Short communication: Diversity of staphylococci isolated from sheep mastitis in northern Algeria

Mastitis in ruminants is an important disease with major effects on both the economy and animal welfare. It is caused by major pathogens such as Staphylococcus aureus and minor pathogens such as coagulase-negative staphylococci. The objective of this study was to identify and characterize staphylococci as a cause of sheep mastitis in Algeria. In this study, 123 milk samples were collected directly from the udder of sheep suffering from clinical mastitis in 2 provinces in Algeria. Recovered isolates were identified using MALDI-TOF mass spectrometry. Virulence-associated and antimicrobial resistance genes as well as clonal complexes (CC) of S. aureus were determined using microarray-based analysis. A total of 45 staphylococci isolates were cultivated from sheep milk samples, and 28 S. aureus were identified as methicillin susceptible (62.2%). Seventeen other Staphylococcus isolates of different species were identified using MALDI-TOF mass spectrometry. Subsequent microarray analysis typed the methicillin-susceptible S. aureus to 6 CC: CC8-MSSA, CC97-MSSA, CC130/521-MSSA, CC479-MSSA, CC522-MSSA, and CC705-MSSA. The accessory gene regulator agrIII and the ruminant leukocidin genes lukF-P83 and lukM were found in all isolates of CC130/521, CC479, CC522, and CC705. The toxic shock syndrome toxin gene tst1 was detected exclusively in CC130/521. Additionally, virulence-associated genes (sea, sed, sak, hld, hlgA, edinB, and others) were detected. The presence of antibiotic resistance genes [blaZ, erm(B), and tet(K)] was detected in small numbers of staphylococci. Staphylococci possessing these genes are considered potential hazards for farm animals, farmers, and consumers. Data concerning the prevalence and diversity of staphylococci causing mastitis in sheep from Algeria are lacking. Presented results on different aspects about staphylococci in Algerian sheep populations should at least partially close that gap. However, further extensive studies covering more geographical regions are needed to assess the epidemiological risk.

Characteristics of resistance and virulence factors in different species of coagulase-negative staphylococci isolated from milk of healthy sheep and animals with subclinical mastitis

Coagulase-negative staphylococci (CNS) are among the main responsible agents for mastitis in sheep. Cure rates can be reduced due to several causes, such as those related to virulence factors presented by microorganisms. This study aims at characterizing the virulence and resistance factors to antimicrobial agents in different CNS species isolated from sheep milk. After collecting milk samples, the samples were analyzed and the CNS species were identified. After identification, the susceptibility-sensitivity profile was examined using the disk diffusion technique for 10 antimicrobial agents. The DNA was extracted to detect the presence of the mecA gene, biofilm (icaADBC, bap, and bhp) and toxin genes (sea, seb, sec, sed, tst, and luk-PV) by PCR. Samples carrying toxin genes had their expression assessed using the reverse-transcription PCR technique. The biofilm production was assessed using the adherence method on a polystyrene plate. One hundred twelve CNS samples were isolated, 53 (47.3%) from animals with subclinical mastitis and 59 (52.7%) from healthy animals. Drugs tested have shown to be efficient for most CNS samples. The largest resistance percentage of CNS was found for the penicillin (17.0%) and tetracycline (10.7%) and 4 samples carried the mecA gene. As for the biofilm genes, the icaADBC operon was found in 10 (8.9%) samples, the bap gene was found in 16 (14.3%), and the bhp gene was found in 3 (2.7%). In addition, 69 (61.6%) samples produced biofilm. The survey of toxin genes has shown that 70 (62.5%) samples showed some toxin-encoding gene. However, none of the samples has expressed any of the genes from those toxins studied.