scholarly journals Mechanisms of Increased Resistance to Chlorhexidine and Cross-Resistance to Colistin following Exposure of Klebsiella pneumoniae Clinical Isolates to Chlorhexidine

2016 ◽  
Vol 61 (1) ◽  
Author(s):  
Matthew E. Wand ◽  
Lucy J. Bock ◽  
Laura C. Bonney ◽  
J. Mark Sutton
Keyword(s):  
Klebsiella Pneumoniae ◽  
Efflux Pump ◽  
Opportunistic Pathogen ◽  
Major Facilitator Superfamily ◽  
Cross Resistance ◽  
Wild Type ◽  
Content Type ◽  
Mutant Strains ◽  
Elevated Expression ◽  
Major Facilitator

ABSTRACT Klebsiella pneumoniae is an opportunistic pathogen that is often difficult to treat due to its multidrug resistance (MDR). We have previously shown that K. pneumoniae strains are able to “adapt” (become more resistant) to the widely used bisbiguanide antiseptic chlorhexidine. Here, we investigated the mechanisms responsible for and the phenotypic consequences of chlorhexidine adaptation, with particular reference to antibiotic cross-resistance. In five of six strains, adaptation to chlorhexidine also led to resistance to the last-resort antibiotic colistin. Here, we show that chlorhexidine adaptation is associated with mutations in the two-component regulator phoPQ and a putative Tet repressor gene (smvR) adjacent to the major facilitator superfamily (MFS) efflux pump gene, smvA. Upregulation of smvA (10- to 27-fold) was confirmed in smvR mutant strains, and this effect and the associated phenotype were suppressed when a wild-type copy of smvR was introduced on plasmid pACYC. Upregulation of phoPQ (5- to 15-fold) and phoPQ-regulated genes, pmrD (6- to 19-fold) and pmrK (18- to 64-fold), was confirmed in phoPQ mutant strains. In contrast, adaptation of K. pneumoniae to colistin did not result in increased chlorhexidine resistance despite the presence of mutations in phoQ and elevated phoPQ, pmrD, and pmrK transcript levels. Insertion of a plasmid containing phoPQ from chlorhexidine-adapted strains into wild-type K. pneumoniae resulted in elevated expression levels of phoPQ, pmrD, and pmrK and increased resistance to colistin, but not chlorhexidine. The potential risk of colistin resistance emerging in K. pneumoniae as a consequence of exposure to chlorhexidine has important clinical implications for infection prevention procedures.

scholarly journals Enhanced Efflux Pump Expression in Candida Mutants Results in Decreased Manogepix Susceptibility

2020 ◽  
Vol 64 (5) ◽  
Author(s):  
Sean D. Liston ◽  
Luke Whitesell ◽  
Mili Kapoor ◽  
Karen Joy Shaw ◽  
Leah E. Cowen
Keyword(s):  
Fungal Pathogens ◽  
Candida Parapsilosis ◽  
Efflux Pump ◽  
Major Facilitator Superfamily ◽  
Transporter Gene ◽  
Transcription Factor Gene ◽  
Content Type ◽  
Atp Binding Cassette Transporter ◽  
Major Facilitator Superfamily Transporter ◽  
Major Facilitator

ABSTRACT Manogepix is a broad-spectrum antifungal agent that inhibits glycosylphosphatidylinositol (GPI) anchor biosynthesis. Using whole-genome sequencing, we characterized two efflux-mediated mechanisms in the fungal pathogens Candida albicans and Candida parapsilosis that resulted in decreased manogepix susceptibility. In C. albicans, a gain-of-function mutation in the transcription factor gene ZCF29 activated expression of ATP-binding cassette transporter genes CDR11 and SNQ2. In C. parapsilosis, a mitochondrial deletion activated expression of the major facilitator superfamily transporter gene MDR1.

scholarly journals Klebsiella pneumoniae Isolate from a New York City Hospital Belonging to Sequence Type 258 and CarryingblaKPC-2andblaVIM-4

2016 ◽  
Vol 60 (3) ◽  
pp. 1924-1927 ◽  
Author(s):  
Mariana Castanheira ◽  
Lalitagauri M. Deshpande ◽  
Janet C. Mills ◽  
Ronald N. Jones ◽  
Rosemary Soave ◽  
...  
Keyword(s):  
New York ◽  
New York City ◽  
Klebsiella Pneumoniae ◽  
Efflux Pump ◽  
Sequence Type ◽  
City Hospital ◽  
Class 1 Integron ◽  
Content Type ◽  
Class 1 ◽  
Elevated Expression

Among 69 of 139 (49.6%) carbapenem-nonsusceptibleEnterobacteriaceaecarryingblaKPC, 1Klebsiella pneumoniaewas also positive forblaVIM. The isolate belonged to sequence type 258 (ST258) and carriedblaKPC-2on a copy ofTn4401a andblaVIM-4on a class 1 integron. Genes were located on distinct plasmids belonging to Inc types A/C and FII. Elevated expression of the efflux pump AcrAB-TolC (acrA, 15.3 times) and reduced expression of outer membrane protein genesompK35andompK37(0.16 and 0.081 times, respectively) associated with various amino acid alterations on OmpK37 were observed. The presence of two carbapenemases in ST258K. pneumoniaeis of great concern due to the ability of this organism to widely disseminate.

scholarly journals AbuO, a TolC-Like Outer Membrane Protein of Acinetobacter baumannii, Is Involved in Antimicrobial and Oxidative Stress Resistance

2014 ◽  
Vol 59 (2) ◽  
pp. 1236-1245 ◽  
Author(s):  
Vijaya Bharathi Srinivasan ◽  
Vasanth Vaidyanathan ◽  
Govindan Rajamohan
Keyword(s):  
Oxidative Stress ◽  
Acinetobacter Baumannii ◽  
Outer Membrane ◽  
Efflux Pump ◽  
Outer Membrane Proteins ◽  
Major Facilitator Superfamily ◽  
Pcr Analysis ◽  
Content Type ◽  
Major Facilitator ◽  
And Oxidative Stress

ABSTRACTAlthoughAcinetobacter baumanniiis well accepted as a nosocomial pathogen, only a few of the outer membrane proteins (OMPs) have been functionally characterized. In this study, we demonstrate the biological functions of AbuO, a homolog of TolC fromEscherichia coli. Inactivation ofabuOled to increased sensitivity to high osmolarity and oxidative stress challenge. The ΔabuOmutant displayed increased susceptibility to antibiotics, such as amikacin, carbenicillin, ceftriaxone, meropenem, streptomycin, and tigecycline, and hospital-based disinfectants, such as benzalkonium chloride and chlorhexidine. The reverse transcription (RT)-PCR analysis indicated increased expression of efflux pumps (resistance nodulation cell division [RND] efflux pumpacrD, 8-fold; SMR-typeemrEhomolog, 12-fold; and major facilitator superfamily [MFS]-typeampGhomolog, 2.7-fold) and two-component response regulators (baeR, 4.67-fold;ompR, 10.43-fold) in the ΔabuOmutant together with downregulation ofrstA(4.22-fold) and the pilin chaperone (9-fold). The isogenic mutant displayed lower virulence in a nematode model (P< 0.01). Experimental evidence for the binding of MerR-type transcriptional regulator SoxR to radiolabeledabuOpromoter suggests regulation ofabuOby SoxR inA. baumannii.

scholarly journals ThephtC-phtDLocus Equips Legionella pneumophila for Thymidine Salvage and Replication in Macrophages

2013 ◽  
Vol 82 (2) ◽  
pp. 720-730 ◽  
Author(s):  
Maris V. Fonseca ◽  
John-Demian Sauer ◽  
Sebastien Crepin ◽  
Brenda Byrne ◽  
Michele S. Swanson
Keyword(s):  
Escherichia Coli ◽  
Life Cycle ◽  
Thymidylate Synthase ◽  
Legionella Pneumophila ◽  
Opportunistic Pathogen ◽  
Nucleoside Transporters ◽  
Major Facilitator Superfamily ◽  
Pyrimidine Nucleoside ◽  
Content Type ◽  
Major Facilitator

ABSTRACTThe phagosomal transporter (Pht) family of the major facilitator superfamily (MFS) is encoded by phylogenetically related intracellular gammaproteobacteria, including the opportunistic pathogenLegionella pneumophila. The location of thephtgenes between the putative thymidine kinase (tdk) and phosphopentomutase (deoB) genes suggested that thephtCandphtDloci contribute to thymidine salvage inL. pneumophila. Indeed, aphtC+allele intransrestored pyrimidine uptake to anEscherichia colimutant that lacked all known nucleoside transporters, whereas aphtD+allele did not. The results of phenotypic analyses ofL. pneumophilastrains lackingphtCorphtDstrongly indicate thatL. pneumophilarequires PhtC and PhtD function under conditions where sustained dTMP synthesis is compromised. First, in broth cultures that mimicked thymidine limitation or starvation,L. pneumophilaexhibited a marked requirement for PhtC function. Conversely, mutation ofphtDconferred a survival advantage. Second, in medium that lacked thymidine, multicopyphtC+orphtD+alleles enhanced the survival ofL. pneumophilathymidylate synthase (thyA)-deficient strains, which cannot synthesize dTMP endogenously. Third, under conditions in which transport of the pyrimidine nucleoside analog 5-fluorodeoxyuridine (FUdR) would inhibit growth, PhtC and PhtD conferred a growth advantage toL. pneumophilathyA+strains. Finally, when cultured in macrophages,L. pneumophilarequired thephtC-phtDlocus to replicate. Accordingly, we propose that PhtC and PhtD contribute to protectL. pneumophilafrom dTMP starvation during its intracellular life cycle.

scholarly journals Efflux Pumps of Mycobacterium tuberculosis Play a Significant Role in Antituberculosis Activity of Potential Drug Candidates

2012 ◽  
Vol 56 (5) ◽  
pp. 2643-2651 ◽  
Author(s):  
Meenakshi Balganesh ◽  
Neela Dinesh ◽  
Sreevalli Sharma ◽  
Sanjana Kuruppath ◽  
Anju V. Nair ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Efflux Pump ◽  
Efflux Pumps ◽  
Vital Role ◽  
Major Facilitator Superfamily ◽  
Content Type ◽  
Active Efflux ◽  
Drug Candidates ◽  
Small Multidrug Resistance ◽  
Major Facilitator

ABSTRACTActive efflux of drugs mediated by efflux pumps that confer drug resistance is one of the mechanisms developed by bacteria to counter the adverse effects of antibiotics and chemicals. To understand these efflux mechanisms inMycobacterium tuberculosis, we generated knockout (KO) mutants of four efflux pumps of the pathogen belonging to different classes. We measured the MICs and kill values of two different compound classes on the wild type (WT) and the efflux pump (EP) KO mutants in the presence and absence of the efflux inhibitors verapamil andl-phenylalanyl-l-arginyl-β-naphthylamide (PAβN). Among the pumps studied, the efflux pumps belonging to the ABC (ATP-binding cassette) class, encoded byRv1218c, and the SMR (small multidrug resistance) class, encoded byRv3065, appear to play important roles in mediating the efflux of different chemical classes and antibiotics. Efflux pumps encoded byRv0849andRv1258calso mediate the efflux of these compounds, but to a lesser extent. Increased killing is observed in WTM. tuberculosiscells by these compounds in the presence of either verapamil or PAβN. The efflux pump KO mutants were more susceptible to these compounds in the presence of efflux inhibitors. We have shown that these four efflux pumps ofM. tuberculosisplay a vital role in mediating efflux of different chemical scaffolds. Inhibitors of one or several of these efflux pumps could have a significant impact in the treatment of tuberculosis. The identification and characterization ofRv0849, a new efflux pump belonging to the MFS (major facilitator superfamily) class, are reported.

scholarly journals Pseudomonas aeruginosa adapts to octenidine via a combination of efflux and membrane remodelling

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Lucy J. Bock ◽  
Philip M. Ferguson ◽  
Maria Clarke ◽  
Vichayanee Pumpitakkul ◽  
Matthew E. Wand ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Efflux Pump ◽  
Resistance Mechanism ◽  
Fold Increase ◽  
Opportunistic Pathogen ◽  
Major Facilitator Superfamily ◽  
Membrane Composition ◽  
Base Pair Deletion ◽  
Family Gene ◽  
Major Facilitator

AbstractPseudomonas aeruginosa is an opportunistic pathogen capable of stably adapting to the antiseptic octenidine by an unknown mechanism. Here we characterise this adaptation, both in the laboratory and a simulated clinical setting, and identify a novel antiseptic resistance mechanism. In both settings, 2 to 4-fold increase in octenidine tolerance was associated with stable mutations and a specific 12 base pair deletion in a putative Tet-repressor family gene (smvR), associated with a constitutive increase in expression of the Major Facilitator Superfamily (MFS) efflux pump SmvA. Adaptation to higher octenidine concentrations led to additional stable mutations, most frequently in phosphatidylserine synthase pssA and occasionally in phosphatidylglycerophosphate synthase pgsA genes, resulting in octenidine tolerance 16- to 256-fold higher than parental strains. Metabolic changes were consistent with mitigation of oxidative stress and altered plasma membrane composition and order. Mutations in SmvAR and phospholipid synthases enable higher level, synergistic tolerance of octenidine.

scholarly journals Involvement of the SmeAB Multidrug Efflux Pump in Resistance to Plant Antimicrobials and Contribution to Nodulation Competitiveness in Sinorhizobium meliloti

2011 ◽  
Vol 77 (9) ◽  
pp. 2855-2862 ◽  
Author(s):  
Shima Eda ◽  
Hisayuki Mitsui ◽  
Kiwamu Minamisawa
Keyword(s):  
Antimicrobial Resistance ◽  
Sinorhizobium Meliloti ◽  
Efflux Pump ◽  
Major Facilitator Superfamily ◽  
Multidrug Efflux ◽  
Multidrug Efflux Pump ◽  
Content Type ◽  
Multidrug Efflux Pumps ◽  
Nodulation Competitiveness ◽  
Major Facilitator

ABSTRACTThe contributions of multicomponent-type multidrug efflux pumps to antimicrobial resistance and nodulation ability inSinorhizobium melilotiwere comprehensively analyzed. Computational searches identified genes in theS. melilotistrain 1021 genome encoding 1 pump from the ATP-binding cassette family, 3 pumps from the major facilitator superfamily, and 10 pumps from the resistance-nodulation-cell division family, and subsequently, these genes were deleted either individually or simultaneously. Antimicrobial susceptibility tests demonstrated that deletion of thesmeABpump genes resulted in increased susceptibility to a range of antibiotics, dyes, detergents, and plant-derived compounds and, further, that specific deletion of thesmeCDorsmeEFgenes in a ΔsmeABbackground caused a further increase in susceptibility to certain antibiotics. Competitive nodulation experiments revealed that thesmeABmutant was defective in competing with the wild-type strain for nodulation. The introduction of a plasmid carryingsmeABinto thesmeABmutant restored antimicrobial resistance and nodulation competitiveness. These findings suggest that the SmeAB pump, which is a major multidrug efflux system ofS. meliloti, plays an important role in nodulation competitiveness by mediating resistance toward antimicrobial compounds produced by the host plant.

scholarly journals Bifunctional Enzyme SpoT Is Involved in Biofilm Formation ofHelicobacter pyloriwith Multidrug Resistance by Upregulating Efflux Pump Hp1174 (gluP)

2018 ◽  
Vol 62 (11) ◽  
Author(s):  
Xiaoran Ge ◽  
Yuying Cai ◽  
Zhenghong Chen ◽  
Sizhe Gao ◽  
Xiwen Geng ◽  
...  
Keyword(s):  
Multidrug Resistance ◽  
Biofilm Formation ◽  
Efflux Pump ◽  
Efflux Pumps ◽  
Multidrug Resistant ◽  
Major Facilitator Superfamily ◽  
Bifunctional Enzyme ◽  
Content Type ◽  
H Pylori ◽  
Major Facilitator

ABSTRACTThe drug resistance ofHelicobacter pyloriis gradually becoming a serious problem. Biofilm formation is an important factor that leads to multidrug resistance (MDR) in bacteria. The ability ofH. pylorito form biofilms on the gastric mucosa is known. However, there are few studies on the regulatory mechanisms ofH. pyloribiofilm formation and multidrug resistance. Guanosine 3′-diphosphate 5′-triphosphate and guanosine 3′,5′-bispyrophosphate [(p)ppGpp] are global regulatory factors and are synthesized inH. pyloriby the bifunctional enzyme SpoT. It has been reported that (p)ppGpp is involved in the biofilm formation and multidrug resistance of various bacteria. In this study, we found that SpoT also plays an important role inH. pyloribiofilm formation and multidrug resistance. Therefore, it was necessary to carry out some further studies regarding its regulatory mechanism. Considering that efflux pumps are of great importance in the biofilm formation and multidrug resistance of bacteria, we tried to determine whether efflux pumps controlled by SpoT participate in these activities. We found that Hp1174 (glucose/galactose transporter [gluP]), an efflux pump of the major facilitator superfamily (MFS), is highly expressed in biofilm-forming and multidrug-resistant (MDR)H. pyloristrains and is upregulated by SpoT. Through further research, we determined thatgluPis involved inH. pyloribiofilm formation and multidrug resistance. Furthermore, the average expression level ofgluPin the clinical MDR strains (C-MDR) was considerably higher than that in the clinical drug-sensitive strains (C-DSS). Taken together, our results revealed a novel molecular mechanism ofH. pyloriresistance to multidrug exposure.

scholarly journals The Transcriptional Repressor SmvR Is Important for Decreased Chlorhexidine Susceptibility in Enterobacter cloacae Complex

2019 ◽  
Vol 64 (1) ◽  
Author(s):  
François Guérin ◽  
François Gravey ◽  
Patrick Plésiat ◽  
Marion Aubourg ◽  
Racha Beyrouthy ◽  
...  
Keyword(s):  
Efflux Pump ◽  
Critical Role ◽  
Transcriptional Repressor ◽  
Enterobacter Cloacae ◽  
Major Facilitator Superfamily ◽  
Clinical Isolates ◽  
Bacterial Cells ◽  
Promoter Regions ◽  
Content Type ◽  
Major Facilitator

ABSTRACT Major facilitator superfamily (MFS) efflux pumps have been shown to be important for bacterial cells to cope with biocides such as chlorhexidine (CHX), a widely used molecule in hospital settings. In this work, we evaluated the role of two genes, smvA and smvR, in CHX resistance in Enterobacter cloacae complex (ECC). smvA encodes an MFS pump whereas smvR, located upstream of smvA, codes for a TetR-type transcriptional repressor. To this aim, we constructed corresponding deletion mutants from the ATCC 13047 strain (CHX MIC, 2 mg/liter) as well as strains overexpressing smvA or smvR in both ATCC 13047 and three clinical isolates exhibiting elevated CHX MICs (16 to 32 mg/liter). Determination of MICs revealed that smvA played a modest role in CHX resistance, in contrast to smvR that modulated the ability of ECC to survive in the presence of CHX. In clinical isolates, the overexpression of smvR significantly reduced MICs of CHX (2 to 8 mg/liter). Sequence analyses of smvR and promoter regions pointed out substitutions in conserved regions. Moreover, transcriptional studies revealed that SmvR acted as a repressor of smvA expression even if no quantitative correlation between the level of smvA mRNA and MICs of CHX could be observed. On the other hand, overproduction of smvA was able to complement the lack of the major resistance-nodulation-cell division (RND) superfamily efflux pump AcrB and restored resistance to ethidium bromide and acriflavine. Although SmvA could expel biocides such as CHX, other actors, whose expression is under SmvR control, should play a critical role in ECC.

scholarly journals In Vitro Selection oframRandsoxRMutants Overexpressing Efflux Systems by Fluoroquinolones as Well as Cefoxitin in Klebsiella pneumoniae

2011 ◽  
Vol 55 (6) ◽  
pp. 2795-2802 ◽  
Author(s):  
Suzanne Bialek-Davenet ◽  
Estelle Marcon ◽  
Véronique Leflon-Guibout ◽  
Jean-Philippe Lavigne ◽  
Frédéric Bert ◽  
...  
Keyword(s):  
Klebsiella Pneumoniae ◽  
In Vitro Selection ◽  
Efflux Pump ◽  
Clinical Isolates ◽  
Cross Resistance ◽  
Efflux System ◽  
Content Type ◽  
New Antibiotics ◽  
Regulator Genes

ABSTRACTThe relationship between efflux system overexpression and cross-resistance to cefoxitin, quinolones, and chloramphenicol has recently been reported inKlebsiella pneumoniae. In 3 previously published clinical isolates and 17in vitromutants selected with cefoxitin or fluoroquinolones, mutations in the potential regulator genes of the AcrAB efflux pump (acrR,ramR,ramA,marR,marA,soxR,soxS, androb) were searched, and their impacts on efflux-related antibiotic cross-resistance were assessed. All mutants but 1, and 2 clinical isolates, overexpressedacrB. No mutation was detected in the regulator genes studied among the clinical isolates and 8 of the mutants. For the 9 remaining mutants, a mutation was found in theramRgene in 8 of them and in thesoxRgene in the last one, resulting in overexpression oframAandsoxS, respectively. Transformation of theramRmutants and thesoxRmutant with the wild-typeramRandsoxRgenes, respectively, abolished overexpression ofacrBandramAin theramRmutants and ofsoxSin thesoxRmutant, as well as antibiotic cross-resistance. Resistance due to efflux system overexpression was demonstrated for 4 new antibiotics: cefuroxime, cefotaxime, ceftazidime, and ertapenem. This study shows that theramRandsoxRgenes control the expression of efflux systems inK. pneumoniaeand suggests the existence of efflux pumps other than AcrAB and of other loci involved in the regulation of AcrAB expression.

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