scholarly journals Genetic determinants of multi-drug resistance in Acinetobacter baumannii at an academic hospital in Pretoria, South Africa

2019 ◽  
Author(s):  
Noel-David Nogbou ◽  
Dikwata Thabiso Phofa ◽  
Maphoshane Nchabeleng ◽  
Andrew Munyalo Musyoki
Keyword(s):  
South Africa ◽  
Antimicrobial Resistance ◽  
Genetic Relatedness ◽  
Efflux Pump ◽  
Multi Drug Resistance ◽  
Drug Resistant ◽  
Genetic Determinants ◽  
Pump System ◽  
Active Efflux ◽  
Almost All

AbstractAntimicrobial resistance is now globally recognised as the greatest threat to human health. Acinetobacter baumanniis’ (A. baumannii) clinical significance has been driven by its ability to obtain and transmit antimicrobial resistance factors. In South Africa, A. baumannii is a leading cause of healthcare associated infections (HAI). In this study, we investigated the genetic determinants of multi-drug resistant A. baumannii (MDRAB) at a teaching hospital in Pretoria, South Africa.One hundred non repetitive isolates of A. baumannii were collected for the study at Dr George Mukhari Tertiary Laboratory (DGMTL). Antimicrobial susceptibility testing was performed using the VITEK2 system (bioMerieux, France). The prevalence of common resistance associated genes and AdeABC efflux pump system associated genes were investigated using conventional PCR. Genetic relatedness of isolates was then determined using rep-PCR.Seventy (70) of 100 isolates collected were confirmed to be multi-drug resistant and were blaOXA51 positive. Phenotypically, the isolates where resistant to almost all tested antibiotics. However, one isolate showed intermediate susceptibility to tigecycline while all were susceptible to colistin. Oxacillinase encoding gene blaOXA-23 was the most detected at 99% and only 1% was positive for blaOXA-40. The PCR results for metallo-betalactamase (MBL) encoding genes showed that MBL blaVIM was the most frequently detected at 86% and blaSIM-1 at 3% was the least detected. Out of 70 isolates, 56 isolates had the required gene combination for an active efflux pump. The most prevalent clone was clone A at 69% of the isolates. Regarding treatment; colistin and tigecycline are the most effective against strains encountered at DGMTL as all tested carbapenems seem to have lost their effectiveness.The major genotypic determinants for drug resistances are oxacillinases: blaOXA-51 (100%) and blaOXA-23 (99%). The study reports for the first time, blaOXA-40 and blaSIM-1 detection in A. baumannii in South Africa.

scholarly journals Occurrence and Antimicrobial Resistance of Arcobacter spp. Recovered from Aquatic Environments

Antibiotics ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 288
Author(s):  
Sonia Sciortino ◽  
Pietro Arculeo ◽  
Vincenzina Alio ◽  
Cinzia Cardamone ◽  
Luisa Nicastro ◽  
...  
Keyword(s):  
Antimicrobial Resistance ◽  
Tetracycline Resistance ◽  
Multi Drug Resistance ◽  
Genetic Determinants ◽  
Antibiotic Resistant ◽  
Resistance Profile ◽  
Antimicrobial Resistance Profile ◽  
Drug Resistance Profile ◽  
Arcobacter Butzleri ◽  
Seawater Samples

Arcobacter spp. are emerging waterborne and foodborne zoonotic pathogens responsible for gastroenteritis in humans. In this work, we evaluated the occurrence and the antimicrobial resistance profile of Arcobacter isolates recovered from different aquatic sources. Besides, we searched for Arcobacter spp. in seaweeds and the corresponding seawater samples. Bacteriological and molecular methods applied to 100 samples led to the isolation of 28 Arcobacter isolates from 27 samples. The highest prevalence was detected in rivers followed by artificial ponds, streams, well waters, and spring waters. Seaweeds contained a higher percentage of Arcobacter than the corresponding seawater samples. The isolates were identified as Arcobacter butzleri (96.4%) and Arcobacter cryaerophilus (3.6%). All the isolates showed a multi-drug resistance profile, being resistant to at least three different classes of antibiotics. Molecular analysis of genetic determinants responsible for tetracycline resistance in nine randomly chosen isolates revealed the presence of tetO and/or tetW. This work confirms the occurrence and the continuous emergence of antibiotic-resistant Arcobacter strains in environmental samples; also, the presence of quinolone-resistant Arcobacter spp. in aquatic sources used for water supply and irrigation represents a potential risk for human health.

Folic acid-modified mesoporous silica nanoparticles with pH-responsiveness loaded with Amp for an enhanced effect against anti-drug-resistant bacteria by overcoming efflux pump systems

2018 ◽  
Vol 6 (7) ◽  
pp. 1923-1935 ◽  
Author(s):  
Xu Chen ◽  
Yanan Liu ◽  
Ange Lin ◽  
Na Huang ◽  
Liquan Long ◽  
...  
Keyword(s):  
Folic Acid ◽  
Multidrug Resistance ◽  
Mesoporous Silica ◽  
Efflux Pump ◽  
Mesoporous Silica Nanoparticles ◽  
Resistant Bacteria ◽  
Drug Resistant ◽  
Pump System ◽  
Drug Resistant Bacteria ◽  
Antibiotic Failure

Efflux pump system-mediated bacterial multidrug resistance is one of the main causes of antibiotic failure.

scholarly journals Antimicrobial Resistance of Neisseria gonorrhoeae Isolates from High-Risk Men in Johannesburg, South Africa

2020 ◽  
Vol 64 (11) ◽  
Author(s):  
Liteboho D. Maduna ◽  
Marleen M. Kock ◽  
Brian M. J. W. van der Veer ◽  
Oscar Radebe ◽  
James McIntyre ◽  
...  
Keyword(s):  
South Africa ◽  
High Risk ◽  
Antimicrobial Resistance ◽  
Neisseria Gonorrhoeae ◽  
Genetic Relatedness ◽  
Scale Up ◽  
Sub Saharan Africa ◽  
Molecular Testing ◽  
Content Type ◽  
Urethral Discharge

ABSTRACT Neisseria gonorrhoeae antimicrobial drug resistance has emerged worldwide; however, the situation in sub-Saharan Africa is not well documented. We investigated the molecular epidemiology and occurrence of antimicrobial resistance in Neisseria gonorrhoeae infections in two core transmission groups of men in Johannesburg, South Africa. We recruited men who have sex with men (MSM) presenting with urethral discharge and men with recurrent episodes of urethral discharge. Molecular testing and culture for N. gonorrhoeae were performed, followed by antimicrobial susceptibility testing. Whole-genome sequencing (WGS) was used to identify resistance-conferring mutations and to determine the genetic relatedness of the isolates. In all, 51 men were recruited; 42 (82%) had N. gonorrhoeae infections. Most gonococcal isolates were resistant to ciprofloxacin (78%) and tetracycline (74%); 33% were penicillin resistant. All gonococcal isolates were susceptible to cephalosporins and spectinomycin. Azithromycin resistance was observed in 4 (15%) isolates (epidemiological cutoff), all with mutations in the mtrR promoter region. Most of the isolates (19/27) harbored the gonococcal genetic island, which is associated with antimicrobial resistance. WGS revealed a diverse epidemic with mostly novel NG-STAR (70%) and NG-MAST (70%) sequence types. Thus, we demonstrate a high prevalence of antimicrobial resistance in Neisseria gonorrhoeae strains obtained from high-risk men in South Africa. The introduction of diagnostics and scale-up of surveillance are warranted to prevent the emergence of multidrug-resistant infections.

scholarly journals Laboratory based antimicrobial resistance surveillance for Pseudomonas aeruginosa blood isolates from South Africa

2018 ◽  
Vol 12 (08) ◽  
pp. 616-624
Author(s):  
Ashika Singh-Moodley ◽  
Adriano Duse ◽  
Preneshni Naicker ◽  
Ranmini Kularatne ◽  
Trusha Nana ◽  
...  
Keyword(s):  
South Africa ◽  
Pseudomonas Aeruginosa ◽  
Antimicrobial Resistance ◽  
Antimicrobial Susceptibility ◽  
Bacterial Infections ◽  
Treatment Guidelines ◽  
Resistance Mechanisms ◽  
Multi Drug Resistance ◽  
Hospital Treatment ◽  
Baseline Information

Introduction: Antimicrobial resistant bacterial infections are widespread globally and increases in antimicrobial resistance presents a major threat to public health. Pseudomonas aeruginosa is an opportunistic healthcare-associated pathogen with high rates of morbidity and mortality and an extensive range of resistance mechanisms. This study describes the antibiotic susceptibility profiles of P. aeruginosa isolates from patients with bacteraemia submitted by sentinel laboratories in South Africa from 2014 to 2015. Methodology: Organism identification and antimicrobial susceptibility testing were done using automated systems. Molecular methods were used to detect common resistance genes and mechanisms. Results: Overall the susceptibility was high for all antibiotics tested with a decrease over the two-year period. There was no change in the MIC50 and MIC90 breakpoints for all antibiotics from 2014 to 2015. The MIC50 was within the susceptible breakpoint range for most antibiotics and the MIC90 was within the susceptible breakpoint range for colistin only. Phenotypically carbapenem non-susceptible isolates harboured the following plasmid-mediated genes: blaVIM (n = 81, 12%) and blaGES (n = 6, 0.9%); blaNDM (n = 4, 0.6%) and blaOXA-48 and variants (n = 3, 0.45%). Porin deletions were observed in one meropenem non-susceptible isolate only, and multi-drug resistance efflux pumps were expressed in the majority of the non-susceptible isolates investigated. BlaVEB-1, blaIMP and blaKPC were not detected. Conclusion: The prevalence of resistance to commonly used antibacterial agents was low for P. aeruginosa isolates and similarly, tested resistance mechanisms were detected in a relatively small proportion of isolates. Findings in this study represent baseline information for understanding antimicrobial susceptibility patterns in P. aeruginosa isolates from blood. Our surveillance report may assist in contributing to hospital treatment guidelines.

scholarly journals Microbial Species Isolated from Infected Wounds and Antimicrobial Resistance Analysis: Data Emerging from A Three-Years Retrospective Study

Antibiotics ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 1162
Author(s):  
Valentina Puca ◽  
Roberta Zita Marulli ◽  
Rossella Grande ◽  
Irene Vitale ◽  
Antonietta Niro ◽  
...  
Keyword(s):  
Retrospective Study ◽  
Antimicrobial Resistance ◽  
Analysis Data ◽  
Common Species ◽  
Drug Susceptibility ◽  
Automated System ◽  
Multi Drug Resistance ◽  
Drug Resistant ◽  
Wound Infections ◽  
Culture Methods

The antimicrobial resistance is a topic of global interest in the treatment of wound infections. The goal of this retrospective study was both the identification of the microorganisms responsible for wound infections and the determination of their drug susceptibility pattern. The study was performed from 2017 to 2019 and included 239 patients. Thirty-four species were isolated by culture methods and identified and analysed for their susceptibility patterns to antimicrobials through the Walk Away automated system. The presence of one species was the most frequent condition (75.3%), whereas a co-infection was detected in 24.7% of samples. The most common species were Gram-negative (57.9%), amongst which the most prevalent were Pseudomonas aeruginosa (40.2%), Escherichia coli (20.7%), Proteus mirabilis (11.2%), and Acinetobacter baumannii/haemolyticus (9.5%). Gram-positive bacteria were observed in 36.6%, Staphylococcus aureus (79.4%) being the most predominant species. At least one resistance to antibiotics was detected in 88.2% of isolates, while a multi-drug-resistance versus no less than 6 antimicrobials was detected in 29.2% of isolates. Although multi-drug resistant species and co-infections were observed, those were less frequently observed at the wound site. These conditions make the microorganisms eradication more difficult. The detection of a polymicrobial infection and multi-drug resistant microorganisms followed by a proper therapeutic treatment would lead to the resolution of the infection, promoting wound healing and the limitation of the spread of antibiotic resistance.

scholarly journals The molecular basis of extensively drug-resistant Salmonella Typhi isolates from pediatric septicemia patients

PLoS ONE ◽  
2021 ◽  
Vol 16 (9) ◽  
pp. e0257744
Author(s):  
Chanmi Kim ◽  
Iqra Latif ◽  
Durga P. Neupane ◽  
Gi Young Lee ◽  
Ryan S. Kwon ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Typhoid Fever ◽  
Molecular Basis ◽  
Efflux Pump ◽  
Detection Methods ◽  
Fluoroquinolone Resistance ◽  
Medium Size ◽  
Drug Resistant ◽  
Pump System ◽  
Extensively Drug Resistant

Sepsis is a syndromic response to infections and is becoming an emerging threat to the public health sector, particularly in developing countries. Salmonella Typhi (S. Typhi), the cause of typhoid fever, is one primary cause of pediatric sepsis in typhoid endemic areas. Extensively drug-resistant (XDR) S. Typhi is more common among pediatric patients, which is responsible for over 90% of the reported XDR typhoid cases, but the majority of antibiotic resistance studies available have been carried out using S. Typhi isolates from adult patients. Here, we characterized antibiotic-resistance profiles of XDR S. Typhi isolates from a medium size cohort of pediatric typhoid patients (n = 45, 68.89% male and 31.11% female) and determined antibiotic-resistance-related gene signatures associated with common treatment options to typhoid fever patients of 18 XDR S. Typhi representing all 45 isolates. Their ages were 1–13 years old: toddlers aging 1–2 years old (n = 9, 20%), pre-schoolers aging 3–5 years old (n = 17, 37.78%), school-age children aging 6–12 years old (n = 17, 37.78%), and adolescents aging 13–18 years old (n = 2, 4.44%). Through analyzing blaTEM1, dhfR7, sul1, and catA1genes for multidrug-resistance, qnrS, gyrA, gyrB, parC, and parE for fluoroquinolone-resistance, blaCTX-M-15 for XDR, and macAB and acrAB efflux pump system-associated genes, we showed the phenotype of the XDR S. Typhi isolates matches with their genotypes featured by the acquisitions of the genes blaTEM1, dhfR7, sul1, catA1, qnrS, and blaCTX-M-15 and a point mutation on gyrA. This study informs the molecular basis of antibiotic-resistance among recent S. Typhi isolates from pediatric septicemia patients, therefore providing insights into the development of molecular detection methods and treatment strategies for XDR S. Typhi.

scholarly journals Time dependent asymptotic analysis of the gene regulatory network of the AcrAB-TolC efflux pump system in gram-negative bacteria

2021 ◽  
Vol 82 (4) ◽  
Author(s):  
George H. Youlden ◽  
Vito Ricci ◽  
Xuan Wang-Kan ◽  
Laura J. V. Piddock ◽  
Sara Jabbari ◽  
...  
Keyword(s):  
Asymptotic Analysis ◽  
Gene Regulatory Network ◽  
Regulatory Network ◽  
Efflux Pump ◽  
Efflux Pumps ◽  
Time Dependent ◽  
Multi Drug Resistance ◽  
Pump System ◽  
Gene Regulation Network ◽  
Gene Regulatory

AbstractEfflux pumps are a mechanism of intrinsic and evolved resistance in bacteria. If an efflux pump can expel an antibiotic so that its concentration within the cell is below a killing threshold the bacteria are resistant to the antibiotic. Efflux pumps may be specific or they may pump various different substances. This is why many efflux pumps confer multi drug resistance (MDR). In particular over expression of the AcrAB−TolC efflux pump system confers MDR in both Salmonella and Escherichia coli. We consider the complex gene regulation network that controls expression of genes central to controlling the efflux associated genes acrAB and acrEF in Salmonella. We present the first mathematical model of this gene regulatory network in the form of a system of ordinary differential equations. Using a time dependent asymptotic analysis, we examine in detail the behaviour of the efflux system on various different timescales. Asymptotic approximations of the steady states provide an analytical comparison of targets for efflux inhibition.

scholarly journals Molecular Typing and Antimicrobial Susceptibility Profiles of Streptococcus uberis Isolated From Sheep Milk

2021 ◽  
Author(s):  
Nives Maria Rosa ◽  
Ilaria Dupre ◽  
Elisa Azara ◽  
Carla Maria Longheu ◽  
Sebastiana Tola
Keyword(s):  
Antimicrobial Resistance ◽  
Antimicrobial Susceptibility ◽  
Genetic Relatedness ◽  
Efflux Pump ◽  
Resistance Mechanism ◽  
Resistance Rate ◽  
Disk Diffusion Test ◽  
Sheep Milk ◽  
Streptococcus Uberis

Intrammary infections are a major problem for dairy sheep farms, and Streptococcus uberis is one of the main etiological agents of ovine mastitis. Surveys on antimicrobial resistance are still limited in sheep and characterization of isolates is important for acquiring information on resistance and for optimizing therapy. In this study, a sampling of 124 S. uberis isolates collected in Sardinia (Italy) from sheep milk was analysed by multilocus-sequence typing (MLST) and pulsed field gel electrophoresis (PFGE) for genetic relatedness. All isolates were also subjected to antimicrobial susceptibility analysis by the disk diffusion test using a panel of 14 antimicrobials. Resistance genes were detected by PCR assays. MLST analysis revealed that the isolates were grouped into 86 sequence types (STs), of which 73 were new genotypes, indicating a highly diverse population of S. uberis. The most frequently detected lineage was the clonal complex (CC)143, although representing only 13.7% of all characterized isolates. A high level of heterogeneity was also observed among the SmaI PFGE profiles, with 121 unique patterns. Almost all (96.8%) isolates were resistant to at least one antimicrobial, while all exhibited phenotypic susceptibility to oxacillin, amoxicillin-clavulanic acid and ceftiofur. Of the antimicrobials tested, the highest resistance rate was found against streptomycin (93.5%), kanamycin (79.8%) and gentamicin (64.5%), followed by novobiocin (25%) and tetracycline-TE (19.3%). Seventy-four (59.7%) isolates were simultaneously resistant to all aminoglycosides tested. Seventeen isolates (13.7%) exhibited multidrug resistance. All aminoglycosides-resistant isolates were PCR negative for aad-6 and aphA-3’ genes. Among the TE-resistant isolates, the tetM gene was predominant, indicating that the resistance mechanism is mainly mediated by the protection of ribosomes and not through the efflux pump. Three isolates were resistant to erythromycin, and two of them harboured the ermB gene. This is the first study reporting a detailed characterization of the S. uberis strains circulating in Sardinian sheep. Further investigations will be needed to understand the relationships between S. uberis genotypes, mastitis severity, and intra-mammary infection dynamics in the flock, as well as to monitor the evolution of antimicrobial resistance.

scholarly journals Extensive Drug-Resistant Salmonella enterica Isolated From Poultry and Humans: Prevalence and Molecular Determinants Behind the Co-resistance to Ciprofloxacin and Tigecycline

2021 ◽  
Vol 12 ◽  
Author(s):  
Norhan K. Abd El-Aziz ◽  
Yasmine H. Tartor ◽  
Rasha M. A. Gharieb ◽  
Ahmed M. Erfan ◽  
Eman Khalifa ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Efflux Pump ◽  
Point Mutations ◽  
Drug Resistant ◽  
Limited Data ◽  
Genetic Determinants ◽  
Efflux Pump Inhibitor ◽  
Loop Region ◽  
Carbonyl Cyanide ◽  
Molecular Determinants

The emergence of extensive drug-resistant (XDR) Salmonella in livestock animals especially in poultry represents a serious public health and therapeutic challenge. Despite the wealth of information available on Salmonella resistance to various antimicrobials, there have been limited data on the genetic determinants of XDR Salmonella exhibiting co-resistance to ciprofloxacin (CIP) and tigecycline (TIG). This study aimed to determine the prevalence and serotype diversity of XDR Salmonella in poultry flocks and contact workers and to elucidate the genetic determinants involved in the co-resistance to CIP and TIG. Herein, 115 Salmonella enterica isolates of 35 serotypes were identified from sampled poultry (100/1210, 8.26%) and humans (15/375, 4.00%), with the most frequent serotype being Salmonella Typhimurium (26.96%). Twenty-nine (25.22%) Salmonella enterica isolates exhibited XDR patterns; 25 out of them (86.21%) showed CIP/TIG co-resistance. Exposure of CIP- and TIG-resistant isolates to the carbonyl cyanide 3-chlorophenylhydrazone (CCCP) efflux pump inhibitor resulted in an obvious reduction in their minimum inhibitory concentrations (MICs) values and restored the susceptibility to CIP and TIG in 17.24% (5/29) and 92% (23/25) of the isolates, respectively. Molecular analysis revealed that 89.66% of the isolates contained two to six plasmid-mediated quinolone resistance genes with the predominance of qepA gene (89.66%). Mutations in the gyrA gene were detected at codon S83 (34.62%) or D87 (30.77%) or both (34.62%) in 89.66% of XDR Salmonella. The tet(A) and tet(X4) genes were detected in 100% and 3.45% of the XDR isolates, respectively. Twelve TIG-resistant XDR Salmonella had point mutations at codons 120, 121, and 181 in the tet(A) interdomain loop region. All CIP and TIG co-resistant XDR Salmonella overexpressed ramA gene; 17 (68%) out of them harbored 4-bp deletion in the ramR binding region (T-288/A-285). However, four CIP/TIG co-resistant isolates overexpressed the oqxB gene. In conclusion, the emergence of XDR S. enterica exhibiting CIP/TIG co-resistance in poultry and humans with no previous exposure to TIG warrants an urgent need to reduce the unnecessary antimicrobial use in poultry farms in Egypt.

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