Background: Klebsiella pneumoniae  has been the leading causative pathogen for adult bacterial meningitis in several Asian countries. The clinical and microbiological characteristics of K. pneumoniae  meningitis in mainland China are still unknown.
Materials and methods: The clinical data of patients with K. pneumoniae  meningitis from January 2011 to July 2017 in a tertiary hospital were retrospectively evaluated. The isolates were tested for antibiotic-resistance genes, virulence-associated genes, and molecular subtypes. Hypervirulent K. pneumoniae  (hvKP) was defined as the presence of pLVPK-like virulence plasmid.
Results: During the study period, a total of 48 patients with meningitis caused by K. pneumoniae  were identified, accounting for 21.2% (48/226) of Gram-negative bacilli meningitis. Of the 44 available isolates, 65.9% (29/44) were carbapenem resistant, and all except one harbored bla _KPC-2. K64 was the most common serotype (n=13), followed by K47 (n=11) and K1 (n=5). The pLVPK-related genetic loci were found in about half of isolates (iutA  : 56.8%, iucA  : 56.8%, rmpA2  :50.0%, rmpA  : 43.2%, and iroN  : 40.9%). Twenty-two strains carrying pLVPK-derived virulence plasmid were defined as hvKP. Notably, the coexistence of bla _KPC-2-encoding plasmid and the pLVPK-derived virulence plasmid was detected in 15 strains (34.1%, 15/44), suggesting K. pneumoniae  carbapenemase-2 (KPC-2)-producing hvKP. The proportion of KPC-2-producing hvKP by year increased remarkably from 0% (2011) to 71.4% (2017). Of the 15 KPC-2-producing hvKP strains, 80.0% (12/15) were assigned to sequence type 11 and 2 strains (13.3%) belonged to clonal complex 23. Most of the patients infected with KPC-2-producing hvKP had preceding postneurosurgical state (93.3%, 14/15) and severe pneumonia (73.3%, 11/15). All the cases (100%, 15/15) had fatal outcome.
Conclusion: The high prevalence and mortality of K. pneumoniae , especially KPC-2-producing hvKP meningitis, in China should be of concern. The implementation of epidemiological surveillance and identification of an effective clinical treatment are paramount.
Keywords: meningitis, hypervirulent K. pneumonia , bla _KPC-2, rmpA2 , pLVPK-like virulence plasmid