RESUMO
OBJECTIVES: Hypermucoviscous Klebsiella pneumoniae (HMKP) has been increasingly observed among clinical isolates. This study sought to examine the microbiological and epidemiological characteristics of HMKP strains in a tertiary hospital in Hangzhou, China. METHODS: HMKP isolates were collected and were identified via matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF/MS). A string test was performed for the hypermucoviscous phenotype. Susceptibility to various antimicrobial agents was determined. Multilocus sequence typing (MLST), capsular serotypes and virulence-associated genes of HMKP isolates were assessed. RESULTS: A total of 42 HMKP strains with a positive string test were collected, of which 32 (76.2%) were carbapenem-susceptible HMKP (CS-HMKP) and 10 (23.8%) were carbapenem-resistant HMKP (CR-HMKP). CS-HMKP strains were more susceptible to antimicrobial agents than CR-HMKP strains. Capsular serotypes K1 (38.1%; 16/42) and K2 (11.9%; 5/42) were the main capsular serotypes of all HMKP isolates. K57 was first reported in CR-HMKP strains. ST163 was the main sequence type (37.5%; 12/32) among CS-HMKP strains, whilst ST11 was unique to CR-HMKP strains. The regulator of the mucoid phenotype A gene (rmpA) and other virulence factors (allS, kfu, iutA, entB, iroN, fimH and wabG) were present in >80% of HMKP strains. Patients with CR-HMKP strains had a higher mortality rate than those with CS-HMKP strains. CONCLUSION: Capsular serotypes K1 and K2 were the main capsular serotypes of the isolated HMKP strains. The emergence of CR-HMKP should be a concern as it was associated with an increased mortality rate, especially for ST11 CR-HMKP strains, demonstrating the global epidemic of carbapenem resistance.