Pathogenic potential of environmental Klebsiella pneumoniae isolates

Abstract

Klebsiella pneumoniae is an important opportunistic pathogen and a frequent cause of nosocomial infections. K. pneumoniae infections can occur at nearly any body site; however, urinary tract infections and infections of the respiratory tract predominate. Infections are frequently preceded by gastrointestinal colonization, and the gastrointestinal tract is believed to be the most important reservoir for transmission of the bacteria. In contrast to many other bacterial pathogens, K. pneumoniae is ubiquitous in nature. Several studies have described Klebsiella isolates of environmental origin to be nearly identical to clinical isolates with respect to several phenotypic properties. However, the pathogenic potential of environmental K. pneumoniae isolates is essentially unknown. We have evaluated the virulence of K. pneumoniae strains of environmental and clinical origin directly in animal models, i.e. in urinary tract infection and intestinal colonization models. Furthermore, the ability to adhere to and invade human epithelial cell lines was examined. Although strain-to-strain differences were observed in the individual infection models, overall, strains of environmental origin were found to be as virulent as strains of clinical origin. The ubiquity of K. pneumoniae in nature and the general ability of K. pneumoniae strains to infect susceptible hosts might explain the high frequency of opportunistic infections caused by this species.

Molecular Epidemiology of TwoKlebsiella pneumoniaeMastitis Outbreaks on a Dairy Farm in New York State

“…The environment can contain a large variety of K. pneumoniae strains with pathogenic potential (26,30), and mastitis cases within a dairy herd are usually caused by many different strains (3,(23)(24)(25). Predominance of a single K. pneumoniae strain, such as RAPD type A in the first outbreak of CM described here, is unusual.…”

“…In the case of gram-positive mastitis pathogens, host adaptation of strains is thought to contribute to strain-specific epidemiology. For K. pneumoniae, there is no indication that host or niche adaptation exists (25,30). Mastitis outbreaks due to a single strain of Klebsiella may be the result of an unknown mechanism of host or niche adaptation or the result of a chance accumulation of events.…”

Genomic analysis of diversity, population structure, virulence, and antimicrobial resistance in Klebsiella pneumoniae , an urgent threat to public health

“…Moreover it can thrive in a range of plant hosts and environmental niches, including water, soil, and plant matter (4,5,11). Although it is clear that K. pneumoniae is genetically and phenotypically diverse (12,13), previous efforts to identify specific features that can distinguish human clinical isolates from plant, animal, or environmental isolates have yielded no markers of humanspecific lineages (14). Three distinct phylogroups of K. pneumoniaeKpI, KpII, and KpIII-have been defined based on sequencing of a small number of genes (15,16), and it has been proposed that these phylogroups be redesignated as distinct species, namely, K. pneumoniae (KpI), K. quasipneumoniae (KpII) (17), and K. variicola (KpIII) (18); however, all three cause infections in humans (15,19).…”

Characterization of Klebsiella isolates by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and determination of antimicrobial resistance with VITEK 2 advanced expert system (AES)

“…is a gram-negative bacillus that belongs to the family Enterobacteriaceae and causes severe nosocomial infections, including pneumonia and primary blood stream infections (1)(2)(3). Klebsiella pneumoniae and Klebsiella oxytoca are ubiquitous in nature and have two common habitats; one is the environment, including surface water, soils, sewage, and plants (4,5) and the other is humans, including the skin, bowels, bladder, and respiratory tract (3,6,7). It can easily survive in hospitals and is usually transmitted from patient to patient via the hands of health care personnel (3,8,9).…”