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

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.

Multidrug-resistant Staphylococcus cohnii and Staphylococcus urealyticus isolates from German dairy farms exhibit resistance to beta-lactam antibiotics and divergent penicillin-binding proteins

“…In our study, the phylogenetic relationship and antimicrobial resistance potential of nine S. cohnii and six S. urealyticus isolates from German dairy farms were analyzed. The staphylococcal species S. cohnii has been reported as a prevalent commensal bacterium on dairy farms that can be found on teat apices and in other milking parlor-related extramammary niches 4,24 . Previous studies suggested that S. cohnii is largely uninvolved in severe infections such as mastitis in dairy cows 2,4 .…”

“…Among others, Staphylococcus ( S .) cohnii was found on farms; however, it has been regarded a commensal bacterium, and not involved in severe animal infections such as bovine mastitis 2 , 4 . S .…”

Characterization of genetic diversity and population structure within Staphylococcus chromogenes by multilocus sequence typing

“…The large cluster ( Fig 2B) includes 32 of the 33 STs in the eBURST core network plus 7 STs differing at 3 or more loci from those in the eBURST core group (STs 13,20,22,35,37,41,& 46). The one member of the eBURST core network that placed outside the phylogenetically defined large group was ST44, previously noted as differing substantially at the sequence level from the other STs in the eBURST network.…”

“…Previous studies have implicated S. chromogenes as a frequent cause of intramammary infections in cattle on dairy farms and have demonstrated strain diversity can vary within and between farms. However the DNA fragment profiling methods used in these studies to characterize strain diversity, notably PFGE, ALPF, RAPD-PCR, and MLVA, have yielded conflicting estimates of diversity, ranging from a high degree of genetic conservation to considerable genetic heterogeneity [10,11,18,19,22,23,[44][45][46][47][48][49]. Given the stand-alone nature of these studies and the incompatibility of their measures of strain diversity, the results of different studies cannot be directly compared or consolidated.…”

“…Pulsed field gel electrophoresis (PFGE), ribotyping, amplification fragment length polymorphism (AFLP), random amplification of polymorphic DNA (RAPD)-PCR, and multiple locus variable-number tandem repeat analysis (MLVA) have been used to discriminate between S . chromogenes strains in epidemiological studies [ 10 , 11 , 15 , 18 , 19 , 22 , 23 ]; these methods demonstrate sufficient discriminatory power in short-term epidemiological investigations. However, DNA fragment electrophoretic band pattern (i.e.…”