Antibiotic-resistant gram-negative bacteria in hospitalized children

"Silent" dissemination of Klebsiella pneumoniae isolates bearing K. pneumoniae carbapenemase in a long-term care facility for children and young adults in Northeast Ohio

BACKGROUND

Klebsiella pneumoniae isolates harboring the K. pneumoniae carbapenemase gene (bla(KPC)) are creating a significant healthcare threat in both acute and long-term care facilities (LTCFs). As part of a study conducted in 2004 to determine the risk of stool colonization with extended-spectrum cephalosporin-resistant gram-negative bacteria, 12 isolates of K. pneumoniae that exhibited nonsusceptibility to extended-spectrum cephalosporins were detected. All were gastrointestinal carriage isolates that were not associated with infection.

METHODS

Reassessment of the carbapenem minimum inhibitory concentrations using revised 2011 Clinical Laboratory Standards Institute breakpoints uncovered carbapenem resistance. To further investigate, a DNA microarray assay, PCR-sequencing of bla genes, immunoblotting, repetitive-sequence-based PCR (rep-PCR) and multilocus sequence typing (MLST) were performed.

RESULTS

The DNA microarray detected bla(KPC) in all 12 isolates, and bla(KPC-3) was identified by PCR amplification and sequencing of the amplicon. In addition, a bla(SHV-11) gene was detected in all isolates. Immunoblotting revealed "low-level" production of the K. pneumoniae carbapenemase, and rep-PCR indicated that all bla(KPC-3)-positive K. pneumoniae strains were genetically related (≥98% similar). According to MLST, all isolates belonged to sequence type 36. This sequence type has not been previously linked with bla(KPC) carriage. Plasmids from 3 representative isolates readily transferred the bla(KPC-3) to Escherichia coli J-53 recipients.

CONCLUSIONS

Our findings reveal the "silent" dissemination of bla(KPC-3) as part of Tn4401b on a mobile plasmid in Northeast Ohio nearly a decade ago and establish the first report, to our knowledge, of K. pneumoniae containing bla(KPC-3) in an LTCF caring for neurologically impaired children and young adults.

Antibiotic-resistant organisms in the neonatal intensive care unit

Neonates, particularly those born prematurely, are at an increased risk of bacterial infection. Empiric treatment with antimicrobials occurs frequently in the neonatal intensive care unit (NICU). Repeated and/or prolonged courses of antibiotic exposure have resulted in an increase in the prevalence of hospital-acquired, antibiotic-resistant organisms such as methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus, and multidrug-resistant Gram-negative rods. As bacterial strains become increasingly resistant to standard antimicrobial therapy, measures to control and prevent this problem are essential. Current efforts have focused on monitoring and restricting the use of antimicrobials, proper hand hygiene, evaluation of potential reservoirs of bacterial acquisition and transmission, cohorting and isolation of colonized infants, decolonization strategies, and fostering of effective inter- and intrahospital communication.