Identification of Species and Capsular Types of Klebsiella Clinical Isolates, with Special Reference to Klebsiella planticola

Abstract

In the 77 reference strains for Klebsiella K types, there are 17 strains (22.1%) of Klebsiella planticola, 6 strains (7.8%) of Klebsiella oxytoca, 1 strain (1.3%) of Klebsiella terrigena, and 53 strains (68.8%) of Klebsiella pneumoniae. The species K. planticola, which was originally isolated from botanical and aquatic environments and hence thus named, was also identified at high incidence (81 strains, 18.5%) among the 439 recent clinical isolates of Klebsiella species. Among these K. planticola strains of hospital origin, 52 (64%) were isolated from sputum, 17 (21%) from urine, and the remaining 12 (15%) from other sources. The capsular types of these isolates were determined by the gel precipitation reaction. Seventy of 81 K. planticola isolates (86.4%) were typable by antisera to Klebsiella reference strains for K types and the K types of the clinical isolates distributed to 35 kinds of K types. The proportion of typable strains among clinical isolates of K. planticola was very similar to those in K. pneumoniae (87.5%) and K. oxytoca (86.0%).

Expression of putative virulence factors by clinical isolates of Klebsiella planticola

“…Its incidence among clinical isolates of Klebsiella spp. ranges from 3.5% to 19% [3,4,24]. The reasons for this emergence are unknown.…”

“…Although originally thought to be an exclusively environmental species without clinical significance, there is growing evidence that K. planticola should be regarded as an opportunist pathogen in hospitals [3,4,23,24]. Its incidence among clinical isolates of Klebsiella spp.…”

“…In 1981, a new species, K. planticola, was described [2]. Although K. planticola was originally thought to be restricted to aquatic, botanic and soil environments, recent studies report the isolation of this organism from human clinical specimens [3,4]. According to these findings, K. planticola occurs at a surprisingly high frequency of 3.5-18.5% among clinical isolates of Klebsiella spp.…”

Involvement of rcsB in Klebsiella K2 capsule synthesis in Escherichia coli K-12

“…Among at least 77 distinct capsular serotypes (17,20), Klebsiella pneumoniae capsular type 2 (K2) strains were most frequently isolated from patients with bacteremia (5, 9, 13). We found that K. pneumoniae K2 strains isolated from clinical specimens usually showed strong virulence for mice, with 50% lethal doses as low as 2 CFU when injected intraperitoneally, although there were a small number of encapsulated K. pneumoniae K2 strains which were avirulent for mice (16).…”

“…Deletion mutants were isolated by using a deletion kit (Nippon Gene Co., Ltd.), and DNA sequencing was performed by the dideoxy method (22). Rabbit antiserum against the Klebsiella K2 capsular polysaccharide was prepared by using K. pneumoniae Chedid (01:K2) as described previously (10,17 nodiffusion was performed as described previously (17). For the fluorescent-antibody staining technique, bacteria cultured in Luria broth at 30°C for 5 h were washed with PBS.…”