scholarly journals SmeDEF Multidrug Efflux Pump Contributes to Intrinsic Multidrug Resistance in Stenotrophomonas maltophilia

2001 ◽  
Vol 45 (12) ◽  
pp. 3497-3503 ◽  
Author(s):  
Li Zhang ◽  
Xian-Zhi Li ◽  
Keith Poole
Keyword(s):  
Multidrug Resistance ◽  
Antimicrobial Resistance ◽  
Stenotrophomonas Maltophilia ◽  
Antimicrobial Agents ◽  
Efflux Pump ◽  
Wild Type ◽  
Multidrug Efflux ◽  
Intrinsic Resistance ◽  
Multidrug Efflux Pump

ABSTRACT Stenotrophomonas maltophilia is an emerging nosocomial pathogen that displays high-level intrinsic resistance to a variety of structurally unrelated antimicrobial agents. Efflux mechanisms are known to contribute to acquired multidrug resistance in this organism, and indeed, one such multidrug efflux system, SmeDEF, was recently identified. Still, the importance of SmeDEF to intrinsic antibiotic resistance in S. maltophilia had not yet been determined. Reverse transcription-PCR confirmed expression of thesmeDEF genes in wild-type S. maltophilia, and deletion of smeE or smeF in wild-type strains rendered the mutants hypersusceptible to several antimicrobials, suggesting that SmeDEF contributes to intrinsic antimicrobial resistance in this organism. Expression of smeDEF was also enhanced in an in vitro-selected multidrug-resistant mutant, although deletion of smeF but not of smeE in these mutants compromised antimicrobial resistance. Apparently, hyperexpressed SmeF is capable of functioning with additional multidrug efflux components to promote multidrug resistance in S. maltophilia.

scholarly journals CmeABC Functions as a Multidrug Efflux System in Campylobacter jejuni

2002 ◽  
Vol 46 (7) ◽  
pp. 2124-2131 ◽  
Author(s):  
Jun Lin ◽  
Linda Overbye Michel ◽  
Qijing Zhang
Keyword(s):  
Campylobacter Jejuni ◽  
Antimicrobial Agents ◽  
Efflux Pump ◽  
Wild Type ◽  
Multidrug Efflux ◽  
Intrinsic Resistance ◽  
Multidrug Efflux Pump ◽  
Efflux Pump Inhibitor ◽  
Gram Negative ◽  
Multidrug Efflux Pumps

ABSTRACT Campylobacter jejuni, a gram-negative organism causing gastroenteritis in humans, is increasingly resistant to antibiotics. However, little is known about the drug efflux mechanisms in this pathogen. Here we characterized an efflux pump encoded by a three-gene operon (designated cmeABC) that contributes to multidrug resistance in C. jejuni 81-176. CmeABC shares significant sequence and structural homology with known tripartite multidrug efflux pumps in other gram-negative bacteria, and it consists of a periplasmic fusion protein (CmeA), an inner membrane efflux transporter belonging to the resistance-nodulation-cell division superfamily (CmeB), and an outer membrane protein (CmeC). Immunoblotting using CmeABC-specific antibodies demonstrated that cmeABC was expressed in wild-type 81-176; however, an isogenic mutant (9B6) with a transposon insertion in the cmeB gene showed impaired production of CmeB and CmeC. Compared to wild-type 81-176, 9B6 showed a 2- to 4,000-fold decrease in resistance to a range of antibiotics, heavy metals, bile salts, and other antimicrobial agents. Accumulation assays demonstrated that significantly more ethidium bromide and ciprofloxacin accumulated in mutant 9B6 than in wild-type 81-176. Addition of carbonyl cyanide m-chlorophenylhydrazone, an efflux pump inhibitor, increased the accumulation of ciprofloxacin in wild-type 81-176 to the level of mutant 9B6. PCR and immunoblotting analysis also showed that cmeABC was broadly distributed in various C. jejuni isolates and constitutively expressed in wild-type strains. Together, these findings formally establish that CmeABC functions as a tripartite multidrug efflux pump that contributes to the intrinsic resistance of C. jejuni to a broad range of structurally unrelated antimicrobial agents.

scholarly journals Cloning and Characterization of SmeT, a Repressor of the Stenotrophomonas maltophilia Multidrug Efflux Pump SmeDEF

2002 ◽  
Vol 46 (11) ◽  
pp. 3386-3393 ◽  
Author(s):  
Patricia Sánchez ◽  
Ana Alonso ◽  
Jose L. Martinez
Keyword(s):  
Stenotrophomonas Maltophilia ◽  
Efflux Pump ◽  
Wild Type ◽  
Multidrug Efflux ◽  
Multidrug Efflux Pump ◽  
S1 Nuclease ◽  
Cellular Factor ◽  
S1 Nuclease Mapping ◽  
Nuclease Mapping

ABSTRACT We report on the cloning of the gene smeT, which encodes the transcriptional regulator of the Stenotrophomonas maltophilia efflux pump SmeDEF. SmeT belongs to the TetR and AcrR family of transcriptional regulators. The smeT gene is located upstream from the structural operon of the pump genes smeDEF and is divergently transcribed from those genes. Experiments with S. maltophilia and the heterologous host Escherichia coli have demonstrated that SmeT is a transcriptional repressor. S1 nuclease mapping has demonstrated that expression of smeT is driven by a single promoter lying close to the 5′ end of the gene and that expression of smeDEF is driven by an unique promoter that overlaps with promoter PsmeT. The level of expression of smeT is higher in smeDEF-overproducing S. maltophilia strain D457R, which suggests that SmeT represses its own expression. Band-shifting assays have shown that wild-type strain S. maltophilia D457 contains a cellular factor(s) capable of binding to the intergenic smeT-smeD region. That cellular factor(s) was absent from smeDEF-overproducing S. maltophilia strain D457R. The sequence of smeT from D457R showed a point mutation that led to a Leu166Gln change within the SmeT protein. This change allowed overexpression of both smeDEF and smeT in D457R. It was noteworthy that expression of wild-type SmeT did not fully complement the smeT mutation in D457R. This suggests that the wild-type protein is not dominant over the mutant SmeT.

scholarly journals Critical Role of Multidrug Efflux Pump CmeABC in Bile Resistance and In Vivo Colonization of Campylobacter jejuni

2003 ◽  
Vol 71 (8) ◽  
pp. 4250-4259 ◽  
Author(s):  
Jun Lin ◽  
Orhan Sahin ◽  
Linda Overbye Michel ◽  
Qijing Zhang
Keyword(s):  
Type Strain ◽  
Wild Type Strain ◽  
Efflux Pump ◽  
In Vitro Growth ◽  
Wild Type ◽  
Multidrug Efflux ◽  
Multidrug Efflux Pump ◽  
Bile Resistance

ABSTRACT CmeABC functions as a multidrug efflux pump contributing to the resistance of Campylobacter to a broad range of antimicrobials. In this study, we examined the role of CmeABC in bile resistance and its contribution to the adaptation of Campylobacter jejuni in the intestinal tract of the chicken, a natural host and a major reservoir for Campylobacter. Inactivation of cmeABC drastically decreased the resistance of Campylobacter to various bile salts. Addition of choleate (2 mM) in culture medium impaired the in vitro growth of the cmeABC mutants but had no effect on the growth of the wild-type strain. Bile concentration varied in the duodenum, jejunum, and cecum of chicken intestine, and the inhibitory effect of the intestinal extracts on the in vitro growth of Campylobacter was well correlated with the total bile concentration in the individual sections of chicken intestine. When inoculated into chickens, the wild-type strain colonized the birds as early as day 2 postinoculation with a density as high as 107 CFU/g of feces. In contrast, the cmeABC mutants failed to colonize any of the inoculated chickens throughout the study. The minimum infective dose for the cmeABC mutant was at least 2.6 × 104-fold higher than that of the wild-type strain. Complementation of the cmeABC mutants with a wild-type cmeABC allele in trans fully restored the in vitro growth in bile-containing media and the in vivo colonization to the levels of the wild-type strain. Immunoblotting analysis indicated that CmeABC is expressed and immunogenic in chickens experimentally infected with C. jejuni. Together, these findings provide compelling evidence that CmeABC, by mediating resistance to bile salts in the intestinal tract, is required for successful colonization of C. jejuni in chickens. Inhibition of CmeABC function may not only control antibiotic resistance but also prevent the in vivo colonization of pathogenic Campylobacter.

scholarly journals The ABC-Type Efflux Pump MacAB Protects Salmonella enterica serovar Typhimurium from Oxidative Stress

mBio ◽  
2013 ◽  
Vol 4 (6) ◽  
Author(s):  
Lydia M. Bogomolnaya ◽  
Katharine D. Andrews ◽  
Marissa Talamantes ◽  
Aimee Maple ◽  
Yury Ragoza ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Salmonella Enterica ◽  
Efflux Pump ◽  
Wild Type ◽  
Multidrug Efflux ◽  
Multidrug Efflux Pump ◽  
Content Type ◽  
Serovar Typhimurium ◽  
Drug Efflux Pump

ABSTRACTMultidrug efflux pumps are integral membrane proteins known to actively excrete antibiotics. The macrolide-specific pump MacAB, the only ABC-type drug efflux pump inSalmonella, has previously been linked to virulence in mice. The molecular mechanism of this link betweenmacABand infection is unclear. We demonstrate thatmacABplays a role in the detoxification of reactive oxygen species (ROS), compounds that salmonellae are exposed to at various stages of infection.macABis induced upon exposure to H2O2and is critical for survival ofSalmonella entericaserovar Typhimurium in the presence of peroxide. Furthermore, we determined thatmacABis required for intracellular replication inside J774.A1 murine macrophages but is not required for survival in ROS-deficient J774.D9 macrophages.macABmutants also had reduced survival in the intestine in the mouse colitis model, a model characterized by a strong neutrophilic intestinal infiltrate where bacteria may experience the cytotoxic actions of ROS. Using an Amplex red-coupled assay,macABmutants appear to be unable to induce protection against exogenous H2O2in vitro, in contrast to the isogenic wild type. In mixed cultures, the presence of the wild-type organism, or media preconditioned by the growth of the wild-type organism, was sufficient to rescue themacABmutant from peroxide-mediated killing. Our data indicate that the MacAB drug efflux pump has functions beyond resistance to antibiotics and plays a role in the protection ofSalmonellaagainst oxidative stress. Intriguingly, our data also suggest the presence of a soluble anti-H2O2compound secreted bySalmonellacells through a MacAB-dependent mechanism.IMPORTANCEThe ABC-type multidrug efflux pump MacAB is known to be required forSalmonella entericaserovar Typhimurium virulence after oral infection in mice, yet the function of this pump during infection is unknown. We show that this pump is necessary for colonization of niches in infected mice where salmonellae encounter oxidative stress during infection. MacAB is required for growth in cultured macrophages that produce reactive oxygen species (ROS) but is not needed in macrophages that do not generate ROS. In addition, we show that MacAB is required to resist peroxide-mediated killingin vitroand for the inactivation of peroxide in the media. Finally, wild-type organisms, or supernatant from wild-type organisms grown in the presence of peroxide, rescue the growth defect ofmacABmutants in H2O2. MacAB appears to participate in the excretion of a compound that induces protection against ROS-mediated killing, revealing a new role for this multidrug efflux pump.

Enhancement of antibiotic susceptibility ofStenotrophomonas maltophiliausing a polyclonal antibody developed against an ABC multidrug efflux pump

2011 ◽  
Vol 57 (10) ◽  
pp. 820-828 ◽  
Author(s):  
Arif Al-Hamad ◽  
James Burnie ◽  
Mathew Upton
Keyword(s):  
Polyclonal Antibody ◽  
Growth Kinetic ◽  
Efflux Pump ◽  
Kinetic Studies ◽  
Efflux Pumps ◽  
Clinical Strain ◽  
Multidrug Efflux ◽  
Intrinsic Resistance ◽  
Multidrug Efflux Pump

Stenotrophomonas maltophilia is an emerging nosocomial pathogen capable of causing healthcare-associated infections, including pneumonia and bacteremia. Intrinsic resistance in S. maltophilia is exhibited towards many broad-spectrum antibiotics, and treatment recommendations are controversial. One of the major causes of antimicrobial resistance is attributed to a robust array of efflux pumps that extrude drug compounds from the cell. Using checkerboard and growth kinetic assays, we evaluated the in vitro activity of a polyclonal antibody raised against an ATP-binding cassette efflux protein in S. maltophilia. Six clinical strains of S. maltophilia and one type strain were challenged with co-trimoxazole, ticarcillin–clavulanate, and ciprofloxacin, alone and in combination with antibody. One clinical strain was tested by growth curve experiments for each antibiotic–antibody combination. The use of antibody resulted in significantly increased susceptibility in 71.4% (15/21) of treatments tested, with 33.3% displaying synergy and 38.1% an additive effect. In growth kinetic studies, synergy was obtained for each antibiotic–antibody combination. Thus, the use of antibody raised against multidrug efflux pumps for the treatment of multidrug-resistant organisms warrants further investigation. Antibody targeting substrate recognition sites, or other functionally important epitopes, may lead to inhibition of multiple efflux pumps that share the same substrate and is an attractive area that should be explored.

scholarly journals The Biocide Triclosan Selects Stenotrophomonas maltophilia Mutants That Overproduce the SmeDEF Multidrug Efflux Pump

2005 ◽  
Vol 49 (2) ◽  
pp. 781-782 ◽  
Author(s):  
Patricia Sanchez ◽  
Eduardo Moreno ◽  
Jose L. Martinez
Keyword(s):  
Type Strain ◽  
Stenotrophomonas Maltophilia ◽  
Wild Type Strain ◽  
Efflux Pump ◽  
Resistant Bacteria ◽  
Wild Type ◽  
Multidrug Efflux ◽  
Multidrug Efflux Pump ◽  
Antibiotic Resistant ◽  
Selection Of

ABSTRACT The possibility that triclosan selects Stenotrophomonas maltophilia mutants overexpressing the multidrug resistance pump SmeDEF is analyzed. Five out of 12 triclosan-selected mutants were less susceptible to antibiotics than the wild-type strain and overproduced SmeDEF. Results are discussed in relation to current debates on the potential selection of antibiotic-resistant bacteria by household biocides.

scholarly journals Antibiotic Susceptibility Profiles ofEscherichia coli Strains Lacking Multidrug Efflux Pump Genes

2001 ◽  
Vol 45 (4) ◽  
pp. 1126-1136 ◽  
Author(s):  
Mark C. Sulavik ◽  
Chad Houseweart ◽  
Christina Cramer ◽  
Nilofer Jiwani ◽  
Nicholas Murgolo ◽  
...  
Keyword(s):  
Multidrug Resistance ◽  
Efflux Pump ◽  
Major Facilitator Superfamily ◽  
Multidrug Efflux ◽  
Intrinsic Resistance ◽  
Multidrug Efflux Pump ◽  
Gene Deletions ◽  
Small Multidrug Resistance ◽  
Major Facilitator ◽  
Susceptibility Profiles

ABSTRACT The contribution of seven known and nine predicted genes or operons associated with multidrug resistance to the susceptibility of Escherichia coli W3110 was assessed for 20 different classes of antimicrobial compounds that include antibiotics, antiseptics, detergents, and dyes. Strains were constructed with deletions for genes in the major facilitator superfamily, the resistance nodulation-cell division family, the small multidrug resistance family, the ATP-binding cassette family, and outer membrane factors. The agar dilution MICs of 35 compounds were determined for strains with deletions for multidrug resistance (MDR) pumps. Deletions in acrAB or tolC resulted in increased susceptibilities to the majority of compounds tested. The remaining MDR pump gene deletions resulted in increased susceptibilities to far fewer compounds. The results identify which MDR pumps contribute to intrinsic resistance under the conditions tested and supply practical information useful for designing sensitive assay strains for cell-based screening of antibacterial compounds.

scholarly journals Prevalence, Development, and Molecular Mechanisms of Bacteriocin Resistance inCampylobacter

2011 ◽  
Vol 77 (7) ◽  
pp. 2309-2316 ◽  
Author(s):  
Ky Van Hoang ◽  
Norman J. Stern ◽  
Arnold M. Saxton ◽  
Fuzhou Xu ◽  
Ximin Zeng ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Efflux Pump ◽  
Acquired Resistance ◽  
Multidrug Efflux ◽  
Intrinsic Resistance ◽  
Multidrug Efflux Pump ◽  
Major Step ◽  
On Farm ◽  
Level Resistance

ABSTRACTBacteriocins (BCNs) are antimicrobial peptides produced by bacteria with narrow or broad spectra of antimicrobial activity. Recently, several unique anti-CampylobacterBCNs have been identified from commensal bacteria isolated from chicken intestines. These BCNs dramatically reducedC. jejunicolonization in poultry and are being directed toward on-farm control ofCampylobacter. However, no information concerning prevalence, development, and mechanisms of BCN resistance inCampylobacterexists. In this study, susceptibilities of 137C. jejuniisolates and 20C. coliisolates to the anti-CampylobacterBCNs OR-7 and E-760 were examined. Only oneC. colistrain displayed resistance to the BCNs (MIC, 64 μg/ml), while others were susceptible, with MICs ranging from 0.25 to 4 μg/ml. TheC. colimutants resistant to BCN OR-7 also were obtained byin vitroselection, but all displayed only low-level resistance to OR-7 (MIC, 8 to 16 μg/ml). The acquired BCN resistance inC. colicould be transferred at intra- and interspecies levels amongCampylobacterstrains by biphasic natural transformation. Genomic examination of the OR-7-resistant mutants by using DNA microarray and random transposon mutagenesis revealed that the multidrug efflux pump CmeABC contributes to both intrinsic resistance and acquired resistance to the BCNs. Altogether, this study represents the first report of and a major step forward in understanding BCN resistance inCampylobacter, which will facilitate the development of effective BCN-based strategies to reduce theCampylobacterloads in poultry.

scholarly journals Molecular Insights into an Antibiotic Enhancer Action of New Morpholine-Containing 5-Arylideneimidazolones in the Fight against MDR Bacteria

2021 ◽  
Vol 22 (4) ◽  
pp. 2062
Author(s):  
Aneta Kaczor ◽  
Karolina Witek ◽  
Sabina Podlewska ◽  
Veronique Sinou ◽  
Joanna Czekajewska ◽  
...  
Keyword(s):  
Molecular Modelling ◽  
Efflux Pump ◽  
Gram Negative Bacteria ◽  
Potential Mechanism ◽  
Multidrug Efflux ◽  
Aromatic Rings ◽  
Allosteric Site ◽  
Multidrug Efflux Pump ◽  
Dual Action

In the search for an effective strategy to overcome antimicrobial resistance, a series of new morpholine-containing 5-arylideneimidazolones differing within either the amine moiety or at position five of imidazolones was explored as potential antibiotic adjuvants against Gram-positive and Gram-negative bacteria. Compounds (7–23) were tested for oxacillin adjuvant properties in the Methicillin-susceptible S. aureus (MSSA) strain ATCC 25923 and Methicillin-resistant S. aureus MRSA 19449. Compounds 14–16 were tested additionally in combination with various antibiotics. Molecular modelling was performed to assess potential mechanism of action. Microdilution and real-time efflux (RTE) assays were carried out in strains of K. aerogenes to determine the potential of compounds 7–23 to block the multidrug efflux pump AcrAB-TolC. Drug-like properties were determined experimentally. Two compounds (10, 15) containing non-condensed aromatic rings, significantly reduced oxacillin MICs in MRSA 19449, while 15 additionally enhanced the effectiveness of ampicillin. Results of molecular modelling confirmed the interaction with the allosteric site of PBP2a as a probable MDR-reversing mechanism. In RTE, the compounds inhibited AcrAB-TolC even to 90% (19). The 4-phenylbenzylidene derivative (15) demonstrated significant MDR-reversal “dual action” for β-lactam antibiotics in MRSA and inhibited AcrAB-TolC in K. aerogenes. 15 displayed also satisfied solubility and safety towards CYP3A4 in vitro.

scholarly journals AcrAB Multidrug Efflux Pump Is Associated with Reduced Levels of Susceptibility to Tigecycline (GAR-936) in Proteus mirabilis

2003 ◽  
Vol 47 (2) ◽  
pp. 665-669 ◽  
Author(s):  
Melissa A. Visalli ◽  
Ellen Murphy ◽  
Steven J. Projan ◽  
Patricia A. Bradford
Keyword(s):  
Proteus Mirabilis ◽  
Efflux Pump ◽  
Wild Type ◽  
Multidrug Efflux ◽  
Multidrug Efflux Pump ◽  
Transposon Insertion ◽  
Spectrum Activity ◽  
Insertion Mutants ◽  
Broad Spectrum Activity ◽  
Increased Susceptibility

ABSTRACT Tigecycline has good broad-spectrum activity against many gram-positive and gram-negative pathogens with the notable exception of the Proteeae. A study was performed to identify the mechanism responsible for the reduced susceptibility to tigecycline in Proteus mirabilis. Two independent transposon insertion mutants of P. mirabilis that had 16-fold-increased susceptibility to tigecycline were mapped to the acrB gene homolog of the Escherichia coli AcrRAB efflux system. Wild-type levels of decreased susceptibility to tigecycline were restored to the insertion mutants by complementation with a clone containing a PCR-derived fragment from the parental wild-type acrRAB efflux gene cluster. The AcrAB transport system appears to be associated with the intrinsic reduced susceptibility to tigecycline in P. mirabilis.

Sign in / Sign up

Export Citation Format

Share Document