glabrata, 50 Candida krusei and 50 Candida spp. and other opportunistic yeasts. The disks were manufactured in the INEI-ANLIS "Dr. Carlos G. Malbrán. The disk diffusion method results were compared to MIC results obtained by the reference CLSI M27-A2 broth microdilution method modified by EUCAST. The interpretative breakpoints for in vitro susceptibility testing of fluconazole were established at: zone diameter > or =16 mm for MIC < or =8 microg/ml (susceptible isolates), between 9 and 15 mm for MIC = 16-32 microg/ml (susceptible dose-dependent isolates), and < or =8 mm for MIC > or =64 microg/ml (resistant isolates). Overall agreement between the two methods was 94.7%, with 0.2% very major errors, and 0.3% major errors. Inter - and intralaboratory agreement was good. The disk diffusion method for drug susceptibility testing of Candida spp. isolates is inexpensive, reliable and reproducible. However, when the inhibition zone diameter is < or =15 mm, it is advisable to test the isolate by the reference microdilution method.

Background: Candida albicans and Rhodotorula mucilaginosa are yeasts of clinical importance in the oral cavity. In immunocompromised patients they can cause some pathologies that must be controlled with antimicrobials., Aims: To evaluate and compare the antimicrobial efficacy of commercially available mouthrinses against strains of C. albicans and R. mucilaginosa., Methods: The six mouthwashes studied in vitro were formulated (alone or in combination) with chlorhexidine (CHX) 0.12%, CHX 0.1%, CHX 0.05%, cetylpyridinium chloride (CPC) 0.075%, CPC 0.05%, and essential oils. Ten C. albicans and R. mucilaginosa isolates each were studied. The agar diffusion method (Mueller Hinton II), with incubation at 32°C was used to evaluate the antifungal activity., Results: The results of this study indicate that mouthwashes with CHX 0.1%, CHX 0.12%, CHX 0.05% + CPC 0.05%, CHX 0.12% + CPC 0.05% and CPC 0.075% have an antifungal effect against C. albicans and R. mucilaginosa. CHX 0.1% led to the broadest inhibition zone for C. albicans and R. mucilaginosa (25.65±2.39mm and 40.05±3.31mm). Essential oils did not show any antifungal activity. Statistical analysis showed no statistical difference between mouth rinses CHX 0.1%, CHX 0.12% and CHX 0.12% + CPC 0.05% (p=0.0001) against C. albicans and R. mucilaginosa., Conclusions: Mouthwashes with CHX showed higher antifungal activity against C. albicans and R. mucilaginosa than other mouthwashes studied., (Copyright © 2020. Publicado por Elsevier España, S.L.U.)

Background: The double disc diffusion method is an alternative diagnostic that allows the identification of Staphylococcus aureus isolates apparently susceptible to clindamycin but that may develop resistance due to an induction phenomena, mainly asociated to the increase in resistance to methicillin, thus increasing the possibility of failure in the treatment., Aim: To determine the frequency of induced clindamycin resistance in methicillin-resistant S. aureus (MRSA) isolated from Paraguayan children., Materials and Methods: In this cross sectional study, we collected 145 S. aureus isolates that caused skin and soft tissue and osteoarticular infections in pediatric patients of the Central Hospital I.P.S. in the period from December-2012 to November-2013. Resistance to clindamycin was determined by automated methods and double disc diffusion. PCR was performed for ermA, ermB, ermC and msrA genes from representative isolates., Results: The global resistance to methicillin and clindamycin was 67 and 13%, respectively (11% attributable to the inducible mechanism). The ermC and msrA genes were detected individually in 25 and 17% of the isolates respectively while an isolate presented both genes simultaneously., Discussion: The frequency of inducible resistance to clindamycin indicates the importance of double disc diffusion methods in microbiological practice, as well as being within the cut off points considered acceptable for the use of this antibiotic for skin infections. and osteoarticular caused by MRSA.

Objective: Methicillin-resistant Staphylococcus aureus (MRSA) is a significant pathogen causing both healthcare-associated and community-acquired infection. Rapid and accurate detection of this pathogen is crucial for the use of appropriate antimicrobial therapy and the control of nosocomial spread., Methods: A total of 107 S. aureus strains were assayed for methicillin resistance: Vitek2® (bioMérieux), CHROMagarTM MRSA II (BD Becton Dickinson), disk diffusion in agar for cefoxitin 30 μg and immunochromatography PBP2a SA Culture Colony Test (AlereTM). The results of conventional tests were compared with the "gold standard" PCR test for mecA gene., Results: Sensitivity and specificity were: disk diffusion for cefoxitin 100% and 100% respectively, Vitek2® 100 and 100%, CHROMagarTM MRSA II 100 and 96%, and ICPBP2a detection 98,25% and 100%., Conclusions: ICPBP2a Culture Colony Test (AlereTM) is fast, efficient and economical technique for detection of penicillin binding protein 2a (PBP2a) from isolates. This assay is a useful tool for the management of hospital outbreaks., (©The Author 2019. Published by Sociedad Española de Quimioterapia. This article is distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)(https://creativecommons.org/licenses/by-nc/4.0/).)

Background: Malassezia furfur is a human skin commensal yeast that can cause skin and opportunistic systemic infections. Given its lipid dependant status, the reference methods established by the Clinical and Laboratory Standards Institute (CLSI) to evaluate antifungal susceptibility in yeasts are not applicable., Aims: To evaluate the in vitro susceptibility of M. furfur isolates from infections in humans to antifungals of clinical use., Methods: The susceptibility profile to amphotericin B, itraconazole, ketoconazole and voriconazole of 20 isolates of M. furfur, using the broth microdilution method (CLSI M27-A3) and Etest ® , was evaluated., Results: Itraconazole and voriconazole had the highest antifungal activity against the isolates tested. The essential agreement between the two methods for azoles antifungal activity was in the region of 60-85% and the categorical agreement was around 70-80%, while the essential and categorical agreement for amphotericin B was 10%., Conclusions: The azoles were the compounds that showed the highest antifungal activity against M. furfur, as determined by the two techniques used; however more studies need to be performed to support that Etest ® is a reliable method before its implementation as a routine clinical laboratory test., (Copyright © 2016 Asociación Española de Micología. Publicado por Elsevier España, S.L.U. All rights reserved.)

Background: The antimicrobial activity of copper (Cu+2) is recognized and used as an antimicrobial agent., Aim: To evaluate the antimicrobial activity of copper against microorganisms obtained from chronic cutaneous wound infections., Material and Methods: Five chemical products that contained copper particles in their composition were tested (zeolite, silica, acetate, nitrate and nanoparticle of copper). The antimicrobial activity against antibiotic resistant strains usually isolated from chronic cutaneous wound infections was determined for two of the products with better performance in copper release., Results: The minimal inhibitory and minimal bactericidal concentrations of copper acetate and nitrate were similar, fluctuating between 400-2,000 µg/ml., Conclusions: The studied copper salts show great potential to be used to control both gram positive and gram negative, antibiotic resistant bacteria isolated from wound infections.

Carbapenems-resistance in Pseudomonas aeruginosa isolates has been widely reported. Fosfomycin has been shown to act synergistically with other antimicrobials. The agar dilution method was approved for susceptibility testing for fosfomycin and Pseudomonas aeruginosa. However, broth microdilution methods are the basis of systems currently used in clinical microbiology laboratories. The results of this study indicate that these methods are acceptable as susceptibility testing methods for fosfomycin against these organisms., (Copyright © 2016. Publicado por Elsevier España, S.L.U.)

Due to the great global concern regarding bacterial resistance to antibiotics, an ongoing search for new molecules having antibacterial activity is necessary. This study evaluated the antibacterial and anticandidal effects of a hexane extract from the root of Salvia apiana. Salvia extracts at concentrations of 27, 13.5, 6.8 and 3.4mg/ml caused growth inhibition of Staphylococcus aureus, Streptococcus pyogenes, Enterococcus faecalis and Candida albicans. However, no significant effect was observed on Escherichia coli and Candida tropicalis in comparison to vehicle. It was here demonstrated for the first time that Salvia apiana has an important antimicrobial effect on human pathogens of great clinical value, thus opening the field to continue the evaluation of this lamiaceous plant for its future use as a therapeutic agent., (Copyright © 2016 Asociación Argentina de Microbiología. Publicado por Elsevier España, S.L.U. All rights reserved.)

Methicillin-resistant Staphylococcus aureus (MRSA) is widely distributed in hospital environments, causing serious infections, mainly the bloodstream, surgical site infection and pneumonia. Vancomycin (VAN) is the antibiotic of choice for treating severe MRSA infections; however, nowadays worldwide resistant strains (VRSA), with intermediate susceptibility (VISA) and decreased susceptibility or hetero-resistance to VAN (hVISA) have been reported, related to treatment failure and increased mortality. This report describes the first confirmed isolation of MRSA with hVISA phenotype in a public hospital in Chile.

Introduction: Propolis is a natural product derived from beekeeping. It has anesthetic, anti-inflammatory, immune-stimulant and antibacterial properties on grampositive and gramnegative bacteria. However, little is known regarding its activity on Helicobacter pylori. This bacteria colonizes about half of the world's population and is associated with chronic gastritis, peptic ulcer and gastric cancer., Objective: The aim of this study was to evaluate the inhibitory activity of 22 propolis extracts from nine of the 11 beekeeping Chilean regions on 10 strains of H. pylori isolated from gastric mucosa., Methods: The antibacterial activity of the extracts was determined using the well diffusion method and diffusion disks., Results: 100% of the extracts were active on the tested strains, showing inhibition halos equal to or greater than 15 mm by both methods., Conclusions: Our results show an effective anti H. pylori activity of propolis. However, additional microbiological studies are needed before a potential clinical utility of these natural products is warranted.

Background: Endophtalmitis post cataract surgery is one of most feared and devastating complications resulting in serious consequences and an uncertain visual prognosis. Antimicrobial prophylaxis against endophtalmitis must be based on the best knowledge of conjuntival microbiota., Objective: To establish microbiological basis for the best antibiotic prophylaxis to prevent endophthalmitis in cataract surgery., Materials and Methods: A descriptive, cross-sectional, prospective study. A preoperative conjunctival sample was taken from the lower fornix of 118 pacients, sowing it immediately in culture media. Identification of growing colonies and susceptibility testing were performed by manual or automated methods., Results: 106 (89.8%) of 118 preoperative cultures were positive. 159 bacteria were isolated in single or mixed flora, with 95% of Gram positive organisms. Staphylococci represented 76.1% of isolated bacteria, with 82.6% of coagulase-negative staphylococci (SCN) and 17.4% of Staphylococcus aureus. Forty two percent of SCN and 38% of S. aureus were methicillin resistan; both groups showed high susceptibility to tobramycin and fourth-generation fluoroquinolones., Conclusions: we recommend the use of topical tobramycin as pre-operative antimicrobial prophylaxis associated with povidone-iodine antisepsis. A fourth-generation quinolone is recommended when there is risk of infection.

Introducción: la sensibilidad antifúngica in vitro en hongos filamentosos no ha tenido el mismo desarrollo que en levaduras. Se dispone de limitada información sobre la susceptibilidad en este tipo de aislamientos en Colombia. Materiales y métodos: se determinó la actividad in vitro de fluconazol, voriconazol, itraconazol, anfotericina B y caspofungina mediante el método de E-Test, de los géneros Aspergillus (36 A. fumigatus, 12 A. flavus, 9 A. niger, 6 A. terreus, 4 A. nidulans y 1 A. versicolor) e hifomicetes hialinos (9 Fusarium sp., 2 Geotrichum sp. y 2 Paecilomyces sp.), provenientes en su mayoría de lavados broncoalveolares (30%) y biopsias pulmonares (36%); 9% provenían de hemocultivos. Resultados: el perfil de resistencia general fue 28% para itraconazol, 15% para caspofungina, 14% para anfotericina B y 5% para voriconazol. En general, todos los aislamientos presentaron una sensibilidad disminuida para fluconazol e itraconazol. La mejor actividad farmacológica la presentaron voriconazol, caspofungina y anfotericina B. Fusarium sp. presentó una mayor actividad con el voriconazol. Se encontraron diferencias entre el tipo de micelio (Aspergillus vs no Aspergillus) y la susceptibilidad a voriconazol, anfotericina B y caspofungina. Conclusión: en general, los antimicóticos disponibles para el tratamiento de infecciones por miceliales muestran una sensibilidad disminuida in vitro en relación con el género y la especie identificada.Introduction: fungal susceptibility against micelial fungi has not been developed at the same pace as susceptibility against yeasts. Scarce information is available about that kind of isolates in Colombia. Materials and methods: in vitro susceptibility against micelial isolates from patients with cancer was determined. The E-test method was used to find out susceptibility against fluconazole, voriconazole, itraconazole, amphotericin B, and caspofungin. Isolates of the genera Aspergillus (36 A. fumigatus, 12 A. flavus, 9 A. niger, 6 A. terreus, 4 A. nidulans and one A. versicolor isolate), Fusarium (n=9), Geotrichum and Paecilomyces (n=2 each one) obtained from patients with cancer were tested. These isolates were obtained from bronchoalveolar lavage (30%), pulmonary biopsies (36%) and bloodstream infections (9%). Results: The general pattern of resistance was 28% against intraconazole, 15% against caspofungin, 14% against amphotericin B, and 5% against voriconazole. In general, susceptibility against fluconazole and itraconazole showed a diminishing trend. Voriconazole, caspofungin, and amphotericin B showed the best pharmacologic potency. Fusarium sp. presented a higher activity level against voriconazole. There were differences in the susceptibility against voriconazole, anphotericin B, and caspofungin depending on the type of micelial isolate (Aspergillus vs. Non- Aspergillus). Conclusion: In general, the available antifungal treatments against mycelial fungi identified in the cancer center show diminished susceptibility.

Introduction: Bacterial resistance is critical for the selection of antibiotics in the treatment of infections, so it is vital to know its current status in our geographical area., Objective: To determine in vitro antibiotic susceptibility of bacterial isolates obtained from keratitis and intraocular infections., Materials and Methods: A retrospective study of microbiological tests in Fundación Oftalmológica de Santander (FOSCAL) was carried out between June, 2011, and January, 2012., Results: A total of 92 samples were examined and 110 bacteria, 27 fungi and 12 free-living amoebae were identified. Polymicrobial infections constituted 50% of the total; 1.1%, 0%, 1.1%, 16.9%, 29.3% and 85% of Gram-positive bacteria were resistant to imipenem, moxifloxacin, gatifloxacin, levofloxacin, ciprofloxacin and tobramycin, respectively, while 0%, 8.3%, 0%, 0%, 18.2% and 27.3% of Gram-negative bacteria were resistant to imipenem, moxifloxacin, gatifloxacin, levofloxacin, ciprofloxacin and tobramycin, respectively. For methicillin-resistant coagulase-positive staphylococci, resistance percentages to imipenem, moxifloxacin, gatifloxacin, levofloxacin, ciprofloxacin and tobramycin were 0%, 0%, 0%, 7%, 17% and 100%, respectively. For methicillin-resistant coagulase-negative staphylococci, resistance percentages to imipenem, moxifloxacin, gatifloxacin, levofloxacin, ciprofloxacin and tobramycin were 3%, 0%, 0%, 24%, 44% and 100%, respectively. Overall bacterial resistance to imipenem, moxifloxacin, gatifloxacin, levofloxacin, ciprofloxacin and tobramycin, for both Gram-positive and Gram-negative, was 1%, 1%, 1%, 15.1%, 28% and 64.5%, respectively., Conclusions: The levels of bacterial resistance to imipenem, moxifloxacin and gatifloxacin were lower than for levofloxacin, ciprofloxacin and tobramycin. The levels of resistance to tobramycin were very high, which calls into question its usefulness in this region of our country.

Objectives: To determine the prevalence ofmethicillin-resistant Staphylococcus aureus (MRSA), its antimicrobial susceptibility patterns and classify strains by pulsed-field gel electrophoresis (PFGE)., Material and Methods: 106 S. aureus strains isolated from patients hospitalized at the Maracaibo city university hospital, Venezuela, were processed during the first quarter of 2009. The culture, isolation and identification of S. aureus were done by conventional methods. Antimicrobial susceptibility was determined by the disk diffusion method. The presence of mecA gene in MRSA strains was verified using the polymerase chain reaction (PCR)., Results: Fifty-four strains (50.94%) were MRSA and twenty three antibiotypes were detected. The most frequently observed was the one including beta-lactams, macrolides, lincosamides, aminoglycosides and quinolones. There were forty multi-resistant isolates (74.0%) between MRSA strains. All methicillin-resistant isolates were mecA positive. PFGE classified MRSA stains in 50 pulsotypes, each one containing between six and thirteen bands. Four small groups, of two strains each, had 80% of similarity. Five of the eight strains in these small clusters (62.50%) had the same pattern of resistance., Conclusion: There is a high prevalence of multi-resistant MRSA strains with polyclonal dissemination in the hospital.

Introduction: Resistance to macrolide antibiotics is increasing in clinical isolates of Streptococcus pneumoniae and is associated with the presence of mobile genetic elements. Objetive: The aim of this study was to determine the distribution of serotypes and transposons among macrolide-resistant invasive isolates of S. pneumoniae in Colombia from 1994 to 2011., Materials and Methods: A total of 225 macrolide-resistant S. pneumoniae isolates were analyzed. The isolates had epidemiological data, serotyping and antimicrobial susceptibility patterns. The phenotypes were tested by erythromycin-clindamycin double-disk test. We investigated the presence of transposons by several multiplex PCRs to identify the genes erm (B), mef(A), mef(E), tet M, Cat , Aph3 -III, int -Tn 916 , xis -Tn 916 , TnpA -Tn 917 , TnpR -Tn 917 and int -Tn 5252 ., Results: Of all isolates, 62.7%, 2.7% and 34.6% of isolates exhibited cMLS B, iMLS B, and M phenotypes, respectively. Multiresistance was observed in 69.3% of these strains. The most prevalent genetic elements in MLS B were the Tn 5253 (34%), mostly carried in serotype 6B isolates and found to be related to the international clone Spain-ST90; Tn 1545 (18.4%), carried by serotype 19A and related to ST276, and Tn 3872 (14.9%), mainly detected in capsular types 6B and 14. Other seven transposons (32.7%) were associated with different serotypes. The mega element (62.8%) was associated to serotype 6A and ST473 in M phenotype., Conclusions: The majority of erythromycin-resistance isolates of S. pneumoniae in Colombia had the cMLS B phenotype and was associated with the presence of transposons, which carry multiple resistance determinants for other antibiotics. Moreover, isolates with M phenotype carried the gene mef( E) in the mega element.

Purpose: To describe the conjunctival bacterial spectrum of our patients undergoing intraocular surgery and their antibiotic sensitivity during the study period., Methods: A retrospective study of preoperative conjunctival culture of patients consecutively scheduled for intraocular surgery from 21 February 2011 to 1 April 2013. Specimens were directly seeded onto blood-agar and MacConkey-agar (aerobiosis incubation, 2 days), and on chocolate-agar (6% CO2 incubation, 7 days). The identified bacteria were divided into 3 groups according to their origin; the bacteria susceptibility tests were performed on those more pathogenic and on some of the less pathogenic when more than 5 colonies were isolated. The sensitivity of the exigent growing bacteria was obtained with disk diffusion technique, and for of the non-exigent bacteria by determining their minimum inhibitory concentration. The Epidat 3.1 program was used for statistical calculations., Results: A total of 13,203 bacteria were identified in 6,051 cultures, with 88.7% being typical colonizers of conjunctiva (group 1), 8.8% typical of airways (group 2), and the remaining 2.5% of undetermined origin (group 3). 530 cultures (8.8%) were sterile. The sensitivity of group 1 was: 99% vancomycin, 95% rifampicin, 87% chloramphenicol, 76% tetracycline. Levels of co-trimoxazole, aminoglycosides, quinolones, β-lactams and macrolides decreased since 2007. The group 2 was very sensitive to chloramphenicol, cefuroxime, rifampicin, ciprofloxacin and amoxicillin/clavulanate. In group 3, to levofloxacin 93%, ciprofloxacin 89%, tobramycin 76%, but ceftazidime 53% and cefuroxime 29% decreased., Conclusions: None of the tested antibiotics could eradicate all possible conjunctival bacteria. Bacteria living permanently on the conjunctiva (group 1) have achieved higher resistance than the eventual colonizers., (Copyright © 2013 Sociedad Española de Oftalmología. Published by Elsevier Espana. All rights reserved.)

Listeria monocytogenes is a bacteria responsible for food borne diseases (FBD). The effect of Aloe vera gel extract as a possible bacteriostatic and/or bactericidal against Listeria monocytogenes, was checked by determined the minimum inhibitory concentration (MIC), the time of minimum inhibition (TMI) and minimum bactericidal concentration (MBC) solutions extract of Aloe vera gel in different concentrations on cultures of Listeria monocytogenes ATCC 7635. We applied the agar diffusion method, using solutions of extract of Aloe vera gel at concentrations of 0 to 100% for the MIC. The TMI was determined by growth curves in trypticase soy broth with an initial inoculum of Listeria monocytogenes ATCC 7635 of 108 CFU/mL in each solution. It was determined that the MIC was 10% extract of Aloe vera gel and TMI was 5 hours at concentrations of 10%, 20% and 30% of Aloe vera, while concentrations of 50, 80, 90 and 100%, the time was 8 hours. It was found that indeed the Aloe vera gel is bacteriostatic power on Listeria monocytogenes (p < 0.001), but yet, no bactericidal effect was obtained in our study.

Introduction: Streptococcus agalactiae (GBS) is the main causative agent of early perinatal sepsis. The acquisition of prevention policies has led to frequent use of intrapartum antibiotics. Surveillance of antimicrobial resistance is indispensable for defining drugs of choice and alternatives for such prophylaxis., Objectives: To determine the evolution of antimicrobial resistance of GBS from maternal colonization to drugs used in the prevention of neonatal sepsis, between 2002 and 2008., Methods: We studied 100 GBS positive vaginal and anal samples from pregnant women. Disc diffussion susceptibility method was performed for penicillin, ampicillin, cefazolin, erythromycin and clindamycin according to the Clinical and Laboratory Standards Institute (CLSI)., Results: We analyzed the susceptibility of 99 strains. Seventeen were resistant to erythromycin (17.1%) and 13 were resistant to clindamycin (13.1%). Thirteen of the 17 strains resistant to erythromycin had the MLS phenotype (resistance to erythromycin and clindamycin) and 4 had the M phenotype (resistance to erythromycin only). Within the MLS phenotype, resistance was constitutive in 9 strains, and induced in 4 strains (positive D test). Compared with 2002 there was a significant increase in resistance to clindamycin (from 3.27% to 13.1% p < 0.002) and erythromycin (1.09% to 17% p < 0.001). 100% GSB remained sensitive to penicillin and ampicillin., Conclusions: GBS remains highly susceptible to drugs of choice for prevention of perinatal sepsis. There is a significant increase in antimicrobial resistance to clindamycin and erythromycin. Therefore, it is necessary to request susceptibility testing in GBS from third trimester of pregnancy screening in patients allergic to penicillin.

Objectives: To determine the Minimum inhibitory concentration (MIC) of Levofloxacin against HELICOBACTER PYLORI (HP)., Materials and Methods: 95 HP Peruvian strains were evaluated in Agar dilution and Disk diffusion tests, as well as the Pearson Coefficient (r) and the inoculum's effect., Results: 36.9% (35 of 95) were resistant (MIC>1 μg/ml) to Levofloxacin. MIC₉₀ was 16 ug/ml (CI:90%). MIC of Levofloxacin did not change at different inoculum concentrations. r: -0.733 (p<0.001)., Conclusions: The proportion of HP Levofloxacin resistant strains in Peru is higher than in developed countries. Periodic testing of antibiotic susceptibility is warranted to select the most accurate therapies.

Antibiotic resistance is an old problem with new face as the rate of infections due to multidrug resistant bacteria is higher everyday and the number of new antibiotics to overwhelm the problem is becoming smaller. E. coli is the most frequent agent causing nosocomial or community-acquired bacteraemia being in our country 10% of them extended-spectrum beta-lactamases (ESBL) producing E. coli isolates. Nowadays the number of community- acquired or health-related infections caused by these ESBL producing E. coli is increasing. CTX-M has also become the most frequent ESBL compared to other enzymes. The role of these enzymes as a virulence factor increasing mortality in patients with bacteraemia due to E. coli is not well defined. The relevance of ESBL-E. coli seems to be related with the higher frequency of inadequate treatment and therefore the importance of identifying factors or features that might predict that the patient's infection is due to one of these isolates. In terms of prevention and control of infection measures, the role of patient's isolation is not clear but a proper prescription of antibiotics and antibiotic control policies are probably important to reduce the problem.

The objective of this study is to perform a comparative evaluation of the prediffusion and minimum inhibitory concentration (MIC) methods for the detection of sensitivity to colistin, and to detect Acinetobacter baumanii-calcoaceticus complex (ABC) heteroresistant isolates to colistin. We studied 75 isolates of ABC recovered from clinically significant samples obtained from various centers. Sensitivity to colistin was determined by prediffusion as well as by MIC. All the isolates were sensitive to colistin, with MIC = 2µg/ml. The results were analyzed by dispersion graph and linear regression analysis, revealing that the prediffusion method did not correlate with the MIC values for isolates sensitive to colistin (r² = 0.2017). Detection of heteroresistance to colistin was determined by plaque efficiency of all the isolates with the same initial MICs of 2, 1, and 0.5 µg/ml, which resulted in 14 of them with a greater than 8-fold increase in the MIC in some cases. When the sensitivity of these resistant colonies was determined by prediffusion, the resulting dispersion graph and linear regression analysis yielded an r² = 0.604, which revealed a correlation between the methodologies used.

Reference methods E.Def 7.1 and M27-A3 detect in vitro resistance; however, they are expensive and very laborious. Thus, their actual use in hospital laboratories is limited. There are commercial techniques available, having easier accessibility and development, which would yield results comparable to those of the reference methods. The objectives of this study were: a) to compare the results of minimal inhibitory concentration of 82 Candida spp. clinic isolates according to reference method E.Def 7.1 and ATB® Fungus 3; b) to compare the results of fluconazole susceptibility testing by disk diffusion in agar with Neo-SensitabsTM tablets and Malbrán disks with those of the reference methods. Minimal inhibitory concentration for amphotericin B, 5-flucytosine, fluconazole and itraconazole was performed according to the E.Def 7.1 and the ATB Fungus 3 methods and diffusion was carried out with fluconazole disks and tablets. General concordance between the reference method and ATB Fungus 3 was 90.2 % and 96.3 and 92.7% for diffusion with disks and tablets. The ATB Fungus 3 method was effective to determine susceptibility against amphotericin B and 5-flucytosine; however, discrepancies were observed with azole drugs. Disk diffusion methods are useful to determine susceptibility to fluconazole; however, 3 very major, 1 major and 2 minor errors were observed with the tablets, whereas only 3 minor errors were observed with the disks.

Background: The microbiology of the diabetic foot is complex, making swab culture controversial; biopsy culture is the gold standard., Objective: To determine the diagnostic utility of swab culture in diabetic foot ulcers., Methods: Comparative study of diagnostic utility. Diabetic foot ulcers were classified according to the University of Texas scale. Cultures by biopsy and swabbing were performed. Bacterial identification was performed by standard biochemical methods. Antimicrobial susceptibility was determined by the plate diffusion method. An analysis of the diagnostic test was made, reporting descriptive measures of frequencies., Results: We obtained specimens for culture from 118 patients. Grade II and III lesions were the most frequently occurring (80%). Overall, 132 organisms were isolated from biopsies and 118 from swabs, with those of the Enterobacteriaceae family being the most frequent (56% from biopsies and 60% from swabs). Swab culture had a calculated sensitivity of 0.85, specificity of 0.86, positive predictive value of 0.98, negative predictive value of 0.43, positive likelihood ratio of 5.9, and negative likelihood ratio of 0.2., Conclusion: Swab culture is a reasonable option to determine the diabetic foot microbiology.

Objective: Determining the microbial aetiology spectrum and antibiotic resistance pattern of uropathogens causing urinary tract infections in hospitalised patients and outpatients., Methods: A descriptive study was carried out between February 2005 and November 2008 at the San Buenaventura University's Clinical Laboratory in Cartagena. Antibiotic sensitivity was determined by the Kirby Bauer method., Results: Out of the total specimens (1,384) analysed over the four-year study period, 455 of the urine samples (32.9 %) were culture positive, most (81.4 %) having come from females. The bacterium isolated most frequently was Escherichia coli (60.1 %) followed by Klebsiella pneumoniae (6.9 %), Pseudomonas aeruginosa (6.6 %), Proteus mirabilis (5.4 %) and Acinetobacter baumannii (1.4 %). The Gram-negative isolates displayed a high level of resistance to ampicillin (range 84.3100 %), amoxicillin/clavulanic acid (range 66.580 %) and ciprofloxacin (range 4057.9 %)., Conclusion: Gram-negative bacteria were responsible for urinary tract infections in the patients involved in this study. The most commonly isolated bacteria were E. coli. Empirical administration of a third-generation cephalosporin for initial treatment of urinary tract infections in this population appears prudent from the perspective of antimicrobial susceptibility.

The capacity of the DIRAMIC system to detect strains producing extended-spectrum-betalactamase (ESBL) was evaluated through the comparison with two phenotypic confirmatory tests: double-disk synergy test and E-test. Ninety seven clinical isolates of Escherichia coli y Klebsiella spp. previously characterized; not repeated and suspected of being ESBL producers were studied by the three methods. In comparison with E-test and double-disk synergy test, DIRAMIC system showed a sensitivity of 85.7% and 92.7% as well as specificity of 100% and 92.9%; respectively. The values found have a very high degree of concordance (kappa index > 0.80). The results obtained vouch for the utility of the DIRAMIC as a rapid method to alert about the presence of strains producing ESBL enzymes.

Infections caused by multidrug resistant (MDRA) Acinetobacter spp. have increased worldwide. Tigecycline provides a new therapeutic option for treating these infections. We conducted a study tailored to validate an in house methodology by broth microdilution (BM) vs. commercial BM in 32 MDRA isolates. Sixty MDRA isolated in 2 time periods (2000-2003 and 2006-2008) were compared by BM, agar dilution (AD) and disk diffusion (DD) methods, as described by the CLSI and the MIC90 for each period was determined. Susceptibility was interpreted by using the breakpoints suggested by the FDA for Enterobacteriaceae. The correlation between the methodologies was performed by a scattergram, and the errors between methods were calculated. The correlation coefficients between AD and BM, and BM and DD were, r: 0.68 in both cases. For 2002-2003, the MIC90 for BM was: 1 g/ml, and for 2006-2008: 2 microg/ml. Using the FDA breakpoints for DD, we observed an unacceptable minor error (17.6%) because of false-intermediate values, considering the MIC90 was 1-2 microg/ml.

Extended spectrum beta-lactamases (ESBL) are capable of inhibiting the action of extended spectrum cephalosporins and monobactams. The objective of this work is to describe six isolates of ESBL producing Pseudomonas aeruginosa, retrieved from intensive care patients. The susceptibility test was performed by diffusion. For the phenotypic detection of ESBL, the following was assessed: the difference between ceftazidime ceftazidime/clavulanic acid (CAZ-CAC) and the synergy between imipenem-ceftazidime (IMI-CAZ) and cefepime-ceftazidime/clavulanic acid -ceftazidime (FEP-CAC-CAZ). The presence of metallo-beta-lactamases (MBL) was discarded through the double disc imipenem-EDTA/mercaptoacetic-meropenem (IMI-EDTA/SMA-MER) method. Molecular characterization of ESBL was performed by polymerase chain reaction (PCR) with blaGES primers. Synergy IMI-CAZ was observed in the studied strains; ESBL type GES was confirmed in five of them. The strategic location of the discs and the evaluation of alert signals for the detection of ESBL is essential, thus contributing to the correct recommendation of treatment in the clinical report.

Ten Pseudomonas aeruginosa strains with resistance to broad-spectrum cephalosporin and carbapenems were studied to determine the presence of genes that mediate the production of metallo-beta-lactamases. These strains were isolated from patients with nosocomial infection at the Intensive Care Unit of the Complejo Hospitalario "Ruiz y Paéz" of Ciudad Bolívar, Bolívar State, Venezuela, from 2003 to 2006. In all isolates a metallo-enzyme activity was detected by using the double disk synergism test. PCR amplification of genes encoding the families IMP, VIM and SPM metallo-beta-lactamases showed the presence of a blaVIM gene in all strains studied. DNA sequencing revealed that all isolates showed the presence of blaVIM-2. These results suggest that it is necessary to keep these strains under epidemiologic surveillance, establish laboratory strategies for opportune detection and the implementation of new policies to ensure the appropriate use of antibiotics in this institution.

Acute diarrhea is still one of the main causes of disease in developing countries. At the National Reference Laboratory for Acute Diarrhoeal Diseases, of the "Pedro Kourí" Tropical Medicine Institute, 54 Plesiomonas shigelloides strains were serotyped. As a result, the circulation of four new serotypes (O20:H2, 056:H18, 071 :H31,081 :H22) was detected. The most common antigenic variant was 094:H3. In addition, the susceptibility pattern to 21 antimicrobial agents (AA) was studied. Highest percentages of resistance were observed to ampicillin (77.7%), tetracycline (29.2%), and erythromycin (18.5%) while, to all other AA the resistance percentages were under 33%. There was no evidence of association between the serotypes and the multi-resistance patterns present in the strains under study. The frequency of virulence factors was determined: 21.15% of the strains turned out to be ss-haemolytic; 73.7% showed the presence of biofilm and 92.31% were hydrophobic. In 17.3% of the strains, the three virulence factors analysed were present. When establishing the relationship among the different virulence factors and the serotypes of the strains through cross reaction with the Shigella genus, there was evidence that 93.3% of the strains showed at least one of the virulence factors studied. Likewise, at least one of the virulence factors analysed was present in 90.9% of the multi-resistant strains.

The objective of this multicenter study was to determine tigecycline susceptibility rates, measured by agar diffusion, in nine hospitals in Santiago and to compare these rates with other antimicrobials. Each center studied 20 strains per month. All intermediate and fully resistant strains as well as 10% of susceptibile strains were also studied by the broth microdilution method. Overall, 2301 strains were studied displaying the following susceptibility rates for tigecycline: 100% for Streptococcus sp, Enterococcus sp, and E. coli respectively, 99.8% for Staphylococcus sp, 93% for Klebsiella and 80% for Acinetobacter baumarmii. For Proteus, Providencia and Morganella the susceptibility rates were 4%. For cefotaxime-resistant Klebsiella and imipenem-resistant A. baumarmii susceptibility rates were 95% and 80% respectively. The agar diffusion and broth dilution method were 100% concordant for tigecycline susceptible strains but only 27% for resistant or intermediate strains represented mostly by Acinetobacter baumannii. The majority of these strains (57/59) proved to be susceptible after retesting. The great majority (96,6%) of strains tested from nine Chilean hospitals proved to be susceptible to tigecycline with exception for Proteus, Providencia and Morganella (66% resistance). Using the agar diffusion method for measuring tigecycline susceptibility to A. baumannii may be misleading.

Objective: To typify by molecular and phenotypical methods, MRSA strains, isolated from patients and nurses to establish their possible clonal origin., Materials and Methods: 50 MRSA strains isolated in a teaching hospital in Maracaibo (Venezuela) were analyzed. The typification of MRSA strains was performed by means of pulsed-field gel electrophoresis (PFGE) and antibiotyping., Results: In patients, 12 clusters (I-XII) and 19 antibiotypes were found; whereas in the health-care personnel, 6 clusters (I-VI) and two antbiotypes were detected. There was no statistically significative association between antibiotypes and band patterns obtained by PFGE (p>0.05)., Conclusions: By means of detection of resistance markers and PFGE, it is feasible to discrimínate the nature of the clinical strains of MRSA. The obtained results show the possible nosocomial transmission of MRSA strains and their clonal spread in hospital departments, particularly at the ICU.

In Corrientes (Argentina), from January 2004 to April 2005, fecal samples from under 5 years-old children with acute diarrhea were collected; the stool samples were cultured onto selective media, and those colonies suspected to be Salmonella, Vibrio, Aeromonas, Shigella, or Escherichia coli O157 were identified. The antimicrobial susceptibility was assessed by the disk diffusion method. Among 590 samples, the 7.7% were positive (Salmonella spp 32.6% and Shigella spp 67.4%). Of 31 Shigella isolates, 81% were S. flexneri, and 19% were S. sonnei. S. flexneri serotype 2 was the more frequent. S. flexneri strains showed higher multidrug resistance than S. sonnei strains. Among the Salmonella enterica serotypes, S. typhimurium and S. newport were the most frequent. Two isolates of Salmonella presented with multidrug resistance. This paper was a contribution to the knowledge of bacterial gastroenteritis etiology in our region and it called the attention to the emergence of multidrug-resistant enteropathogenic strains.

Ninety strains of Pseudomonas aeruginosa isolated from pediatric patients with cystic fibrosis and respiratory infections at "William Soler" pediatric hospital were studied in the period from February to August, 2001, as part of a joint research project of the two hospitals. In vitro susceptibility of these strains to 10 antimicrobials, that is, azlocylline, ceftazidime, cefotaxime, ceftriaxone, gentamicin, tetracycline, ciprofloxacine, ofloxacine, chloranphenicol and trimethroprim/sulfamet-hoxazole was studied by Kirby-Bauer disk diffusion. The reference strain was ATCC 27853. The research work results showed that antimicrobial susceptibility values were within the allowable limits. Increased resistance to chloranphenicol (87.03%) and trimethoprim/sulfametoxazole (92.28%) as well as high sensitivity to azlocylline (85%), ceftazidime (87.09%), gentamicyn (94.09%), ciprofloxacine (94.8%) and ofloxacine (92.5%) were observed.

Margyricarpus pinnatus (Lam.) Kuntze, commonly name nigua or piquiyuyo in Ecuador, is a subshrub and grows primarily in the montane tropical biome. The chemical composition, antioxidant and antimicrobial activities of its essential oil from the leaves and flowers of plants grown in the Ecuadorian Andes were studied. The essential oil was obtained by hydrodistillation with a yield of 0.36 % v/m. With the aid of gas chromatography with mass and flame ionization detectors (GC-MS and GC-FID), 134 volatile constituents making up 97.5 % of the total oil constituents were identified. The major groups of compounds were aromatic compounds (51.9 %), oxygenated monoterpenes (16.3 %) and monoterpene hydrocarbons (12.5 %). The most abundant compounds were carvacrol (23.1%) and carvacryl acetate (19.2 %). Antioxidant activity was examined using DPPH and ABTS assays. The essential oil had a high scavenging effect and reduction of ferric ion capacity through FRAP assay. The results show that the essential oil scavenged DPPH∙ radical and ABTS·+ radical capacity as reflected by the IC50 values 1.18 ± 0.27 mg/mL and 4.47 ± 0.31mg/mL, respectively. These results agreed with the literature for essential oils that phenols possess high antioxidant activity. The antimicrobial activity was determined against four pathogenic bacterial strains and a pathogenic fungus strain using a modified agar-diffusion method. The results of the antimicrobial tests showed that Escherichia coli and Candida albicans were very sensitive to the effects of the essential oil

Essential oils are products from aromatic plants, which, due to their biological, allelopathic, antioxidant and antimicrobial effects, are important for food preservation. Kajikia audax is a fish of great commercial importance, however, it is highly perishable, requiring strategies to extend its shelf life. In vitro antimicrobial activity of Bursera graveolens essential oil was determined against microorganisms isolated from K. audax. Essential oil was extracted by steam distillation, obtaining a yield of 1.25%, a density of 0.83 g/ml and a refractive index of 1.473°, in addition, it was determined by GC-MS that D-limonene (77.6%) is the majority compound. Antimicrobial tests showed that the minimum inhibitory concentration (MIC) for Aeromonas salmonicida and Pichia kudriavzevii was 1.62 mg/ml and 6.48 mg/ml respectively, and the minimum bactericidal concentration (MBC) was 25.92 mg/ml for both microorganisms. Pseudomonas aeruginosa showed total resistance against the concentrations used. B. graveolens essential oil turned out to be a potential product to control the growth of microorganisms isolated from K. audax, however, it should be tested against species of the genera Vibrio, Flavobacterium, Shewanella, Lactococcus and Streptococcus that cause spoiling of hydrobiological products.

The objective of this study is to evaluate chemical characteristics, as well as antioxidant and antibacterial activities of organic compounds extracted from three Eucalyptus woods and Corymbia maculate wood using ethanol as a solvent. To obtain the ethanolic extracts, 15 g of a powdered wood sample was mixed with 150 mL of ethyl alcohol 99 % PA by constant mechanical stirring, which was further magnetically mixed at 60 ºC for 24 h. The extractives were analyzed by means of percent yield, Fourier-transform infrared spectrum, inhibitory index (measured after antimicrobial tests), antioxidant activity, and condensed tannins content. The Eucalyptus dunnii extract showed the highest percent yield. The infrared spectra of all the extractives presented similar profiles, with remarkable bands ascribed to the presence of lipophilic extracts, sterols, fatty acids, and other hydroxylated substances, such as carbohydrates and phenolic compounds. In all cases, the higher the concentration of the extractive was, the higher the antioxidant activity was. The antioxidant activity of Eucalyptus saligna extract stood out since overcame that of the positive control (ascorbic acid). Regarding the condensed tannins content, that extract from Eucalyptus grandis excelled.

Objective: The aim of the present study was to evaluate the hygienic-sanitary aspect of artisan and industrial ice creams and to analyze genetic variability and antimicrobial resistance in Escherichia coli isolates. Methods: Twenty-seven ice cream samples were purchased, detecting total coliforms at 30-35 °C by fermentation in multiple tubes. The positive tubes were inoculated in EC broth and in SS agar for the detection of Escherichia coli and Salmonella spp, respectively. To antimicrobial tests, the disk diffusion technique was used, discriminating levels of resistance. Genetic variability was diagnosed by the RAPD-PCR and ERIC-PCR techniques through the degree of polymorphism determined by the band pattern. Results and Discussion: From the microbiological samples, there was positivity for E. coli (48%) and Salmonella spp (22%). The antimicrobial resistance tests in E. coli diagnosed resistance to 85% of the obtained samples, and of these, 34% were multiresistant. A high degree of polymorphism was found in the RAPD-PCR and ERIC-PCR assays, demonstrating the great genetic variability among the bacteria. Conclusion: The samples presented unsatisfactory conditions, offering risks to consumers' health. The antibiotic sensitivity test expressed resistance and multiresistance, while the RAPD-PCR and ERIC-PCR assays indicated great genetic variability among the bacteria, considering multiple sources of contamination. Therefore, measures to control contamination prevention are considered important. DOI: 10.12957/demetra.2017.26754