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

Silva, Juliana Rosa da; Castro, Glei dos Anjos de Carvalho; Gonçalves, Maysa Serpa; Custódio, Dircéia Aparecida da Costa; Mian, Gláucia Frasnelli; Costa, Geraldo Márcio da

doi:10.5433/1679-0359.2017v38n4supl1p2581

Cited by 5 publications

(2 citation statements)

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“…The ermB and ermA genes were detected in 73.33% and 66.68% of the 15 S. agalactiae isolates, respectively, suggesting that erythromycin-resistant methylase may be the major mechanism of resistance in the present study. Similar findings were reported by Hernandez et al (18) for S. agalactiae strains isolated from Argentinean cattle with mastitis and by da Silva et al (10). The prevalence of the ermB determinant shows that S. agalactiae often uses a target methylation mechanism for macrolide resistance.…”

Section: Discussionsupporting

confidence: 86%

Antimicrobial resistance and virulence genes of Streptococcus agalactiae isolated from mastitis milk samples in China

Zhao

Shao

Wang

et al. 2022

Journal of Veterinary Research

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Introduction Streptococcus agalactiae is an important zoonotic pathogen that affects milk production and quality and poses a threat to public health. Treatment of infections with this bacterium exploits antimicrobials, to which the resistance of S. agalactiae is a growing problem. Addressing the possibility of a correlation between this pathogen’s genetic factors for antimicrobial resistance and virulence, this study attempted to identify the relevant genes. Material and Methods Antimicrobial resistance of S. agalactiae isolated from 497 Chinese bovine mastitic milk samples was detected by the broth microdilution method. Eight drug resistance genes and eleven virulence genes were detected using PCR. Results Streptococcus agalactiae was 100% susceptible to rifampicin and vancomycin, 93.33% susceptible to sulfisoxazole and sulfamethoxazole, but 100% resistant to ≥3 of the 16 antimicrobial agents, thereby being multidrug resistant, with resistance to oxacillin, tetracycline, erythromycin, clindamycin, and gentamicin being common. The ermB, ermA and lnuA genes were carried by 73.33%, 66.67% and 60.00% of the strains, respectively. The carriage rates of the glnA, clyE, hylB, bibA, iagA, and fbsA virulence genes were greater than 40%, lmb and bac were not observed in any strain, and glnA+hylB+bibA+iagA+fbsA+clyE combined virulence gene patterns were the most commonly detected. Conclusion Antimicrobial resistance of S. agalactiae is still a great concern for cattle health in China, and multidrug resistance coupled with the high positive rates of this bacterium’s strains for virulence genes indicates the importance of S. agalactiae surveillance and susceptibility tests.

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Section: Discussionsupporting

confidence: 86%

Antimicrobial resistance and virulence genes of Streptococcus agalactiae isolated from mastitis milk samples in China

Zhao

Shao

Wang

et al. 2022

Journal of Veterinary Research

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“…Among the isolates of S. agalactiae, 97.8% of strains showed multi-resistance, with MAR indices varying from 0.11 to 0.95, and mean of 0.65 ( Table 9). Silva et al (2017) analyzed the antimicrobial susceptibility profiles of S. agalactiae isolates in cattle herds in different Brazilian regions. Their study showed the following drug resistance rates: erythromycin (26.23%), tetracycline (47.54%), gentamycin (3.28%), sulfonamide (98.36%), and clindamycin (29.51%).…”

Section: Resultsmentioning

confidence: 99%

Staphylococcus aureus and Streptococcus agalactiae: prevalence, resistance to antimicrobials, and their relationship with the milk quality of dairy cattle herds in Minas Gerais state, Brazil

et al. 2019

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Bovine mastitis is the most frequent disease worldwide in dairy herds, causing high economic losses to producers and industry, as well as having implications for public health due to the zoonotic potential of some agents involved in its etiology and the increased risk of antimicrobial residues in milk and its derivatives. Considering the multifactorial aspect of this disease, knowledge of the agents involved in its etiology and their antimicrobial susceptibility profiles is very important. This study was conducted with 306 dairy herds from the Campo das Vertentes region, located in the south of Minas Gerais state, whose owners were milk suppliers to a dairy in the same region. The study involved approximately 34,000 dairy cows and covered an area of approximately 12,564 km2. In these herds, prevalence rates of Staphylococcus aureus and Streptococcus agalactiae and their relationship with bulk milk somatic cell counts (BMSCC), total bacterial counts (TBC), and daily production were evaluated. In addition, analyses of resistance of these pathogens to the antimicrobials most commonly used in the treatment of mastitis in dairy herds were performed. Microbiological analyses of milk samples from collect from bulk milk tanks were performed aiming to evaluate the prevalence of S. aureus and S. agalactiae. For these proposes, the modified Baird-Parker Agar medium was used for detection of S. aureus and the modified Edwards Agar medium, enriched with 5% defibrinated sheep blood, was used for detection of S. agalactiae. The disc diffusion technique was applied to evaluate antimicrobial resistance. Results show high prevalence rates of S. aureus (70.3%) and S. agalactiae (67.0%) in the dairy farms studied, with 47.71% of the herds showing both pathogens. Associations between BMSCC and the presence of pathogens S. aureus and S. agalactiae and between TBC and the presence of S. agalactiae were observed, demonstrating the influence of these pathogens in milk quality. No variation was observed in the distribution of S. aureus and S. agalactiae in the different strata of daily production. High levels of resistance and multi-resistance were observed among the pathogens S. aureus and S. agalactiae. The results indicate the need for more effective control measures for mastitis caused by S. aureus and S. agalactiae in the dairy herds of the region studied and more judicious use of antimicrobials in order to reduce the problem of resistance to them.

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Virulence factors and antimicrobial resistance in Staphylococcus aureus isolated from bovine mastitis in Brazil

et al. 2020

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This study aimed to evaluate virulence factors and genetic markers of antimicrobial resistance in 400 Staphylococcus aureus strains isolated from bovine mastitis in four Brazilian states, as well as to assess the association between these characteristics and field information. Virulence factors and drug resistance genes were identified by PCR screening. Biofilm-forming and hemolytic phenotype were detected using Congo red Tryptic Soy Broth and defibrinated sheep blood agar, respectively. Of all isolates, 83.5% were biofilm-forming and 98.5% strains exhibited biofilm gene icaAD, and a significant association between phenotype and genotype for biofilm was observed (P = 0.0005). Hemolysin genes were observed in 82.85% (hla + hlb +), 16.5% (hla +) and 0.75% (hlb +) isolates, whereas the hemolytic phenotype exhibited was complete and incomplete hemolysis in 64.25%, complete in 28.25%, incomplete in 4.75%, and negative in 2.75% of the strains. Virulence factors genes luk, seb, sec, sed, and tst were observed in 3.5%, 0.5%, 1%, 0.25%, and 0.74% isolates, respectively. The gene blaZ was detected in 82.03% of penicillin-resistant isolates, whereas tetK and aac(6′)-Ie-aph(2′)-Ia were observed in 33.87% and 45.15% of the tetracycline and aminoglycosides-resistant isolates, respectively. Fluoroquinolone resistance gene mepA was detected for the first time in S. aureus from bovine mastitis. Resistance genes tetM (3.22%), tetL (1.61%), ermA (14.29%), ermB (14.29%), ermC (33.3%), ermT (9.52%), ermY (4.76%), msrA (9.52%), and mphC (9.52%) were also detected among resistant isolates. No association between virulence factors or antimicrobialresistant genes and year of isolation, geographic origin, or antimicrobial resistance profile was observed. Our results showed that S. aureus strains isolated from bovine mastitis in the four Brazilian states sampled are mainly biofilmforming and hemolytic, whereas virulence genes associated with enterotoxins, luk and tst, were less frequently observed. Moreover, a wide variety of resistance genes that confer resistance to almost all classes of antimicrobial agents approved for use in animals and humans were found. Overall, the data point to a great pathogenic potential of S. aureus associated with bovine mastitis and to the non-negligible risks to public health of staphylococcal infections from animal origin.

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

Cited by 5 publications

References 20 publications

Antimicrobial resistance and virulence genes of Streptococcus agalactiae isolated from mastitis milk samples in China

Antimicrobial resistance and virulence genes of Streptococcus agalactiae isolated from mastitis milk samples in China

Staphylococcus aureus and Streptococcus agalactiae: prevalence, resistance to antimicrobials, and their relationship with the milk quality of dairy cattle herds in Minas Gerais state, Brazil

Virulence factors and antimicrobial resistance in Staphylococcus aureus isolated from bovine mastitis in Brazil

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