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Nosocomial, Multidrug-Resistant Klebsiella pneumoniae Strains Isolated from Mexico City Produce Robust Biofilms on Abiotic Surfaces but Not on Human Lung Cells.

ABSTRACT: BACKGROUND:Klebsiella pneumoniae (Kpn) strains are a leading cause of hospital-acquired infections, including ventilator-associated pneumonia. Resistance to antibiotics, biofilm formation, and the production of certain fimbriae play an important role in the pathogenesis. AIM:We investigated the genetic relatedness, antibiotic resistance, virulence potential, and ability to form biofilms of Kpn strains isolated from hospital-acquired infections (n?=?76). Strains were isolated at three major hospitals serving the largest metropolitan urban area in Mexico City, Mexico. RESULTS:Enterobacterial repetitive intergenic consensus (ERIC)-PCR demonstrated that clonal groups predominate in each hospital. Selected strains chosen from clonal groups (n?=?47) were multidrug resistant (MDR, 83%), although the majority (?70%) were susceptible to carbapenems. All strains produced robust biofilms on abiotic surfaces, and ?90% harbored adhesin genes fimH, mrkA, and ecpA. The ultrastructure of biofilms was further studied by high-resolution confocal microscopy. The average height of Kpn biofilms on abiotic surfaces was ?40??m. We then assessed formation of biofilms on human lung cells, as a surrogate of lung infection. While Kpn strains formed robust biofilms on abiotic surfaces, studies on lung cells revealed attachment to human cells but scarce formation of biofilms. Gene expression studies revealed a differential temporal expression of an adhesin (ecpA) and a capsule (galF) gene when biofilms were formed on different substrates. CONCLUSIONS:Kpn strains isolated from nosocomial infections in Mexico City are MDR, although the majority are still susceptible to carbapenems and form more robust biofilms on polystyrene in comparison to those formed on human cells.

SUBMITTER: Ostria-Hernandez ML

PROVIDER: S-EPMC5946738 | biostudies-literature | 2018 May

REPOSITORIES: biostudies-literature

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Nosocomial, Multidrug-Resistant Klebsiella pneumoniae Strains Isolated from Mexico City Produce Robust Biofilms on Abiotic Surfaces but Not on Human Lung Cells.

Ostria-Hernandez Martha Lorena ML Juárez-de la Rosa Karla Cecilia KC Arzate-Barbosa Patricia P Lara-Hernández Antonino A Sakai Fuminori F Ibarra J Antonio JA Castro-Escarpulli Graciela G Vidal Jorge E JE

Microbial drug resistance (Larchmont, N.Y.) 20170915 4

<h4>Background</h4>Klebsiella pneumoniae (Kpn) strains are a leading cause of hospital-acquired infections, including ventilator-associated pneumonia. Resistance to antibiotics, biofilm formation, and the production of certain fimbriae play an important role in the pathogenesis.<h4>Aim</h4>We investigated the genetic relatedness, antibiotic resistance, virulence potential, and ability to form biofilms of Kpn strains isolated from hospital-acquired infections (n = 76). Strains were isolated at th ...[more]

PMID: 28915364

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Project description:The continuous expansion of nosocomial infections around the globe has become a precarious situation. Key challenges include mounting dissemination of multiple resistances to antibiotics, the easy transmission and the growing mortality rates of hospital-acquired bacterial diseases. Thus, new ways to rapidly detect these infections are vital. Consequently, researchers around the globe pursue innovative approaches for point-of-care devices. In many cases the specific interaction of an antigen and a corresponding antibody is pivotal. However, the knowledge about suitable antigens is lacking. The aim of this study was to identify novel antigens as specific diagnostic markers. Additionally, these proteins might be aptly used for the generation of vaccines to improve current treatment options. Hence, a cDNA-based expression library was constructed and screened via microarrays to detect novel antigens of Klebsiella pneumoniae, a prominent agent of nosocomial infections well-known for its extensive antibiotics resistance, especially by extended-spectrum beta-lactamases (ESBL). After screening 1536 clones, 14 previously unknown immunogenic proteins were identified. Subsequently, each protein was expressed in full-length and its immunodominant character examined by ELISA and microarray analyses. Consequently, six proteins were selected for epitope mapping and three thereof possessed linear epitopes. After specificity analysis, homology survey and 3d structural modelling, one epitope sequence GAVVALSTTFA of KPN_00363, an ion channel protein, was identified harboring specificity for K. pneumoniae. The remaining epitopes showed ambiguous results regarding the specificity for K. pneumoniae. The approach adopted herein has been successfully utilized to discover novel antigens of Campylobacter jejuni and Salmonella enterica antigens before. Now, we have transferred this knowledge to the key nosocomial agent, K. pneumoniae. By identifying several novel antigens and their linear epitope sites, we have paved the way for crucial future research and applications including the design of point-of-care devices, vaccine development and serological screenings for a highly relevant nosocomial pathogen.

Project description:Klebsiella pneumoniae is emerging as an important nosocomial pathogen due to its rapidly increasing multidrug resistance, which has led to a renewed interest in polymyxin antibiotics, such as colistin, as antibiotics of last resort. However, heteroresistance (i.e., the presence of a subpopulation of resistant bacteria in an otherwise susceptible culture) may hamper the effectiveness of colistin treatment in patients. In a previous study, we showed that colistin resistance among extended-spectrum-beta-lactamase (ESBL)-producing K. pneumoniae isolates emerged after the introduction of selective digestive tract decontamination (SDD) in an intensive care unit (ICU). In this study, we investigated heteroresistance to colistin among ESBL-producing K. pneumoniae isolates by using population analysis profiles (PAPs). We used whole-genome sequencing (WGS) to identify the mutations that were associated with the emergence of colistin resistance in these K. pneumoniae isolates. We found five heteroresistant subpopulations, with colistin MICs ranging from 8 to 64 mg/liter, which were derived from five clonally related, colistin-susceptible clinical isolates. WGS revealed the presence of mutations in the lpxM, mgrB, phoQ, and yciM genes in colistin-resistant K. pneumoniae isolates. In two strains, mgrB was inactivated by an IS3-like or ISKpn14 insertion sequence element. Complementation in trans with the wild-type mgrB gene resulted in these strains reverting to colistin susceptibility. The MICs for colistin-susceptible strains increased 2- to 4-fold in the presence of the mutated phoQ, lpxM, and yciM alleles. In conclusion, the present study indicates that heteroresistant K. pneumoniae subpopulations may be selected for upon exposure to colistin. Mutations in mgrB and phoQ have previously been associated with colistin resistance, but we provide experimental evidence for roles of mutations in the yciM and lpxM genes in the emergence of colistin resistance in K. pneumoniae.

Dataset Information

Nosocomial, Multidrug-Resistant Klebsiella pneumoniae Strains Isolated from Mexico City Produce Robust Biofilms on Abiotic Surfaces but Not on Human Lung Cells.

Publications

Nosocomial, Multidrug-Resistant Klebsiella pneumoniae Strains Isolated from Mexico City Produce Robust Biofilms on Abiotic Surfaces but Not on Human Lung Cells.

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