A small study by researchers at The Johns Hopkins University School of Medicine has identified risk factors for extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae carriage in patients admitted to a pediatric intensive care unit (PICU).
In a letter yesterday in Infection Control and Hospital Epidemiology, the researchers describe a case-control study among patients admitted to The Johns Hopkins Hospital PICU. In the study, rectal swabs were obtained from all children admitted to the unit from July 2014 to January 2015, and genomic DNA was extracted from all isolates that demonstrated decreased susceptibility to ceftriaxone.
Further molecular analysis was conducted to identify and sequence beta-lactamase-encoding genes. Case-patients were defined as children whose admission surveillance culture grew an ESBL-producing organism.
Of the 854 children who were swabbed upon admission, 24 were found to be colonized with ESBLs (2.8%). ESBL-producing Escherichia coli sequence type (ST)131 was identified in 63% of isolates, and blaCTX-M genes were identified in 96% of isolates.
When the 24 ESBL-positive children were matched with 72 ESBL-negative control patients, the researchers found that within the previous 6 months, the case-patients were more likely to have had previous ESBL colonization or infection (17% vs. 1%) or to have been hospitalized in a high-ESBL-burden country (17% vs. 1%). Case-patients were also more likely to have had chemotherapy (odds ratio [OR], 4.6) or a hematopoietic stem cell transplantation (OR, 10.1).
Nine case patients developed invasive infections with ESBL-producing organisms, compared with none of the control patients.
Identifying at-risk children
The researchers say the findings are significant because ESBL-producing organisms are frequently resistant to antibiotics used in empiric sepsis regimens, and genes encoding ESBLs often carry other antibiotic resistance mechanisms. In addition, colonization with ESBLs has been associated with subsequent invasive infections, and PICU patients are a particularly high-risk cohort for such infections.
While noting that the findings need to be replicated in larger and more diverse settings, the authors of the letter argue that targeted screening of high-risk patients, in addition to reviewing culture histories, may be a reasonable consideration to identify ESBL colonization.
"As the incidence of ESBLs increases and they contribute to considerable morbidity and mortality, it is imperative to develop systems to identify children who are most at risk of infections caused by ESBL-producing organisms," they write.
Dec 5 Infect Control Hosp Epidemiol letter to the editor