Antibiotic resistance of Streptococcus agalactiae from cows with mastitis

Gao, Jian; Yu, Fuqing; Luo, Lei; He, Jianzhong; Hou, Rong-guang; Zhang, Hanqi; Li, Shumei; Su, Jingliang; Han, Bo

doi:10.1016/j.tvjl.2012.04.020

Cited by 58 publications

(66 citation statements)

References 8 publications

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“…The reasons that resistance genes are not always expressed need to be further evaluated. Possible explanations include promoter absence, weakness, or distance, and the presence of mutations in the genes in question, as suggested by Gao et al (2012). We found that 89.5% of strains carrying ermB also carried tetO, an association that has been previously documented.…”

Section: Discussionsupporting

confidence: 79%

“…High rates of tetracycline resistance (60-90%) have been reported among both human and bovine S. agalactiae isolates (DOGAN et al, 2005;DUARTE et al, 2004;GAO et al, 2012;PINTO et al, 2013;RATO et al, 2013). In the current work, resistance to this antimicrobial was found to be approximately 35.6%.…”

Section: Resultsmentioning

confidence: 99%

“…Gao et al (2012), in a study of 55 S. agalactiae isolates collected from Chinese cows, reported that 29.4% were resistant to this antimicrobial. In contrast, all 85 strains of this bacterium recovered from Brazilian cattle in an investigation by Duarte et al (2004) were found to be resistant.…”

Section: Discussionmentioning

confidence: 99%

“…These genes have been reported in human and bovine S. agalactiae strains in other countries, associated with infections resistant to one or more aminoglycoside antimicrobials (GAO et al, 2012;POYART et al, 2003). To date, however, there have been no reports of these genes in bovine S. agalactiae strains isolated from Brazilian dairy herds.…”

Section: Discussionmentioning

confidence: 99%

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In vitro antimicrobial susceptibility and genetic resistance determinants of Streptococcus agalactiae isolated from mastitic cows in Brazilian dairy herds

Silva

Castro

Gonçalves

et al. 2017

SCA

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Streptococcus agalactiae is one of the main causative agents of bovine mastitis and is associated with several economic losses for producers. Few studies have evaluated antimicrobial susceptibility and the prevalence of genetic resistance determinants among isolates of this bacterium from Brazilian dairy cattle. This work aimed to evaluate the frequency of the antimicrobial resistance genes ermA, ermB, mefA, tetO, tetM, aphA3, and aad-6, and in vitro susceptibility to the antimicrobials amikacin, erythromycin, clindamycin, tetracycline, gentamicin, penicillin, ceftiofur, and cefalotin, and the associations between resistance genotypes and phenotypes among 118 S. agalactiae isolates obtained from mastitic cows in Brazilian dairy herds. Of the resistance genes examined, ermB was found in 19 isolates (16.1%), tetO in 23 (19.5%), and tetM in 24 (20.3%). The genes ermA, mefA, aphA3, and aad-6 were not identified. There was an association between the presence of genes ermB, tetM, and tetO and phenotypic resistance to erythromycin, clindamycin, and tetracycline. Rates of resistance to the tested antibiotics varied, as follows: erythromycin (19.5%), tetracycline (35.6%), gentamicin (9.3%), clindamycin (20.3%), penicillin (3.4%), and amikacin (38.1%); conversely, all isolates were susceptible to ceftiofur and cefalotin. Antimicrobial resistance testing facilitates the treatment decision process, allowing the most judicious choice of antibiotics. Moreover, it enables regional and temporal monitoring of the resistance dynamics of this pathogen of high importance to human and animal health. Key words: Antimicrobial resistance genes. Bovine diseases. Bovine mastitis. GBS, MIC. ResumoStreptococcus agalactiae é um dos principais agentes causadores de mastite em bovinos e de consequentes perdas econômicas aos produtores. Poucos estudos que avaliaram a susceptibilidade a antimicrobianos e a presença de determinantes genéticos de resistência para este agente em bovinos leiteiros do Brasil. Este trabalho teve por objetivo avaliar a frequência dos genes de resistência a antimicrobianos ermA, ermB, mefA, tetO, tetM, aphA3, aad-6, bem como a susceptibilidade in vitro aos antimicrobianos amicacina, eritromicina, clindamicina, tetraciclina, gentamicina, penicilina, ceftiofur e cefalotina, e as associações entre genótipos e fenótipos de resistência em 118 isolados de S. agalactiae provenientes de casos de mastite em rebanhos bovinos brasileiros. Dentre os genes de resistência pesquisados, ermB foi encontrado em 19 isolados (16,1%), tetO em 23 (19,5%) e tetM em 24 (20,3%). Os genes ermA, mefA, apha3 e aad6 não foram detectados. Verificou-se associação entre a presença dos genes ermB, tetM e tetO e os fenótipos de resistência à eritromicina, clindamicina e tetraciclina. Foram encontrados diferentes índices de resistência aos antibióticos testados: Eritromicina (19,5%), tetraciclina (35,6%), gentamicina (9,3%), clindamicina (20,3%), penicilina (3,4%) e amicacina (38,1%). Todos os isolados foram susceptíveis ceftiofur e cefalotina. ...

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Section: Discussionsupporting

confidence: 79%

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

See 2 more Smart Citations

In vitro antimicrobial susceptibility and genetic resistance determinants of Streptococcus agalactiae isolated from mastitic cows in Brazilian dairy herds

Silva

Castro

Gonçalves

et al. 2017

SCA

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“…In this study, not all the penicillin-resistant S. aureus isolates exhibited genotypic resistance to penicillin, corresponding well to the findings of previous studies (12). This is in agreement with data from Gao et al (13), showing that no resistance genes could be determined in some phenotypically resistant Streptococcus agalactiae isolates. In some isolates, phenotypic resistance may have been caused by point mutations rather than gene acquisition.…”

supporting

confidence: 93%

Prevalence of blaZ gene and other virulence genes in penicillin-resistantStaphylococcus aureus isolated from bovine mastitis cases in Gansu, China

Yang¹,

Wang²,

Wang³

et al. 2015

Turk J Vet Anim Sci

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Staphylococcus aureus is a major etiological agent of bovine mastitis worldwide. In this study, 37 strains of S. aureus resistant to penicillin were isolated from bovine mastitis cases in Gansu Province for investigating blaZ and virulence-related genes, including tst, eta, etb, lukPV, lukED, lukM, hla, hlb, hld, and edin. Antibiotic resistance was based on disk diffusion method and blaZ and virulenceassociated genes were studied by polymerase chain reaction. Penicillin resistance gene blaZ was detected in 35/37 (94.6%) of penicillinresistant S. aureus isolates. tst, lukPV, lukED, hla, hlb, and hld were observed in 5.4%, 2.7%, 89.2%, 70.3%, 73.0%, and 70.3% of the penicillin-resistant isolates, respectively, while eta, etb, lukM, and edin were not detected in any isolates. blaZ carried by penicillinresistant S. aureus isolates may be the main reason for phenotypic penicillin resistance. Virulence determinants encoded by lukED, hla, hlb, and hld genes may play important roles in bovine mastitis pathogenesis of penicillin-resistant S. aureus in Gansu Province.

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Synergistic streptococcal phage λSA2 and B30 endolysins kill streptococci in cow milk and in a mouse model of mastitis

Schmelcher

Powell

Camp

et al. 2015

Appl Microbiol Biotechnol

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Bovine mastitis results in billion dollar losses annually in the United States alone. Streptococci are among the most relevant causative agents of this disease. Conventional antibiotic therapy is often unsuccessful and contributes to development of antibiotic resistance. Bacteriophage endolysins represent a new class of antimicrobials against these bacteria. In this work, we characterized the endolysins (lysins) of the streptococcal phages λSA2 and B30 and evaluated their potential as anti-mastitis agents. When tested in vitro against live streptococci, both enzymes exhibited near-optimum lytic activities at ionic strengths, pH, and Ca2+ concentrations consistent with cow milk. When tested in combination in a checkerboard assay, the lysins were found to exhibit strong synergy. The λSA2 lysin displayed high activity in milk against Streptococcus dysgalactiae (reduction of CFU/ml by 3.5 log units at 100 μg/ml), Streptococcus agalactiae (2 log), and Streptococcus uberis (4 log), whereas the B30 lysin was less effective. In a mouse model of bovine mastitis, both enzymes significantly reduced intramammary concentrations of all three streptococcal species (except for B30 vs. S. dysgalactiae), and the effects on mammary gland wet weights and TNFα concentrations were consistent with these findings. Unexpectedly, the synergistic effect determined for the two enzymes in vitro was not observed in the mouse model. Overall, our results illustrate the potential of endolysins for treatment of Streptococcus-induced bovine mastitis.

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Antibiotic resistance of Streptococcus agalactiae from cows with mastitis

Cited by 58 publications

References 8 publications

In vitro antimicrobial susceptibility and genetic resistance determinants of Streptococcus agalactiae isolated from mastitic cows in Brazilian dairy herds

In vitro antimicrobial susceptibility and genetic resistance determinants of Streptococcus agalactiae isolated from mastitic cows in Brazilian dairy herds

Prevalence of blaZ gene and other virulence genes in penicillin-resistantStaphylococcus aureus isolated from bovine mastitis cases in Gansu, China

Synergistic streptococcal phage λSA2 and B30 endolysins kill streptococci in cow milk and in a mouse model of mastitis

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