Risk Factors Associated with Extended-Spectrum β-Lactamase-Producing Enterobacteriaceae Nosocomial Bloodstream Infections in a Tertiary Care Hospital: A Clinical and Molecular Analysis

Abstract

<b><i>Aim:</i></b> To describe the risk factors and molecular epidemiology of nosocomial bloodstream infections caused by extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae in a tertiary care hospital. <b><i>Methods:</i></b> Patients with enterobacteria-positive blood cultures were included. ESBL expression in the isolates was detected using the combination disk method. Antimicrobial susceptibility testing was performed using the disk diffusion method. <i>bla</i><sub>SHV</sub>, <i>bla</i><sub>TEM</sub>, and <i>bla</i><sub>CTX-M</sub> genes were identified in the isolated strains by PCR and sequencing. <i>Klebsiella pneumoniae</i> isolates were genotyped by PFGE. <b><i>Results:</i></b> Of the 90 isolates recovered, half were found to express ESBLs. Twenty-eight (62%) of these isolates were <i>K. pneumoniae,</i> 8 (18%) were <i>Escherichia coli,</i> 6 (13%) were <i>Enterobacter cloacae,</i> and 3 (7%) were <i>Serratia marcescens</i>. Multivariate logistic regression analysis showed that the only independent risk factor associated with infection by ESBL-producing strains was use of broad-spectrum cephalosporins. None of the isolates was resistant to imipenem. The<i> bla</i><sub>SHV5</sub> gene was detected in 84% of isolates, followed by <i>bla</i><sub>CTX-M15</sub> (27%), <i>bla</i><sub>SHV2</sub> (9%), and <i>bla</i><sub>SHV12</sub> (7%). PFGE identified six clones among the 28 ESBL-producing <i>K. pneumoniae </i>isolates. <b><i>Conclusions:</i></b> ESBL-producing <i>K. pneumoniae</i> clones were detected throughout the hospital. Use of broad-spectrum cephalosporins is the most important risk factor associated with the proliferation of ESBL-producing strains.

Antibiotic Resistance of Gram-Negative Bacilli Isolated from Pediatric Patients with Nosocomial Bloodstream Infections in a Mexican Tertiary Care Hospital

“…In another study, an antimicrobial susceptibility test was performed and none of the isolates was resistant to imipenem [20]. We also found low rates of resistance to imipenem for isolated Enterobacteriaceae family members.…”

One-Year Surveillance of ESKAPE Pathogens in an Intensive Care Unit of Monterrey, Mexico

“…ESBL-producing strains have been reported around the world in different genera of the Enterobacteriaceae family and have been isolated from different clinical specimens [27,28,29,30]. In this study, 39.6% of K. pneumoniae isolates were found to be ESBL producers.…”

High Diversity of CTX-M Extended-Spectrum β-Lactamases in Municipal Wastewater and Urban Wetlands

“…While no studies of CTX-M diversity in the cities of San Diego, California, and Tijuana, Mexico, are available for comparison, CTX-M-15 appears to be the predominant CTX-M variant in the state of California 2,40 and across Mexico. 18,35,36,49,50 The low representation of the globally predominant variant of CTX-M in the WWTPs and wetlands may reflect regional variation in its distribution or it may be due to a unique genetic context that impeded detection by our primers. Recall that the PCR primers used in this study anneal to sequences within the ISEcp1 element, thus only allowing for the amplification of those bla CTX-M genes located within this genetic context.…”