Molecular characterisation for clonality and transmission dynamics of an outbreak of Klebsiella pneumoniae amongst neonates in a tertiary care centre in South India

Abstract

Purpose:: Sepsis is a significant cause of morbidity and mortality amongst neonates. Klebsiella pneumoniae is a common cause of nosocomial outbreaks causing bacteraemia and having potential of acquiring plasmids enhancing antimicrobial resistance. In the present study, we investigate K. pneumoniae outbreak causing bacteraemia amongst neonates over a span of 2 months. Isolates were characterised for antimicrobial resistance, virulence, molecular typing for clonality and plasmid typing for transmission dynamics, and patient outcome was investigated.

Methods: Thirteen isolates of K. pneumoniae were obtained during October-November 2016. Antimicrobial susceptibility testing was performed, and multiplex polymerase chain reaction (PCR) for β-lactamases and PCR for ompK35 and ompK36 were performed. To study hypervirulence, string test and PCR for rmpA and rmpA2 were performed. Multilocus sequence typing and Inc plasmid typing were carried out to study transmission dynamics.

Results: Amongst 13 isolates, all isolates harboured bla_SHVand bla_TEM; 12 isolates carried bla_CTX-M-1. ompK35 was present in all, but ompK36 was absent in 12 isolates. Ten isolates belonged to ST48, 6 amongst which contained IncFII (K) plasmid. One isolate each belonged to ST29, ST111 and ST2647 (novel clone). None of the isolates was hypervirulent.

Conclusion: Extended-spectrum β-lactamase K. pneumoniae is commonly seen in Indian hospitals and main mechanisms being production of SHV, TEM and CTX-M enzymes as seen in the present study. Outer membrane porins contribute significantly to antimicrobial resistance. Emergence of new clones such as ST2647 implies continuous evolution of the organism and also potential for rapid genetic recombination leading to multidrug resistance. Outbreaks amongst neonates lead to fatal outcome, and stringent hospital infection control is necessary.

Keywords: Bacteraemia; Klebsiella pneumoniae; ST48; extended-spectrum β-lactamases; neonates; outbreak.