• Journal of Veterinary Science
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• v.23 no.6
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• pp.12.01-12.10
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• 2022

Background: Staphylococcus aureus and Streptococcus agalactiae are the main cause of clinical mastitis in dairy cattle in Argentina, whereas coagulase-negative staphylococci (CNS) and environmental streptococci are the main cause of subclinical mastitis. Bacteria isolated from infected animals show increasing antimicrobial resistance. Objectives: This study aims to determine the antimicrobial resistance of staphylococci and streptococci isolated from milk with mastitis, and to genotypically characterize the methicillin-resistant (MR) staphylococci. Methods: Isolation was performed on blood agar and identification was based on biochemical reactions. Antimicrobial susceptibility was according to the Clinical and Laboratory Standards Institute guidelines. The antimicrobial resistance genes, SCCmec type and spa type were detected by the polymerase chain reaction method. Results: We isolated a total of 185 staphylococci and 28 streptococci from 148 milk samples. Among the staphylococcal isolates, 154 were identified as CNS and 31 as S. aureus. Among the 154 CNS, 24.6% (n = 38) were resistant to penicillin, 14.9% (n = 23) to erythromycin, 17.5% (n = 27) to clindamycin, 6.5% (n = 10) to cefoxitin and oxacillin. Among the S. aureus isolates, 16.1% (n = 5) were resistant to penicillin, 3.2% (n = 1) to cefoxitin and oxacillin (MRSA). Six MR isolates (5 CNS and 1 MRSA) were positive to the mecA gene, and presented the SCCmec IVa. The MRSA strain presented the sequence type 83 and the spa type 002. Among the 28 streptococcal isolates, 14.3% (n = 4) were resistant to penicillin, 10.7% (n = 3) to erythromycin and 14.3% (n = 4) to clindamycin. Conclusions: The present findings of this study indicate a development of antimicrobial resistance in main bacteria isolated from cows with mastitis in Argentina.

• Korean Journal of Veterinary Research
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• v.15 no.1
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• pp.101-108
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• 1975

The susceptibility of 536 isolates of Staphylococcus and 313 isolates of Streptococcus to a number of chemotherapeutics were studied. These organisms were isolated from bovine mastitis during 1973 and 1974. In addition to this, the rate of multiple resistance of 425 isolates of Staphylococcus and 164 isolates of Streptococcus, isolated in 1974, to the chemotherapeutics was analysed. The results obtained in this work were summerized as follows: 1. Staphylococcus and Streptococcus isolated in 1974 showed a higher resistance, with 3 exceptions of chemotherapeutics, than the isolates of 1973. 2. Staphylococcus isolated in 1973 and 1974 showed a higher susceptibility than Streptococcus. 3. The strains of Staphylococcus resistant to colistin were 39 strains (9.2%), to colistin and sulfisoxazole 33 (7.8%), to streptomycin, kanamycin, colistin and sulfisoxazole 20 (4.7%), and to penicillin, colistin and sulfisoxazole 18 (4.2%). 4. The strains of Streptococcus resistant to colistin were 17 strains (10.4%), to streptomycin, kanamycin, colistin and sulfisoxazole 13 (7.9%), to colistin and sulfisoxazole 11 (6.7%) and to penicillin, colistin and sulfisoxazole 11 (6.7%).

• Journal of Environmental Health Sciences
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• v.21 no.2
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• pp.42-53
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• 1995

광주시 지역에서 사육하고 있는 젖소 1,614두중 유방염으로 의심되는 730분방 중에서 170분방을 검사분석하여 유방률, 균의 분리와 간이검사법과의 관계, 계절별 분리균의 분포, 항균 요법제에 대한 감수성 등을 검사하였다. 본 원인균은 730분방 중 134분방(18.4%)에서 분리되었으며 체세포 숫자는 평균 $1.620 imes 10^6pm 1.167 imes 10^6/ml$(C.V. 72.0%)이었다. CMT 반응치는 평균 $2.9pm 1.2$(C.V. 41.4%)이었으며 WT 반응치는 평균 $2.8pm 1.2$(C.V. 42.9%)이었다. RBVT와 CMT의 상관계수는 0.82(P<0.001)이었고 RBVT와 WT의 상관계수는 0.75 (P<0.001)이었으며 CMT와 WT의 상관계수는 0.93 (P<0.001)이었다. 체세포 숫자를 기준으로 하여 CMT 및 WT의 양성율을 비교하여 보면 원인균이 분리된 경우에는 체세포 숫자가 $0.49 imes 10^6$ 이하/ml의 경우에 반응치가 1+일때의 CMT는 72.4%, WT는 42.1%이었고 체세포 숫자가 $0.50 imes 10^6~1.00 imes 10^6/ml$의 경우에 반응치가 2+일 대의 CMT는 45.5%, WT는 48.8%이었으며, 체세포 숫자가 $3.01 imes 10^6$ 이상/ml의 경우에 반응치가 3+일 때의 CMT는 73.7%, WT는 92.3%이었다. 원인균의 월별 분리 빈도를 보면 8월 (17.9%)이 가장 높았고 다음은 9월(16.4%), 7월 (12.7%), 6월 (11.2%), 1월 (9.0%)의 순이었다. 원인균의 분리 빈도를 보면 Staphylococcus sp. (51.4%)가 가장 높았고 다음은 Escherichia coli(23.9%), Pseudomonas sp. (11.2%). Streptococcus sp. (6.7%)의 순이었다. 항균 요법제에 대한 감수성은 trimethoprim/sulfamethoxazole은 Streptococcus sp., Staphylococcus epidermidis, Proteus sp., Salmonella sp. 등에 높았고 gentamycin은 Streptococcus sp., Staphylococcus aureus, Enterobacteriaceae, Klebsiella sp., Proteus sp., Salmonella sp. 등에 높았으며 enrofloxacin은 일반적으로 거의 모든 균에서 감수성이 높았다.

• Korean Journal of Veterinary Research
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• v.58 no.1
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• pp.51-55
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• 2018

Bovine mastitis (BM) has resulted in enormous economic loss in the dairy industry and coagulase-negative staphylococci (CNS) have caused subclinical BM. Although VITEK 2 GP ID card (VITEK 2) has been used for CNS identification, the probability of identification varies. The rpoB sequence typing (RSTing) method has been used for molecular diagnosis and epidemiology of bacterial infections. In this study, we undertook RSTing of CNS and compared the results with those of VITEK2 and 16S rRNA gene sequencing. As compared VITEK2, the molecular-based methods were more reliable for species identification; moreover, RSTing provided more molecular epidemiological information than that from 16S rRNA gene sequencing.

• Journal of Embryo Transfer
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• v.14 no.2
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• pp.121-129
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• 1999

The objective of this study was to produce calves by transfer of embryos derived from slaughter house(SHD) and ultrasound-guided ovum pick-up (OPU). At 60 hrs after injection of 400 mg FSH dissolved in 25% polyvinylpyrrolidone(PVP) by single dose, ultrasound-guided follicular oocyte aspiration was ferformed. Day-7 and day-8 blastocysts produced by in vitro maturation (IVM), fertilization (IVF) and culture(IVC) of the oocytes derived from SHD and OPU were nonsurgically transferred into recipients. The results obtained were as follows. The cleavage rate and the development rate to blastocysts were not significantly (P<0.05) different between the oocytes obtained by SHD (72.9% vs. 34.1%) and OPU (75.9% vs. 38.4%). The oocyte recovery rate from the number of follicles by ultrasound-guided aspiration were not significantly (P<0.05) different between Holstein (61.7%) and Hanwoo (60.1%), but the rate of oocytes useful for IVF was significantly (P<0.05) higher in Hanwoo (69.3%) than Holstein (59.6%). The cleavage rate and the development rate to blastocysts was not significantly (P<0.05) different between Holstein (74.9% vs. 39.2%) and recipients on day 8 of estrus cycle resulted in 13 pregnancies (34.2%). One of them was sacrificed during gestation period due to mastitis and another was aborted spontaneous. The resulting 14 calves were morphologically normal at birth. Seventy eight fresh OPU-IVF embryos were transferred into 21 recipients on day 8 of estrus cycles, resulting in pregnancy of 12 recipients (41.4%). Two of them were sacrificed during gestation period due to mastitis and the other two were aborted. Nevertheless, the 11 OPU-calves have been born normally.

• Journal of Veterinary Science
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• v.21 no.6
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• pp.87.1-87.11
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• 2020

Background: A new, extended long-acting tilmicosin (TLAe) preparation was tested against intramammary ceftiofur (CEF) using a non-inferiority trial model during dry-cow therapy (DCT) in a farm with high bovine population density and deficient hygiene application. Objectives: To evaluate the possibility that TLAe administered parenterally can achieve non-inferiority status compared to CEF administered intramammary for DCT. Methods: Cows were randomly assigned to TLAe (20 mg/kg subcutaneous; n = 53) or CEF (CEF-HCl, 125 mg/quarter; n = 38 cows) treatment groups. California mastitis testing, colony-forming unit assessment (CFU/mL), and number of cases positive for Staphylococcus aureus were quantified before DCT and 7 d after calving. A complete cure was defined as no bacteria isolated; partial cure when CFU/mL ranged from 150 to 700, and cure-failure when CFU/mL was above 700. Results: TLAe and CEF had overall cure rates of 57% and 53% (p > 0.05) and S. aureus cure rates of 77.7% and 25%, respectively (p < 0.05). The pathogens detected at DCT and 7 days after calving were S. aureus (62.71% and 35.55%), Staphylococcus spp. (22.03% and 35.55%), Streptococcus uberis (10.16% and 13.33%), and Escherichia coli (5.08% and 15.55%). Non-inferiority and binary logistic regression analyses revealed a lack of difference in overall efficacies of TLAe and CEF. Apart from S. aureus, S. uberis was the predominant pathogen found in both groups. Conclusions: This study is the first successful report of parenteral DCT showing comparable efficacy as CEF, the gold-standard. The extended long-term pharmacokinetic activity of TLAe explains these results.

• Journal of Veterinary Clinics
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• v.17 no.1
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• pp.152-158
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• 2000

capsular polysaccharide(CPS), alpha toxin과 재조합 fibronectin binding protein (FnBP)으로 구성된 유방염 백신을 개발하여 야외효능실험을 수행하였다. 이 subunit 백신은 비유우 23두와 처녀우 20두를 대상으로 10개월동안 각각 수행되었다. 비유우는 매 3주간격으로 2회 백신접종을 하였으며 대조군은 PBS를 상유방림조절 주위에 피하주사하였다. 처녀우를 대상으로 한 실험에서는 분만 8주전부터 시작하여 매 3주간격으로 2회 비유우 백신접종부위와 동일하게 접종하였다. 접종후 비유우에서는 황색포도상구균에 의한 총유선내 감염율이 대조균에 비해 유의성있게 감소하였으며 (p<0.001) 처녀우에서도 총유선내 감염이 백신 접종균(1.6%)이 대조군(11.7%)에 비해 다음 비유기동안 유의성있게 낮았다. (p<0.001). 비유기동안 백신접종한 젖소의 체세포수는 변화가 없었으며 처녀우에서는 추가접종후 백신접종군에서 대조군의 체세포수에 비해 낮았지만 통계학적으로 유의성은 없었다(p>0.05). 본 실험결과 황색포도구균에 대한 유방염 아단위 백신은 비유우와 처녀우에서 체세포수를 증가시키지 않고 총 유선내 감염율을 낮추어주었다. 하지만 본 실험은 1군데의 목장을 대상으로 하였기 때문에 향후 대규모 목장을 대상으로 하는 유방염 백신의 야외효능실험이 심도있게 이루어져야 한다고 생각된다.

• Journal of Microbiology and Biotechnology
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• v.14 no.3
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• pp.503-508
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• 2004

The antimicrobial substance produced by Lactobacillus bulgaricus was inactivated by protease. It showed inhibitory activity against Staphylococcus aureus ATCC6538, Streptococcus agalactiae ATCC14364, some Gram-positive and Gram-negative bacteria, and characteristics of a bacteriocin. The optimal temperature and culture time for the production of bacteriocin were $30^{\circ}C$ and 10 h, respectively, in the culture of L. bulgaricus. The bacteriocin production started in the exponential phase and reached a maximum at the early stationary phase. Using Staph. aureus ATCC6538 and Strep. agalactiae ATCC14364, known as common bovine mastitis pathogens, as indicator strains for determination of the bacteriocin activity, the antimicrobial activity of the bacteriocin was found to be stable in acidic and neutral pH's (2- 7) even at lOOT, whereas it was lost at high pH (10- 11) and $100^{\circ}C$. The mode of action for the antimicrobial activity was bacteriocidal, and the molecular weight determined by SDS-PAGE and overlay method was 14 kDa.

• Korean Journal of Veterinary Research
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• v.40 no.3
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• pp.645-652
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• 2000

This study was performed to investigate Mycoplasma (M) spp. infection status of dairy cow in South Korea. Among 8,485 bulk tank milk collected from dairy farms of the 5 areas, 26 samples (0.30%) were positive for Mycoplasma by direct culture method. The isolation rates of Mycoplasma spp. according to the areas were 0.51% in Kyonggi, 0.16% in Cholla, 0.23% in Gyoungsang, 0.12% in Chungchong, and 0.08% in Kangwon. In the species identification test by indirect immunoperoxidase test, 16 out of 26 isolates were identified as M bovis (61.53%), M bovigenitalium (23.07%), M californicum (7.69%), M alkalescens and Acholeplasma laidlawii (3.84%), respectively. The isolation rate of Mycoplasma spp. from 208 quarter milk samples in culling cows due to severe clinical mastitis was 3.0%. These Mycoplasma spp. were identified as M bovis (62.0%), M bovigenitalium (12.0%), M californicaum (12.0%), and M alkalescens (12.0%). This study shows that the bovine mammary gland infected by Mycoplasma spp. is present in some dairy farms and the routine culture test of bulk tank milk samples for Mycoplasma is needed for a high quality milk promotion services.

• Korean Journal of Veterinary Research
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• v.36 no.3
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• pp.635-646
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• 1996

To establish the effective ways to prevent bovine mastitis, the study has been performed to investigate the attributable factors causing down-regulation of immune responses in mammary gland of non-lactating cows. Lymphocytes from peripheral blood and mammary gland secretions(MGS) were obtained from normal healthy cows and mastitic cows, respectively. Cellular immune responses were examined by comparison of proportion of lymphocyte subpopulations using a set of monoclonal antibodies and flow cytometry. The results obtained are as follows. 1. Proportions of peripheral blood lymphocyte subpopulations expressing BoCD2 and BoCD4 molecules were 32.9%, 15.4% in mastitic cows and 43.3%, 28.3% in normal healthy cows, respectively. The ratios of BoCD4 to BoCD8 were 0.76 and 1.47, respectively. 2. Proportions of mammary gland lymphocyte subpopulations expressing BoCD2 and BoCD4 molecules were 18.5%, 8.3% in mastitic cows and 38.2%, 14.2% in normal healthy cows, respectively. The ratios of BoCD4 to BoCD8 were 0.6 and 2.0, respectively. 3. Proportions of T lymphocyte subpopulations from MGS were significantly lower than those from peripheral blood both in mastitic cows and normal healthy cows. However, lymphocyte subpopulations expressing ACT2 and ACT3, which represent activated T suppressor cells, were significantly higher in MGS than those in peripheral blood.