Surveillance of antimicrobial resistance of maltose negative Staphylococcus aureus in South African dairy herds

Abstract Background The discovery of antimicrobials in the 1930s was one of the greatest achievements in medicine. However, bacterial resistance to antimicrobials was already observed in the 1940s and has been reported since then in both human and veterinary medicine, including in dairy cows. Many years of monitoring milk samples in South Africa, has led to the identification of a new strain of Staphylococcus aureus (S. aureus), which is maltose negative and appears to be an emerging pathogen. In this study the differences in susceptibility to antimicrobials of this strain were evaluated over time, over different seasons, in different provinces, and according to somatic cell count (SCC) categories. Results A data set of 271 maltose negative S. aureus isolates, cultured from milk samples from 117 herds out of the estimated 2000 commercial dairy herds in South Africa between 2010 and 2017, was studied using the disk diffusion method. This analysis was done using the Clinical Laboratory Standards Institute (CLSI) breakpoints in order to compare using both the previous (Intermediate category grouped with Resistant) and current definitions, (Intermediate category grouped with Susceptible). The results of the analysis between the previous and the current definitions differed for tylosin, cefalonium, oxy-tetracycline and cloxacillin. Neither the analysis using the previous nor the current systems showed an effect of province for the maltose negative S. aureus. This was in contrast to the results for maltose positive S. aureus where differences between provinces were shown in a previous study, with the lowest prevalence of resistance shown in KwaZulu-Natal during spring. For the susceptibility testing of 57 maltose negative and 57 maltose positive S. aureus isolates from 38 farms, from KwaZulu Natal, Eastern Cape and Western Cape. The minimum inhibitory concentration (MIC) results for the maltose negative S. aureus isolates confirmed the results of the disk diffusion method. Conclusions The maltose negative strains of S. aureus differed in general, in their antimicrobial resistance patterns over time, in comparison to maltose-positive S. aureus strains. MIC testing also indicated that more multidrug -resistant isolates were seen with the maltose negative S. aureus than in the maltose positive strains.

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Surveillance of antimicrobial resistance of maltose negative Staphylococcus aureus in South African dairy herds

10.21203/rs.2.18013/v2 ◽

2020 ◽

Author(s):

Joanne Karzis ◽

Inge-Marié Petzer ◽

Edward F. Donkin ◽

Vinny Naidoo ◽

Eric M. C. Etter

Keyword(s):

South Africa ◽

Staphylococcus Aureus ◽

Antimicrobial Resistance ◽

Disk Diffusion ◽

Diffusion Method ◽

Dairy Herds ◽

Disk Diffusion Method ◽

Milk Samples ◽

Kwazulu Natal ◽

Over Time

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Surveillance of antimicrobial resistance of maltose negative Staphylococcus aureus in South African dairy herds

10.21203/rs.2.18013/v1 ◽

2019 ◽

Author(s):

Joanne Karzis ◽

Inge-Marié Petzer ◽

Edward F. Donkin ◽

Vinny Naidoo ◽

Eric M. C. Etter

Keyword(s):

South Africa ◽

Staphylococcus Aureus ◽

Antimicrobial Resistance ◽

Diffusion Method ◽

Dairy Herds ◽

Disc Diffusion ◽

Disc Diffusion Method ◽

Data Set ◽

Milk Samples ◽

Over Time

Abstract BackgroundThe discovery of antimicrobials in the 1930s was one of the greatest achievements in medicine. However, bacterial resistance to antimicrobials was already observed in the 1940s and has been reported since then in both human and veterinary medicine, including in dairy cows. Many years of monitoring milk samples in South Africa, has led to the identification of a new strain of Staphylococcus aureus (S. aureus), which is maltose negative and appears to be an emerging pathogen. In this study the differences in susceptibility to antimicrobials of this strain were evaluated over time, over different seasons, in different provinces, and according to somatic cell count (SCC) categories.Results A data set of 271 maltose negative S. aureus isolates, cultured from milk samples from 117 herds out of the estimated 2000 commercial dairy herds in South Africa between 2010 and 2017, was studied using the disc diffusion method. This analysis was done using the Clinical Laboratory Standards Institute (CLSI) breakpoints in order to compare using both the previously used system (intermediate category grouped with resistant) and more recent system, (intermediate category grouped with susceptible). The results between the previously used system and the more recent system analysis differed for tylosin, cefalonium, oxy-tetracycline and cloxacillin. Neither the analysis using the previous system nor the more recent system showed an effect of province for the maltose negative S. aureus. This was in contrast to the results for maltose positive S. aureus where differences between provinces were shown in a previous study. For the susceptibility testing of 57 maltose negative S. aureus and 57 maltose positive S. aureus the minimum inhibitory concentration (MIC) results for the maltose negative S. aureus confirmed the results of the disc diffusion method. ConclusionsThe maltose negative strains of S. aureus differed in general, in their antimicrobial resistance patterns over time, in comparison to maltose-positive S. aureus strains. MIC testing also indicated that more multi-resistant isolates were seen with the maltose negative S. aureus than in the maltose positive strains.

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Surveillance of Antibiotic Resistance of Maltose-Negative Staphylococcus aureus in South African Dairy Herds

Antibiotics ◽

10.3390/antibiotics9090616 ◽

2020 ◽

Vol 9 (9) ◽

pp. 616

Author(s):

Joanne Karzis ◽

Inge-Marié Petzer ◽

Edward F. Donkin ◽

Vinny Naidoo ◽

Eric M.C. Etter

Keyword(s):

Staphylococcus Aureus ◽

Antibiotic Resistance ◽

South African ◽

Inhibitory Concentration ◽

Aureus Strain ◽

Diffusion Method ◽

Dairy Herds ◽

Disk Diffusion Method ◽

Data Set ◽

Milk Samples

Antibiotic resistance has been reported since the 1940s in both human and veterinary medicine. Many years of monitoring milk samples in South Africa led to identification of a novel maltose-negative Staphylococcus aureus (S. aureus) strain, which appears to be an emerging pathogen. In this study, the susceptibility of this strain to antibiotics was evaluated over time, during diverse seasons in various provinces and according to somatic cell count (SCC) categories. A data set of 271 maltose-negative S. aureus isolates, from milk samples of 117 dairy herds, was examined using the disk diffusion method, between 2010 and 2017. This study also compared the susceptibility testing of 57 maltose-negative and 57 maltose-positive S. aureus isolated from 38 farms, from three provinces using minimum inhibitory concentration (MIC). The MIC results for the maltose-negative S. aureus isolates showed highest resistance to ampicillin (100%) and penicillin (47.4) and lowest resistance (1.8%) to azithromycin, ciprofloxacin and erythromycin. The maltose-negative S. aureus isolates showed overall significantly increased antibiotic resistance compared to the maltose-positive strains, as well as multidrug resistance. Producers and veterinarians should consider probability of cure of such organisms (seemingly non-chronic) when adapting management and treatment, preventing unnecessary culling.

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Faculty Opinions recommendation of Practical disk diffusion method for detection of inducible clindamycin resistance in Staphylococcus aureus and coagulase-negative staphylococci.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1013359.200155 ◽

2003 ◽

Author(s):

Gary Lum

Keyword(s):

Staphylococcus Aureus ◽

Disk Diffusion ◽

Diffusion Method ◽

Coagulase Negative Staphylococci ◽

Disk Diffusion Method ◽

Inducible Clindamycin Resistance

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Prevalence of methicillin-resistant Staphylococcus aureus and pattern of antimicrobial resistance in mastitis milk of cattle in Chitwan, Nepal

BMC Veterinary Research ◽

10.1186/s12917-021-02942-6 ◽

2021 ◽

Vol 17 (1) ◽

Author(s):

Asmita Shrestha ◽

Rebanta Kumar Bhattarai ◽

Himal Luitel ◽

Surendra Karki ◽

Hom Bahadur Basnet

Keyword(s):

Public Health ◽

Staphylococcus Aureus ◽

Antimicrobial Resistance ◽

Subclinical Mastitis ◽

World Health ◽

Dairy Herds ◽

Microbiological Analysis ◽

Biochemical Tests ◽

Methicillin Resistant ◽

Milk Samples

Abstract Background The threat of methicillin-resistant Staphylococcus aureus (MRSA) exists globally and has been listed as a priority pathogen by the World Health Organization. One of the sources of MRSA emergence is livestock and its products, often raised in poor husbandry conditions. There are limited studies in Nepal to understand the prevalence of MRSA in dairy animals and its antimicrobial resistance (AMR) profile. A cross-sectional study was conducted in Chitwan, one of the major milk-producing districts of Nepal, from February 2018 to September 2019 to estimate the prevalence of MRSA in milk samples and its AMR profile. The collected milk samples (n = 460) were screened using the California Mastitis Test (CMT) and positive samples were subjected to microbiological analysis to isolate and identify S. aureus. Polymerase Chain Reaction (PCR) was used to identify the presence of the mecA gene and screen for MRSA. Results In total, 41.5% (191/460) of milk samples were positive in the CMT test. Out of 191 CMT positive milk samples, the biochemical tests showed that the prevalence of S. aureus was 15.2% (29/191). Among the 29 S. aureus isolates, 6.9% (2/29) were identified as MRSA based on the detection of a mecA gene. This indicates that that 1.05% (2/191) of mastitis milk samples had MRSA. The antibiotic sensitivity test showed that 75.9% (22/29) and 48.3% (14/29) S. aureus isolates were found to be sensitive to Cefazolin and Tetracycline respectively (48.3%), whereas 100% of the isolates were resistant to Ampicillin. In total 96.6% (28/29) of S. aureus isolates were multidrug-resistant (MDR). Conclusions This study revealed a high prevalence of S. aureus-mediated subclinical mastitis in dairy herds in Chitwan, Nepal, with a small proportion of it being MRSA carrying a mecA gene. This S. aureus, CoNS, and MRSA contaminated milk poses a public health risk due to the presence of a phenotype that is resistant to very commonly used antibiotics. It is suggested that dairy herds be screened for subclinical mastitis and treatments for the animals be based on antibiotic susceptibility tests to reduce the prevalence of AMR. Furthermore, future studies should focus on the Staphylococcus spp. to explore the antibiotic resistance genes in addition to the mecA gene to ensure public health.

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Screening commercial teat disinfectants against bacteria isolated from bovine milk using disk diffusion

Veterinary World ◽

10.14202/vetworld.2019.629-637 ◽

2019 ◽

Vol 12 (5) ◽

pp. 629-637 ◽

Cited By ~ 3

Author(s):

Sarah Rose Fitzpatrick ◽

Mary Garvey ◽

Kieran Jordan ◽

Jim Flynn ◽

Bernadette O'Brien ◽

...

Keyword(s):

Bacterial Species ◽

Screening Method ◽

Bovine Milk ◽

Disk Diffusion ◽

Diffusion Method ◽

Bacterial Strains ◽

Disk Diffusion Method ◽

Associated Bacteria ◽

Bacterial Inhibition ◽

Milk Samples

Background and Aim: Teat disinfection is an important tool in reducing the incidence of bovine mastitis. Identifying the potential mastitis-causing bacterial species in milk can be the first step in choosing the correct teat disinfectant product. The objective of this study was to screen commercial teat disinfectants for inhibition against mastitis-associated bacteria isolated from various types of milk samples. Materials and Methods: Twelve commercially available teat disinfectant products were tested, against 12 mastitis-associated bacteria strains isolated from bulk tank milk samples and bacterial strains isolated from clinical (n=2) and subclinical (n=3) quarter foremilk samples using the disk diffusion method. Results: There was a significant variation (7-30 mm) in bacterial inhibition between teat disinfection products, with products containing a lactic acid combination (with chlorhexidine or salicylic acid) resulting in the greatest levels of bacterial inhibition against all tested bacteria (p<0.05). Conclusion: In this study, combined ingredients in teat disinfection products had greater levels of bacterial inhibition than when the ingredients were used individually. The disk diffusion assay is a suitable screening method to effectively differentiate the bacterial inhibition of different teat disinfectant products.

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Evaluation of antibiotic resistance pattern and mecA gene frequency in methicillin-resistant Staphylococcus aureus strains collected from clinical specimens in Marand hospital and treatment centers, Iran

Tabari Biomedical Student Research Journal ◽

10.18502/tbsrj.v2i4.5469 ◽

2021 ◽

Author(s):

Abolfazl Jafari-Sales ◽

Zahra Sadeghi Deylamdeh ◽

Afsoon Shariat

Keyword(s):

Staphylococcus Aureus ◽

Antibiotic Resistance ◽

Methicillin Resistant Staphylococcus Aureus ◽

Meca Gene ◽

Disk Diffusion ◽

Diffusion Method ◽

Disk Diffusion Method ◽

Methicillin Resistant ◽

Medical Centers ◽

Wide Range

Introduction: Staphylococcus aureus causes a wide range of infections and as a multivalent pathogen is one of the causative agents of nosocomial and community infections. Therefore, the aim of this study was to identify and determine the pattern of antibiotic resistance of methicillin-resistant Staphylococcus aureus (MRSA) isolates from patients in hospitals and medical centers in Marand city and also to evaluate the presence of mecA gene. Materials and Methods: In this cross-sectional descriptive study, 385 samples of S. aureus were collected from different clinical samples of patients in hospitals and medical centers of Marand city. S. aureus was identified using standard biochemical methods. Methicillin resistance was determined by disk diffusion method in the presence of oxacillin and cefoxitin. The pattern of antibiotic resistance of the strains was determined by disk diffusion method and according to CLSI recommendation and also PCR method was used to evaluate the frequency of MecA gene. Results: In the present study, out of 385 samples of S. aureus, 215 (55.84%) samples were methicillin resistant. PCR results for mecA gene showed that 110 samples had mecA gene. The highest antibiotic resistance was observed against penicillin (100%) and erythromycin (83.63%). Most MRSA were isolated from urine and wound samples. Conclusion: The results of this study indicate the prevalence of methicillin-resistant species and also the increase in antibiotic resistance of MRSA to various antibiotics. Therefore, in order to prevent increased resistance to other antibiotics, it is recommended to avoid inappropriate use of antibiotics.

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Genetic Characterization of Methicillin-Resistant Staphylococcus aureus Isolates from Human Bloodstream Infections: Detection of MLSB Resistance

Antibiotics ◽

10.3390/antibiotics9070375 ◽

2020 ◽

Vol 9 (7) ◽

pp. 375

Author(s):

Vanessa Silva ◽

Sara Hermenegildo ◽

Catarina Ferreira ◽

Célia M. Manaia ◽

Rosa Capita ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Antimicrobial Agents ◽

Methicillin Resistant Staphylococcus Aureus ◽

Bloodstream Infections ◽

Disk Diffusion ◽

Diffusion Method ◽

Accessory Gene ◽

Spa Typing ◽

Disk Diffusion Method ◽

Methicillin Resistant

In this study we aimed to characterize antimicrobial resistance in methicillin-resistant Staphylococcus aureus (MRSA) isolated from bloodstream infections as well as the associated genetic lineages of the isolates. Sixteen MRSA isolates were recovered from bacteremia samples from inpatients between 2016 and 2019. The antimicrobial susceptibility of these isolates was tested by the Kirby–Bauer disk diffusion method against 14 antimicrobial agents. To determine the macrolide–lincosamide–streptogramin B (MLSB) resistance phenotype of the isolates, erythromycin-resistant isolates were assessed by double-disk diffusion (D-test). The resistance and virulence genes were screened by polymerase chain reaction (PCR). All isolates were characterized by multilocus sequence typing (MLST), spa typing, staphylococcal chromosomal cassette mec (SCCmec) typing, and accessory gene regulator (agr) typing. Isolates showed resistance to cefoxitin, penicillin, ciprofloxacin, erythromycin, fusidic acid, clindamycin, and aminoglycosides, confirmed by the presence of the blaZ, ermA, ermC, mphC, msrA/B, aac(6’)-Ie-aph(2’’)-Ia, and ant(4’)-Ia genes. Three isolates were Panton–Valentine-leukocidin-positive. Most strains (n = 12) presented an inducible MLSB phenotype. The isolates were ascribed to eight spa-types (t747, t002, t020, t1084, t008, t10682, t18526, and t1370) and four MLSTs (ST22, ST5, ST105, and ST8). Overall, most (n = 12) MRSA isolates had a multidrug-resistance profile with inducible MLSB phenotypes and belonged to epidemic MRSA clones.

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