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1.
Antimicrobial therapy is a useful tool to control bovine mastitis caused by Staphylococcus aureus, as consequence an increase in staphylococci resistant cases has been registered. Alternative strategies are desirable and bacteriocins represent attractive control agents to prevent bovine mastitis. The aim of this work was to evaluate the activity of five bacteriocins synthesized by Bacillus thuringiensis against S. aureus isolates associated to bovine mastitis. Fifty S. aureus isolates were recovered from milk composite samples of 26 Holstein lactating cows from one herd during September 2007 to February 2008 in México and susceptibility of those isolates to 12 antibiotics and 5 bacteriocins from B. thuringiensis was evaluated. S. aureus isolates were mainly resistant to penicillin (92%), dicloxacillin (86%), ampicillin (74%) and erythromycin (74%); whereas susceptibility to gentamicin, trimethoprim and tetracycline was detected at, respectively, 92%, 88%, and 72%. All S. aureus isolates showed susceptibility to the five bacteriocins synthesized by B. thuringiensis, mainly to morricin 269 and kurstacin 287 followed by kenyacin 404, entomocin 420 and tolworthcin 524. Our results showed that S. aureus isolates had differences in the antimicrobial resistance patterns and were susceptible to bacteriocins produced by B. thuringiensis, which could be useful as an alternative method to control bovine mastitis.  相似文献   

2.
The study was undertaken to determine the aetiology and prevalence of mastitis in hand-milked cows (n = 186) in two major Ethiopian dairies. The California Mastitis Test and culturing for bacteria revealed that 21.5% of the cows were clinically infected and 38.2% had subclinical mastitis. Most mastitis pathogens isolated from milk samples testing positive by the California Mastitis Test were Gram-positive cocci. Staphylococci constituted 57% of the isolates, of which the predominant cause of bovine mastitis was Staphylococcus aureus (40.5%). Other mastitis pathogens isolated include streptococci (16.5%), coliforms (9%) and corynebacteria (5%). Retrospective analysis of farm records indicated that mastitis was the second most important cause of culling and accounted for 27% of the cows removed from these two dairies.  相似文献   

3.
Bovine Mastitis in Selected Areas of Southern Ethiopia   总被引：3，自引：0，他引：3  
A study on bovine mastitis, designed to determine the causal agents, prevalence of infection and impact of risk factors in three cattle breeds, was conducted in selected areas of southern Ethiopia. A total of 307 lactating and non-lactating cows, of which 162 were indigenous Zebu, 85 Jersey and 60 Holstein-Friesian, were examined by clinical examination and the California mastitis (CMT) test. Of these, 40.4% were positive by CMT and bacteriology for clinical or subclinical mastitis, with prevalence rates of 37.1% and 62.9%, respectively. Out of 1133 quarters examined, 212 (18.7%) were found to be infected, 83 (39.2%) clinically and 129 (60.8%) subclinically. The prevalence of mastitis was significantly higher in Holstein-Friesian than in indigenous Zebu, in non-lactating cows than in lactating cows, in the early lactation stage than in the mid-lactation stage, in cows with lesions and/or tick infestation on skin of udder and/or teats than in cows without this factor, and in the wet season than in the dry season. Mastitis increased with parity number (R = 0.9). Of 248 CMT and clinically positive udder quarter samples analysed microbiologically, 212 were culturally positive for known mastitis pathogens and 36 were negative. Of the 199 positive samples, Staphylococcus accounted for 39.2%, Streptococcus for 23.6%, coliforms for 14.1%, Micrococcus and Bacillus species for 8.0% each and Actinomyces or Arcanobacterium (Corynebacterium) for 7.0%. It was concluded that there was a high prevalence of clinical and subclinical mastitis, mainly caused by Staphylococcus aureus, Streptococcus agalactiae and Escherichia coli, in this study area.  相似文献   

4.
The German wasp, Vespula germanica has been observed to injure teats of dairy cows, causing lesions that are associated with clinical and subclinical mastitis. The presence of skin lesions on the teats, caused by the wasps, was recorded in a dairy cattle herd located in the Samaria foothills during July–October 1999. Wasp‐inflicted injuries were found in 43.6% (58 of 133) of the adult cows and 1.4% (one of 71) of the first‐calving cows. They were located in 42.4% of cows (n = 25) on all quarters, 18 cows (30.5%) had lesions on the front quarters and 27.1% (n = 16) of cows on the hind quarters only. Clinical and subclinical mastitis were diagnosed in 61% (36 of 59) and 28.8% (17 of 59), respectively, of the injured adult and first‐calving cows. The most common bacterial isolates from the mastitic cows were Staphylococcus aureus 45.1% (n = 14), Streptococcus dysgalactiae 16.1% (n = 5), Streptococcus spp. 19.4% (n = 7) and others 13.9% (n = 5). The loss of milk production was estimated at 300 kg milk for each cow injured by wasps and exhibiting clinical mastitis. An increase in the bulk‐milk somatic cell count, from 186 × 103 at 1 month prior to the outbreak to a peak of 1200 × 103 in the post‐outbreak month, was noted. The culling rate reached 13.6% (eight of 59) of the affected cows. In summary, the considerable economic losses caused by the wasp infestation resulted from decreased milk production and a decline in milk quality, culling of affected cows, and increased demand for use of drugs and veterinary care.  相似文献   

5.
A study was conducted on 207 lactating camels in six herds in Kenya to evaluate the California mastitis test (CMT) for the detection of intramammary infections (IMIs) caused by Streptococcus agalactiae and Staphylococcus aureus and to investigate the prevalence of both the pathogens in the camel udder. IMI with S. agalactiae was found in 12% of all camels sampled. IMI with S. aureus was present in 11% of all camels sampled. The herd-level prevalence of IMI varied between 0 and 50% for S. agalactiae and between 0 and 13% for S. aureus. Longitudinal observations over 10–12 months confirmed persistent infections for both pathogens. Observations in one herd suggested that camel pox was a contributing factor in spreading and exacerbating S. agalactiae udder infections.The CMT had quarter-level sensitivities of 77 and 68% for S. agalactiae and S. aureus in camels, respectively. The CMT specificities were 91% for both the pathogens.  相似文献   

6.

Mastitis may be caused by a wide range of microorganisms able to induce distinct lesions in mammary tissues. This study aims to characterize the gross and microscopic features of mastitis in dairy cows and to correlate them with the pathogens involved. The udders of slaughtered dairy cows were inspected and milk samples from each mammary quarter or fragments of the parenchyma were sent for microbiological analysis, and tissue collected for histopathological evaluation. A total of 148 cows and 592 mammary quarters were collected. From these, 432 quarters (73%) had mastitis and in 160 (27%), no changes were observed. Mastitis was classified into seven patterns based on the histopathological findings, of which mixed, lymphoplasmacytic, and suppurative mastitides were the most prevalent with 35.9% (155/432), 27.1% (117/432), and 14.3% (62/432) of the cases, respectively. These patterns were associated with the same set of pathogens: Streptococcus spp., coagulase-negative Staphylococcus (CNS), Staphylococcus aureus, Streptococcus agalactiae, Streptococcus uberis, and Corynebacterium bovis. The pyogranulomatous pattern represented 7.2% (31/432) of the cases with distinct distribution based on the agent involved, mostly S. aureus and Nocardia sp. Abscedative mastitis accounted for 6.0% (26/432) of the cases; it was characterized by multiple abscesses in the parenchyma and was mainly caused by Trueperella pyogenes. Necrosuppurative mastitis represented 5.8% (25/432) of the cases which were characterized by severe parenchyma necrosis and were caused by bacteria such as CNS and Escherichia coli. The granulomatous pattern represented 3.7% (16/432) of the cases and was occasionally associated with Mycobacterium sp.

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7.
A fluorochrome microassay was used to investigate peripheral blood polymorphonuclear leukocyte (PMNL) function in cattle. Glass-adherent PMNL were reacted withStaphylococcus aureus princubated in 20% bovine serum for 30, 60 and 90 min. Coverslips were stained with acridine organge (AO) followed by crystal violet to quench extracellular bacterial fluorescence. PMNL function was evaluated by counting the number of dead (stained red with AO) and live (stained green with AO)S. aureus contained within 100 PMNL. A phagocytic index was calculated as the average number of bacteria contained within PMNL. The percentage killing ofS. aureus was calculated from the average proportion ofS. aureus within PMNL that were dead.Six clinically normal Holstein calves, 3–4 months of age, were sampled on 6 consecutive days. PMNL phagocytosis and killing did not vary significantly (p>0.05) among repeated samplings per calf. PMNL function increased with increasing time of incubation of PMNL withS. aureus. Means (± SD) for percentage killing were 46.7±13.1, 57.4±11.6, and 62.1±9.8% for 30, 60 and 90 min of reaction, respectively. Means (± SD) for the phagocytic index were 2.9±0.8, 3.6±1.0, and 4.2±1.1 bacteria/PMNL for 30, 60 and 90 min of reaction, respectively. PMNL function was determined in 30 normal cattle of various breeds, age and sex, and these values were pooled to provide normal values for PMNL function.When values for bovine clinical patients (n=25) with various diagnoses were compared with normal values (defined by the mean ± 2SD for the 30 normal cattle) for PMNL function, only one patient was observed to exhibit PMNL hypofunction. A cow with disseminated intravascular coagulation in association with peracute coliform mastitis exhibited decreased PMNL killing capacity. Abnormal PMNL function was uncommon in the hospital population studied.Peripheral blood PMNL function was evaluated in lactating Holstein cows with (n=15) or without (n=15) chronic subclinicalS. aureus mastitis. There was no significant (p>0.05) difference in PMNL function among these cows.  相似文献   

8.
Milk samples (n=160) from 7 clinically healthy bactrian camels were cultured to detect subclinical udder infection. The samples were assessed by the Californian mastitis test (CMT) and somatic cell count (SCC). Bacteria were recovered from 36 (22.5%) of the milk samples. Staphylococcus aureus and coagulase-negative staphylococci (CNS) were the main organisms found.Infected quarters had significantly higher mean values for the SCC (p<0.01) and CMT (p<0.001) than non-infected quarters. All 7 camels were infected with CNS but only 4 with S. aureus. CMT values for S. aureus-infected camels were significantly higher than for those only infected with CNS. The values for SCC and CMT were significantly influenced by the stage of lactation (p<0.05). No significant difference was found from the effect of the quarters. Both SCC and CMT were of value in predicting the infection status of the udder.Abbreviations CMT California mastitis test - SCC somatic cell count - CNS coagulase-negative staphylococci  相似文献   

9.
This study was conducted to evaluate alterations in coagulation parameters in dairy cows affected with acute Escherichia coli (E. coli) mastitis and to compare those values to cows affected with Staphylococcus aureus (S. aureus ) mastitis. Twenty-four, adult Holstein-Friesian dairy cows affected with acute E. coli mastitis and 17 cows affected with S. aureus mastitis were studied. Cows affected with E. coli mastitis had significantly prolonged activated partial thromboplastin time (APTT) (P < 0.01), prothrombin time (PT) (P < 0.05) and decreased (P < 0.05) platelets numbers. Cows with S. aureus mastitis had only significantly prolonged APTT (P < 0.05) and decreased (P < 0.05) platelet counts. In the hematology evaluation, cows affected with E. coli and those affected with S. aureus mastitis had elevated hematocrit values but only significantly (P < 0.05) so in mastitic cows caused by E. coli. Both groups of mastitic cows had significantly (P < 0.05) lower leukocyte counts. Only cows with E. coli mastitis had significantly (P < 0.05) lower neutrophil count. In the plasma biochemical evaluation, creatinine concentrations were significantly (P < 0.05) elevated in both groups of cows. Blood urea nitrogen (BUN) concentration was only significantly elevated in cows affected with E. coli mastitis. Results of this study indicated that dairy cows affected with acute E. coli mastitis are more likely to develop clinical manifestations of disseminated intravascular coagulation than cows affected with S. aureus mastitis.  相似文献   

10.
The aims of this study were to determine the existence of pvl gene, some toxin genes, and mecA gene in Staphylococcus aureus strains isolated from sheep milk and to examine antimicrobial resistance profiles in staphylococci from sheep and goats' milk. The milk samples were collected from 13 different small ruminant farms in Kirikkale province from February to August 2009. A total of 1,604 half-udder milk samples from 857 ewes and 66 half-udder milk samples from 33 goats were collected. Staphylococcus spp. were isolated and identified from the samples. Toxin genes and mecA gene among S. aureus strains were determined by PCR. Antimicrobial susceptibility of staphylococci was examined by the disk diffusion method on Mueller-Hinton agar, and interpreted according to the Clinical Laboratory Standards Institute (CLSI) guidelines. The prevalence of subclinical intramammary infection in both ewes and goats was 5.2%. The most prevalent subclinical mastitis agents were coagulase-negative staphylococci and S. aureus with prevalences 2.8% (n:46) and 1.3% (n = 21), respectively. The prevalence of resistances in isolated Staphylococcus spp. to penicilin G, tetracycline, erythromycin, gentamicin, and enrofloxacin were found as 26.9% (18), 7.5% (5), 6.0% (4), 3.0% (2), and 1.5% (1), respectively. Only 3 of the 21 S. aureus ewe isolates (13.4%) were shown to harbor enterotoxin genes being either seh, sej or sec. However, fourteen (66.6%) of the 21 S. aureus isolates had pvl gene while none of the isolates harbored mecA gene. In conclusion, Staphylococci were shown to be the most prevalent bacteria isolated from subclinical mastitis of ewes and goats and these isolates were susceptible to most of the antibiotics. In addition, S. aureus strains isolated from ewes were harboring few staphylococcal enterotoxin genes. However, Panton–Valentine leukocidin produced by S. aureus could be an important virulence factor and contribute to subclinical mastitis pathogenicity.  相似文献   

11.
Biofilm formation and antimicrobial resistance of Staphylococcus aureus are important virulence factors in cases of mastitis in dairy cows. However, few studies have investigated mastitis strains isolated from heifers. Within this context, the objective of the present study was to investigate biofilm formation on Congo red agar, the presence of the icaA and icaD genes by polymerase chain reaction (PCR), and the percentage of in vitro antimicrobial resistance of 110 S. aureus isolates from mammary gland secretions of heifers and cows with mastitis. PCR detected the icaA and icaD genes in 98% and 100% of isolates, respectively. However, only 55.5% of all isolates produced a biofilm on Congo red agar. Antimicrobial susceptibility testing revealed that 47.0% of isolates from heifers and 70.4% of isolates from cows were resistant to at least one of the antimicrobial agents tested. Resistance to penicillin and/or ampicillin was the most frequent (44.5%). These results indicate the need to implement prophylactic and control measures of mastitis for heifers. Heifers and cows can carry resistant strains with the capacity of biofilm production, a fact representing a threat to public health and animal well‐being and generating losses to dairy farmers.  相似文献   

12.
AIM: To identify and enumerate colony forming units (cfu) of mastitis pathogens in bulk tank milk (BTM) from pasture-fed New Zealand dairy cows in the Waikato region.

METHODS: BTM samples from seven seasonal-calving dairy herds in the Waikato region were collected monthly from August to December 2004 (cows calved during July-September). Milk samples were cultured on blood aesculin and MacConkey agar plates for 24 h, and the number of mastitis pathogens identified and counted.

RESULTS: Colonies identified in BTM included aesculinpositive streptococci, Staphylococcus aureus, coagulase-negative staphylococci (CNS), and coliforms; counts ranged from zero to >1,000 cfu/ml. Counts >1,000 cfu/ml for total aesculin-positive streptococci, CNS and coliforms were present in 48%, 51% and 11% of BTM samples, respectively. Counts of Staph. aureus ranged from zero to 1,000 cfu/ml, but first appeared in BTM samples only in October. Staphylococcus aureus was repeatedly isolated in BTM from 4/7 farms during the testing period.

CONCLUSIONS: Counts of mastitis pathogens in this study appeared high relative to interpretive criteria set by other workers, which may indicate a high prevalence of mastitis risk factors on these farms. Interpretation of results is difficult as aesculinpositive streptococci, CNS and coliforms can be isolated from the environment as well as from cows with clinical or subclinical mastitis. Furthermore, Staph. aureus is inconsistently excreted from infected bovine mammary glands. More extensive study of this method is required in New Zealand to attempt to further validate the interpretation of results of bacterial culture of BTM.

CLINICAL RELEVANCE: This method may be used to monitor challenge from mastitis pathogens over time as part of milk quality control programmes. The technique may be of use as a screening test to provide information to veterinarians, affording them the opportunity to have an input into mastitis control on dairy farms in New Zealand.  相似文献   

13.
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   

14.
We conducted a prospective observational study on clinical and subclinical mastitis in 30 commercial meat-producing sheep flocks from 2 regions of the province of Quebec, Canada. A total of 2792 ewes selected in late gestation were followed from lambing to weaning of lambs. The incidence of clinical mastitis for the total lactation period (average of 58 days) ranged among flocks from 0 to 6.6%, with a median of 1.2%. The most frequently isolated bacteria from the cases of clinical mastitis, in pure or mixed culture, were Mannheimia haemolytica (26%), Staphylococcus aureus (23%), and coagulase-negative staphylococci (17%). Incidence of clinical mastitis was higher in ewes that gave birth to 3 or more lambs and from the Estrie region, and was associated with an increase in ewe mortality, an increase in lamb mortality at the litter level, and a decrease in lamb's weaning weight for lambs born in multiple litter size or from ewes ≥4 years old.Among 354 selected ewes with clinically normal udder at the end of lactation, 28.8% had potentially pathogenic bacteria isolated from milk. The most prevalent bacteria were S. aureus (9.3%) and coagulase-negative staphylococci (9.3%). The risk of having a positive culture in at least one half was different between the two regions. Prevalence of ewes (n = 261) with California Mastitis Test (CMT) positive result in at least one half was 24.1 and 14.9% using a cut-off of ≥1+ and ≥2+, respectively. Prevalence of culture-positive udder halves was 11.7% for CMT-negative compared with 53.6% for CMT 3+ halves. CMT status was positively associated with the isolation of coagulase-negative staphylococci, M. haemolytica, S. aureus, and various Streptococcus species, but not with other isolated bacteria. Additionally, prevalence of CMT-positive halves was higher in ewes from the Estrie region, aged of ≥4 years versus 1 year, having clinical mastitis previously detected in the lactation and/or with low body condition score. Lamb weaning weight was associated with CMT status of ewes, while weaning weight was not associated with milk culture results. More research is needed to understand the dynamic of milk SCC and IMI in ewes from meat-producing flocks, its economical impact and best ways to control it.  相似文献   

15.
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16.
The effect of intramammary injection of recombinant bovine interleukin‐8 (rbIL‐8, 1 mg/10 ml of saline) on quarter milk levels of somatic cell count (SCC), chemiluminescence (CL) activity and counts of total bacteria and Staphylococcus aureus (S. aureus) was investigated, using 10 Holstein cows with an early stage or a late stage of subclinical mastitis naturally infected with S. aureus. In the late‐stage group, milk SCC and CL activity had significant rises with maximum levels at 6 h, following maintained high levels thereafter post‐cytokine injection. The counts in milk total bacteria and S. aureus were insignificantly decreased, being increased back on day 7 post‐cytokine injection. Thus, the cytokine was inefficient for the late‐stage subclinical mastitis. However, in the early‐stage group milk SCC and CL activity declined to under pre‐injection levels on day 7 after marked and significant rises at 6 h and day 1 post‐cytokine injection. The milk total bacterial count decreased significantly on days 0.25 and 2. Furthermore, the milk S. aureus count was decreased significantly on days 1, 2, 3 and 7 by the cytokine injection. These results suggest that the rbIL‐8 has a potential as a therapeutic agent of the subclinical mastitis of dairy cows, if the cytokine is applied at an initial stage of infection.  相似文献   

17.
Udder health problems associated with Staphylococcus aureus infections in dairy cows are difficult to control and antibiotics have limited effects. Lately, more interest has been directed towards ways to stimulate the innate immune mechanisms of the animal for better prevention and treatment of mastitis. The objectives of this study were to investigate if intramammary infusion at drying off with the immune modulator β1,3‐glucan can make the udder more resistant to experimental intra mammary S. aureus infection at this time, and to study if intramammary infusion of β1,3‐glucan into lactating udder quarters with chronic subclinical S. aureus infection can stimulate the clearing of the infection. Another aim was to evaluate the effect of β1,3‐glucan on the expression of major histocompatibility complex (MHC class II) on mammary leucocytes, measured by flow cytometry, during these circumstances. The results indicated a slight, but not statistically significant, positive effect of β1,3‐glucan at drying off on the clinical and anti‐bacterial response to S. aureus infection, but no therapeutic effect of β1,3‐glucan treatment of udder quarters with chronic subclinical S. aureus mastitis. However, the proportion of MHCII+ milk lymphocytes tended to increase after glucan infusion in those udder quarters indicating a stimulation of the antigen presenting ability. To further evaluate a possible preventive effect of β1,3‐glucan infusion at drying off more studies are needed involving a larger number of animals.  相似文献   

18.
Mammary gland problems occur incidentally in horses and one of the rarer conditions is botryomycosis (bacterial pseudomycosis, bacterial granuloma, staphylococcal pseudomycetoma). This article includes a short review of equine mammary gland problems inappropriate lactation, mastitis and neoplasia and botryomycosis, and additionally 2 clinical cases of botryomycosis of the udder resulting from Staphyloccocus aureus infection will be discussed. Both cases involved nonpregnant, nonlactating mares referred for chronic mammary inflammation with draining abcessation. In both mares, botryomycosis caused by S. aureus was confirmed by histopathology and a bacterial culture. Both mares recovered fully after surgical hemimastectomy under general anaesthesia.  相似文献   

19.
Summary

A possible association of a chronic indurative mastitis with mvv (maedi visna virus) infection in sheep was investigated. Sheep of four flocks (group A), in which insufficient lamb growth apparently associated with insufficient milk production and probably related to udder induration, was a serious problem, were clinically examined in mid‐lactation. The results were compared with four mvv‐free flocks (group B) without such complaints.

The incidence of udder induration in group A (n = 263) was about eight times higher than in group B(n = 206): 63.1 versus 8.0%. The clinical picture differed essentially between the groups. In group A the udder abnormalities were of a diffuse and indurative nature, involving both udder halves, while in group B the udder lesions were mainly nodular and often limited to one udder half.

Bacteriological examination revealed a difference in infection rate of the udders (6.8% in group A versus 14.1% in group B). A substantial difference was observed in a comparison of the bacteriological infection rate of the clinically abnormal udders (5.4% in group A, versus 47.0% in group B). Serological examination with an indirect ELISA revealed 81%, seropositive sheep in group A, versus 0% in group B. Twelve sheep of group A and five of group B, culled for reason of mastitis, were selected for pathological examination. The gross and microscopic lesions showed a pronounced difference between both groups. In group A a diffuse interstitial mastitis with slight to moderate fibrosis and a pronounced lymphoid hyperplasia was observed. In group B the mastitis had a nodular character, with a chronic galactophoritis, extensive fibrosis, and in some cases chronic abscesses. The lesions were often limited to one udder half Among the necropsied ewes of group A, nine showed lesions characteristic of maedi, whereas in group B no such lesions were observed.

The possible causal relation of this chronic indurative mastitis with mvv infection is discussed.  相似文献   

20.
Explant cultures of bovine mammary tissue taken from virgin heifers were used to examine adherence, colonization and cytopathogenesis ofStreptococcus uberis, Streptococcus agalactiae, Streptococcus dysgalactiae, Staphylococcus aureus andEscherichia coli in the putative target tissue. None of the five bacteria was able to adhere to healthy ductular epithelium but all showed a marked tropism for exposed connective tissue.S. aureus andE. coli induced a marked cytopathic effect in ductular epithelium after 6 hours in culture but the bacteria were not in close association with the affected tissue. No evidence could be found to support the hypothesis that adherence to epithelium might be the first stage in the pathogenesis of mastitis caused by these organisms.  相似文献   

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