Methods: Patients with KPLA were retrospectively identified at Taipei Veterans General Hospital during January 2013 to February 2018. Capsular genotypes were analyzed in all K. pneumoniae isolates. Antimicrobial resistant mechanisms were determined for MDR isolates. Pulse-field gel electrophoresis (PFGE), conjugation experiment and in vivo mice lethality were determined on the strains from a patient with recurrent infection.
Results: During the study period, a total of 211 patients with KPLA, and 5 patients with recurrence were identified. Most of K. pneumoniae isolates (n=175, 83.3 %) belonged to capsular type K1/K2/K5/K20/K54/K57. Nineteen MDR strains were identified and 15 of them had virulent capsular types (K1=7, K2=5, K5=2, K54=1). The major resistance mechanisms of these MDR strains involved the presence of β-lactamases and the overexpression of efflux pumps. The in-hospital mortality of KPLA caused by MDR strains was not significantly higher than wild-type stains (10.53% versus 4.69%, p=0.275). In a case with recurrent KPLA, the recurrent capsular type K1 strain (TVGHKP2611) with blaSHV-12 was genetically identical to the primary wild-type resistance strain (TVGHKP2329) by PFGE. The SHV-12-carrying plasmid from TVGHKP2611 was successfully conjugated to Eschericia coli J53. TVGHKP2611 retained high virulence similar to TVGHKP2329 in mice lethality study (median lethal dose < 500 CFU) despite carrying the resistance determinant.
Conclusion: MDR K. pneumoniae strains belonging to virulent capsular types have emerged in KPLA. One SHV-12 producing capsular K1 strain causing recurrent KPLA retained its high virulence, which signals this highly pathogenic and resistant strain could be a major concern in the future.
Y. T. Lin,
C. Chuang, None
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