Shabbir Simjee

U.S. Food and Drug Administration, Washington, Washington, D.C., United States

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Publications (34)115.65 Total impact

  • [show abstract] [hide abstract]
    ABSTRACT: Resistance monitoring programmes are essential to generate data for inclusion in the scientific risk assessment of the potential for transmission of antimicrobial-resistant bacteria or their resistance determinants from food-producing animals to humans. This review compares the technical specifications on monitoring of antimicrobial resistance in zoonotic Salmonella, Campylobacter and indicator Escherichia coli and Enterococcus as performed by the European Food Safety Authority (EFSA) with veterinary pharmaceutical industry's European Antimicrobial Susceptibility Surveillance in Animals (EASSA) programme. The authors conclude that most of EFSA's recent monitoring recommendations have been covered by EASSA since the start of the latter programme in 1998. The major difference between the two programmes is the classification into ‘susceptible’ versus ‘resistant’. Whilst EFSA categorises all isolates with an MIC value above the epidemiological cut-off value as ‘resistant’, EASSA differentiates between ‘percentage decreased susceptible’ and ‘percentage clinical resistant’ strains by applying both epidemiological cut-off values and clinical breakpoints. Because there is still a need to further improve harmonisation among individual EU Member State activities, Animal Health Industry welcomes EFSA's initiative to further improve the quality of resistance monitoring as it is of utmost importance to apply standardised collection procedures and harmonised susceptibility testing, when monitoring antimicrobial resistance across Europe.
    Veterinary Microbiology 01/2014; · 3.13 Impact Factor
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    ABSTRACT: Antimicrobial resistance is a concern both for animal and human health. Veterinary programmes monitoring resistance of animal and zoonotic pathogens are therefore essential. Various European countries have implemented national surveillance programmes, particularly for zoonotic and commensal bacteria, and the European Food Safety Authority (EFSA) is compiling the data. However, harmonisation is identified as a weakness and an essential need in order to compare data across countries. Comparisons of resistance monitoring data among national programmes are hampered by differences between programmes, such as sampling and testing methodology, and different epidemiological cut-off values or clinical breakpoints. Moreover, only very few valid data are available regarding target pathogens both of farm and companion animals. The European Animal Health Study Centre (CEESA) attempts to fill these gaps. The resistance monitoring programmes of CEESA have been a collaboration of veterinary pharmaceutical companies for over a decade and include two different projects: the European Antimicrobial Susceptibility Surveillance in Animals (EASSA) programme, which collects food-borne bacteria at slaughter from healthy animals, and the pathogen programmes that collect first-intention target pathogens from acutely diseased animals. The latter comprises three subprogrammes: VetPath; MycoPath; and ComPath. All CEESA projects include uniform sample collection and bacterial identification to species level in various European Union (EU) member states. A central laboratory conducts quantitative susceptibility testing to antimicrobial agents either important in human medicine or commonly used in veterinary medicine. This 'methodology harmonisation' allows easy comparisons among EU member states and makes the CEESA programmes invaluable to address food safety and antibiotic efficacy.
    International journal of antimicrobial agents 02/2013; · 3.03 Impact Factor
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    ABSTRACT: To determine the stability/reversibility and mechanism of monensin adaptation in monensin-treated cattle isolates compared with reference bacterial isolates, exposed in vitro to high monensin concentrations. We evaluated the potential for cattle-origin strains of Clostridium perfringens, Enterococcus faecium and Enterococcus faecalis exposed to monensin in vivo (in vivo monensin-exposed isolates) to maintain or achieve the ability to grow in the presence of high monensin concentrations (in vitro monensin-adapted isolates). Twenty-one consecutive subcultures of the in vitro monensin-adapted strains were performed, and monensin MICs were determined for the 3rd, 7th, 14th and 21st subcultures (subcultured isolates). SDS-PAGE and transmission electron microscopy (TEM) were used to determine protein expression and visualize extracellular morphology changes. Monensin-non-exposed isolates did not display monensin adaptation during in vitro monensin exposure. In contrast, in vivo monensin-exposed isolates displayed monensin adaptation enabling growth at 32× MIC. Upon consecutive subculturing, monensin MICs returned to baseline, or one dilution above, for the monensin-adapted strains. SDS-PAGE identified overexpression of a 14 kDa protein (C. perfringens) and a 20.5 kDa protein (E. faecium and E. faecalis) in the monensin-adapted isolates. TEM demonstrated that in vitro monensin-adapted strains had a significantly thicker cell wall or glycocalyx compared with in vivo monensin-exposed or subcultured isolates. In vivo monensin-exposed isolates of C. perfringens, E. faecium and E. faecalis have the ability to grow in the presence of high monensin concentrations in vitro. This is associated with an increased thickening of the cell wall or glycocalyx that is reversible upon serial passage, suggesting a phenotypically expressed, but not genetically stable, trait.
    Journal of Antimicrobial Chemotherapy 06/2012; 67(10):2388-95. · 5.34 Impact Factor
  • Source
    15th International Congress on Infectious Diseases (ICID).; 06/2012
  • P Silley, S Simjee, S Schwarz
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    ABSTRACT: Surveillance and monitoring studies of antimicrobial resistance in bacteria of human and animal origin and antimicrobial consumption in humans and animals have been conducted in various countries throughout the world. In the veterinary field, in particular, programmes have been installed which target bacteria of zoonotic, foodborne and/or veterinary relevance. Each year, the European Surveillance of Veterinary Antimicrobial Consumption project summarises and evaluates antimicrobial consumption in ambulatory and hospital care in many European countries. In contrast, antimicrobial consumption data in veterinary medicine are available from only a few countries and the type of information that is collected or reported varies. To address this challenge, the European Surveillance of Veterinary Antimicrobial Consumption project was launched by the European Medicines Agency in September 2009 and has just published its first report. This comparison of the different studies for surveillance and monitoring of antimicrobial resistance and antimicrobial consumption in humans and animals shows the need to improve harmonisation.
    Revue scientifique et technique (International Office of Epizootics) 04/2012; 31(1):105-20. · 0.69 Impact Factor
  • 15th International Congress on Infectious Diseases (ICID)15th International Congress on Infectious Diseases (ICID); 01/2012
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    ABSTRACT: To determine the antimicrobial susceptibility of Escherichia coli, Salmonella, Campylobacter and Enterococcus from cattle, pigs and chickens across the European Union (EU) using uniform methodology. Intestinal samples (1624) were taken at slaughter across five EU countries. Bacteria were isolated in national laboratories, whilst MICs were determined in a central laboratory for key antimicrobials used in human medicine. Clinical resistance was based on CLSI breakpoints and decreased susceptibility based on European Food Safety Authority (EFSA)/EUCAST epidemiological cut-off values. Isolation rates were high for E. coli (n=1540), low for Salmonella (n=201) and intermediate for Campylobacter (n=940) and Enterococcus (n=786). For E. coli and Salmonella, clinical resistance to newer compounds (cefepime, cefotaxime and ciprofloxacin) was absent or low, but decreased susceptibility was apparent, particularly in chicken strains. Resistance to older compounds (except gentamicin) was variable and higher. Colistin resistance was absent for E. coli, but apparent for Salmonella. For Campylobacter jejuni, ciprofloxacin resistance was markedly prevalent for chickens, whereas clinical resistance and decreased susceptibility to erythromycin was absent or very low. For Campylobacter coli, resistance was notably higher. None of the Enterococcus faecium strains was resistant to linezolid, but some were resistant to ampicillin or vancomycin. Resistance to quinupristin/dalfopristin was frequent. Resistance patterns varied widely depending on bacterial species, antibiotics, hosts and region. Resistance varied among countries, particularly for older antimicrobials, but clinical resistance to newer antibiotics used to treat foodborne disease in humans was generally very low. In the absence of resistance to newer compounds in E. coli and Salmonella, the apparent decreased susceptibility should be monitored.
    Journal of Antimicrobial Chemotherapy 12/2011; 67(3):638-51. · 5.34 Impact Factor
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    ABSTRACT: Antimicrobial surveillance systems in Denmark (DANMAP), The Netherlands (MARAN), Spain (VAV) and Sweden (SVARM) as well as the European Antimicrobial Susceptibility Surveillance in Animals (EASSA) were reviewed. Data have been considered for extended-spectrum cephalosporins, fluoroquinolones and macrolides against food-borne and commensal bacteria. The greatest challenge arises from the lack of agreement between programmes on what is meant by resistance through the use of different interpretive criteria. Indeed, it is shown here that the extent of the differences depends on the antibacterial compound being investigated, the methodology and the interpretive criteria used. This emphasises a need to agree a definition for resistance and for epidemiological cut-off values and to consider harmonising the antimicrobials used in surveillance. This analysis of the data highlights the usefulness of using both epidemiological cut-off values and clinical resistance breakpoints for the purpose of detection of decreased susceptibility and development of clinical resistance, respectively. It is concluded that harmonisation in resistance monitoring programmes is needed since there is potential for data to be appropriately used within risk analysis, providing the opportunity to implement appropriate risk management steps as a response to the public health issues arising from changes in antibiotic resistance in food-borne pathogens and commensal organisms.
    International journal of antimicrobial agents 02/2011; 37(6):504-12. · 3.03 Impact Factor
  • Clinical and Laboratory Standards Institute. 01/2011;
  • Veterinary Microbiology 02/2010; 141(1-2):1-4. · 3.13 Impact Factor
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    ABSTRACT: The accurate performance of antimicrobial susceptibility testing of bacteria from animal sources and the correct presentation of the results is a complex matter. A review of the published literature revealed a number of recurring errors with regard to methodology, quality control, appropriate interpretive criteria, and calculation of MIC(50) and MIC(90) values. Although more subjective, there is also no consensus regarding the definition of multiresistance. This Editorial is intended to provide guidance to authors on how to avoid these frequently detected shortcomings.
    Journal of Antimicrobial Chemotherapy 02/2010; 65(4):601-4. · 5.34 Impact Factor
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    ABSTRACT: The aim of the study was to study antimicrobial susceptibility in Escherichia coli, Salmonella, Campylobacter and Enterococcus recovered from chickens, pigs and cattle using uniform methodology. Intestinal samples were taken at slaughter in five EU countries per host and bacteria isolated in national laboratories. MICs were determined in a central laboratory of key antimicrobials used in human medicine. Clinical resistance was based on CLSI breakpoints and decreased susceptibility on EFSA epidemiological cut-off values. Isolation rates from a total of 1500 samples were high for E. coli (n=1465), low for Salmonella (n=205) and intermediate for Campylobacter (n=785) and Enterococcus (n=718). Resistance prevalence varied among antibiotics, bacteria, hosts and countries. For E. coli and Salmonella, clinical resistance to newer compounds (cefepime, cefotaxime, ciprofloxacin) was absent or low, but a decreased susceptibility was apparent, particularly in chickens. Clinical resistance to older compounds (except colistin and gentamicin) was variable and higher. For Campylobacter jejuni from chickens, ciprofloxacin resistance was markedly higher than in isolates from cattle. Clinical resistance to erythromycin was absent for both hosts; decreased susceptibility very low. Similar trends were determined for Campylobacter coli, but C. jejuni was less resistant. None of the enterococcal strains was resistant to linezolid, but a few displayed resistance to ampicillin or vancomycin. Resistance prevalence to quinupristin/dalfopristin was clearly higher. Antimicrobial resistance among enteric organisms in food animals varied among countries, particularly for older antimicrobials, but clinical resistance to essential compounds used to treat disease in humans was generally zero or low. In the absence of clinical resistance to newer compounds in E. coli and Salmonella, the apparent decreased susceptibility should be monitored carefully.
    Journal of Antimicrobial Chemotherapy 03/2009; 63(4):733-44. · 5.34 Impact Factor
  • 02/2008: pages 239 - 256; , ISBN: 9780470752579
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    ABSTRACT: resistance was not part of the investigations of the two studies.2,3 On the basis of these two recent reports, Deane and Young4 express the belief that in view of these new findings, the use of the combination of erythromycin and metoclopramide to reduce residual gastric volume outweighs the risks of the associated promotion of antimicrobial resistance. We remain to be con- vinced that their belief is sufficiently substantiated for reasons as follows. First, no improved clinical outcome could be found in the study group, which was given the combination therapy, the ulti- mate goal of any intervention in intensive care. This is consist- ent with previous findings that increased gastric emptying does not correlate with improved outcome;5 second, both studies demonstrated that the most critically ill patients, i.e. patients with a high Acute Physiology and Chronic Health Evaluation II score (APACHE II), patients requiring sedation by either opiates or benzodiazepines, patients with hyperglycaemia requiring insulin therapy, or patients who were already malnourished as indicated by hypoalbuminaemia responded least to either ery- thromycin or the combination of erythromycin plus metoclopra- mide as gastric prokinetic agents;2,3 third, as with other studies, the weakness of these studies is that the GRV has been taken as the endpoint of successful treatment. As members of our local intensive care team, we share the concerns about optimizing enteric feeding as expressed by Deane and Young.4 However, neither the studies by Nguyen et al.2,3 nor Deane and Young4 provide any epidemiological data supporting their belief that the accumulating amount of low doses of erythromycin given as prokinetic agent does not promote the emergence of antibiotic resistance, as discussed in our review article. Therefore, we are convinced that our cautious approach " ... that the use of erythromycin A as a prokinetic agent in the critical care unit should be restricted to only those patients who have already failed all other treatments for impaired gastric motility and are intolerant of a first-line agent such as metoclopramide" is still justified.1 Failing other treat- ments would, of course, include failure to insert a jejunal feeding tube.
    Journal of Antimicrobial Chemotherapy 02/2008; 61(1):228-9. · 5.34 Impact Factor
  • Journal of Applied Microbiology 01/2008; 103(6):2730-1; author reply 2732. · 2.20 Impact Factor
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    ABSTRACT: Data on the prevalence of antimicrobial resistant enterococci and staphylococci from the poultry production environment are sparse in the United States. This information is needed for science-based risk assessments of antimicrobial use in animal husbandry and potential public-health consequences. In this study, we assessed the susceptibility of staphylococci and enterococci isolated from poultry litter, recovered from 24 farms across Georgia, to several antimicrobials of veterinary and human health importance. Among the 90 Enterococcus isolates recovered, E. hirae (46%) was the most frequently encountered species, followed by E. faecium (27%), E. gallinarum (12%), and E. faecalis (10%). Antimicrobial resistance was most often observed to tetracycline (96%), followed by clindamycin (90%), quinupristin-dalfopristin (62%), penicillin (53%), erythromycin (50%), nitrofurantoin (49%), and clarithromycin (48%). Among the 110 staphylococci isolates recovered, only coagulase-negative staphylococci (CNS) were identified with the predominant Staphylococcus species being S. sciuri (38%), S. lentus (21%), S. xylosus (14%) and S. simulans (12%). Resistance was less-frequently observed among the Staphylococcus isolates for the majority of antimicrobials tested, as compared with Enterococcus isolates, and was primarily limited to clarithromycin (71%), erythromycin (71%), clindamycin (48%), and tetracycline (38%). Multidrug resistance (MDR) phenotypes were prevalent in both Enterococcus and Staphylococcus; however, Enterococcus exhibited a statistically significant difference in the median number of antimicrobials to which resistance was observed (median = 5.0) compared with Staphylococcus species (median = 3.0). Because resistance to several of these antimicrobials in gram-positive bacteria may be attributed to the shuttling of common drug-resistance genes, we also determined which common antimicrobial-resistance genes were present in both enterococci and staphylococci. The antimicrobial resistance genes vat(D) and erm(B) were present in enterococci, vgaB in staphylococci, and mobile genetic elements Tn916 and pheromone-inducible plasmids were only identified in enterococci. These data suggest that the disparity in antimicrobial-resistance phenotypes and genotypes between enterococci and staphylococci isolated from the same environment is, in part, because of barriers preventing exchange of mobile DNA elements.
    Avian Diseases 01/2008; 51(4):884-92. · 1.73 Impact Factor
  • International Journal of Antimicrobial Agents - INT J ANTIMICROBIAL AGENTS. 01/2007; 29.
  • R Bywater, P Silley, S Simjee
    Veterinary Microbiology 12/2006; 118(1-2):158-9. · 3.13 Impact Factor
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    ABSTRACT: Molecular characterization (e.g., DNA-based typing methods) of Salmonella isolates is frequently employed to compare and distinguish clinical isolates recovered from animals and from patients with food-borne disease and nosocomial infections. In this study, we compared the abilities of different phenotyping and genotyping methods to distinguish isolates of Salmonella enterica serovar Typhimurium from different food animal sources. One hundred twenty-eight S. enterica serovar Typhimurium strains isolated from cattle, pigs, chickens, and turkeys or derived food products were characterized using pulsed-field gel electrophoresis (PFGE), repetitive element PCR (Rep-PCR), multilocus sequence typing (MLST), plasmid profiling, and antimicrobial susceptibility testing. Among the 128 Salmonella isolates tested, we observed 84 Rep-PCR profiles, 86 PFGE patterns, 89 MLST patterns, 36 plasmid profiles, and 38 susceptibility profiles. The molecular typing methods, i.e., PFGE, MLST, and Rep-PCR, demonstrated the best discriminatory power among Salmonella isolates. However, no apparent correlation was evident between the results of one molecular typing method and those of the others, suggesting that a combination of multiple methods is needed to differentiate S. enterica serovar Typhimurium isolates that genetically cluster according to one particular typing method.
    Journal of Clinical Microbiology 11/2006; 44(10):3569-77. · 4.07 Impact Factor
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    ABSTRACT: Three hundred sixty-one quinupristin-dalfopristin (Q-D)-resistant Enterococcus faecium (QDREF) isolates were isolated from humans, turkeys, chickens, swine, dairy and beef cattle from farms, chicken carcasses, and ground pork from grocery stores in the United States from 1995 to 2003. These isolates were evaluated by pulsed-field gel electrophoresis (PFGE) to determine possible commonality between QDREF isolates from human and animal sources. PCR was performed to detect the streptogramin resistance genes vatD, vatE, and vgbA and the macrolide resistance gene ermB to determine the genetic mechanism of resistance in these isolates. QDREF from humans did not have PFGE patterns similar to those from animal sources. vatE was found in 35%, 26%, and 2% of QDREF isolates from turkeys, chickens, and humans, respectively, and was not found in QDREF isolates from other sources. ermB was commonly found in QDREF isolates from all sources. Known streptogramin resistance genes were absent in the majority of isolates, suggesting the presence of other, as-yet-undetermined, mechanisms of Q-D resistance.
    Journal of Clinical Microbiology 10/2006; 44(9):3361-5. · 4.07 Impact Factor

Publication Stats

605 Citations
58 Downloads
2k Views
115.65 Total Impact Points

Institutions

  • 2001–2008
    • U.S. Food and Drug Administration
      • • Office of Research
      • • Center for Veterinary Medicine
      Washington, Washington, D.C., United States
  • 2006
    • Wayne State University
      Detroit, Michigan, United States
    • United States Department of Agriculture
      • Agricultural Research Service (ARS)
      Washington, Washington, D.C., United States
  • 2004
    • University of Central Arkansas
      • Department of Biology
      Conway, AR, United States
  • 2003
    • University of Maryland, College Park
      • Department of Cell Biology & Molecular Genetics
      Maryland, United States