Prevalence of resistance and molecular characterization of extended spectrum beta-lactamase (ESBL)-producing bacteria isolated in a hospital in Southern Brazil

Infectious diseases are a major cause of morbidity worldwide, and the indiscriminate use of antibiotics favors the development of bacterial resistance mechanisms, making it difficult to control infection. This study aimed to determine the prevalence of bacterial infection, their antibiotic resistance genes and extended spectrum beta-lactamase (ESBL)-producing genes. It was divided into two stages. The first stage was a retrospective analysis of infections by multidrug-resistant bacteria in a hospital, from January 2011 to June 2012. The most prevalent isolates were selected for verification of ESBL-producing related genes. The analysis of 374 samples showed that tracheal aspirates showed the highest infection rate, followed by urine and sputum. The most prevalent bacteria were Acinetobacter sp., Klebsiella sp., Pseudomonas aeruginosa and Staphylococcus aureus. Bacteria resistant to a large number of antibiotics were Klebsiella sp., Acinetobacter sp., Enterobacter sp., Escherichia coli, Serratia sp., Pseudomonas sp. and S. aureus. Of the 62 isolates, 43.54% were classified as ESBL-producing. The second stage was molecular analysis, which showed that TEM gene was present in 70.96, 56.45% for SHV and 90.32% for CTX-M gene. As for CTX family groups, 22.58% were CTX-M1, 14.51% CTX-M2 and 24.19% CTX-M9. This study showed a high incidence of infection caused by multidrug-resistant bacteria and a high prevalence of CTX-M and TEM genes.