scholarly journals Role of the SOS Response in the Generation of Antibiotic Resistance In Vivo

Author(s):  
John K. Crane ◽  
Cassandra L. Alvarado ◽  
Mark D. Sutton

The SOS response to DNA damage is a conserved stress response in Gram-negative and Gram-positive bacteria. Although this pathway has been studied for years, its relevance is still not familiar to many working in the fields of clinical antibiotic resistance and stewardship. In some conditions, the SOS response favors DNA repair and preserves the genetic integrity of the organism. On the other hand, the SOS response also includes induction of error-prone DNA polymerases, which can increase the rate of mutation, called the mutator phenotype or “hypermutation.” As a result, mutations can occur in genes conferring antibiotic resistance, increasing the acquisition of resistance to antibiotics. Almost all of the work on the SOS response has been on bacteria exposed to stressors in vitro. In this study, we sought to quantitate the effects of the SOS-inducing drugs in vivo, in comparison with the same drugs in vitro. We used a rabbit model of intestinal infection with enteropathogenic E. coli, strain E22. SOS -inducing drugs triggered the mutator phenotype response in vivo as well as in vitro. Exposure of E. coli strain E22 to ciprofloxacin or zidovudine, both of which induce the SOS response in vitro, resulted in increased antibiotic resistance to 3 antibiotics: rifampin, minocycline, and fosfomycin. Zinc was able to inhibit SOS-induced emergence of antibiotic resistance in vivo, as previously observed in vitro. Our findings may have relevance in reducing emergence of resistance to new antimicrobial drugs.

2017 ◽  
Vol 8 (2) ◽  
pp. 101-106
Author(s):  
Ruth Elenora Kristanty ◽  
Junie Suriawati ◽  
Priyanto Dwi Nugroho

Honey is a highly nutritious food product and consumed by almost all the population in the world. It has a function as an antimicrobial. Staphylococcus aureus (S. aureus) is a common Gram-positive bacteria in food and Escherichia coli (E. coli) is a Gram-negative bacteria that often appears in environmental sanitation issues that both can cause infectious diseases.  Some infectious diseases can be treated with antimicrobials such as honey. The purpose of this study was to test the antimicrobial effects on honey products distributed in Pasar Minggu area. The antimicrobial effect test was performed in vitro using agar diffusion method by measuring the inhibition zone formed where the bacteria growth was inhibited by the presence of sample. The concentration of samples were 25%, 50%, 75%, and 100% (not diluted) and as aquades control. The results showed that honey tested with various dilution concentrations resulted inhibition zone and. The higher concentration of the inhibited zone zone showed antimicrobial activity against S. aureus and E. coli.


Author(s):  
Nehad J. Ahmed ◽  
Mohd F. Khan

Introduction: Antibiotics are medications that are used to kill a bacterium which causes different infections. The misuse of these medications has contributed to the development of bacterial resistance. In order to predict the efficacy of the antimicrobial drugs and to guide antimicrobial therapy, antibiogram should be used. Objective: This study aims to explore the Antibiotic resistance patterns in a university hospital in AL-kharj city. Methods: Data from a university hospital in Al-Kharj city were used to assess the in vitro antimicrobial susceptibility rates for different types of bacteria. We included all bacterial and fungal cultures in the last 2 years. Results: The most common bacterium was E. coli and the most common fungus pathogen was Candida albicans. There was a low resistance rate to gentamicin, imipenem, meropenem and amikacin for the studied bacteria pathogens and high resistance rate for some antibiotics such as erythromycin, tetracycline and ampicillin. Conclusion: The physicians should follow the treatment guidelines and they should know the susceptibility rate of different bacteria to prescribe antibiotics appropriately.


mBio ◽  
2017 ◽  
Vol 8 (5) ◽  
Author(s):  
E. Recacha ◽  
J. Machuca ◽  
P. Díaz de Alba ◽  
M. Ramos-Güelfo ◽  
F. Docobo-Pérez ◽  
...  

ABSTRACT Suppression of the SOS response has been postulated as a therapeutic strategy for potentiating antimicrobial agents. We aimed to evaluate the impact of its suppression on reversing resistance using a model of isogenic strains of Escherichia coli representing multiple levels of quinolone resistance. E. coli mutants exhibiting a spectrum of SOS activity were constructed from isogenic strains carrying quinolone resistance mechanisms with susceptible and resistant phenotypes. Changes in susceptibility were evaluated by static (MICs) and dynamic (killing curves or flow cytometry) methodologies. A peritoneal sepsis murine model was used to evaluate in vivo impact. Suppression of the SOS response was capable of resensitizing mutant strains with genes encoding three or four different resistance mechanisms (up to 15-fold reductions in MICs). Killing curve assays showed a clear disadvantage for survival (Δlog10 CFU per milliliter [CFU/ml] of 8 log units after 24 h), and the in vivo efficacy of ciprofloxacin was significantly enhanced (Δlog10 CFU/g of 1.76 log units) in resistant strains with a suppressed SOS response. This effect was evident even after short periods (60 min) of exposure. Suppression of the SOS response reverses antimicrobial resistance across a range of E. coli phenotypes from reduced susceptibility to highly resistant, playing a significant role in increasing the in vivo efficacy. IMPORTANCE The rapid rise of antibiotic resistance in bacterial pathogens is now considered a major global health crisis. New strategies are needed to block the development of resistance and to extend the life of antibiotics. The SOS response is a promising target for developing therapeutics to reduce the acquisition of antibiotic resistance and enhance the bactericidal activity of antimicrobial agents such as quinolones. Significant questions remain regarding its impact as a strategy for the reversion or resensitization of antibiotic-resistant bacteria. To address this question, we have generated E. coli mutants that exhibited a spectrum of SOS activity, ranging from a natural SOS response to a hypoinducible or constitutively suppressed response. We tested the effects of these mutations on quinolone resistance reversion under therapeutic concentrations in a set of isogenic strains carrying different combinations of chromosome- and plasmid-mediated quinolone resistance mechanisms with susceptible, low-level quinolone resistant, resistant, and highly resistant phenotypes. Our comprehensive analysis opens up a new strategy for reversing drug resistance by targeting the SOS response. IMPORTANCE The rapid rise of antibiotic resistance in bacterial pathogens is now considered a major global health crisis. New strategies are needed to block the development of resistance and to extend the life of antibiotics. The SOS response is a promising target for developing therapeutics to reduce the acquisition of antibiotic resistance and enhance the bactericidal activity of antimicrobial agents such as quinolones. Significant questions remain regarding its impact as a strategy for the reversion or resensitization of antibiotic-resistant bacteria. To address this question, we have generated E. coli mutants that exhibited a spectrum of SOS activity, ranging from a natural SOS response to a hypoinducible or constitutively suppressed response. We tested the effects of these mutations on quinolone resistance reversion under therapeutic concentrations in a set of isogenic strains carrying different combinations of chromosome- and plasmid-mediated quinolone resistance mechanisms with susceptible, low-level quinolone resistant, resistant, and highly resistant phenotypes. Our comprehensive analysis opens up a new strategy for reversing drug resistance by targeting the SOS response.


2021 ◽  
Author(s):  
Peyton J. Spreacker ◽  
Nathan E. Thomas ◽  
Will F. Beeninga ◽  
Merissa Brousseau ◽  
Kylie M. Hibbs ◽  
...  

AbstractSmall multidrug resistance (SMR) transporters perform coupled antiport of protons and toxic substrates, contributing to antibiotic resistance through efflux of these compounds from the bacterial cytoplasm. Extensive biophysical studies of the molecular transport mechanism of the E. coli SMR transporter EmrE indicate that it should also be capable of performing proton/drug symport or uniport, either of which will lead to drug susceptibility rather than drug resistance in vivo. Here we show that EmrE does indeed confer susceptibility to some small molecule substrates in the native E. coli in addition to conferring resistance to known polyaromatic cation substrates. In vitro experiments show that substrate binding at a secondary site triggers uncoupled proton uniport that leads to susceptibility. These results suggest that the SMR transporters provide one avenue for bacterial-selective dissipation of the proton-motive force. This has potential for antibiotic development and disruption of antibiotic resistance due to drug efflux more broadly.


2001 ◽  
Vol 69 (9) ◽  
pp. 5626-5634 ◽  
Author(s):  
David A. Lewis ◽  
Marla K. Stevens ◽  
Jo L. Latimer ◽  
Christine K. Ward ◽  
Kaiping Deng ◽  
...  

ABSTRACT Haemophilus ducreyi expresses a soluble cytolethal distending toxin (CDT) that is encoded by the cdtABC gene cluster and can be detected in culture supernatant fluid by its ability to kill HeLa cells. The cdtA, cdtB, and cdtCgenes of H. ducreyi were cloned independently into plasmid vectors, and their encoded proteins expressed singly or in various combinations in an Escherichia coli background. All three gene products had to be expressed in order for E. coli-derived culture supernatant fluids to demonstrate cytotoxicity for HeLa cells. Isogenic H. ducreyi cdtA and cdtB mutants were constructed and used in combination with the wild-type parent strain and a previously describedH. ducreyi cdtC mutant (M. K. Stevens, J. L. Latimer, S. R. Lumbley, C. K. Ward, L. D. Cope, T. Lagergard, and E. J. Hansen, Infect. Immun. 67:3900–3908, 1999) to determine the relative contributions of the CdtA, CdtB, and CdtC proteins to CDT activity. Expression of CdtA, CdtB, and CdtC appeared necessary for H. ducreyi-derived culture supernatant fluid to exhibit cytotoxicity for HeLa cells. Whole-cell sonicates and periplasmic extracts from the cdtB and cdtC mutants had no effect on HeLa cells, whereas these same fractions from a cdtA mutant had a very modest cytotoxic effect on these same human cells. CdtA appeared to be primarily associated with the H. ducreyi cell envelope, whereas both CdtB and CdtC were present primarily in the soluble fraction from sonicated cells. Both the cdtAmutant and the cdtB mutant were found to be fully virulent in the temperature-dependent rabbit model for experimental chancroid.


2017 ◽  
Vol 6 (1) ◽  
pp. 34
Author(s):  
Atere Victor ◽  
Alo Samuel ◽  
Daniel Folashade

The emergence of antibiotic resistance has caused a threat to both human and animal population. This research was designed to investigate and compare the antibiotic resistance of bacteria isolated from chicken and dogs. A hundred and twelve samples of freshly dead chicken and eighty nine blood samples of sick dogs were analyzed. Pure culture of isolates were identified using cultural, morphological and biochemical characteristic. In vitro, susceptibility of the identified isolates against antimicrobial agents were determined by the standard disk diffusion procedure. One hundred and six isolates were recovered from chicken while 27 isolates were recovered from dogs. The organisms isolated include E. coli, Haemophilus sp, Pasturella sp, Klebsiella sp, Enterobacter sp, Salmonella sp, Staphylococcus sp., Micrococcus sp., Pseudomonas sp, Proteus sp, and Listeria sp. The antibiotic resistance showed that, gram-negative bacteria showed more resistance to the antibiotics used in this research compare to the gram-positive bacteria. This trend was found in isolates from both dog and chicken. In like manner, the bacteria isolates recovered from chicken showed a greater resistance when compare with the bacteria isolates recovered from dog. The increased resistance found in poultry makes poultry a suspect of residual resistance gene and probably reservoir for transmission.


2021 ◽  
Author(s):  
Jacob J. Zulk ◽  
Justin R. Clark ◽  
Samantha Ottinger ◽  
Mallory B. Ballard ◽  
Marlyd E. Mejia ◽  
...  

ABSTRACTUrinary tract infections (UTIs) are among the most common infections treated worldwide each year and are primarily caused by uropathogenic E. coli (UPEC). Rising rates of antibiotic resistance among uropathogens have spurred consideration of alternative strategies such as bacteriophage (phage) therapy; however, phage-bacterial interactions within the urinary environment are poorly defined. Here, we assess the activity of two phages, HP3 and ES17, against clinical UPEC isolates using in vitro and in vivo models of UTI. In both bacteriologic medium and pooled human urine, we identified phage resistance arising within the first 6-8 hours of coincubation. Whole genome sequencing revealed that UPEC resistant to HP3 and ES17 harbored mutations in genes involved in lipopolysaccharide (LPS) biosynthesis. These mutations coincided with several in vitro phenotypes, including alterations to adherence to and invasion of human bladder epithelial HTB-9 cells, and increased biofilm formation. Interestingly, these phage-resistant UPEC demonstrated reduced growth in pooled human urine, which could be partially rescued by nutrient supplementation, and were more sensitive to several outer membrane targeting antibiotics than parental strains. Additionally, these phage-resistant UPEC were attenuated in a murine UTI model. In total, our findings suggest that while resistance to phages, such as LPS-targeted HP3 and ES17, may readily arise in the urinary environment, phage resistance is accompanied by fitness costs rendering UPEC more susceptible to host immunity or antibiotics.IMPORTANCEUTIs are one of the most common causes of outpatient antibiotic use, and rising antibiotic resistance threatens the ability to control these infections unless alternative treatments are developed. Bacteriophage (phage) therapy is gaining renewed interest, however, much like antibiotics, bacteria can readily become resistant to phage. For successful UTI treatment, we must predict how bacteria will evade killing by phage and identify the downstream consequences of phage-resistant bacterial infections. In our current study, we found that while phage-resistant mutant bacteria quickly emerged, these mutations left bacteria less capable of growing in human urine and colonizing the murine bladder. These results suggest that phage therapy poses a viable UTI treatment if phage resistance confers fitness costs for the uropathogen. These results have implications for developing cocktails of phage with multiple different bacterial targets, each of which is only evaded at the cost of bacterial fitness.


2019 ◽  
Vol 63 (8) ◽  
Author(s):  
Typhaine Billard-Pomares ◽  
Olivier Clermont ◽  
Miguel Castellanos ◽  
Fatma Magdoud ◽  
Guilhem Royer ◽  
...  

ABSTRACTWe previously identified an operon involved in an arginine deiminase (ADI) pathway (arcoperon) on a CTX-M-producing plasmid from an O102-ST405 strain ofEscherichia coli. As the ADI pathway was shown to be involved in the virulence of various Gram-positive bacteria, we tested whether the ADI pathway could be involved in the epidemiological success of extended-spectrum-β-lactamase (ESBL)-producingE. colistrains. We studied two collections of humanE. coliisolated in France (n = 493) and England (n = 1,509) and show that the prevalence of thearcoperon (i) is higher in ESBL-producing strains (12.1%) than in nonproducers (2.5%), (ii) is higher in CTX-M-producing strains (16%) than in other ESBL producers (3.5%), and (iii) increased over time in ESBL-producing strains from 0% before 2000 to 43.3% in 2011 to 2012. Thearcoperon, found in strains from various phylogenetic backgrounds, is carried by IncF plasmids (85%) or chromosomes (15%) in regions framed by numerous insertion sequences, indicating multiple arrivals. Competition experiments showed that thearcoperon enhances fitness of the strainin vitroin lysogeny broth with arginine.In vivocompetition experiments showed that thearcoperon is advantageous for the strain in a mouse model of urinary tract infection (UTI), whereas it is a burden in a mouse model of intestinal colonization. In summary, we have identified a trait linked to CTX-M-producing strains that is responsible for a trade-off between two mainE. colilifestyles, UTI and gut commensalism. This trait alone cannot explain the wide spread of ESBLs inE. colibut merits epidemiological surveillance.


Author(s):  
John K. Crane ◽  
Sarah R. Burke ◽  
Cassandra L. Alvarado

BackgroundPrevious reports have differed as to whether nitric oxide inhibits or stimulates the SOS response, a bacterial stress response that is often triggered by DNA damage. The SOS response is an important regulator of production of Shiga toxins (Stx) in Shiga-toxigenic E. coli (STEC). In addition, the SOS response is accompanied by hypermutation, which can lead to de novo emergence of antibiotic resistance. We studied these effects in vitro as well as in vivo.ResultsNitric oxide donors inhibited induction of the SOS response by classical inducers such as mitomycin C, ciprofloxacin, and zidovudine, as measured by assays for E. coli RecA. Nitric oxide donors also inhibited Stx toxin protein production as well as stx2 RNA in vitro and in vivo. In vivo experiments were performed with ligated ileal segments in the rabbit using a 20 h infection. The NO donor S-nitroso-acetylpenicillamine (SNAP) reduced hypermutation in vitro and in vivo, as measured by emergence of rifampin resistance. SNAP blocked the ability of the RecA protein to bind to single-stranded DNA in an electrophoretic mobility shift assay (EMSA) in vitro, an early event in the SOS response. The inhibitory effects of SNAP were additive with those of zinc acetate.ConclusionsNitric oxide donors blocked the initiation step of the SOS response. Downstream effects of this blockade included inhibition of Stx production and of hypermutation. Infection of rabbit loops with STEC resulted in a downregulation, rather than stimulation, of nitric oxide host defenses at 20 h of infection.


2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Doa’a Anwar Ibrahim ◽  
Rowida Noman Albadani

Green tea and hibiscus are widely consumed as traditional beverages in Yemen and some regional countries. They are relatively cheap and the belief is that they improve health state and cure many diseases. The aim of this study was to evaluate the potential protective and antibacterial activity of these two famous plantsin vitrothrough measuring their antibacterial activity andin vivothrough measuring nonenzymatic kidney markers dysfunction after induction of nephrotoxicity by gentamicin. Gram positive bacteria like MRSA (methicillin resistantStaphylococcus aureus) were isolated from hospitalized patients’ different sources (pus and wound) and Gram negative bacteria includingE. coliandP. aeruginosawere usedin vitrostudy. In addition, the efficacy of these plants was assessedin vivothrough measuring nonenzymatic kidney markers including S. creatinine and S. urea. Green tea was shown antimicrobial activity against MRSA with inhibition zone 19.67 ± 0.33 mm and MIC 1.25 ± 0.00 mg/mL compared with standard reference (vancomycin) 18.00 ± 0.00 mg/mL. Hibiscus did not exhibit a similar effect. Both Hibiscus- and green tea-treated groups had nephroprotective effects as they reduced the elevation in nonenzymatic kidney markers. We conclude that green tea has dual effects: antimicrobial and nephroprotective.


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