BACKGROUND

Ventilator-associated pneumonia (VAP) is a common nosocomial infection associated with high morbidity due to multidrug-resistant (MDR) pathogens. The purpose of this study was to determine the occurrence of extended-spectrum β-lactamase (ESBL) genes, especially , in ()-associated VAP and to investigate the antimicrobial resistance patterns and molecular epidemiological characteristics of strains.

MATERIALS AND METHODS

From January 2013 to December 2015, we retrospectively collected 89 VAP-causing isolates from tertiary-care hospitals in China, among which ESBL-producing strains were assessed for antimicrobial susceptibility. Several antibiotic resistance genes of clinical relevance in isolates producing ESBL were investigated. Polymerase chain reaction (PCR) and DNA sequencing were employed to characterize the genetic contexts of . Conjugative plasmids carrying were obtained by mating and further subjected to replicon typing. The genetic relatedness of isolates was assessed by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing.

RESULTS

All of the 30 ESBL-producing isolates identified displayed MDR phenotype, with , , , and detected in 21, 21, 1, and 20 isolates, respectively. was the most prevalent ESBL gene (19/30, 63.33%), and IS was detected 48 bp upstream of 15 genes. Based on S1-PFGE analyses, 25 isolates exhibited different plasmid profiles, ranging from ~70 to 320 kb. The with and genes and the IS element from eight isolates were co-transferrable to recipients via conjugation, with IncFIB, IncFIC, and IncFII being the most prevalent replicons. Twenty different PFGE patterns and 11 sequence types were identified, with ST304 being dominant.

CONCLUSION

This work reports the emergence of in -induced VAP in China. We showed that IncFIB, IncFIC, and/or IncFII plasmids carrying with , resistance genes, and the IS element mediate the local prevalence in associated VAP.