Community-onset Klebsiella pneumoniae pneumonia in Taiwan: clinical features of the disease and associated microbiological characteristics of isolates from pneumonia and nasopharynx

Abstract

Klebsiella pneumoniae is an important cause of community-onset pneumonia in Asian countries and South Africa. We investigated the clinical characteristics of K. pneumoniae causing community-onset pneumonia, and the associated microbiological features between K. pneumoniae isolates from pneumonia and those from the nasopharynx in Taiwan. This study was conducted at the Taipei Veterans General Hospital during July, 2012 to February, 2014. The clinical characteristics in patients with community-onset K. pneumoniae pneumonia were analyzed. K. pneumoniae isolates from the nasopharynx of adults attending otorhinolaryngology outpatient clinics were collected to compare their microbiological features with those from pneumonia. Capsular genotypes, antimicrobial susceptibility, and multilocus sequence type (MLST) were determined among these strains. Ninety-one patients with community-onset K. pneumoniae pneumonia were enrolled. We found a high mortality (29.7%) among these patients. Capsular types K1, K2, K5, K20, K54, and K57 accounted for ∼70% of the K. pneumoniae isolates causing pneumonia, and ∼70% of all the K. pneumoniae strains isolated from the nasopharynx of patients in outpatient clinics. The MLST profiles further demonstrated the genetic relatedness between most pneumonia isolates and those from the nasopharynx. In conclusion, our results show that community-onset pneumonia caused by K. pneumoniae was associated with high mortality and could have a reservoir in the nasopharynx. To tackle this high-mortality disease, the distribution of capsular types in the nasopharynx might have implications for future vaccine development.

Keywords: Klebsiella pneumoniae; MLST; capsular types; nasopharynx; pneumonia.

Figure 1

Size distribution of (A) trimmed, (B) non-redundant, (C) viral, redundant sequenced reads of the sequenced libraries.

Figure 2

RT-PCR validation of sRNA NGS for (A) Nepo-, Leafroll-, and Vitiviruses, (B) Tymoviruses, (C) viruses which presence is not routinely tested and (D) viroids. cDNA was synthetized from pooled RNA extracts representing each vineyard using random primer and used as templates for PCR reactions with published diagnostic primers or new ones designed according to the consensus sequence generated by mapping our small RNA reads to the reference genomes. To detect GRVFV we used cDNA generated with a GRVFV-specific primer. PCR products were analyzed by agarose gel electrophoresis. (M), GenRuler 100 bp+; (+C), cDNA containing the tested virus was used as positive, or (–C), water as negative control.

Figure 3

Validation of the sRNA NGS by Northern blot hybridization for A/GPGV, B/RBDV RNA1, and C/GSV. Four to five micrograms total RNA from pooled samples was separated on 1,2% agarose gel, blotted to Nytran membrane and hybridized with radioactively labeled virus specific probes. Relative gel loadings are indicated by ethidium bromide staining of ribosomal RNAs. (A) The presence of GPGV was investigated in all vineyards. In lane 1-13 library pools, in lane 14 plantation pool prepared from library 14-18 was used. RNA from grapevine (–C1) or Nicotiana benthamiana (–C2) not containing GPGV was used as negative control. (B)The presence of RBDV_RNA1 was investigated in 11_SZHU vineyard. RNA from library 3_HT, not containing this virus was used as negative control. (C)The presence of investigated in 1_TK vineyard. RNA from library 2_PH, not containing this virus was used as a negative control.