Occurrence and characterization of hyperviscous K1 and K2 serotype in Klebsiella pneumoniae .

BACKGROUND: Klebsiella pneumoniae causes both nosocomial and community-associated infections. Hypervirulent K. pneumoniae (hvKP), new variant of K. pneumoniae , can cause invasive infections in young healthy individuals as well as in the immunocompromised population. Hypervirulent strains frequently belong to capsular serotypes K1 or K2. Emergence of antimicrobial resistance in hvKP is a cause for concern.

AIM AND OBJECTIVE: The present study was done to detect the K1 and K2 serotypes among clinical isolates of K. pneumoniae , spectrum of infections caused by them and presence of common beta-lactamases encoding genes in them.

MATERIALS AND METHODS: A total of 370 isolates of K. pneumoniae , isolated from various clinical samples over a period of 1 year was included in this study. Antibiotic susceptibility testing to various classes of antimicrobials was done as per Clinical and Laboratory Standard Institute guidelines. The presence of K2A (specific to serotype K2), magA (specific to serotype K1), and rmpA genes was detected by multiplex polymerase chain reaction (PCR). Extended-spectrum beta-lactamases (TEM, SHV, and CTX-M), plasmid-mediated AmpCs (MOX, CIT, DHA, ACC, EBC, and FOX), and carbapenemase genes (IMP, VIM, NDM, KPC, and OXA-48) were also determined by PCR.

RESULTS: Among the 370 isolates, 8 harbored K2A gene and one harbored magA . rmpA gene was detected in three isolates along with K1 or K2 serotypes. Seven K2A -positive isolates were resistant to one or more classes of antimicrobials. The studied ESBL genes were present in four isolates. Two isolates harbored carbapenemase genes (NDM-1, OXA-48) along with ESBLs.

CONCLUSION: K2 serotype is more prevalent among hvKP isolates. They can harbor ESBLs and Carbapenemase genes. K1 serotype is rather uncommon in K. pneumoniae . Acquisition of multidrug-resistant genes by these strains adds to their virulence and limits the treatment options.