Sabiha Essack | University of KwaZulu-Natal (original) (raw)
Professor Sabiha Essack (B. Pharm., M. Pharm., PhD), Professor in Pharmaceutical Sciences at the University of KwaZulu-Natal (UKZN) is the South African Research Chair in Antibiotic Resistance and One Health and a Wellcome Trust Research Fellow who completed research towards her PhD in Pharmaceutical Microbiology at St Bartholomew’s and the Royal London School of Medicine and Dentistry in the United Kingdom. She received several prestigious scholarships and bursaries from the Wellcome Trust, the Medical Research Council (MRC), the National Research Foundation (NRF) and the University of Durban-Westville during the course of her Masters and PhD studies. Her research has been published in several journals and has been presented at a number of national and international conferences.
Professor Essack began her professional career with the B. Pharm degree in 1988 and practiced as a hospital pharmacist for three years in the KwaZulu-Natal Department of Health before returning to the University of Durban-Westville in 1992 to pursue the M. Pharm and PhD degrees.
She is a C-rated researcher by the NRF, has established the Antimicrobial Research Unit at UKZN and has secured several research grants for Essential National Health Research, from the World Health Organization (WHO), the Norwegian Agency for Development Cooperation (NORAD), MRC and the NRF investigating strategies for the prevention and containment of antibiotic resistance.
Professor Essack is expert consultant on antimicrobial resistance to the WHO Africa Office, founder and co-chair of the South African Chapter of the Alliance for the Prudent Use of Antibiotics (APUA), country representative on the Global Respiratory Infections Partnership (GRIP), serves on the South African Chapter of the Global Antibiotic Resistance Partnership (GARP), the South African Antibiotic Stewardship Programme, WHO’s Technical Working Group on Health Workforce Education Assessment Tools, and is co-founder of the South African Committee of Health Sciences Deans. She is a Ministerial appointee on the Board of the Office of Health Standards Compliance, an elected member of the Academy of Sciences of South Africa (ASSAf), a peer-reviewed member of the Southern Africa FAIMER Regional Institute (SAFRI) community, member of the Bio-economy Heath Innovation Sector Coordination Committee of the Department of Science and Technology. She previously served as Ministerial appointee on the National Health Research Ethics Council, as well as on the national Department of Health, on the National Executive of the Pharmaceutical Society of South Africa, the Professional Body Reference Group of the South African Qualifications Authority (SAQA) and the Programme Accreditation Panel and Standards Development Reference Group of the Council for Higher Education (CHE).
Professor Essack is Associate Editor of the South African Journal of Epidemiology and Infection, serves on the Editorial Board of the African Journal of Microbiology Research, frequently reviews papers for several international journals as well as research proposals and rating applications for the FP7 Programme, the MRC and the NRF and is a member of the Society for Clinical Microbiology and the Federation of Infectious Diseases Societies of South Africa.
Professor Essack’s current research interests include:
• Evidence-informed strategies for the prevention and containment of antibiotic resistance based on:
o the surveillance of antibiotic use and resistance in human, animal and environmental heath (One Health),
o Risk factors for the infection/colonization by antibiotic resistant bacteria,
o Infection control, and,
o Antibiotic pharmacokinetics and pharmacodynamics.
• Molecular epidemiology of antibiotic resistance.
• Phenotypic and genotypic characterization of antibiotic resistance, including but not limited to antibiotic resistance genes, genetic determinants of resistance and clonality.
• Virulence factors and their associated genetic determinants in antibiotic-resistant bacteria.
• ESKAPE pathogens
• Health policy and health systems strengthening to optimize the management of infections in the context of antibiotic resistance and stewardship.
• Efficacy and safety of new potential antibiotic moieties
Phone: +27312608019
Address: Antimicrobial Research Unit, College of Health Sciences,
University of KwaZulu-Natal,
Private Bag X54001, Durban,
4000, South Africa
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Papers by Sabiha Essack
The minimal antibiotic options for carbapenemase producing Gram-negative bacteria necessitate the... more The minimal antibiotic options for carbapenemase producing Gram-negative bacteria necessitate their rapid detection. A literature review of a variety of phenotypic and genotypic methods is presented. Advances in culture methods and screening media are still subject to long incubation hours. Biochemical methods have shorter turnaround times and higher sensitivities and specificities, but cannot differentiate between various types and variants. Spectrophotometric methods are cheap and efficient, but are uncommon in many clinical settings, while the MALDI-TOF MS is promising for species identification, typing and resistance gene determination. Although next generation sequencing (NGS) technologies provide a better platform to detect, type and characterise carbapenem resistant bacteria, the different NGS platforms, the large computer memories and space needed to process and store genomic data and the non-uniformity in data analysis platforms are still a challenge. The sensitivities, spe...
Letters in Applied Microbiology, 2019
Significance and impact of study We report on the first clinical Morganella morganii draft genome... more Significance and impact of study
We report on the first clinical Morganella morganii draft genomes from Africa. The isolates were found in the urine of patients presenting with urinary tract infections (UTIs). Notably, they were resistant to important clinical antibiotics, including those used to treat UTIs. Due to the common occurrence of UTIs, particularly among pregnant women for whom drug options are limited, the presence of antibiotic-resistant uropathogens such as M. morganii is a serious public health concern. We therefore characterised the resistance mechanisms and epidemiology of these isolates to provide further insights into their dissemination and background data for future studies.
Abstract
Morganella morganii is an opportunistic bacterial pathogen of the Enterobacteriaceae family that is occasionally isolated from clinical (animal and human) specimens with varying resistance profiles. Detailed genomic analyses of drug-resistant M. morganii strains are relatively limited, particularly in Africa, which is also due to their relatively low isolation rates from clinical settings. Here, we report on two multidrug-resistant clinical M. morganii isolates from urine specimens of two hospitalised patients in South Africa who presented with urinary tract infections in 2013. The isolates, M006 and E042, were only susceptible to carbapenems, amikacin and tigecycline. One strain, M006, had a novel class 1 integron, ln1484, associated with aadA7, sul1and gcuD gene cassettes and a Col3M plasmid replicase gene. The ln1484 intI1:aadA7:sul1 genes were bracketed by a TnAs3 composite transposon while a tet(B) gene was found on an IS4 family transposon. The rare blaDHA-4 and blaDHA-1 AmpC β-lactamase genes were identified on the isolates’ chromosome. The isolates were phylogenetically distant and closely related to other international strains, suggesting that they were not obtained from a single epidemiological source. Further molecular surveillance is necessary to establish the prevalence of these MDR strains in the tertiary hospital. Moreover, antibiotic stewardship and antibiotic sensitivity testing of all clinical isolates should be undertaken after empirical treatment to inform tailored therapy as well as reduce escalation of resistance and associated morbidities and mortalities.
Haemophilus parain uenzae is part of the HACEK group of fastidious bacteria commonly implicated i... more Haemophilus parain uenzae is part of the HACEK group of fastidious bacteria commonly implicated in endocarditis and bacteremia. Previously considered as a normal respiratory, oral and sometimes genitourinary commensal, it has been recognised as a pathogen that can cause life-threatening infections in both immunocompromised and healthy individuals. It has also been reported as a bacterium that can harbor transferable antibiotic resistance genes. This paper presents a literature review on the molecular mechanisms of resistance of H. parain uenzae to commonly prescribed antibiotics and discusses areas for further research.
Fluoroquinolones and ketolides are among the drugs of choice for the treatment of Haemophilus par... more Fluoroquinolones and ketolides are among the drugs of choice for the treatment of Haemophilus parainfluenzae infections. There has been a report of an emerging fluoroquinolone and telithromycin resistance in H. para-influenzae isolates from the private sector of KwaZulu-Natal Province of South Africa that necessitates molecular investigation. The aim of this study is to characterize these resistance delineating mutations in genes commonly associated with reduced susceptibility. Ten H. parainfluenzae isolates retrieved from the sputum of 10 patients with H. parainfluenzae pneumonia were subjected to sensitivity testing by the disc diffusion and CLSI broth microdilution methods, polymerase chain reaction (PCR) and DNA sequencing of selected genes associated with resistance were carried out, while repetitive extragenic palindromic PCR (REP-PCR) was used to ascertain clonality. Fluoroquinolone resistance was attributed to the following amino acid substitutions: S84F, D88Y in GyrA, and S84Y/L, S138T, and M198 L change in ParC of the isolates. The plasmid-mediated quinolone resistance gene aac-(6¢)-Ib-cr was detected for the first time in four isolates of H. parainfluenzae and D420 N change was observed in ParE in one isolate. Macrolide and ketolide resistance were ascribed to the resistance genes mef (A), msr (D), and erm (B) detected in the isolates. REP-PCR analysis showed that the isolates were not clonal. All the observed resistance mechanisms are first reports in Africa. There is an emerging fluoroquinolone and macrolide resistance in H. parainfluenzae in South Africa that is attributable to known/ novel resistance mechanisms, necessitating the monitoring of this pathogen as a potential opportunistic pathogen in a country with a high HIV and AIDS prevalence.
Abstract A literature review was undertaken to ascertain the molecular basis for tigecycline and ... more Abstract
A literature review was undertaken to ascertain the molecular basis for tigecycline and colistin resistance mechanisms and the experimental basis for the detection and delineation of this resistance particularly in carbapenemase-producing Gram-negative bacteria. Pubmed, Google Scholar and Science Direct were searched with the keywords colistin, tigecycline, resistance mechanisms and detection methods. Trans-complementation and comparative MIC studies, mass spectrometry, chromatography, spectrofluorometry, PCR, qRT-PCR and whole genome sequencing (WGS) were commonly used to determine tigecycline and colistin resistance mechanisms, specifically modifications in the structural and regulatory efflux (acrAB, OqxAB, kpgABC adeABC-FGH-IJK, mexAB-XY-oprJM and soxS, rarA robA, ramRAB marRABC, adeLRS, mexRZ and nfxb ) and lipid A (pmrHFIJFKLM, lpxA, lpxC lpxD and mgrB, pmrAB, phoPQ,) genes respectively. Mutations in the ribosomal 16S rRNA operon rrnBC, also yielded resistance to tigecycline through target site modifications. The mcr-1 gene conferring resistance to colistin was identified via WGS, trans-complementation and a murine thigh infection model studies.Common detection methods are mainly antibiotic sensitivity testing with broth microdilution while molecular identification tools are mostly PCR and WGS. Spectrofluorometry, MALDI-TOF MS, micro-array and real time multiplex PCR hold much promise for the future as new detection tools
South African Family Practice, Sep 14, 2006
Pharmaceutical Research
beta-Lactam antibiotics, viz., penicillin, penicillin derivatives, cephalosporins, cephamycins, c... more beta-Lactam antibiotics, viz., penicillin, penicillin derivatives, cephalosporins, cephamycins, carbapenems, monobactams. and monocarbams, are the most widely used of all antimicrobial classes by virtue of their high efficacy and specificity and the availability of several derivatives. The expression of one or several beta-lactamases (beta-lactam antibiotic-inactivating enzymes) represents the most widespread and the most clinically relevant resistance mechanism to these antibiotics. The development of beta-lactam antibiotics has thus been a continuous battle of the design of new compounds to withstand inactivation by the ever-increasing diversity of beta-lactamases. This article traces antibiotic development in response to the evolution of beta-lactamases.
Journal of Food Protection, 2012
Campylobacter bacteria are important foodborne pathogens that cause acute diarrheal illness, and ... more Campylobacter bacteria are important foodborne pathogens that cause acute diarrheal illness, and infection is often associated with contaminated poultry. In a blind observational study, the prevalence and resistance profiles of thermophilic Campylobacter strains collected from different poultry production systems were tested against the clinically used antibiotics ciprofloxacin, tetracycline, erythromycin, gentamicin, and streptomycin. Campylobacter strains were isolated from chickens in rural production systems, a free-range commercial facility, and industrially raised broiler and egg-laying chickens all situated in KwaZulu-Natal, South Africa. Isolates were collected from the chicken cecae and were identified with conventional methods and tested for antibiotic resistance with the Clinical and Laboratory Standards Institute agar dilution method. The prevalence of Campylobacter spp. isolates in chickens was 68% (56 samples) in rural production, 47% (140 samples) in commercial free-range broilers, 47% (133 samples) in industrial broilers, and 94% (34 samples) in industrial layer hens. Isolates from the rurally raised chickens showed significantly (P < 0.01) less resistance against ciprofloxacin (7.9%), erythromycin (0%), and tetracycline (21.6%) than those from commercially produced chickens. Isolates from the commercially raised chickens (free range and industrial) were highly resistant to tetracycline (98.9 to 100%). The incidence of gentamicin and streptomycin resistance was 1.6 and 11.5%, respectively, in commercial free-range broilers, 1.7 and 16.4%, respectively, in industrially raised broilers, and 12.9 and 40%, respectively, in industrially raised layers. It is possible that variations among the poultry production systems, including antimicrobial usage, result in differences in antibiotic resistance profiles in Campylobacter.
FEMS microbiology letters, Jan 15, 2000
A review of antibiotic options for the treatment of infections caused by extended-spectrum beta-l... more A review of antibiotic options for the treatment of infections caused by extended-spectrum beta-lactamase-producing isolates is presented. The use of the third-generation cephalosporin, cefotaxime, for infections caused by isolates producing ceftazidimase-type extended-spectrum beta-lactamases is controversial, despite in vitro susceptibility to the antibiotic in many instances. The fourth-generation cephalosporin, cefipime, although active against most extended-spectrum beta-lactamases, is reported to show a marked inoculum effect. The cephamycins, such as cefoxitin. are generally effective against Enterobacteriaceae producing TEM- and SHV-derived extended-spectrum beta-lactamases, but Klebsella pneumoniae strains are prone to cephamycin resistance as a result of porin loss. The use of beta-lactamase inhibitor combinations is variable. Sulbactam is less effective than clavulanate for the inhibition of SHV-derived extended-spectrum beta-lactamases and a marked inoculum effect has be...
FEMS Microbiology Letters, 2000
... 10] Katsanis, GP, Spargo, J., Ferraro, MJ, Sutton, L., Jacoby, GA (1994) Detection of Klebsie... more ... 10] Katsanis, GP, Spargo, J., Ferraro, MJ, Sutton, L., Jacoby, GA (1994) Detection of Klebsiella pneumoniae and Escherichia coli strains producing extended-spectrum β-lactamases. J. Clin. Microbiol. 32, 691696. ... 33] French, GL, Shannon, KP, Simmons, N. (1996) Hospital ...
AFRICAN JOURNAL OF BIOTECHNOLOGY
Southern African Journal of Infectious Diseases, 2015
South African Family Practice, 2015
Southern African Journal of Infectious Diseases, 2015
The ampC promoter and attenuator regions of an Escherichia coli clinical isolate from a public ho... more The ampC promoter and attenuator regions of an Escherichia coli clinical isolate from a public hospital in KwaZulu-Natal was investigated to detect the presence of mutations in these regions. The isolate was subjected to MIC determinations, IEF analysis, PCR for the presence of �-lactamases and sequencing of the ampC gene. Analysis of the ampC promoter and attenuator regions of the
Research articles describing carbapenemases and their genetic environments in Gram-negative bacte... more Research articles describing carbapenemases and their genetic environments in Gram-negative bacteria were reviewed to determine the molecular epidemiology of carbapenemases in Africa. The emergence of resistance to the carbapenems, the last resort antibiotic for difficult to treat bacterial infections, affords clinicians few therapeutic options, with a resulting increase in morbidities, mortalities, and healthcare costs. However, the molecular epidemiology of carbapenemases throughout Africa is less described. Research articles and conference proceedings describing the carbapenemase genetic environment and molecular epidemiology in Africa were retrieved from Google Scholar, Scifinder, Pubmed, Web of Science, and Science Direct databases. Predominant carbapenemase genes so far described in Africa include the blaOXA-48 type, blaIMP, blaVIM, and blaNDM in Acinetobacter baumannii, Klebsiella pneumoniae, Enterobacter cloacae, Citrobacter spp., and Escherichia coli carried on various plasmid types and sizes, transposons, and integrons. Consequently, the true molecular epidemiology of carbapenemases and their genetic environment in Africa is still unknown. Class D and class B carbapenemases, mainly prevalent in A. baumannii, K. pneumoniae, E. cloacae, Citrobacter spp., and E. coli were the commonest carbapenemases. Carbapenemases are mainly reported in North and South Africa as under-resourced laboratories, lack of awareness and funding preclude the detection and reporting of carbapenemase-mediated resistance.
South African medical journal = Suid-Afrikaanse tydskrif vir geneeskunde
To investigate a possible association between level of care, antibiotic use and antimicrobial res... more To investigate a possible association between level of care, antibiotic use and antimicrobial resistance in 16 public-sector hospitals providing different levels of care in KwaZulu-Natal. A multicentre surveillance study was undertaken in 16 hospitals at three progressive levels of health care (district, regional, tertiary) where each hospital submitted 100 consecutive, non-repetitive isolates judged in the laboratory to be of potential clinical significance. Isolates were identified and susceptibility testing was undertaken using the Kirby-Bauer disc diffusion method with minimum inhibitory concentrations (MICs) extrapolated on an automated reading system. Isolates were grouped according to their natural resistance profiles, and percentage susceptibility, mean percentage susceptibility and standard deviation to each antibiotic were stratified within and across hospital levels. Antibiotic use data were expressed as the number of daily divided doses (DDDs) per 1000 patient-days. Two ...
Physiology has an anecdotal track record of having lower pass rates than other professional modul... more Physiology has an anecdotal track record of having lower pass rates than other professional modules in the Health Sciences (HS). The aim of this study was to compare the performance and associated contributory factors of students in physiology modules with professional modules at the same level of study. This was done by way of overall pass rates and average, maximum, and minimum marks for the period 2008–2010 stratified by programme/qualification, matriculation/National Senior Certificate achievement and language. The latter two served as proxies for alternative access and previously disadvantaged students, respectively. There was a notable difference in the mean 2008– 2010 pass rates of students from the different professional qualifications and students generally performed considerably better in their professional modules as compared with their performance in the physiology modules. The performance in physiology modules of English first language (EFL) students was not significant...
The minimal antibiotic options for carbapenemase producing Gram-negative bacteria necessitate the... more The minimal antibiotic options for carbapenemase producing Gram-negative bacteria necessitate their rapid detection. A literature review of a variety of phenotypic and genotypic methods is presented. Advances in culture methods and screening media are still subject to long incubation hours. Biochemical methods have shorter turnaround times and higher sensitivities and specificities, but cannot differentiate between various types and variants. Spectrophotometric methods are cheap and efficient, but are uncommon in many clinical settings, while the MALDI-TOF MS is promising for species identification, typing and resistance gene determination. Although next generation sequencing (NGS) technologies provide a better platform to detect, type and characterise carbapenem resistant bacteria, the different NGS platforms, the large computer memories and space needed to process and store genomic data and the non-uniformity in data analysis platforms are still a challenge. The sensitivities, spe...
Letters in Applied Microbiology, 2019
Significance and impact of study We report on the first clinical Morganella morganii draft genome... more Significance and impact of study
We report on the first clinical Morganella morganii draft genomes from Africa. The isolates were found in the urine of patients presenting with urinary tract infections (UTIs). Notably, they were resistant to important clinical antibiotics, including those used to treat UTIs. Due to the common occurrence of UTIs, particularly among pregnant women for whom drug options are limited, the presence of antibiotic-resistant uropathogens such as M. morganii is a serious public health concern. We therefore characterised the resistance mechanisms and epidemiology of these isolates to provide further insights into their dissemination and background data for future studies.
Abstract
Morganella morganii is an opportunistic bacterial pathogen of the Enterobacteriaceae family that is occasionally isolated from clinical (animal and human) specimens with varying resistance profiles. Detailed genomic analyses of drug-resistant M. morganii strains are relatively limited, particularly in Africa, which is also due to their relatively low isolation rates from clinical settings. Here, we report on two multidrug-resistant clinical M. morganii isolates from urine specimens of two hospitalised patients in South Africa who presented with urinary tract infections in 2013. The isolates, M006 and E042, were only susceptible to carbapenems, amikacin and tigecycline. One strain, M006, had a novel class 1 integron, ln1484, associated with aadA7, sul1and gcuD gene cassettes and a Col3M plasmid replicase gene. The ln1484 intI1:aadA7:sul1 genes were bracketed by a TnAs3 composite transposon while a tet(B) gene was found on an IS4 family transposon. The rare blaDHA-4 and blaDHA-1 AmpC β-lactamase genes were identified on the isolates’ chromosome. The isolates were phylogenetically distant and closely related to other international strains, suggesting that they were not obtained from a single epidemiological source. Further molecular surveillance is necessary to establish the prevalence of these MDR strains in the tertiary hospital. Moreover, antibiotic stewardship and antibiotic sensitivity testing of all clinical isolates should be undertaken after empirical treatment to inform tailored therapy as well as reduce escalation of resistance and associated morbidities and mortalities.
Haemophilus parain uenzae is part of the HACEK group of fastidious bacteria commonly implicated i... more Haemophilus parain uenzae is part of the HACEK group of fastidious bacteria commonly implicated in endocarditis and bacteremia. Previously considered as a normal respiratory, oral and sometimes genitourinary commensal, it has been recognised as a pathogen that can cause life-threatening infections in both immunocompromised and healthy individuals. It has also been reported as a bacterium that can harbor transferable antibiotic resistance genes. This paper presents a literature review on the molecular mechanisms of resistance of H. parain uenzae to commonly prescribed antibiotics and discusses areas for further research.
Fluoroquinolones and ketolides are among the drugs of choice for the treatment of Haemophilus par... more Fluoroquinolones and ketolides are among the drugs of choice for the treatment of Haemophilus parainfluenzae infections. There has been a report of an emerging fluoroquinolone and telithromycin resistance in H. para-influenzae isolates from the private sector of KwaZulu-Natal Province of South Africa that necessitates molecular investigation. The aim of this study is to characterize these resistance delineating mutations in genes commonly associated with reduced susceptibility. Ten H. parainfluenzae isolates retrieved from the sputum of 10 patients with H. parainfluenzae pneumonia were subjected to sensitivity testing by the disc diffusion and CLSI broth microdilution methods, polymerase chain reaction (PCR) and DNA sequencing of selected genes associated with resistance were carried out, while repetitive extragenic palindromic PCR (REP-PCR) was used to ascertain clonality. Fluoroquinolone resistance was attributed to the following amino acid substitutions: S84F, D88Y in GyrA, and S84Y/L, S138T, and M198 L change in ParC of the isolates. The plasmid-mediated quinolone resistance gene aac-(6¢)-Ib-cr was detected for the first time in four isolates of H. parainfluenzae and D420 N change was observed in ParE in one isolate. Macrolide and ketolide resistance were ascribed to the resistance genes mef (A), msr (D), and erm (B) detected in the isolates. REP-PCR analysis showed that the isolates were not clonal. All the observed resistance mechanisms are first reports in Africa. There is an emerging fluoroquinolone and macrolide resistance in H. parainfluenzae in South Africa that is attributable to known/ novel resistance mechanisms, necessitating the monitoring of this pathogen as a potential opportunistic pathogen in a country with a high HIV and AIDS prevalence.
Abstract A literature review was undertaken to ascertain the molecular basis for tigecycline and ... more Abstract
A literature review was undertaken to ascertain the molecular basis for tigecycline and colistin resistance mechanisms and the experimental basis for the detection and delineation of this resistance particularly in carbapenemase-producing Gram-negative bacteria. Pubmed, Google Scholar and Science Direct were searched with the keywords colistin, tigecycline, resistance mechanisms and detection methods. Trans-complementation and comparative MIC studies, mass spectrometry, chromatography, spectrofluorometry, PCR, qRT-PCR and whole genome sequencing (WGS) were commonly used to determine tigecycline and colistin resistance mechanisms, specifically modifications in the structural and regulatory efflux (acrAB, OqxAB, kpgABC adeABC-FGH-IJK, mexAB-XY-oprJM and soxS, rarA robA, ramRAB marRABC, adeLRS, mexRZ and nfxb ) and lipid A (pmrHFIJFKLM, lpxA, lpxC lpxD and mgrB, pmrAB, phoPQ,) genes respectively. Mutations in the ribosomal 16S rRNA operon rrnBC, also yielded resistance to tigecycline through target site modifications. The mcr-1 gene conferring resistance to colistin was identified via WGS, trans-complementation and a murine thigh infection model studies.Common detection methods are mainly antibiotic sensitivity testing with broth microdilution while molecular identification tools are mostly PCR and WGS. Spectrofluorometry, MALDI-TOF MS, micro-array and real time multiplex PCR hold much promise for the future as new detection tools
South African Family Practice, Sep 14, 2006
Pharmaceutical Research
beta-Lactam antibiotics, viz., penicillin, penicillin derivatives, cephalosporins, cephamycins, c... more beta-Lactam antibiotics, viz., penicillin, penicillin derivatives, cephalosporins, cephamycins, carbapenems, monobactams. and monocarbams, are the most widely used of all antimicrobial classes by virtue of their high efficacy and specificity and the availability of several derivatives. The expression of one or several beta-lactamases (beta-lactam antibiotic-inactivating enzymes) represents the most widespread and the most clinically relevant resistance mechanism to these antibiotics. The development of beta-lactam antibiotics has thus been a continuous battle of the design of new compounds to withstand inactivation by the ever-increasing diversity of beta-lactamases. This article traces antibiotic development in response to the evolution of beta-lactamases.
Journal of Food Protection, 2012
Campylobacter bacteria are important foodborne pathogens that cause acute diarrheal illness, and ... more Campylobacter bacteria are important foodborne pathogens that cause acute diarrheal illness, and infection is often associated with contaminated poultry. In a blind observational study, the prevalence and resistance profiles of thermophilic Campylobacter strains collected from different poultry production systems were tested against the clinically used antibiotics ciprofloxacin, tetracycline, erythromycin, gentamicin, and streptomycin. Campylobacter strains were isolated from chickens in rural production systems, a free-range commercial facility, and industrially raised broiler and egg-laying chickens all situated in KwaZulu-Natal, South Africa. Isolates were collected from the chicken cecae and were identified with conventional methods and tested for antibiotic resistance with the Clinical and Laboratory Standards Institute agar dilution method. The prevalence of Campylobacter spp. isolates in chickens was 68% (56 samples) in rural production, 47% (140 samples) in commercial free-range broilers, 47% (133 samples) in industrial broilers, and 94% (34 samples) in industrial layer hens. Isolates from the rurally raised chickens showed significantly (P < 0.01) less resistance against ciprofloxacin (7.9%), erythromycin (0%), and tetracycline (21.6%) than those from commercially produced chickens. Isolates from the commercially raised chickens (free range and industrial) were highly resistant to tetracycline (98.9 to 100%). The incidence of gentamicin and streptomycin resistance was 1.6 and 11.5%, respectively, in commercial free-range broilers, 1.7 and 16.4%, respectively, in industrially raised broilers, and 12.9 and 40%, respectively, in industrially raised layers. It is possible that variations among the poultry production systems, including antimicrobial usage, result in differences in antibiotic resistance profiles in Campylobacter.
FEMS microbiology letters, Jan 15, 2000
A review of antibiotic options for the treatment of infections caused by extended-spectrum beta-l... more A review of antibiotic options for the treatment of infections caused by extended-spectrum beta-lactamase-producing isolates is presented. The use of the third-generation cephalosporin, cefotaxime, for infections caused by isolates producing ceftazidimase-type extended-spectrum beta-lactamases is controversial, despite in vitro susceptibility to the antibiotic in many instances. The fourth-generation cephalosporin, cefipime, although active against most extended-spectrum beta-lactamases, is reported to show a marked inoculum effect. The cephamycins, such as cefoxitin. are generally effective against Enterobacteriaceae producing TEM- and SHV-derived extended-spectrum beta-lactamases, but Klebsella pneumoniae strains are prone to cephamycin resistance as a result of porin loss. The use of beta-lactamase inhibitor combinations is variable. Sulbactam is less effective than clavulanate for the inhibition of SHV-derived extended-spectrum beta-lactamases and a marked inoculum effect has be...
FEMS Microbiology Letters, 2000
... 10] Katsanis, GP, Spargo, J., Ferraro, MJ, Sutton, L., Jacoby, GA (1994) Detection of Klebsie... more ... 10] Katsanis, GP, Spargo, J., Ferraro, MJ, Sutton, L., Jacoby, GA (1994) Detection of Klebsiella pneumoniae and Escherichia coli strains producing extended-spectrum β-lactamases. J. Clin. Microbiol. 32, 691696. ... 33] French, GL, Shannon, KP, Simmons, N. (1996) Hospital ...
AFRICAN JOURNAL OF BIOTECHNOLOGY
Southern African Journal of Infectious Diseases, 2015
South African Family Practice, 2015
Southern African Journal of Infectious Diseases, 2015
The ampC promoter and attenuator regions of an Escherichia coli clinical isolate from a public ho... more The ampC promoter and attenuator regions of an Escherichia coli clinical isolate from a public hospital in KwaZulu-Natal was investigated to detect the presence of mutations in these regions. The isolate was subjected to MIC determinations, IEF analysis, PCR for the presence of �-lactamases and sequencing of the ampC gene. Analysis of the ampC promoter and attenuator regions of the
Research articles describing carbapenemases and their genetic environments in Gram-negative bacte... more Research articles describing carbapenemases and their genetic environments in Gram-negative bacteria were reviewed to determine the molecular epidemiology of carbapenemases in Africa. The emergence of resistance to the carbapenems, the last resort antibiotic for difficult to treat bacterial infections, affords clinicians few therapeutic options, with a resulting increase in morbidities, mortalities, and healthcare costs. However, the molecular epidemiology of carbapenemases throughout Africa is less described. Research articles and conference proceedings describing the carbapenemase genetic environment and molecular epidemiology in Africa were retrieved from Google Scholar, Scifinder, Pubmed, Web of Science, and Science Direct databases. Predominant carbapenemase genes so far described in Africa include the blaOXA-48 type, blaIMP, blaVIM, and blaNDM in Acinetobacter baumannii, Klebsiella pneumoniae, Enterobacter cloacae, Citrobacter spp., and Escherichia coli carried on various plasmid types and sizes, transposons, and integrons. Consequently, the true molecular epidemiology of carbapenemases and their genetic environment in Africa is still unknown. Class D and class B carbapenemases, mainly prevalent in A. baumannii, K. pneumoniae, E. cloacae, Citrobacter spp., and E. coli were the commonest carbapenemases. Carbapenemases are mainly reported in North and South Africa as under-resourced laboratories, lack of awareness and funding preclude the detection and reporting of carbapenemase-mediated resistance.
South African medical journal = Suid-Afrikaanse tydskrif vir geneeskunde
To investigate a possible association between level of care, antibiotic use and antimicrobial res... more To investigate a possible association between level of care, antibiotic use and antimicrobial resistance in 16 public-sector hospitals providing different levels of care in KwaZulu-Natal. A multicentre surveillance study was undertaken in 16 hospitals at three progressive levels of health care (district, regional, tertiary) where each hospital submitted 100 consecutive, non-repetitive isolates judged in the laboratory to be of potential clinical significance. Isolates were identified and susceptibility testing was undertaken using the Kirby-Bauer disc diffusion method with minimum inhibitory concentrations (MICs) extrapolated on an automated reading system. Isolates were grouped according to their natural resistance profiles, and percentage susceptibility, mean percentage susceptibility and standard deviation to each antibiotic were stratified within and across hospital levels. Antibiotic use data were expressed as the number of daily divided doses (DDDs) per 1000 patient-days. Two ...
Physiology has an anecdotal track record of having lower pass rates than other professional modul... more Physiology has an anecdotal track record of having lower pass rates than other professional modules in the Health Sciences (HS). The aim of this study was to compare the performance and associated contributory factors of students in physiology modules with professional modules at the same level of study. This was done by way of overall pass rates and average, maximum, and minimum marks for the period 2008–2010 stratified by programme/qualification, matriculation/National Senior Certificate achievement and language. The latter two served as proxies for alternative access and previously disadvantaged students, respectively. There was a notable difference in the mean 2008– 2010 pass rates of students from the different professional qualifications and students generally performed considerably better in their professional modules as compared with their performance in the physiology modules. The performance in physiology modules of English first language (EFL) students was not significant...