Association between antimicrobial use and resistance of Streptococcus uberis causing clinical mastitis.

• Grant number: 18/23040-1
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: April 01, 2019
• End date: November 30, 2019
• Field of knowledge: Agronomical Sciences - Animal Husbandry - Animal Production
• Principal Investigator: Marcos Veiga dos Santos
• Grantee: Larissa Martins
• Host Institution: Faculdade de Medicina Veterinária e Zootecnia (FMVZ). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

The aim of this study will be to evaluate the association between antimicrobial use (UAM) and resistance of Streptococcus uberis causing clinical mastitis (CM) in Brazilian herds. The specific objectives will be: (a) determine the distribution of the bacterial species previously identified as Strep. uberis by conventional phenotypic identification and Matrix Associated Laser Desorption-Ionization - Time of Flight (MALDI-TOF MS); and, (b) evaluate the susceptibility of Strep. uberis to antimicrobials with high frequency of use for treatment of CM in Brazilian herds. The MALDI score cut off values will applied to each measurement as follows: (score of >2) indicate species-level identification; (scoree1.7 and <2) genus-level identification; and (score<1.7) indicate that no reliable identification can be made. Isolates with result discrepancy between microbiologic techniques (MALDI vs. conventional culture) will be submitted for 16S rRNA gene sequencing. Subsequently, the antimicrobial susceptibility of isolates identified as Streptococcus spp. by MALDI-TOF MS will be tested in vitro for the following antimicrobials: amoxicillin, ampicillin, cephalexin, ceftiofur, ciprofloxacin, gentamicin, oxytetracycline, tetracycline, sulfa + trimetropin, penicillin, enrofloxacin and florfenicol. Analysis of minimal inhibitory concentration (MIC) will be performed using the microdilution test. Results will be determined by visual inspection of the plates' wells, in which the lowest antimicrobial concentrations required to inhibit bacterial growth will be recorded. The association between the UAM and resistance profile of isolates will be performed by multivariate logistic regression models, in whichthe frequency of resistant isolates will be considered as dependent variable and antimicrobial consumption as independent variable in the models created for each tested compound. Antimicrobial consumption data will be obtained from a previous study on the use of antimicrobials (intramammary and systemic) recorded for treatment of CM in Brazilian dairy herds (Tomazi, 2017). The conduction of the present study will advance the etiological and pharmaco-epidemiological understanding of Strep. uberis causing CM in dairy herds in Brazil. In addition, the association analysis between antimicrobial consumption and resistance profile of Strep. uberis will allow greater understanding on the development of bacterial resistance in dairy herds, which may encourage producers for the rational use of antimicrobials for mastitis control.

Scientific publications

(The scientific publications listed on this page originate from the Web of Science or SciELO databases. Their authors have cited FAPESP grant or fellowship project numbers awarded to Principal Investigators or Fellowship Recipients, whether or not they are among the authors. This information is collected automatically and retrieved directly from those bibliometric databases.)

MARTINS, LARISSA; GONCALVES, JULIANO L.; LEITE, RENATA F.; TOMAZI, TIAGO; RALL, VERA L. M.; SANTOS, V, MARCOS. Association between antimicrobial use and antimicrobial resistance of Streptococcus uberis causing clinical mastitis. JOURNAL OF DAIRY SCIENCE, v. 104, n. 11, p. 12030-12041, NOV 2021. (13/23613-8, 18/23040-1, 14/17411-6, 13/22286-3)