Infection and colonization by Gram-negative bacilli in neonates hospitalized in High Risk Nursery at Uberlandia Federal University Hospital: etiology, resistant phenotypes and risk factors

the aims of this study were to determine endemic and epidemic infection due to gram-negative bacilli, risk factors associated with colonization and infection by these organisms and the resistance phenotypes (esbl, ampc) in neonates admitted in a high risk nursery. the study was conducted during a 21 month period and included: a prospective study to evaluate the neonates with hospital infection and the use of third-generation cephalosporins; a case-control study to determine the risk factors associated with colonization/infection. rectal and oropharynx cultures were also performed in four opportunities (september and november 2001, february and august 2002). the isolates for which the resistance of ceftazidime was 2 mg/ml were suspected of producing esbl or ampc b-lactamases. the incidence of infection by gram-negative bacilli was 2.4% (89/3.708 neonates), and sepsis (35.9%) and conjunctivitis (31.4%) were the most common infections. the endemic infections were more prevalent (73.9%) and usually associated with enterobacteriaceae (95.5%), being these organisms also related to colonization, corresponding mainly to isolates of enterobacter spp. and klebsiella spp. two outbreaks of pseudomonas aeruginosa (n=10) and acinetobacter baumannii (n=11) were identified during the survey. univariate analysis showed that risk factors for gram-negative bacilli infection considered significant included: the length of stay before infection/colonization, exposure to antimicrobial agents, mechanical ventilation, central venous catheters, parenteral nutrition and surgery. the majority of resistance to ceftazidime among enterobacteriaceae isolates (80.9%) was from esbl phenotype. administration of third-generation cephalosporins (ceftriaxone) led to the emergence of these multiresistant gram-negative bacilli in the neonatal unit.