scholarly journals Proactive udder health management in South Africa and monitoring of antibiotic resistance of Staphylococcus aureus in dairy herds from 2001 to 2010

Author(s):  
Joanne Karzis ◽  
Inge-Marie Petzer ◽  
Edward F. Donkin ◽  
Vinny Naidoo

Antibiotic resistance of strains of Staphylococcus aureus isolated from bovine milk is of concern internationally. The objective of this study was to investigate trends of resistance of S. aureus to antibiotics administered to dairy cows in 19 South African and one Zambian dairy herds (participating in the South African proactive udder health management programme) and to identify possible contributing factors. The resistance of S. aureus strains to eight commonly used antibiotics in South Africa from 2001 to 2010 was evaluated. Staphylococcus aureus isolates (n = 2532) were selected from cows with subclinical mastitis in 20 herds routinely sampled as part of the proactive udder health management programme. The isolates were selected from milk samples that had somatic cell counts more than 400 000 cells/mL and were tested for antibiotic resistance using a standard Kirby–Bauer test with published clinical breakpoints. The prevalence of antibiotic resistance was evaluated as a percentage of S. aureus isolates susceptible out of the total numbers for each antibiotic selected per year. Staphylococcus aureus showed a significant increase in percentage of susceptible isolates over time for all antibiotics tested except for ampicillin. The overall prevalence of mastitis did not change during the study period. However, the prevalence of mastitis caused by S. aureus (mostly subclinical cases) in the selected herds decreased numerically but not significantly. Reduction in the incidence of antibiotic resistance shown by S. aureus was presumed to be a result of the application of the proactive udder health management programme. The fact that the overall prevalence of mastitis was kept stable was possibly because of the influence of the management programme in conjunction with the return of infections caused by non-resistant strains.

Author(s):  
I.M. Petzer ◽  
J. Karzis ◽  
J.C. Watermeyer ◽  
T.J. Van der Schans ◽  
R. Van Reenen

The aim of this study was to retrospectively analyse the results of milk samples obtained from South African dairy herds during the period 1996 to April 2007 in order to identify possible trends in isolates of microorganisms and their pathogenicity under field conditions. Milk samples were obtained from 7 of the 9 provinces in South Africa where there are low numbers of dairy cows. Although there is scientific limitation to a country wide survey, such as the variation in herd size, management skills, parity, milk yield, milking frequency and other parameters, the size of this database helps to give a fair indication of general udder health in South Africa. Cytology and routine bacteriology were performed on 379 000 milk samples of lactating cows and bacteriology on 11 946 samples from non-lactating cows. According to the results obtained, mastitis did not decrease in South Africa over the test period. The prevalence of mastitis and teat canal infection was lowest in 2002. Mastitis and teat canal infection increased from 2002 to 2006 from 8.1 % and 24.1 % to 15.4 and 30.0 % respectively. The percentage of mastitogenic pathogens isolated from cows over these years also varied. Previously unknown or almost eradicated mastitogenic pathogens such as αβ haemolytic Staphylococcus aureus which is thought to be of human origin, Streptococcus agalactiae and Enterococcus canis were responsible for numerous mastitis outbreaks seen in the test samples. Coagulase-negative staphylococci were the most frequently isolated bacteria in milk samples from both lactating and dry cows, followed by Staphylococcus aureus and Streptococcus agalactiae. Although Staphylococcus aureus remained the principal mastitogenic pathogen in South Africa, owing to its chronic nature and resultant economic losses, most cases of mastitis were caused by coagulase-negative staphylococci. This finding increases the importance of coagulase-negative staphylococci (formerly described as a minor pathogen) significantly. Isolations of Streptococcus agalactiae peaked between 2000 and 2005 and decreased again by 2007. Coagulase-negative staphylococcal isolates increased from 2002 and were still on the increase in 2007. Streptococcus agalactiae, Streptococcus uberis and Enterococcus canis were isolated more frequently from milk samples of lactating cows compared with dry cows, while Enterococcus faecalis was isolated more frequently from dry cow samples.


Antibiotics ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 616
Author(s):  
Joanne Karzis ◽  
Inge-Marié Petzer ◽  
Edward F. Donkin ◽  
Vinny Naidoo ◽  
Eric M.C. Etter

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.


Author(s):  
Inge-Marié Petzer ◽  
Joanne Karzis ◽  
Edward F. Donkin ◽  
Edward C. Webb

A dedicated udder health diagnostic programme was developed and used over a 15-year period in South Africa to analyse milk samples based on microbiological and cytological patterns within various groups and for individual cows and udder quarters in dairy herds. These pathogen-specific analyses are utilised for pro-active improvement and management of udder health in South African commercial dairy herds. The programme acts as a monitoring tool and identifies management areas at risk and individual cows with udder disease and uses both quarter and composite milk samples. Intra-mammary infection (IMI) is a dynamic situation and depending on the time a milk sample is taken, false-negative results may be obtained. A new IMI and an infection that is curing may both have low somatic cell counts (SCCs), masking the true bacterial status. SCC in individual infected udder quarters may differ greatly depending on the causative bacterial species, its pathogenicity, the host immune status and the environmental factors involved. A pathogen-specific udder health approach was followed with repeated herd tests to take account of these udder health dynamics. The results of the herd IMI investigation are applied in practice to assist veterinarians, udder health consultants and managers to make informed and specific detailed decisions at both a herd and on an individual cow basis regarding udder health.


Author(s):  
Shani Van Lochem ◽  
Peter N. Thompson ◽  
Cornelius H. Annandale

The prevalence of nasal carrier status of methicillin-resistant Staphylococcus aureus (MRSA) in pigs has been described elsewhere, but is unknown in South Africa. To address concerns that exist regarding the zoonotic risk that carriers pose to workers, the herd-level prevalence of MRSA was determined among 25 large (> 500 sows) commercial pig herds in South Africa, representing 45% of the large commercial herds in the country. From each herd, the nasal contents of 18 finisher pigs were sampled at the abattoir, pooled into three and selectively cultured to determine the presence of MRSA. A herd was classified as MRSA-positive if one or more of the three pooled samples cultured positive. Three of the 25 herds tested positive for MRSA, equating to a 12% herd prevalence (95% CI: 7% – 23%) among South African commercial piggeries. The prevalence of nasal MRSA carriers among large commercial pig herds in South Africa was low compared to what has been reported elsewhere and suggests a relatively low zoonotic MRSA risk to workers in South African commercial piggeries and abattoirs.


2019 ◽  
Vol 115 (11/12) ◽  
Author(s):  
Enrico Gennari ◽  
Alison A. Kock ◽  
Malcolm J. Smale ◽  
Alison Towner ◽  
Nasreen Khan ◽  
...  

The white shark (Carcharodon carcharias) is responsible for 49% of shark-related injuries in South Africa, yet no information currently exists on the composition or antibiotic resistance of bacteria hosted by these apex predators in South African waters. This study aimed to address this gap by sampling the bacteria present in the oral cavities of 28 live C. carcharias along South Africa’s southern coastline. The antibiotic resistance of the range of microbiota was also assessed using antibiotic disc diffusion tests. A total of 51 strains from at least 20 species of bacteria were isolated from the oral cavities of C. carcharias. Of these strains, the most common bacteria present were Serratia spp., Proteus vulgaris and Vibrio alginolyticus. The overall antibiotic resistance was relatively higher in this study than that reported for bacterial microbiota sampled from other shark species. Results indicate that the combination therapy of imipenem (carbapenem antibiotic) and vancomycin (glycopeptide antibiotic) might be the most parsimonious option to effectively treat infections resulting from white shark bites, particularly in South Africa. It is hoped that, in addition to assisting medical professionals to treat shark bite victims, these findings enhance the understanding of the microbial communities present in large coastal predators and their surrounding environments.


1980 ◽  
Vol 60 (2) ◽  
pp. 231-239 ◽  
Author(s):  
SUSAN HIGGINS ◽  
R. K. MOORE ◽  
B. W. KENNEDY

Teat conformation characteristics were measured on 402 Holstein-Friesian cows in 18 dairy herds in western Quebec and eastern Ontario. The purpose of the study was to determine the effects of heridity on teat conformation traits as well as to examine phenotypic relationships between the traits and somatic cell count as a measure of udder health. Maximum likelihood estimates of heritabilities of teat conformation traits and cell count, transformed to a log scale, were low; usually less than 0.10. Exceptions were length of front teat (h2 = 0.44) and distance of udder to the floor (h2 = 0.41). Significantly higher cell counts were associated with teats that were long, wide, not plumb and bottle (as opposed to cylindrical or funnel) shaped. The most highly correlated trait with cell count was distance of udder to the floor (r = − 0.24). However, many of the significant gross relationships observed were jointly related with age of cow, and when the effects of age of cow at calving, stage of lactation and herd were removed, only length of rear teat and front and rear teat medial diameters had significant influences on cell count.


Author(s):  
Ezekiel Green ◽  
Abongile Pekana

Background: Staphylococcus aureus (S. aureus) occasionally threatens the life of the host as a persistent pathogen even though it is normal flora of humans and animals. We characterized drug resistance in S. aureus isolated from animal carcasses and milk samples from the abattoirs and dairy farms in the Eastern Cape Province. Methods: A 1000 meat swab samples and 200 raw milk samples were collected from selected abattoirs and dairy farms in the Eastern Cape Province, South Africa. S. aureus was isolated and positively identified using biochemical tests and confirmed by molecular methods. Antibiotic susceptibility test against 14 different antibiotics was performed against all isolates. Antibiotic resistance genes were also detected. Results: Of the 1200 samples collected, 134 (11.2%) samples were positive for S. aureus. Resistance ranged from 71.6% for penicillin G to 39.2% for tetracycline. Resistance gene (blaZ) was detected in 13 (14.9%), while msrA was found in 31 (52.5%) of S. aureus isolates. Conclusions: The present result shows the potential dissemination of multidrug-resistant S. aureus strains in the dairy farms and abattoirs in the Eastern Cape. Therefore, this implies that the organism may rapidly spread through food and pose serious public health risk


Animals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 992
Author(s):  
Alfonso Zecconi ◽  
Lucio Zanini ◽  
Micaela Cipolla ◽  
Bruno Stefanon

Differential leukocyte count (DSCC) in milk is considered important to improve knowledge of udder immune response. The investigations on milk DSCC were limited by the techniques available until recently, when a high-throughput tool to perform DSCC opened the way to explore these factors in rapid and economically sustainable ways. We hypothesized that DSCC alone does not fully describe the pattern of these cells, since the total amount is also influenced by milk yield and SCC. Therefore, this study was designed to describe DSCC and total amount of different leukocytes in milk during the course of lactation in cows differing in parity and in levels of SCC. This study considered 17,939 individual milk tests from 12 dairy herds in Lombardy Region, where DCC testing was applied in the period of February 2018–December 2019 (23 months). The samples were divided into two subsets—“healthy” (HS) with SCC ≤200,000 cells/mL and “inflamed” (IS) with SCC >200,000 cells/mL. Cow in HS have a P + LT average between 5.0 × 108 and 3.0 × 109 cells. In IS cows, the values were 1.6 × 1010 and 2.5 × 1010. Therefore, the presence of a well-defined inflammatory process increased the overall amount of polymorphonuclear neutrophils (PMN) and lymphocytes (LYM) of 1 log, from 1 × 109 to 1 × 1010. The assessment of the total amount of PMN and LYM, to our knowledge, have never been reported in scientific literature; the values observed may be proposed as benchmarks for studies on udder immune response. When data were analyzed by days in milk (DIM), they showed that cows in first and second lactation have a significantly lower amount of PMN + LYM, when compared to cows in third and higher lactation. However, these differences are numerically not very large (7%), and suggest that, in healthy animals, the number of immune cells is kept as constant as possible. In IS, the analysis of trends based on DIM showed that both DSCC and P + LT have a significant negative trend. These data suggest that only in this group, the presence of high SCC as lactation proceeds is associated with a progressive increase in the number of macrophages. To the best of our knowledge, this is the first study describing the pattern of DSCC and the total amount of PMN + LYM in relation to parity, days in milk, and SCC, and it may be considered as the first contribution in the investigation on mammary gland immune response by the means of differential cell counts in milk.


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