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1.
The aim of this study was to identify methicillin‐resistant Staphylococcus aureus (MRSA) strains gathered from 2002 to 2006 from milk samples in Aydin region in Turkey. Among 93 S. aureus strains isolated from bovine milk with mastitis, 16 were resistant to methicillin. Methicillin‐resistant S. aureus strains were studied further for their staphylococcal cassette chromosome mec (SCCmec) types, pulsotypes, spa and MLST types, antimicrobial susceptibilities, mechanisms of resistance and presence of Panton–Valentine leucocidin (PVL) toxin gene. The MRSA strains were multi‐drug resistant. The susceptibility rates to antimicrobials tested were 0%, 0%, 0%, 0%, 6.25%, 16.25% and 56.25% for erythromycin, clindamycin, chloramphenicol, gentamicin, tetracyclin, ciprofloxacin and vancomycin, respectively. All tetracycline and gentamicin resistant strains carried tet(M) and aac(6)‐aph(2) gene, respectively. Among macrolide‐resistant isolates, nine had erm(A), and seven had both erm(A) and erm(B) genes. The molecular characterization by pulsed‐field gel electrophoresis showed presence of three pulsotypes with their variants. The pulsotype B strains were type IV with SCCmec typing, and representative of pulsotype B was t190 by spa typing and ST8 by MLST typing. The strains with pulsotype A and C were SCCmec III, and representative of these pulsotypes was t030 by spa typing. The MLST type of pulsotype A was ST239 and pulsotype C was one allele variant of ST239. None of the isolates harboured the PVL gene. Presence of hospital‐related MRSA strains may indicate transmission of these strains between human and animals. In case of clonal spread beside the infected animals’ treatment of MRSA carrier, farm workers should also be considered. Hygienic measures and rational antibiotic use may avoid resistance selection, clonal dissemination of resistant strains and decrease losses because of mastitis in dairy herds.  相似文献   

2.
Objective To evaluate if methicillin‐resistant Staphylococcus aureus (MRSA) is present in the horse population in Australia. Design A two‐part retrospective study of laboratory submissions of microbial culture results from horses. Methods Part A: medical records of 216 horses that had MRSA screening performed on nasal swabs collected over a 30‐day period at admission to the Scone Equine Hospital Clovelly Intensive Care Unit were retrieved. Part B: laboratory records from 2004 to 2009 of culture submissions to the Scone Veterinary Laboratory were reviewed and cultures that grew MRSA were identified. The MRSA isolates from Parts A and B were genotyped over an 18‐month period. Results MRSA screening of 216 horses identified eight (3.7%) positive samples. MRSA was isolated from cultures of 80 (0.002%) clinical bacteriology samples over a 6‐year period. Genotypic analysis was performed on 36 isolates. All MRSA characterised had the same pulse field gel electrophoresis pattern (type 1), with eight closely related subtypes identified (subtypes A–F and H) and 66% of isolates classified as subtype D, which multilocus sequence and staphylococcal cassette chromosome mec typing analysis identified as ST612‐MRSA‐IVa, a clonal complex (CC) 8 S. aureus strain. Antimicrobial resistance to more than two classes of antimicrobials was common. Conclusions MRSA was present in a population of horses in Australia. Genotypic analysis of the isolates identified the MRSA strain as CC8 S. aureus. Further research needs to be undertaken to evaluate MRSA infection and colonisation of horses and personnel in Australia.  相似文献   

3.
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4.
Elevated rates of methicillin‐resistant Staphylococcus aureus (MRSA) carriage have been reported in veterinary personnel, suggesting an occupational colonization risk. Hong Kong veterinary personnel (n = 150) were sampled for coagulase‐positive staphylococci (CPS) nasal colonization. Risk factors for colonization were assessed by questionnaire. Isolates were identified and antibiotic susceptibility determined. All CPS isolates were investigated for mecA carriage, SCCmec type and PVL genes. Two subjects were colonized with methicillin‐resistant CPS: one with MRSA (spa type t002 (CC5), SCCmec type II) and one with methicillin‐resistant Staphylococcus pseudintermedius (MRSP) (MLST type ST71, SCCmec type II‐III). MLST type ST71 S. pseudintermedius strain is the predominant MRSP clone circulating in dogs in Europe and in Hong Kong. The low MR‐CPS colonization rate may be associated with low levels of large animal exposure or low rates of MRSA colonization of companion animals in Hong Kong. Colonization with non‐aureus CPS, which may cause human infection, must also be considered in veterinary personnel.  相似文献   

5.
There is concern that therapeutic use of zinc oxide (ZnO) in swine production may select for methicillin‐resistant Staphylococcus aureus (MRSA) due to co‐location of the zinc resistance gene (czrC) and methicillin resistance gene (mecA) within the staphylococcal cassette chromosome mec (SCCmec). The objective of this investigation was to determine whether MRSA carriage in pigs is influenced by exposure to therapeutic doses of in‐feed ZnO (3000 mg/kg) when compared to the recommended dietary levels (100 mg/kg). A randomized controlled trial was completed using 110 pigs that were naturally colonized with czrC‐positive MRSA. The pigs were followed from birth to weaning (21 d), at which point they were randomized into 8 pens and exposed to either a control feed (100 mg ZnO/kg feed; n = 49 pigs) or a treatment feed (3000 mg ZnO/kg feed; n = 50 pigs); neither feed contained additional antimicrobials. MRSA carriage was monitored weekly in each group for 4 weeks post‐weaning. The prevalence of MRSA was significantly higher in the treatment group at 1‐week (OR = 18.1; P < 0.01) and 2 weeks (OR = 3.01; P = 0.01) post‐weaning when compared to the control group, but there was no difference later in the nursery phase. Persistent MRSA carriage (testing positive ≥2 times post‐weaning) was observed in 2% (1/49) of control pigs and 22% (11/50) of treated pigs (P < 0.01). All MRSA isolates (spa types t034 and t3075) carried czrC and showed uniform resistance to zinc. These findings demonstrate that the prevalence and persistence of MRSA in nursery pigs can be affected by high levels of in‐feed ZnO in the absence of antibiotics.  相似文献   

6.
Assessment of risk factors associated with milk production systems is central to ensuring quality and safety of milk and milk products. This study was aimed at identifying possible risk factors in milk contamination in urban and peri‐urban areas of the central high lands of Ethiopia. A total of 477 on‐farm pooled milk (n = 433) and combined bulk milk samples (n = 44) were collected and processed using standard microbiological techniques to isolate and characterize Staphylococcus aureus. In addition, 433 individual farm owners and 22 collection centre owners were interviewed using a structured and pre‐tested questionnaire. Multivariate logistic regression was used to determine risk factors. Of the total individual on‐farm pooled milk samples analysed (n = 433), it was found that 103 of the individual milk samples (24%) and 17 of the combined bulk milk (39%) were positive for S. aureus. This difference in prevalence was statistically significant. Even though there were a number of potential variables associated with the recovery of S. aureus in bovine milk, four variables including cleaning milk container with hot water and detergent [Adjusted OR: 0.342, 95% CI, (0.166, 0.701)], mastitis check [Adjusted OR: 3.019, 95% CI (1.542, 5.913)], travel time to collection centres [Adjusted OR: 4.932, 95% CI, (2.265, 10.739)] and amount of milk delivered by farmers to collection centres per day [Adjusted OR: 1.059 (1.032, 1.087 β = 0.057)] were found to be statistically significantly associated with isolation of S. aureus. We recommend a targeted educational intervention on defined risk factors to reduce the post‐harvest S. aureus contamination of raw milk in urban and peri‐urban milk shed areas of central Ethiopia.  相似文献   

7.
This study describes the isolation and characterization of methicillin‐resistant Staphylococcus aureus (MRSA) from slaughtered pigs sampled from local markets in Hong Kong. The nares of 400 slaughtered pigs were cultured and MRSA isolates characterized for the presence of antibiotic‐resistance determinants, toxins and SCCmec and spa types using PCR. Clonality was investigated using PFGE and MLST. The prevalence of MRSA colonization of slaughter pigs was 39.3%, the majority (92%) harbouring SCCmec type IVb. Of the 157 samples yielding MRSA, 13 had two distinct MRSA strains present. Spa type t899 was predominant, with only 5/170 isolates displaying closely related types (t4474, t1939, t2922 and t5390). PFGE with sma1 and MLST confirmed the strains as ST9. Most isolates were multidrug resistant. Tetracycline resistance (97%) was mainly attributable to tet(K) with only 3% of isolates additionally harbouring tet(M). Resistance to erythromycin (89%) and chloramphenicol (71%) was associated with the presence of erm(C), and fex( A), respectively. No strains carried cfr and there was no resistance to linezolid, although minimum inhibitory concentration (MICs) were close to the resistance break point. Resistance to clindamycin (99%), ciprofloxacin(78%), quinopristin–dalfopristin (44%) and cotrimoxazole (32%) was common, but remained low for fusidic acid (4%) and rifampicin (2%). All strains were negative for PVL, exfoliative, and enterotoxins. This survey confirmed the uniformity of MRSA isolates in pigs from several regions of China, in contrast to more diversified characteristics reported in European studies. Colonization rates were higher than previously reported. Isolates were resistant to a wide range of antibiotics, but resistance was not detected to linezolid, nitrofurantoin, vancomycin or tigecycline. Although the clinical importance of ST9 in humans is uncertain, continued surveillance, in particular of those occupationally‐exposed, is recommended.  相似文献   

8.
AIM: To gauge how well prior laboratory test results predict in vitro penicillin resistance of Staphylococcus aureus isolates from dairy cows with mastitis.

METHODS: Population-based data on the farm of origin (n=79), genotype based on pulsed-field gel electrophoresis (PFGE) results, and the penicillin-resistance status of Staph. aureus isolates (n=115) from milk samples collected from dairy cows with mastitis submitted to two diagnostic laboratories over a 6-month period were used. Data were mined stochastically using the all-possible-pairs method, binomial modelling and bootstrap simulation, to test whether prior test results enhance the accuracy of prediction of penicillin resistance on farms.

RESULTS: Of all Staph. aureus isolates tested, 38% were penicillin resistant. A significant aggregation of penicillin-resistance status was evident within farms. The probability of random pairs of isolates from the same farm having the same penicillin-resistance status was 76%, compared with 53% for random pairings of samples across all farms. Thus, the resistance status of randomly selected isolates was 1.43 times more likely to correctly predict the status of other isolates from the same farm than the random population pairwise concordance probability (p=0.011). This effect was likely due to the clonal relationship of isolates within farms, as the predictive fraction attributable to prior test results was close to nil when the effect of within-farm clonal infections was withdrawn from the model.

CONCLUSIONS: Knowledge of the penicillin-resistance status of a prior Staph. aureus isolate significantly enhanced the predictive capability of other isolates from the same farm. In the time and space frame of this study, clinicians using previous information from a farm would have more accurately predicted the penicillin-resistance status of an isolate than they would by chance alone on farms infected with clonal Staph. aureus isolates, but not on farms infected with highly genetically heterogeneous bacterial strains.  相似文献   

9.
Enterotoxigenic Staphylococcus aureus frequently contaminate milk and milk products causing food poisoning. Staphylococcus aureus were isolated from bovine, ovine and caprine milk and milk filters from 78 dairy production holdings supplying the farmhouse cheese sector in Ireland, using standard culture methods. Molecular methods were applied to study the distribution of genes encoding staphylococcal enterotoxins and toxic shock syndrome toxin in the collection. Multilocus variable number tandem repeat analysis was used to subtype the collection. One hundred and two Staphylococcus aureus (54 milk filters and 48 bulk milk) were recovered from apparently healthy animals; half of the isolates were toxigenic. Our findings are discussed in light of the risks posed to public health.  相似文献   

10.
The exfoliation rate of mammary epithelial cells (MECs) in milk is affected by physiological, breeding and environmental factors. Little is known about the relationship between the MEC exfoliation into milk and mammary‐infected Staphylococcus aureus (S. aureus) load on bovine mastitis caused by S. aureus. The aim of this study was to investigate the relationship between S. aureus load and the proportion of MEC exfoliation in milk using five substantial bovine mastitis models. In 64 randomly extracted milk samples from udders at 3–21 days after S. aureus infusion, there were various samples with different numbers of S. aureus counts and somatic cell counts. No significant correlations were found between the S. aureus counts and somatic cell count (r = 0.338). In contrast, a significant correlation was noted between S. aureus counts and the proportion of cytokeratin‐positive cells in the milk from the infused udders (r = 0.734, P < 0.01). In conclusion, the increasing MEC exfoliation rate in milk from mastitis udders caused by S. aureus may contribute to reduced milk yield.  相似文献   

11.
Community‐associated methicillin‐resistant Staphylococcus aureus (MRSA) is a serious public health concern and in Australia, one that disproportionately affects Aboriginal people. Paralleling MRSA in human medicine, methicillin‐resistant S. pseudintermedius (MRSP) is an increasingly prevalent pathogen in veterinary medicine. We aimed to characterize the carriage of MRSA and MRSP in dogs and cats from predominantly Aboriginal communities in a very remote region of New South Wales (NSW), Australia. Pets (303 dogs and 80 cats) were recruited from six communities in western NSW. Three swabs were collected from each animal (anterior nares, oropharynx and perineum) and from skin lesions or wounds (if present) and cultured on selective media for methicillin‐resistant staphylococci. Human host‐adapted community‐associated MRSA representing four multilocus sequence types (ST1‐IV, ST5‐IV, ST72‐IV, ST93‐IV) were isolated from eight dogs (prevalence 2.6%, 95% confidence interval 1.3%–5.1%). Two ST5‐IV isolates from a single dog were phenotypically trimethoprim‐resistant, harbouring trimethoprim‐resistant gene dfrG within the SCCmec type IVo mobile genetic element. MRSA was not isolated from any cats and MRSP was not isolated from any dogs or cats. This study estimated a high prevalence of human host‐adapted community‐associated MRSA carriage in dogs despite an absence of MRSP. This suggests MRSA carried by dogs in remote NSW originate from human hosts. The cycle of transmission between people, dogs and common environmental sources warrants further investigation. To our knowledge, this is the first report of trimethoprim‐resistant ST5‐IV in eastern Australia and the first report of trimethoprim‐resistant ST5‐IV from a dog.  相似文献   

12.
The objective of this study was to analyse the occurrence of methicillin‐resistant Staphylococcus aureus (MRSA) in three dairy herds in the southwest of Germany that had experienced individual cases of clinical and subclinical mastitis associated with MRSA. The herds were identified by the detection of MRSA during routine resistance testing of mastitis pathogens. All quarters of all cows in the herds that were positive on California Mastitis Test were sampled for bacteriological analysis on two occasions. Bulk tank milk samples were also tested. Furthermore, nasal swabs were collected from people working on the farms and from cattle. Environmental samples were collected from associated pig holdings. Isolates were characterized using spa‐typing and testing for antimicrobial resistance. Our results revealed a substantial spread of MRSA in the three dairy herds. In the first of the two investigations carried out on all cows in the three herds, milk samples of 5.1–16.7% of dairy cows were found positive for MRSA. The respective proportions in the second herd level investigation were 1.4–10.0%. Quarters harbouring MRSA had higher somatic cell counts than quarters that were negative on culture. Methicillin‐resistant Staphylococcus aureus were also detected in nasal swabs of staff (7/9), cows (7/15) and calves (4/7), bulk tank milk samples (3/3) and environmental samples from pig premises (4/5) on the farm. Herds B and C had no contact to herd A. However, in all three herds MRSA of spa‐type t011 were detected in milk samples. Results show that MRSA of spa‐type t011 is a problem in dairy farms that needs urgent attention.  相似文献   

13.
The occurrence of multidrug‐resistant zoonotic bacteria in animals has been increasing worldwide. Working in close contact with livestock increases the risk of carriage of these bacteria. We investigated the occurrence of extended‐spectrum beta‐lactamase (ESBL) and plasmidic AmpC beta‐lactamase producing Enterobacteriaceae (ESBL/pAmpC‐PE) and livestock‐associated methicillin‐resistant Staphylococcus aureus (LA‐MRSA) in Finnish veterinarians (n = 320). In addition to microbiological samples, background information was collected. Bacterial whole genome sequencing was performed to deduce sequence types (STs), spa types and resistance genes of the isolates. In total, 3.0% (9/297) of the veterinarians carried ESBL producing Escherichia coli, with one ESBL producing E. coli isolate producing also AmpC. Seven different STs, sequences of several different plasmid groups as well as several different blaESBL/pAmpC genes existed in different combinations. No carbapenemase or colistin resistance genes were detected. MRSA was detected in 0.3% (1/320) of the samples. The strain belonged to LA‐MRSA clonal complex (CC) 398 (ST398, spa type 011, lacking Panton‐Valentine leukocidin genes). In conclusion, this study shows low carriage of multidrug‐resistant zoonotic bacteria in Finnish veterinarians. However, finding LA‐MRSA for the first time in a sample from a veterinarian in a country with prudent use of animal antimicrobials and regarding the recent rise of LA‐MRSA on Finnish pig farms, a strong recommendation to protect people working in close contact with animals carrying LA‐MRSA CC398 is given. Further studies are needed to explain why the prevalence of LA‐MRSA in veterinarians is lower in Finland than in other European countries.  相似文献   

14.
This observational study aimed to determine MRSA prevalence using strain‐specific real‐time PCR at the pig level, stratified by age groupings, within a pig enterprise. A total of 658 samples were collected from individual pigs (n = 618) and the piggery environment (n = 40), distributed amongst five different pig age groups. Presumptive MRSA isolates were confirmed by the presence of mecA, and MALDI‐TOF was performed for species verification. All isolates were tested against 18 different antimicrobials. MRSA was isolated from 75.2% (95% CI 71.8–78.6) of samples collected from pigs, and 71% of the MRSA isolates from this source were identified as community‐associated (CA)‐MRSA ST93, while the remainder were livestock‐associated (LA)‐MRSA ST398. Amongst environmental isolates, 80% (CI 64.3–95.7) were ST93 and the remainder ST398. All MRSA isolates from pigs and the environment were susceptible to ciprofloxacin, gentamicin, linezolid, mupirocin, rifampicin, sulfamethoxazole–trimethoprim, teicoplanin and vancomycin. Phenotypic rates of resistance were penicillin (100%), clindamycin (97.6%), erythromycin (96.3%), ceftiofur (93.7%), chloramphenicol (81.2%), tetracycline (63.1%) and amoxicillin–clavulanate (63.9%). A low prevalence of resistance (9.2%) was observed against neomycin and quinupristin–dalfopristin. The probability of MRSA carriage in dry sows (42.2%) was found to be significantly lower (p < .001) when compared to other age groups: farrowing sows (76.8%, RR1.82), weaners (97.8%, RR 2.32), growers (94.2%, RR 2.23) and finishers (98.3%, RR 2.33). Amongst different production age groups, a significant difference was also found in antimicrobial resistance for amoxicillin–clavulanate, neomycin, chloramphenicol and tetracycline. Using the RT‐PCR assay adopted in this study, filtering of highly prevalent ST93 and non‐ST93 isolates was performed at high throughput and low cost. In conclusion, this study found that weaner pigs presented a higher risk for CA‐MRSA and antimicrobial resistance compared to other age groups. These findings have major implications for how investigations of MRSA outbreaks should be approached under the One‐Health context.  相似文献   

15.
The cathelicidin family is one of the several families of antimicrobial peptides (AMPs). A bovine myeloid antimicrobial peptide (BMAP‐28) belongs to this family. Recently, the emergence of drug‐resistant bacteria such as methicillin‐resistant Staphylococcus aureus (MRSA) has become a big problem. AMPs are expected to be leading compounds of new antibiotics against drug‐resistant bacteria. In this study, we focused on the activity of BMAP‐28 against bacterial cell surfaces. First, we observed morphological change of MRSA caused by BMAP‐28 using a scanning probe microscope. We also studied activities of BMAP‐28 against adherence of S. aureus to fibronectin, collagen type I, collagen type IV. We confirmed whether BMAP‐28 can bind to lipoteichoic acid (LTA) of S. aureus. BMAP‐28 was indicated as damaging the cell surface of MRSA. In a particular range of concentrations, BMAP‐28 promoted adherence of S. aureus against fibronectin and collagens. It was revealed that BMAP‐28 and LTA of S. aureus bound with each other. Our study showed the potential of BMAP‐28 which can damage MRSA and interact with LTA of S. aureus but promote its adherence in some concentrations. This study provides new points of which to take notice when we use AMPs as medicines.  相似文献   

16.
Four thousand six hundred forty– five quarter milk samples from 1179 cows from 20 commercial dairy herds were examined in order to determine the prevalence of bacterial species. A total of 859 isolates from 839 (18.1%) culture positive samples could be assigned to 34 different species and subspecies. Diagnostics of staphylococcal species was based on conventional procedures able to differentiate between all 36 species and subspecies presently acknowledged. Staphylococcus aureus was found in 10.2% of the samples and was the most common species isolated. Streptococcus dysgalactiae (1.6%) and Streptococcus uberis (1.4%) were the second and third most common species isolated. Seventeen different coagulase negative staphylococcal species (CNS) were found in 4.1% of the samples. The most frequently isolated CNS were S. epidermidis (1.3%), S. chromogenes (1.0%) and S. simulans (0.7%). Isolates of S. aureus were phage typed, and isolates of S. epidermidis were investigated by phage typing, antibiogram typing, and biotyping. A total of 378 (79.9%) isolates of S. aureus could be typed by phages, assigning them to 18 different phage types. However, 6 phage types accounted for 92.1% of the typable isolates. One to 2 phage types predominated within each herd. Eleven (18%) isolates of S. epidermidis could be typed by phages, assigning the isolates to 3 different types. Biotyping of S. epidermidis produced a total of 8 different types, the most common accounting for 29.5% of the isolates. A total of 6 different antibiogram types were observed among all isolates of S. epidermidis. Resistance towards penicillin (36.1%), tetracycline (9.8%) and streptomycin (9.8%), were recorded in the isolates of S. epidermidis. However, 35 (57.4%) of the isolates were susceptible to all 12 antibiotics tested.  相似文献   

17.
Objective To describe the bacterial flora present in the normal conjunctiva of donkeys from Sicily (Italy). Animals studied A total of 46 healthy donkeys housed in 3 locations within the territory of Palermo (Sicily, Italy) were studied. Donkeys ranged from 2 to 13 years of age, with a median age of 6 years. Procedures Forty‐six conjunctival swabs were obtained from both eyes of each animal, and specimens were cultured for aerobic bacteria. Furthermore, the antimicrobial activity of methicillin (1 μg) and oxacillin (5 μg) on Staphylococcus spp. isolates was evaluated, and a specific PCR assay, which allows the detection of mecA gene specific for methicillin‐resistant Staphylococcus aureus (MRSA) strains, was performed. Results Forty of 46 (86.9%) donkeys were positive for bacteria. Eighty bacterial isolates, representing 9 bacteria genera, were successfully cultured. The most frequently recovered bacterial genus was Staphylococcus (52/80 isolates; 65%). Several strains (20/80 isolates; 25%) belonging to the Enterobacteriaceae family were also isolated, among which the most frequently isolated genus was Enterobacter (eight isolates). Of the 52 Staphylococcus spp. isolates, 14 (26.9%) strains were oxacillin/methicillin resistant. The mecA gene was detected in 6/52 (11.5%) strains. Conclusions This study contributes to the knowledge about normal ocular flora and MRSA occurrence in donkey farms in Sicily.  相似文献   

18.
Although methicillin-resistant Staphylococcus aureus (MRSA) were generally isolated from human beings; these agents were recently isolated from various animal species. It has been shown that MRSA isolates are not only resistant to beta-lactam antibiotics, but can also be resistant to the other commonly used antibiotics. In this study, 18 phenotypic methicillin resistant S. aureus isolates from bovine mastitis cases were analyzed by PCR for the presence of mecA gene encoding methicillin resistance and aac(6′)/aph(2″), aph(3′)-IIIa and ant(4′)-Ia genes encoding aminoglycoside resistance. Out of 18 S. aureus isolates (oxacillin MICs, ≥4 μg/ml), 3 were positive for mecA gene. Only one from 3 mecA positive isolates was positive for genes encoding aminoglycoside-modifying enzymes and this isolate carried aac(6′)/aph(2″) in combination with aph(3′)-IIIa gene. The aph(3′)-IIIa gene was detected in 3 isolates. These three isolates carrying the aminoglycoside-modifying enzyme genes were resistant to gentamicin, kanamycin and neomycin. The mecA gene of 3 MRSA isolates was sequenced. All three mecA genes of these isolates were identical to that found in human MRSA strains, except a one-base substitution at nucleotide position 757. From the data presented in this study, it can be concluded that MRSA isolated from bovine mastitis may be originated from human beings, but further studies are needed to investigate the possibility of zoonotic transfer of MRSA.  相似文献   

19.
Abstract

AIMS: To determine the pattern of isolation of major mastitis-causing organisms isolated from milk samples submitted to five veterinary diagnostic laboratories in New Zealand.

METHODS: The culture results of 25,288 milk samples that were collected from dairy cows throughout New Zealand from August 2003 to December 2006 and submitted to a group of veterinary diagnostic laboratories were assembled, reviewed and summarised. Logistic regression was used to analyse the effect of year, region (i.e. North vs South Island), and season on the probability of isolating the two most common organisms.

RESULTS: The most commonly isolated mastitis causing organisms from all samples were: Streptococcus uberis (23.6%), Staphylococcus aureus (23.5%), coagulase-negative staphylococci (CNS; 7.2%), Strep. dysgalactiae (6.2%), Bacillus spp. (4.0%), and coliforms (3.7%). The percentage of samples with isolates of Strep. uberis or Staph. aureus was affected by island, year and season (p<0.001). For most of the year, except in late winter and early spring when Strep. uberis was much more common, the percentage of isolates of Strep. uberis and Staph. aureus were not apparently different despite the former being an environmental pathogen and the other a contagious one.

CONCLUSION: The pattern of isolation of major mastitis-causing organisms, as determined from culture of milk samples submitted to diagnostic laboratories in New Zealand, has changed significantly over the last 40 years, with a substantial increase in the percentage of isolates that are Strep. uberis and a decrease in isolates of Strep. agalactiae. There is a clear seasonal pattern to the isolation of both Strep. uberis and Staph. aureus, particularly the former.

CLINICAL RELEVANCE: Knowledge of the aetiological agents causing bovine mastitis on a farm is of value in determining the choice of treatment. This dataset shows that, although there is seasonal pattern to the isolation of mastitis-causing organisms in New Zealand, both Strep. uberis and Staph. aureus are isolated throughout the year, so bacteriology is of value in determining aetiology even in late winter/early spring.  相似文献   

20.
The present study was carried out to genotypically characterize Staphylococcus aureus (S. aureus) isolated from bovine mastitis cases. A total of 37 strains of S. aureus were isolated during processing of 552 milk samples from 140 cows. The S. aureus strains were characterized phenotypically, and were further characterized genotypically by polymerase chain reaction using oligonucleotide primers that amplified genes encoding coagulase (coa), clumping factor (clfA), thermonuclease (nuc), enterotoxin A (entA), and the gene segments encoding the immunoglobulin G binding region and the X region of protein A gene spa. All of the isolates yielded an amplicon with a size of approximately 1,042 bp of the clfA gene. The amplification of the polymorphic spa gene segment encoding the immunoglobulin G binding region was observed in 34 isolates and X-region binding was detected in 26 isolates. Amplification of the coa gene yielded three different products in 20, 10, and 7 isolates. The amplification of the thermonuclease gene, nuc, was observed in 36 out of 37 isolates. All of the samples were negative for the entA gene. The phenotypic and genotypic findings of the present strategies might provide an understanding of the distribution of the prevalent S. aureus clones among bovine mastitis isolates, and might aid in the development of steps to control S. aureus infections in dairy herds.  相似文献   

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