The aim of this study was to determine the prevalence of vaginal Escherichia coli colonization and perianal carriage of Enterobacteriaceae resistant to third generation cephalosporins in pregnant women. Vaginal and perianal samples from 259 pregnant women were studied. Vaginal swabs were inoculated onto MacConkey agar plates and perianal swabs were inoculated onto CHROMagar extended-spectrum beta-lactamase (ESBL) plates. The minimal inhibitory concentration of the isolates was determined using the Epsilometer test method. The phenotypic detection of ESBLs was performed by the combined disc method using cefotaxime versus cefotaxime plus clavulanate. The prevalence of vaginal E. coli colonization during pregnancy was 14.3%. The resistance rate to ampicillin, gentamicin, and cefotaxime was 48.6, 10.8, and 0.8%, respectively. Enterobacteriaceae resistant to third generation cephalosporins were recovered in 7.3% of all perianal specimens. Among them, 5.4% of pregnant women were colonized with E. coli ESBL-producer strains. The present study revealed that colonization with Enterobacteriaceae resistant to third generation cephalosporins is significant in pregnancy. ESBL-producing E. coli were the most prevalent organisms. Screening strategies designed to monitor for ESBL-producing E. coli could be useful in endemic areas to prevent perinatal transmission and the introduction of multiresistant strains to the maternity ward.

Introduction: The aim of this study was to determine the prevalence of intestinal carriage of extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae and carbapenem-resistant Gram-negative bacilli in the community in Buenos Aires, Argentina. Methodology: Faecal samples from 164 non-hospitalized patients were cultured on CHROMagar KPC and CHROMagar ESBL plates. Isolates resistant to third-generation cephalosporins or carbapenems were selected for further study. The minimal inhibitory concentration (MIC) of the isolates was determined using the E-test method. The phenotypic detection of ESBLs and carbapenemases was performed using the double-disc synergy test. Results: The rate of faecal carriage of Enterobacteriaceae resistant to third-generation cephalosporins was 26.8%. Escherichia coli represented a large majority (75%) of the isolates recovered. Thirty-three ESBL-producing isolates were detected from 31 faecal samples (18.9% of the collected specimens). Eight carbapenem-resistant Gram-negative bacilli were recovered from eight specimens (4.9%). Conclusions: This study revealed a high prevalence of faecal carriage of multidrug-resistant Gram-negative bacteria, including ESBLs, in Buenos Aires. Therefore, the use of surveillance cultures will be helpful for tracking and monitoring the spread of ESBL-producing Enterobacteriaceae within community settings.

Introduction: Knowledge of the etiology and antimicrobial susceptibility patterns of uropathogens is important for determining the best treatment option. This study aimed to determine the distribution and antibiotic susceptibility patterns of bacterial strains isolated from adult male outpatients. Methodology: Between November 2012 and April 2013, 3,105 community urine samples were analyzed from adult male patients who attended the Laboratorio Hidalgo, Buenos Aires, Argentina. Antimicrobial susceptibility testing was performed by the Kirby-Bauer disc diffusion method. Isolates resistant to third generation cephalosporin were tested for extended-spectrum beta-lactamase (ESBL) production using the double-disk synergy test. Results: Of the 3,105 urine samples analyzed, 791 (25.5%) had significant bacteriuria. The frequency of positive urine cultures increased significantly with patient age. Escherichia coli was isolated most frequently (47.3%), followed by Enterococcus faecalis (13.6%), and Klebsiella pneumoniae (11.9%). Gram-negative organisms represented 78.8% of urinary pathogens. The highest activities against Gramnegative bacteria were found with imipenem (99.0%), amikacin (98.1%), ertapenem (94.2%), fosfomycin (90.7%), and piperacillintazobactam (90.1%). The frequencies of ESBLs among E. coli, K. pneumoniae, and P. mirabilis were 15.2 %, 22.3%, and 8%, respectively. Fosfomycin, piperacillin-tazobactam, and nitrofurantoin were most effective against Gram-positive organisms. Conclusions: Fosfomycin may be an excellent option for cystitis treatment in patients without risk factors, whereas piperacillin-tazobactam is preferred for the treatment of parenchymatous UTIs, complicated UTIs, and UTIs associated with risk factors. To ensure the optimal selection of antibiotics, physicians should have access to up-to-date information about the local prevalence of antimicrobial resistance.

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