Characterization of Antibiotic and Biocide Resistance Genes and Virulence Factors of Staphylococcus Species Associated with Bovine Mastitis in Rwanda.

Sarah Lepuschitz,Jean Claude Masengesho,Vedaste Nyirimbuga,Rosa Mayrhofer,Stefan Schwarz,Andrea T. Feßler,Werner Ruppitsch,Stefan Monecke,Monika Ehling-Schulz,Helene Marbach,Joachim Spergser,Fruzsina Irén Antók,Otto Fischer,Ralf Ehricht,Helga Keinprecht,Tom Grunert,Igor Loncaric

doi:10.3390/antibiotics9010001

Abstract

The present study was conducted from July to August 2018 on milk samples taken at dairy farms in the Northern Province and Kigali District of Rwanda in order to identify Staphylococcus spp. associated with bovine intramammary infection. A total of 161 staphylococcal isolates originating from quarter milk samples of 112 crossbred dairy cattle were included in the study. Antimicrobial susceptibility testing was performed and isolates were examined for the presence of various resistance genes. Staphylococcus aureus isolates were also analyzed for the presence of virulence factors, genotyped by spa typing and further phenotypically subtyped for capsule expression using Fourier Transform Infrared (FTIR) spectroscopy. Selected S. aureus were characterized using DNA microarray technology, multi-locus sequence typing (MLST) and whole-genome sequencing. All mecA-positive staphylococci were further genotyped using dru typing. In total, 14 different staphylococcal species were detected, with S. aureus being most prevalent (26.7%), followed by S. xylosus (22.4%) and S. haemolyticus (14.9%). A high number of isolates was resistant to penicillin and tetracycline. Various antimicrobial and biocide resistance genes were detected. Among S. aureus, the Panton–Valentine leukocidin (PVL) genes, as well as bovine leukocidin (LukM/LukF-P83) genes, were detected in two and three isolates, respectively, of which two also carried the toxic shock syndrome toxin gene tsst-1 bovine variant. t1236 was the predominant spa type. FTIR-based capsule serotyping revealed a high prevalence of non-encapsulated S. aureus isolates (89.5%). The majority of the selected S. aureus isolates belonged to clonal complex (CC) 97 which was determined using DNA microarray based assignment. Three new MLST sequence types were detected.

Highlights

Bovine mastitis is an important disease that affects the dairy sector and is one of the economically most important diseases worldwide [1]
From 303 CMT-positive milk samples collected from 112 crossbred milking cows, 161 non-repetitive staphylococcal isolates comprising 14 staphylococcal species were recovered: S. aureus (n = 43), S. xylosus (n = 36), S. haemolyticus (n = 24), S. sciuri (n = 14), S. chromogenes (n = 10), S. saprophyticus (n = 9), S. epidermidis (n = 8), S. succinus (n = 5), S. capitis (n = 3), S. hominis (n = 2), S. devriesei (n = 2), S. auricularis (n = 2), S. equorum (n = 2), and S. simulans (n = 1)
S. aureus was the predominant Staphylococcus spp., which is in accordance with studies from other countries in that region, such as Tanzania, and Kenya [16,18]

Summary

Introduction

Bovine mastitis is an important disease that affects the dairy sector and is one of the economically most important diseases worldwide [1]. In Rwanda, it has a significant relevance because livestock production is rapidly increasing [2]. One reason is that milk consumption and the demand for dairy products are increasing with the rapid growth of the human population, from 3 million to 12 million people [3] in the last 60 years. Mastitis is an inflammation of the udder tissue and the mammary gland. It is usually caused by bacteria invading through the teat canal. There are two types of mastitis: clinical and subclinical

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Conclusion