Fecal non-aureus Staphylococci are a potential cause of bovine intramammary infection

Ameline Wuytack,Sofie Piepers,Anneleen De Visscher,Freddy Haesebrouck,Sarne De Vliegher

doi:10.1186/s13567-020-00761-5

Abstract

The presence of non-aureus staphylococci (NAS) in bovine rectal feces has recently been described. Similar to other mastitis causing pathogens, shedding of NAS in the environment could result in intramammary infection. The objective of this study was to investigate whether NAS strains present in feces can cause intramammary infection, likely via teat apex colonization. During a cross-sectional study in 5 dairy herds, samples were collected from the habitats quarter milk, teat apices, and rectal feces from 25%, 10%, and 25% of the lactating cows, respectively, with a cow serving as the source of one type of sample only. Samples from clinical mastitis cases were continuously collected during the 1-year study period as well. The 6 most prevalent NAS species, Staphylococcus (S.) chromogenes, S. cohnii, S. devriesei, S. equorum, S. haemolyticus, and S. hominis, were further subtyped by random amplification of polymorphic deoxyribonucleic acid polymerase chain reaction (RAPD-PCR), when the same NAS species was present in the same herd in the three habitats. For S. chromogenes, S. cohnii, S. devriesei, and S. haemolyticus, the same RAPD type was found in rectal feces, teat apices, and quarter milk, indicating that fecal NAS can infect the mammary gland. For S. hominis and S. equorum, we were unable to confirm the presence of the same RAPD types in the three habitats.

Highlights

Non-aureus staphylococci (NAS), a heterogeneous group of bacteria, are the most frequently identified bacteria in bovine milk samples worldwide [1–4]
We recently reported that Staphylococcus (S.) agnetis, S. auricularis, S. chromogenes, S. cohnii, S. epidermidis, S. equorum, S. haemolyticus, S. hominis, S. kloosii, S. rostri, and S. xylosus can be isolated from rectal feces [9], indicating cows are shedding NAS into the environment which could eventually give rise to the establishment of intramammary infection (IMI), most likely after
Nine NAS species were present in quarter milk, on teat apices, and in rectal feces in the same herd, namely S. arlettae, S. auricularis, S. chromogenes, S. cohnii, S. devriesei, S. equorum, S. haemolyticus, S. hominis, and S. vitulinus

Summary

Introduction

Non-aureus staphylococci (NAS), a heterogeneous group of bacteria, are the most frequently identified bacteria in bovine milk samples worldwide [1–4]. They are colonizing the teat apex of both lactating and dry cows [5, 6] as well as the teat canal [7] and other body parts [8]. We recently reported that Staphylococcus (S.) agnetis, S. auricularis, S. chromogenes, S. cohnii, S. epidermidis, S. equorum, S. haemolyticus, S. hominis, S. kloosii, S. rostri, and S. xylosus can be isolated from rectal feces [9], indicating cows are shedding NAS into the environment which could eventually give rise to the establishment of intramammary infection (IMI), most likely after. E.g. teat apex colonization with S. chromogenes, S. equorum, and S. haemolyticus has been described as a risk factor for NAS IMI based on species-level identification [10–12]. A possible link between the presence of NAS species in feces and on Wuytack et al Vet Res (2020) 51:32 teat apices and IMI has not been studied using a straintyping approach

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Results