Outer membrane protein alterations and blaTEM-1 variants: their role in  -lactam resistance in Klebsiella pneumoniae

Nelson, E. C.; Segal, Heidi

doi:10.1093/jac/dkg486

Cited by 29 publications

(17 citation statements)

References 27 publications

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“…Indeed, a recent PubMed search for "resistant Klebsiella pneumoniae" yielded nearly 6,000 references. This is largely due to the rapid acquisition of extended-spectrum ␤-lactamases on plasmids (see reference 42), but many of the resistant isolates are also found to be lacking major porins (we cite here only early reports [6,[43][44][45][46]; in the review coauthored by one of us [4], we found that similar reports are so numerous in recent years that it was impossible to give exhaustive citations).…”

Section: Discussionmentioning

confidence: 99%

Klebsiella pneumoniae Major Porins OmpK35 and OmpK36 Allow More Efficient Diffusion of β-Lactams than Their Escherichia coli Homologs OmpF and OmpC

2016

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Klebsiella pneumoniae, one of the most important nosocomial pathogens, is becoming a major problem in health care because of its resistance to multiple antibiotics, including cephalosporins of the latest generation and, more recently, even carbapenems. This is largely due to the spread of plasmid-encoded extended-spectrum ␤-lactamases. However, antimicrobial agents must first penetrate the outer membrane barrier in order to reach their targets, and hydrophilic and charged ␤-lactams presumably diffuse through the porin channels. Unfortunately, the properties of K. pneumoniae porin channels are largely unknown. In this study, we made clean deletions of K. pneumoniae porin genes ompK35 and ompK36 and examined the antibiotic susceptibilities and diffusion rates of ␤-lactams. The results showed that OmpK35 and OmpK36 produced larger more permeable channels than their Escherichia coli homologs OmpF and OmpC; OmpK35 especially produced a diffusion channel of remarkably high permeability toward lipophilic (benzylpenicillin) and large (cefepime) compounds. These results were also confirmed by expressing various porins in an E. coli strain lacking major porins and the major multidrug efflux pump AcrAB. Our data explain why the development of drug resistance in K. pneumoniae is so often accompanied by the mutational loss of its porins, especially OmpK35, in addition to the various plasmid-carried genes of antibiotic resistance, because even hydrolysis by ␤-lactamases becomes inefficient in producing high levels of resistance if the bacterium continues to allow a rapid influx of ␤-lactams through its wide porin channels. IMPORTANCEIn Gram-negative bacteria, drugs must first enter the outer membrane, usually through porin channels. Thus, the quantitative examination of influx rates is essential for the assessment of resistance mechanisms, yet no such studies exist for a very important nosocomial pathogen, Klebsiella pneumoniae. We found that the larger channel porin of this organism, OmpK35, produces a significantly larger channel than its Escherichia coli homolog, OmpF. This makes unmodified K. pneumoniae strains more susceptible to relatively large antibiotics, such as the third-and fourth-generation cephalosporins. Also, even the acquisition of powerful ␤-lactamases is not likely to make them fully resistant in the presence of such an effective influx process, explaining why so many clinical isolates of this organism lack porins. K lebsiella pneumoniae is currently one of the most important Gram-negative nosocomial pathogens, which are often carbapenem resistant (1), and its wide dissemination is helped by its capacity to survive in the hospital environment (2), presumably aided by the production of thick capsules. A remarkable feature of multidrug-resistant isolates of this species is the absence of porin(s) (for an early report, see reference 3, and for reviews, see references 4 and 5). K. pneumoniae produces two classical trimeric porins, OmpK35 and OmpK36, which are homologs of OmpF and OmpC of Escherichia col...

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Section: Discussionmentioning

confidence: 99%

Klebsiella pneumoniae Major Porins OmpK35 and OmpK36 Allow More Efficient Diffusion of β-Lactams than Their Escherichia coli Homologs OmpF and OmpC

2016

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“…In many parts of the world, K. pneumoniae is the most common species of the Enterobacteriaceae to contain one or more extended-spectrum ␤-lactamases that can confer resistance to expanded-spectrum cephalosporins (24,38,53). Several Ambler class C ␤-lactamases, many of them encoded on mobile genetic elements, have also been found in this species, further expanding ␤-lactam resistance to include cefoxitin and piperacillin-tazobactam (41).…”

Section: Discussionmentioning

confidence: 99%

“…OmpK37 is a small porin related to OmpN of Escherichia coli and is not normally expressed, while porins OmpK35 and OmpK36 play an important role in the penetration of antibiotics into the cell. Their loss can confer resistance to cephalosporins and carbapenems, particularly in strains containing Ambler group A, B, C, or D ␤-lactamases (5,8,19,30,38,40,44). Loss of OmpK35 plays a major role in antibiotic resistance, as illustrated in the K. pneumoniae CSUB10R deletion mutant (⌬ompK35 and ⌬ompK36) under complementation following transformation with a plasmid-encoded ompK35 gene (22).…”

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confidence: 99%

High-Level Carbapenem Resistance in a Klebsiella pneumoniae Clinical Isolate Is Due to the Combination of bla _ACT-1 β-Lactamase Production, Porin OmpK35/36 Insertional Inactivation, and Down-Regulation of the Phosphate Transport Porin PhoE

Kaczmarek

Dib-Hajj

Shang

et al. 2006

Antimicrob Agents Chemother

225

159

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Clinical isolates of Klebsiella pneumoniae resistant to carbapenems and essentially all other antibiotics (multidrug resistant) are being isolated from some hospitals in New York City with increasing frequency. A highly related pair of K. pneumoniae strains isolated on the same day from one patient in a hospital in New York City were studied for antibiotic resistance. One (KP-2) was resistant to imipenem, meropenem, and sulopenem (MICs of 16 to 32 g/ml) while the other (KP-1) was susceptible (MIC of 0.5 g/ml); both contained the bla ACT-1 , bla SHV-1 , and bla TEM-1 ␤-lactamases. bla ACT-1 in both strains was encoded on a large ϳ150-kb plasmid. Both isolates contained an identical class 1 integron encoding resistance to aminoglycosides and chloramphenicol. They each had identical insertions in ompK35 and ompK36, resulting in disruption of these key porin genes. The carbapenem-resistant and -susceptible isolates were extensively studied for differences in the structural and regulatory genes for the operons acrRAB, marORAB, romA-ramA, soxRS, micF, micC, phoE, phoBR, rpoS, and hfq. No changes were detected between the isolates except for a significant down-regulation of ompK37, phoB, and phoE in KP-2 as deduced from reverse transcription-PCR analysis of mRNA and polyacrylamide gel electrophoresis separation of outer membrane proteins. Backcross analysis was conducted using the wild-type phoE gene cloned into the vector pGEM under regulation of its native promoter as well as the lacZ promoter following transformation into the resistant KP-2 isolate. The wild-type gene reversed carbapenem resistance only when under control of the heterologous lacZ promoter. In the background of ompK35-ompK36 gene disruption, the up-regulation of phoE in KP-1 apparently compensated for porin loss and conferred carbapenem susceptibility. Down-regulation of phoE in KP-2 may represent the normal state of this gene, or it may have been selected from KP-1 in vivo under antibiotic pressure, generating the carbapenemresistant clone. This is the first study in the Enterobacteriaceae where expression of the phosphate-regulated PhoE porin has been associated with resistance to antimicrobials. Our results with this pair of Klebsiella clinical isolates highlight the complex and evolving nature of multiple drug resistance in this species.

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“…Porin loss is often caused by the insertion of an insertion sequence (IS) element (279). In the present century, reports on porin loss are so numerous that it is impossible to give an exhaustive list of the literature; we give only a few representative examples (280,281). We note, however, that clinical isolates resistant to carbapenems often lack porins (257,282,283).…”

Section: Klebsiella Pneumoniaementioning

confidence: 94%

The Challenge of Efflux-Mediated Antibiotic Resistance in Gram-Negative Bacteria

2015

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SUMMARY The global emergence of multidrug-resistant Gram-negative bacteria is a growing threat to antibiotic therapy. The chromosomally encoded drug efflux mechanisms that are ubiquitous in these bacteria greatly contribute to antibiotic resistance and present a major challenge for antibiotic development. Multidrug pumps, particularly those represented by the clinically relevant AcrAB-TolC and Mex pumps of the resistance-nodulation-division (RND) superfamily, not only mediate intrinsic and acquired multidrug resistance (MDR) but also are involved in other functions, including the bacterial stress response and pathogenicity. Additionally, efflux pumps interact synergistically with other resistance mechanisms (e.g., with the outer membrane permeability barrier) to increase resistance levels. Since the discovery of RND pumps in the early 1990s, remarkable scientific and technological advances have allowed for an in-depth understanding of the structural and biochemical basis, substrate profiles, molecular regulation, and inhibition of MDR pumps. However, the development of clinically useful efflux pump inhibitors and/or new antibiotics that can bypass pump effects continues to be a challenge. Plasmid-borne efflux pump genes (including those for RND pumps) have increasingly been identified. This article highlights the recent progress obtained for organisms of clinical significance, together with methodological considerations for the characterization of MDR pumps.

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Outer membrane protein alterations and blaTEM-1 variants: their role in -lactam resistance in Klebsiella pneumoniae

Abstract: Resistance to selected beta-lactams in two clinical isolates of K. pneumoniae was due to interplay between the expression of OMPs and TEM-1.

Cited by 29 publications

References 27 publications

Klebsiella pneumoniae Major Porins OmpK35 and OmpK36 Allow More Efficient Diffusion of β-Lactams than Their Escherichia coli Homologs OmpF and OmpC

Klebsiella pneumoniae Major Porins OmpK35 and OmpK36 Allow More Efficient Diffusion of β-Lactams than Their Escherichia coli Homologs OmpF and OmpC

High-Level Carbapenem Resistance in a Klebsiella pneumoniae Clinical Isolate Is Due to the Combination of bla _ACT-1 β-Lactamase Production, Porin OmpK35/36 Insertional Inactivation, and Down-Regulation of the Phosphate Transport Porin PhoE

The Challenge of Efflux-Mediated Antibiotic Resistance in Gram-Negative Bacteria

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Outer membrane protein alterations and blaTEM-1 variants: their role in -lactam resistance in Klebsiella pneumoniae

Abstract: Resistance to selected beta-lactams in two clinical isolates of K. pneumoniae was due to interplay between the expression of OMPs and TEM-1.

Cited by 29 publications

References 27 publications

Klebsiella pneumoniae Major Porins OmpK35 and OmpK36 Allow More Efficient Diffusion of β-Lactams than Their Escherichia coli Homologs OmpF and OmpC

Klebsiella pneumoniae Major Porins OmpK35 and OmpK36 Allow More Efficient Diffusion of β-Lactams than Their Escherichia coli Homologs OmpF and OmpC

High-Level Carbapenem Resistance in a Klebsiella pneumoniae Clinical Isolate Is Due to the Combination of bla ACT-1 β-Lactamase Production, Porin OmpK35/36 Insertional Inactivation, and Down-Regulation of the Phosphate Transport Porin PhoE

The Challenge of Efflux-Mediated Antibiotic Resistance in Gram-Negative Bacteria

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High-Level Carbapenem Resistance in a Klebsiella pneumoniae Clinical Isolate Is Due to the Combination of bla _ACT-1 β-Lactamase Production, Porin OmpK35/36 Insertional Inactivation, and Down-Regulation of the Phosphate Transport Porin PhoE