Banca de DEFESA: AMANDA THAÍS FERREIRA SILVA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : AMANDA THAÍS FERREIRA SILVA
DATE: 23/02/2024
TIME: 08:30
LOCAL: http://meet.google.com/bhj-jtjm-drh
TITLE:

Epidemiological and economic study of bovine subclinical mastitis caused by Staphylococcus aureus, non-aureus Staphylococcus and Mammaliicoccus in the State of Pernambuco, Brazil

 

KEY WORDS:

Staphylococcus spp. Mammaliicoccus. Mammary gland. Cows. Multidrug resistance. Epidemiology. Economy.

PAGES: 139
BIG AREA: Ciências Agrárias
AREA: Medicina Veterinária
SUBÁREA: Medicina Veterinária Preventiva
SUMMARY:

This study aimed to investigate the prevalence of subclinical mastitis caused by S. aureus and Non-aureus Staphylococcus and Mammaliicoccus (NASM), emphasizing multidrug-resistant S. aureus (MDRSA), and to assess the economic impact in milk production in Pernambuco state, Northeastern Brazil. A total of 2,444 milk samples, 40 swabs from milking equipment, five tank milk samples, and 22 swabs from milkers (11 nasal and 11 hand swabs) were collected from five dairy farms located in the Southern Agreste region of Pernambuco. A total of 308 Staphylococcus spp. isolates were identified, of which 191 were classified as S. aureus and 124 as NASM, using the MALDI-TOF MS technique. Among the S. aureus isolates, 98.43% were obtained from milk samples (n = 188), 0.52% from tank milk samples (n = 1), and 1.05% from milking equipment (n = 2). The detection of blaZ, mecA, and mecC resistance genes was carried out by PCR, and the antimicrobial resistance testing and screening of MDRSA isolates were performed using the Disk Diffusion technique. It was found that 7.33% of the S. aureus isolates were MDRSA (n = 14), with 85.7% isolated from milk samples (n = 12), 7.15% from tank milk samples (n = 1), and 7.15% from milking equipment (n = 1). For these multidrug-resistant isolates, PCR was carried out to identify efflux pump genes (norA, norC, msrA, and tet38) and biofilm formation genes (bap, icaA, and icaD), as well as their biofilm production ability. Additionally, PFGE and MLST techniques were employed to investigate the genetic correlation of these isolates, identifying the clonal complexes CC97 (ST126) and CC1 (ST7440). A logistic regression analysis was conducted to study the risk factors associated with subclinical mastitis caused by MDRSA. It was observed that these isolates were more likely to be exclusive to a specific herd (p = 0.05), and multiparous and primiparous cows had similar chances of developing subclinical mastitis caused by MDRSA (p = 0.56). For economic analysis, using a linear regression model, data from 342 lactating cows were used, with 155 cows as negative controls (155 healthy quarters) and 187 cows with subclinical mastitis by Staphylococcus and Mammaliicoccus (257 infected quarters). It was found that intramammary infections resulted in a decrease in milk production and an increase in SCC, affecting the economic return. Although there was no statistically significant difference in economic returns between healthy and infected cows (p = 0.09), there was an indication that the return was US$ 0.35 lower in infected cows. To investigate subclinical mastitis caused by MDRSA in a herd with a history of S. aureus mastitis, 224 lactating cows (88 primiparous and 136 multiparous) were tested for three consecutive weeks. A total of 49 S. aureus isolates were identified causing subclinical mastitis in 16.5% (37/224) of the cows. Only one S. aureus isolate (1/49) was confirmed as MDRSA, using the Disk-Diffusion technique, causing subclinical mastitis in a primiparous cow during the third week. This identification raises an alert regarding the possible role of primiparous cows as "reservoirs" of MDRSA in dairy herds. In this scenario, the results highlight the importance of epidemiological studies and economic analysis of mastitis, providing support for the development of targeted strategies for infection prevention and control.

COMMITTEE MEMBERS:
Presidente - JOSE WILTON PINHEIRO JUNIOR
Externa à Instituição - MARIA APARECIDA SCATAMBURLO MOREIRA
Externa à Instituição - VERA LUCIA MORES RALL
Externo à Instituição - JOSÉ GIVANILDO DA SILVA
Externa à Instituição - KARLA PATRICIA CHAVES DA SILVA