Objective:We assessed the antimicrobial resistance patterns of pathogens responsible for urinary tract infections (UTI) in outpatients in São Paulo, Brazil, as well as the Escherichia coli antimicrobial resistance trend. Materials and Methods: Outpatients urine cultures were collected from January 2000 to December 2003. Statistical analysis considered positive results for one bacterial species with colony count ≥ 100,000 CFU/mL. Stratification was done on age group and gender. Statistical tests used included chi-square and the chi-square test for trend to evaluate differences between susceptibility rates among age groups and ordering in the E. coli resistance rates per year, respectively. Results: There were 37,261 positive results with Enterobacteriaceae isolated in 32,530 (87.3%) and Gram-positive cocci in 2,570 (6.9%) cultures. E. coli had the highest prevalence (71.6%). Susceptibility tests were performed in 31,716 cultures. E. coli had elevated resistance rates (> 30%) to ampicillin, trimethoprim-sulfamethoxazole, and tetracycline. Significant differences between age groups and ordering among years were observed. Conclusions: The use of trimethoprim-sulfamethoxazole is precluded in the population studied due to elevated resistance rates (> 30%) among most prevalent pathogens. Significant resistance rate differences among age groups and years were observed, particularly for fluoroquinolones. Fluoroquinolones should be used with caution. Nitrofurantoin should be used as empirical therapy for primary, non-complicated urinary tract infections.

Establish the susceptibility pattern of Gram-negative bacteria causing infections in ICU patients, MYSTIC Program Brazil 2003. Gram-negative bacteria (n = 1,550) causing nosocomial infections were collected at 20 Brazilian centers. The central laboratory confirmed the identification and performed the susceptibility tests by Etest methodology (AB Biodisk, Solna, Sweden) for meropenem, imipenem, ciprofloxacin, ceftazidime, cefepime, cefotaxime, piperacillin/tazobactam, gentamicin, and tobramycin. Interpretation criteria used were according to National Committee for Clinical Laboratory Standards (NCCLS). Pseudomonas aeruginosa (30.3%) was the most frequent isolate, followed by E. coli (18.6%), Klebsiella pneumoniae (16.9%), Acitenobacter baumannii (8.8%), and Enterobacter cloacae (7.1%). Pseudomonas aeruginosa (n=470) isolates presented susceptibility rates of 64% to meropenem, 63.8% to piperacillin/tazobactam, 63.4% to amikacin, 58.7% to imipenem. Acitenobacter baumannii presented susceptibility rates to meropenem of 97.1%, and 73% to tobramycin. E. coli and K. pneumoniae were highly susceptible to both carbapenems. Carbapenem resistance among the Enterobacteriaceae is still rare in the region. Acitenobacter baumannii and P. aeruginosa presented elevated resistance rates to all antimicrobials. Since they play an important role in nosocomial infections in this environment, the use of empirical combination therapy to treat these pathogens may be justified.

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Pseudomonas aeruginosa (33%) was the most frequently isolated, followed by A. baumannii (17.1%), K. pneumoniae (12.1%), E. coli (10.5%), and E. cloacae (7.9%). Pseudomonas aeruginosa isolates had susceptibility rates of 67.5% to piperacillin/tazobactam, 59.8% to meropenem, 57.3% to imipenem. A. baumannii presented susceptibility rates to meropenem of 89.5%, 88.4% to imipenem, and 74.4% to tobramycin. E. coli and K. pneumoniae were fully susceptible to both carbapenems. Conclusions. Carbapenem resistance among Enterobacteriaceae is still rare in this region. A. baumannii and P. aeruginosa presented elevated resistance rates to all antimicrobials. Since these two bacterial species play an important role in nosocomial infections, the use of empirical combination therapy to treat these pathogens may be justified.

Surveillance programs are essential to detect the increase of antimicrobial resistance, and several different programs are being conducted in many countries. The RESISTNET is a surveillance program for bacterial resistance against several antimicrobial agents initiated in 1998 among Latin American countries. In Brazil, several centers were invited to join this surveillance and a total of 11 centers (6 from São Paulo and 5 from other states) participated in the study. All results were analyzed using the WHONET program. A total of 894 Escherichia coli, 386 Klebsiella pneumoniae, 70 Shigella spp and 57 Salmonella spp strains were analyzed in this study from April, 1998, to April, 1999. Susceptibility testing was performed by the disk diffusion method using NCCLS 1998 guidelines for several different drugs. For all strains, imipenem was the most effective drug (100% of the strains were susceptible). Klebsiella pneumoniae presented a high resistance rate to ampicillin (96.4%). The rate of probable ESBL producers among K. pneumoniae strains was 36.3%, most of them being isolated from catheters (58.8%). Among all Escherichia coli strains analyzed, the highest resistance rate was found for trimethoprim/ sulfamethoxazole (46.9%) and the majority of the resistant strains were isolated from urine samples (47.8%). Among Salmonella spp, the resistance rates were low for all antibiotics tested. For Shigella spp strains there was a high resistance to trimethoprim/sulfamethoxazole (80.0%). No resistance to ceftriaxone was observed in these strains. Surveillance of antimicrobial resistance is critical for the successful management of infectious diseases. The results of this survey show significant resistance rates among these bacteria which are responsible for several types of human infections.