TAM mediates adaptation of carbapenem-resistant Klebsiella pneumoniae to antimicrobial stress during host colonization and infection

Abstract

Gram-negative pathogens, such as Klebsiella pneumoniae, remodel their outer membrane (OM) in response to stress to maintain its integrity as an effective barrier and thus to promote their survival in the host. The emergence of carbapenem-resistant K. pneumoniae (CR-Kp) strains that are resistant to virtually all antibiotics is an increasing clinical problem and OM impermeability has limited development of antimicrobial agents because higher molecular weight antibiotics cannot access sites of activity. Here, we demonstrate that TAM (translocation and assembly module) deletion increases CR-Kp OM permeability under stress conditions and enhances sensitivity to high-molecular weight antimicrobials. SILAC-based proteomic analyses revealed mis-localization of membrane proteins in the TAM deficient strain. Stress-induced sensitization enhances clearance of TAM-deficient CR-Kp from the gut lumen following fecal microbiota transplantation and from infection sites following pulmonary or systemic infection. Our study suggests that TAM, as a regulator of OM permeability, represents a potential target for development of agents that enhance the effectiveness of existing antibiotics.

Genomic and Immunological Characterization of Hypermucoviscous Carbapenem-Resistant Klebsiella pneumoniae ST25 Isolates from Northwest Argentina

“…Furthermore, it has been shown that K. pneumoniae strains deficient in the tamA gene are cleared more rapidly in respiratory-challenged mice. Animals challenged with tamA-deficient mutants had longer survival, lower bacterial counts in the lung, and less blood shedding compared to mice challenged with tamA-carrying K. pneumoniae [49]. Therefore, the presence of tamA in the genome of LABACER 01 and not in LABACER 27 could be associated with the ability of the former to colonize the lungs and spread to the blood of infected mice more efficiently.…”

“…K. pneumoniae can remodel its outer membrane in response to stress to maintain its integrity as a barrier and thus promote its survival in the infected host. This property has been associated with the presence of the tamA and tamB genes [49,50]. Furthermore, it has been shown that K. pneumoniae strains deficient in the tamA gene are cleared more rapidly in respiratory-challenged mice.…”

High Osmotic Stress Increases OmpK36 Expression through the Regulation of KbvR to Decrease the Antimicrobial Resistance of Klebsiella pneumoniae

“…Membrane permeability assay was performed by measuring the permeabilization of the outer membrane to N-phenyl-1-naphthylamine (NPN; Aladdin), as described by Jung et al ( 43 ). The overnight cultures were diluted by 1:100 into 3 mL of LB broth and grown to an OD 600 of 1.6.…”

A noncanonical chaperone interacts with drug efflux pumps during their assembly into bacterial outer membranes

“…The TAM has a more limited phylogenetic distribution than the BAM complex [ 28 ] and has only been characterised functionally in 3 bacterial species: E . coli , Citrobacter rodentium , and Klebsiella pneumoniae [ 25 – 27 , 29 ].…”

“…The TAM is a second module of the BAM composed of an inner membrane protein, TamB, and a protein of the Omp85 superfamily, TamA, in the outer membrane [20,[25][26][27]. The TAM has a more limited phylogenetic distribution than the BAM complex [28] and has only been characterised functionally in 3 bacterial species: E. coli, Citrobacter rodentium, and Klebsiella pneumoniae [25][26][27]29].…”