Members of the Staphylococcaceae family, particularly those of the genus Staphylococcus, encompass important human and animal pathogens. We collected and characterized Staphylococcaceae strains from apparently healthy and diseased camels (n = 84) and cattle (n = 7) in Somalia and Kenya. We phenotypically characterized the strains, including their antimicrobial inhibitory concentrations. Then, we sequenced their genomes using long-read sequencing, closed their genomes, and subsequently compared and mapped their virulence- and resistance-associated gene pools. Genome-based phylogenetics revealed 13 known Staphylococcaceae and at least two novel species. East African strains of different species encompassed novel sequence types and phylogenetically distant clades. About one-third of the strains had non-wild-type MICs. They were resistant to at least one of the following antimicrobials: tetracycline, benzylpenicillin, oxacillin, erythromycin, clindamycin, trimethoprim, gentamicin, or streptomycin, encoded by tet(K), blaZ/blaARL, mecA/mecA1, msrA/mphC, salA, dfrG, aacA-aphD, and str, respectively. We identified the first methicillin- and multidrug-resistant camel S. epidermidis strain of sequence type (ST) 1136 in East Africa. The pool of virulence-encoding genes was largest in the S. aureus strains, as expected, although other rather commensal strains contained distinct virulence-encoding genes. We identified toxin-antitoxin (TA) systems such as the hicA/hicB and abiEii/abiEi families, reported here for the first time for certain species of Staphylococcaceae. All strains contained at least one intact prophage sequence, mainly belonging to the Siphoviridae family. We pinpointed potential horizontal gene transfers between camel and cattle strains and also across distinct Staphylococcaceae clades and species. IMPORTANCE Camels are a high value and crucial livestock species in arid and semiarid regions of Africa and gain importance giving the impact of climate change on traditional livestock species. Our current knowledge with respect to Staphylococcaceae infecting camels is very limited compared to that for other livestock species. Better knowledge will foster the development of specific diagnostic assays, guide promising antimicrobial treatment options, and inform about potential zoonotic risks. We characterized 84 Staphylococcaceae strains isolated from camels with respect to their antimicrobial resistance and virulence traits. We detected potentially novel Staphylococcus species, resistances to different classes of antimicrobials, and the first camel multidrug-resistant S. epidermidis strain of sequence type 1136.

Food, particularly milk and cheese, may be a reservoir of multi-drug resistant Staphylococcus aureus strains, which can be considered an important issue in terms of food safety. Furthermore, foods of animal origin can be a cause of staphylococcal food poisoning via the production of heat-stable enterotoxins (SE). For this reason, we investigated the prevalence of and characterized Staphylococcus aureus strains isolated from milk and fresh soft cheese obtained from farms located in Wielkopolskie and Zachodniopomorskie Provinces in Poland. Overall, 92% of S. aureus isolates were positive for at least one of the 18 enterotoxin genes identified, and 26% of the strains harbored 5 to 8 enterotoxin genes. Moreover, the S. aureus strains contained genes conferring resistance to antibiotics that are critically important in both human and veterinary medicine, i.e., β-lactams (mecA), aminoglycosides (aac(6')/aph(2″), aph(3')-IIIa, ant(4')-Ia) and MLSB (erm(A), msr(A), lun(A)). The antimicrobial susceptibility of S. aureus to 16 antibiotics representing 11 different categories showed that 74% of the strains were resistant to at least 1 antibiotic. Moreover, 28% of the strains showed multidrug resistance; in particular, two methicillin-resistant S. aureus strains (MRSA) exhibited significant antibiotic resistance. In summary, our results show that dairy products are contaminated by S. aureus strains carrying genes encoding a variety of enterotoxins as well genes conferring resistance to antibiotics. Both MRSA strains and MSSA isolates showing multidrug resistance were present in foods of animal origin.

Virulence-factor encoding genes (VFGs) and antimicrobial resistance genes (ARGs) of ocular Methicillin-Resistant Staphylococcus aureus (MRSA), are the reason behind the common cause of severe and untreatable ocular infection and are largely unknown. The unavailability of the complete genome sequence of ocular MRSA strains hinders the unambiguous determination of ARGs and VRGs role in disease pathogenesis and their genomic location. To fulfill this critical need, we achieved the high-quality complete genome of four ocular MRSA strains (AMRF3 - AMRF6) by combining MinION nanopore sequencing technology, followed by polishing with Illumina sequence reads. We obtained a single chromosome and a plasmid in each strain. Sequence typing revealed that AMRF3 and AMRF5 strains harbored ST772, whereas AMRF4 and AMRF6 harbored ST 2066. All plasmids carried heavy metal cadmium resistance genes cadC and cadD, while cadA was detected only in the plasmid pSaa6159 of AMRF4 and AMRF6 strains. Further, pSaa6159 contains a complete Tn552 transposon with beta-lactamase genes, blaI, blaR1, and blaZ. Interestingly, pSaa6159 in AMRF6 carried five copies of Tn552 transposon. Several exotoxins and enterotoxins were identified across ocular MRSA strains and ST2066 strains found to be not carried any enterotoxins; this finding suggests that these two strains are exotoxigenic. Besides, ST2066 strains carried serine proteases (splA, splB, splD, splE and spIF) and exotoxin (seb and set 21) for their virulence, while ST772 carried antimicrobial resistance genes (blaZ, dfrG, msrA, mphC and fosB) and enterotoxin sec for virulence, suggesting sequence type-specific resistance and virulence. Also, we identified many VFGs and ARGs, that provided multi-drug resistance, enterotoxigenic, exotoxigenic, biofilm-forming, host tissue adhesion and immune response evasion in ocular MRSA strains. Thus, our study provides a better insight into the genomes of ocular MRSA strains that would provide more effective treatment strategies for ocular MRSA infection.

Dairy goats play a significant role in socio-economic, cultural, and nutritional development in many countries. This study aimed to identify multiresistant zoonotic pathogens causing mastitis in goats, in addition to characterizing them for the presence of resistance genes and phenotypic resistance. A total of 714 milk samples from 357 lactating goats in 12 farms in the Northeast region of Brazil were analyzed. The isolates were submitted to Matrix Associated Laser Desorption-Ionization - Time of Flight to identify bacterial species, Polymerase Chain Reaction (PCR) to search for resistance genes, and an antibiogram to evaluate the phenotypic profile of antimicrobial resistance. A total of 214 pathogens were identified and bacterial prevalence was 83.29 % (178/214) Staphylococcus spp.; 6.50 % (14/214) Micrococcus luteus; 3.73 % (8/214) Corynebacterium spp.; 2.80 % (6/214) Bacillus spp.; 1.38 % (3/214) Escherichia coli; 0.92 % (2/214) Enterobacter cloacae; 0.46 % (1/214) Aerococcus viridans; 0.46 % (1/214) Morganella morganii; and 0.46 % (1/214) Turicella otitidis. As for gene frequency, 64.60 % (115/178) of the isolates carried the blaZ gene; 37.07 % (66/178) norA; 22.47 % (40/178) tet(L); 16.85 % (30/178) tet(M); 14.04 % (25/178) norB; 8.42 % (15/178) vanA; 7.30 % (13/178) msrA; 6.41 % (5/178) tet-38; 4.49 % (8/178) norC; 2.25 % (4/178) mecA; and 0.56 % (1/178) vanB. Emerging multiresistant zoonotic pathogens are present in the goat milk production chain, especially the coagulase-negative Staphylococcus species that pose a risk to human and animal health.

Genomic characterization was conducted on 2 methicillin-resistant Staphylococcus aureus (MRSA) strains isolated from 2 horses hospitalized during an overlapping period of time and 2 methicillin-sensitive S. aureus (MSSA) strains isolated from 2 distinct horses. Phylogenetic proximity was traced and the genotypic and phenotypic characteristics of the antimicrobial resistance of the strains were compared. Whole genome sequencing of MRSA strains for this report was similar but differed from whole genome sequencing of MSSA strains. The MRSA strains were closely related, belonging to sequence type (ST) 612, spa type t1257, and SCCmec type IVd2B. The MSSA strains were also closely related, belonging to ST1660, spa type t3043, and having no detectable staphylococcal cassette chromosome mec elements. All MSRA and MSSA strains were Panton-Valentine leukocidin negative. There were discrepancies in the genotypic analysis and the antimicrobial susceptibility testing (phenotypic analysis) of MRSA strains for rifampin, trimethoprim-sulfamethoxazole, gentamicin, amikacin, and enrofloxacin.

The genus Staphylococcus is recognized worldwide as a cause of bacterial infections in humans and animals. Antibiotics used in dairy cattle combined with ineffective control can increase antimicrobial resistance. The objective of this study was to characterize 95 Staphylococcus strains isolated from organic and conventional Minas Frescal cheese production regarding antibiotic resistance (phenotype and genotype), presence of sanitizer-resistant genes and biofilm-formation genes, and SCCmec typing. Most strains (25.3%) showed higher resistance to penicillin, followed by oxacillin (21.1%) and clindamycin (11.6%). Among antibiotic resistance genes, the most prevalent were blaZ (25.3%), mecA (13.7%), lsaB (6.3%), msrA (4.2%), ant4 (3.2%), and tetM (2.1%); among sanitizer-resistance genes they were qacA/B (5.3%) and qacC (6.3%); and among biofilm, bap (4.2%), icaA (29.5%), icaD (41.1%). However, there was no statistically significant difference between organic and conventional dairy products, possibly due to the lack of synthetic antibiotic use on conventional farms during the sample collection period. Methicillin-resistant Staphylococcus aureus (MRSA) had their SCCmec identified as types I and IVc, and the methicillin-resistant coagulase-negative staphylococci had nontypeable SCCmec. These results suggest that there are antibiotic-resistant strains in both organic and conventional Minas Frescal cheese production in the state of São Paulo, Brazil. This supports the idea that improved quality control is needed from the milking stage up to the final product.

This study was designed to determine antimicrobial resistance phenotypes and genotypes and virulence factors in Staphylococcus aureus and coagulase-negative staphylococci (CNS) in unpasteurized milk sold in Djelfa, Algeria. Eighty-two unpasteurized cow milk samples were randomly obtained from 82 retail stores in Djelfa and tested to detect staphylococci. Species were identified by biochemical tests and MALDI-TOF. Antimicrobial resistance phenotypes and genotypes were determined by disk diffusion test, PCR, and sequencing. The Staph. aureus isolates were subjected to spa typing, multilocus sequence typing, and detection of virulence genes and the scn gene by PCR and sequencing. Forty-five (54.9%) milk samples were contaminated by staphylococci and 45 isolates were recovered: 10 Staph. aureus (12.2% of total samples) and 35 CNS (42.7%). Resistance to penicillin (blaZ), tetracycline (tetL/tetK), and erythromycin (ermB/msrA/ermC) were the most common phenotypes (genotypes). Three CNS were methicillin-resistant and all were mecA-positive. The Staph. aureus isolates were ascribed to the following lineages [spa type/sequence type/associated clonal complex (number of isolates)]: t267/ST479/CC479 (n = 6), t1510/ST5651/CC45 (n = 1), t359/ST97/CC97/ (n = 1), t346/ST15/CC15 (n = 1), and t044/ST80 (n = 1). The mecA gene was detected in the cefoxitin-susceptible t044/ST80 isolate and co-harbored the lukF/lukS-PV and scn genes. The detection of mecA-PVL-positive Staph. aureus, methicillin-resistant CNS, and multidrug-resistant staphylococcal species indicates a potentially serious health issue and reveals that unpasteurized milk sold in Djelfa city could be a potential vehicle for pathogenic and antimicrobial-resistant staphylococci.

The present study aimed to provide a detailed characterization of coagulase-negative staphylococci (CoNS) isolated from cows and buffaloes with mastitis. The study included seventy-five CoNS isolates (60 came from cattle and 15 from buffaloes) originating from 68 individual quarters of 67 dairy cows (53 cattle and 14 buffaloes). The animals belonged to five different small holding dairy herds (n = 140 cows) that show clinical or subclinical mastitis. CoNS isolates were phenotypically characterized using MALDI-TOF-MS and were further genotypically characterized by microarray-based assays. Furthermore, the antimicrobial susceptibility of CoNS strains which carried the mecA gene was examined by broth microdilution. The occurrence of CoNS in the respective five herds was 10.5%, 14.7%, 14.8%, 12.8%, and 9.9%, with an average of 12.4%. Six different CoNS species were identified: S. sciuri (n = 37; 30 from cattle and 7 from buffaloes), S. chromogenes (n = 14; 8 from cattle and 6 from buffaloes), S. haemolyticus (n = 10; nine from cattle and one buffalo), S. xylosus (n = 10; nine from cattle and one buffalo), S. hyicus (n = 2), S. warneri (n = 1), and unidentified CoNS (n = 1). Twenty percent (20%) of CoNS isolates (17.3% of cattle origin) carried at least one antimicrobial resistance gene, while 4% of the isolate including two isolates of S. haemolyticus and one S. warneri of cattle origin carried the mecA gene and were phenotypically identified as methicillin-resistant strains. The genes detected were blaZ (16%), followed by tet(K) (8%), aacA-aphD (4%), aphA3 (2.6%), msr(A) (2.6%), [far1 (2.6%), and fusC (2.6%)], sat (2.6%), and cat (1.3%) conferring resistance to penicillin, tetracycline, gentamicin, neomycin/kanamycin, erythromycin, fusidic acid, streptothricin, and chloramphenicol, respectively. The majority of investigated CoNS strains displayed considerably low prevalence of resistance genes, while resistance to more than three antibiotics was found in S. haemolyticus and S. warneri. Implementing effective preventive measures is, therefore, important for limiting the transmission of CoNS, rather than using antibiotics to control mastitis in bovines.

Oxidative modification of protein structure has been shown to play a significant role in bacterial virulence and metabolism. The sulfur-containing residues are susceptible to oxidation and the enzymatic reversal of oxidized cysteine or methionine is detected in many organisms. Methionine sulfoxide reductases (Msr) are responsible for reducing oxidized methionine. The two different Msrs, MsrA and MsrB, reduce methionine R-sulfoxide and methionine S-sulfoxide, respectively through self-oxidation. This study elucidated the structure of MsrB from Staphylococcus aureus Mu50 and its changes upon oxidation. The active site shows two reduced cysteines in a close contact, implying disulfide bond would form without major structural rearrangement. When the protein is exposed to an oxidative condition, a dimeric state is observed. The dimerization of SAMsrB creates a valley structure for accepting peptidyl substrates. To the best of our knowledge, oxidation induced dimerization of SAMsrB would help to understand mechanism behind redox control that has not been well characterized.

This study aimed to evaluate virulence factors and genetic markers of antimicrobial resistance in 400 Staphylococcus aureus strains isolated from bovine mastitis in four Brazilian states, as well as to assess the association between these characteristics and field information. Virulence factors and drug resistance genes were identified by PCR screening. Biofilm-forming and hemolytic phenotype were detected using Congo red Tryptic Soy Broth and defibrinated sheep blood agar, respectively. Of all isolates, 83.5% were biofilm-forming and 98.5% strains exhibited biofilm gene icaAD, and a significant association between phenotype and genotype for biofilm was observed (P = 0.0005). Hemolysin genes were observed in 82.85% (hla+hlb+), 16.5% (hla+) and 0.75% (hlb+) isolates, whereas the hemolytic phenotype exhibited was complete and incomplete hemolysis in 64.25%, complete in 28.25%, incomplete in 4.75%, and negative in 2.75% of the strains. Virulence factors genes luk, seb, sec, sed, and tst were observed in 3.5%, 0.5%, 1%, 0.25%, and 0.74% isolates, respectively. The gene blaZ was detected in 82.03% of penicillin-resistant isolates, whereas tetK and aac(6')-Ie-aph(2')-Ia were observed in 33.87% and 45.15% of the tetracycline and aminoglycosides-resistant isolates, respectively. Fluoroquinolone resistance gene mepA was detected for the first time in S. aureus from bovine mastitis. Resistance genes tetM (3.22%), tetL (1.61%), ermA (14.29%), ermB (14.29%), ermC (33.3%), ermT (9.52%), ermY (4.76%), msrA (9.52%), and mphC (9.52%) were also detected among resistant isolates. No association between virulence factors or antimicrobial-resistant genes and year of isolation, geographic origin, or antimicrobial resistance profile was observed. Our results showed that S. aureus strains isolated from bovine mastitis in the four Brazilian states sampled are mainly biofilm-forming and hemolytic, whereas virulence genes associated with enterotoxins, luk and tst, were less frequently observed. Moreover, a wide variety of resistance genes that confer resistance to almost all classes of antimicrobial agents approved for use in animals and humans were found. Overall, the data point to a great pathogenic potential of S. aureus associated with bovine mastitis and to the non-negligible risks to public health of staphylococcal infections from animal origin.

In this study we aimed to characterize antimicrobial resistance in methicillin-resistant Staphylococcus aureus (MRSA) isolated from bloodstream infections as well as the associated genetic lineages of the isolates. Sixteen MRSA isolates were recovered from bacteremia samples from inpatients between 2016 and 2019. The antimicrobial susceptibility of these isolates was tested by the Kirby-Bauer disk diffusion method against 14 antimicrobial agents. To determine the macrolide-lincosamide-streptogramin B (MLSB) resistance phenotype of the isolates, erythromycin-resistant isolates were assessed by double-disk diffusion (D-test). The resistance and virulence genes were screened by polymerase chain reaction (PCR). All isolates were characterized by multilocus sequence typing (MLST), spa typing, staphylococcal chromosomal cassette mec (SCCmec) typing, and accessory gene regulator (agr) typing. Isolates showed resistance to cefoxitin, penicillin, ciprofloxacin, erythromycin, fusidic acid, clindamycin, and aminoglycosides, confirmed by the presence of the blaZ, ermA, ermC, mphC, msrA/B, aac(6')-Ie-aph(2'')-Ia, and ant(4')-Ia genes. Three isolates were Panton-Valentine-leukocidin-positive. Most strains (n = 12) presented an inducible MLSB phenotype. The isolates were ascribed to eight spa-types (t747, t002, t020, t1084, t008, t10682, t18526, and t1370) and four MLSTs (ST22, ST5, ST105, and ST8). Overall, most (n = 12) MRSA isolates had a multidrug-resistance profile with inducible MLSB phenotypes and belonged to epidemic MRSA clones.

The oral microbial community is widely regarded as a latent reservoir of antibiotic resistance genes. This study assessed the molecular epidemiology, susceptibility profile, and resistance mechanisms of 35 methicillin-resistant Staphylococcus epidermidis (MRSE) strains isolated from the dental plaque of a healthy human population. Broth microdilution minimum inhibitory concentrations (MICs) revealed that all the isolates were nonsusceptible to oxacillin and penicillin G. Most of them were also resistant to trimethoprim (65.7%) and erythromycin (54.3%). The resistance to multiple antibiotics was found to be largely due to the acquisition of plasmid-borne genes. The mecA and dfrA genes were found in all the isolates, mostly dfrG (80%), aacA-aphD (20%), aadD (28.6%), aphA3 (22.9%), msrA (5.7%), and the ermC gene (14.3%). Classical mutational mechanisms found in these isolates were mainly efflux pumps such as qacA (31.4%), qacC (25.7%), tetK (17.1%), and norA (8.6%). Multilocus sequence type analysis revealed that sequence type 59 (ST59) strains comprised 71.43% of the typed isolates, and the eBURST algorithm clustered STs into the clonal complex 2-II(CC2-II). The staphyloccoccal cassette chromosome mec (SCCmec) type results showed that 25 (71.43%) were assigned to type IV. Moreover, 88.66% of the isolates were found to harbor six or more biofilm-associated genes. The aap, atlE, embp, sdrF, and IS256 genes were detected in all 35 isolates. This research demonstrates that biofilm-positive multiple-antibiotic-resistant ST59-SCCmec IV S. epidermidis strains exist in the dental plaque of healthy people and may be a potential risk for the transmission of antibiotic resistance.

Implant infection is one of the most severe complications after orthopedic surgery. The construction of an antibacterial coating on orthopedic implants with release-killing or contact-killing is one of the most efficient strategies to prevent implant-related infections. Here we reported a hydroxypropyltrimethyl ammonium chloride chitosan (HACC) based multilayer modified plasma-sprayed porous titanium coating generated via the layer-by-layer covalent-immobilized method. We demonstrated that the multilayer coating inhibited the colonization and biofilm formation of several bacterial strains, including Staphylococcus aureus (ATCC 25923), methicillin-resistant Staphylococcus aureus (MSRA, ATCC 43300) and clinical isolates of methicillin-resistant Staphylococcus epidermidis (MRSE 287), in vitro. HACC in the multilayer was released slowly with the degradation of the coating under the action of collagenase, further killing the planktonic bacteria, while the remaining HACC could kill the colonized bacteria. In a rat model of femur implants, the HACC-based multilayer-modified TCs effectively controlled the infection caused by MRSA and prevented bone destruction. Therefore, the HACC-based multilayer modified TCs with multiple antimicrobial properties could be a new potential ideal surface modification strategy to prevent implant associated infections.

Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) of lineage CC398 is an emerging clone causing human infections but is mostly found in pigs. The aim of this study was to characterize the antimicrobial resistance phenotypes/genotypes of a collection of 137 MRSA CC398 isolates obtained in a previous study from 17 Spanish hospitals, using tetracycline resistance as marker for selection. A multidrug-resistant (MDR) phenotype was present in 79% of analysed isolates, with 17% of them resistant to at least six different antimicrobial families. All tetracycline-resistant isolates (n=137) carried the tetM gene and 75% also carried the tetK gene. Almost 50% of MRSA CC398 isolates showed macrolide and/or lincosamide resistance: a) 39% of isolates were ERYR-CLIR (all with constitutive phenotype), with 87% of them carrying the ermC gene, followed by msrA (25%), ermB (21%), vgaA (17%), ermA (6%), lsaB (4%), linA (2%), linB (2%), and ermT (2%, this isolate with the new spa-type t18071); and b) 9% of MRSA CC398 isolates showed the dissociated ERYS-CLIR phenotype carrying the linA, linB, lsaB and vgaA genes. Other antimicrobial resistance phenotypes in these MRSA CC398 isolates included resistance to ciprofloxacin (67%), aminoglycosides (21%), mupirocin (6%), chloramphenicol (4%) or fusidic acid (2%). The more common resistance genes detected for some of these antimicrobials were: aac(6')-Ie-aph(2'')-Ia (16%) and ant(4')-Ia (12%) for aminoglycosides, and fexA (3%) for chloramphenicol. The high rate of MDR phenotypes with a wide range of antimicrobial resistance genes shown in this study reduce the potential therapeutic options in case of infections.

This study was undertaken to investigate the resistance phenotypes to macrolide-lincosamide-streptogramin B (MLSB) antibiotics and their associated genotypes in isolates of Staphylococcus aureus. We analyzed one hundred, consecutive, non-duplicate isolates (methicillin-susceptible MSSA, n=53 and methicillin-resistant MRSA, n=47) obtained from various clinical samples between July 2012 to December 2013. The resistance profile to MLSB antibiotics was determined by phenotypic methods and the resistance genes were detected by PCR assays. All of the isolates were subjected to pulsed-field gel electrophoresis (SmaI-PFGE). The overall prevalence of resistance to MLSB antibiotics was 38% and the resistance phenotype distribution was as follows: cMLSB, 22%; iMLSB, 10%; MSB, 5% and L, 1%. We detected ermA, ermC, ermB and mrsA/B genes in these resistant isolates. The single ermA gene was commonly observed mainly in those with a cMLSB R phenotype, whereas the combination ermA and ermC was more commonly observed in isolates with inducible expression. The patterns of SmaI-PFGE suggest a great genetic diversity in both MRSA and MSSA resistant to MLSB antibiotics. The results demonstrate the local presence of S. aureus resistant to MLSB antibiotics and its most frequently described responsible genes. Some of these isolates, especially those with the iMLSB phenotype, may be associated with therapeutic failure. Therefore, efforts should be directed to the correct detection of all MLSB resistant isolates using appropriate laboratory tests. PFGE results reveal a wide spread of resistance genes rather than the circulation of S. aureus clones resistant to MLSB antibiotics.

In Europe, a novel mecA homologue - mecC (formerly mecALGA251) - has emerged recently in staphylococci from animals, humans and the environment. This paper reports the first occurrence of the mecC gene in Staphylococcus sciuri from cows and manure in Tunisia and Africa. Forty-nine coagulase-negative staphylococci (CNS) were isolated from the milk of cows with mastitis (n=20), manure (n=20) and human nares (n=9), including 16 Staphylococcus equoruim (32.6%), 12 S. xylosus (24.5%), 12 S. sciuri (24.5%), two S. saprophyticus (4.1%), two S. haemolyticus (4.1%), two S. lentus (4.1%), two S. vitulinus (4.1%) and one S. cohnii (2%). CNS from the three origins carried various resistance genes [mecA, blaZ, tet(K), erm(A), erm(B), msr(A)], suggesting an ongoing genetic exchange among CNS from the three niches. The mecA gene was detected in CNS (n=11) recovered from cows, manure and humans, whereas the mecC gene (n=3) was only detected in CNS from cows and manure. Various staphylococcal cassette chromosome mec (SCCmec) - SCCmec type I (n=1), II (n=3), IV (n=2), V/VII (n=2) and untypeable (n=3) - and diverse pulsed-field gel electrophoresis (PFGE) patterns were observed in mecA-positive CNS. Otherwise, similar SCCmec types and PFGE patterns were found in meticillin-resistant CNS within different farms and origins, showing the potential of SCCmec interspecies exchange and circulation of the same clones of meticillin-resistant CNS in the human-animal-environment interface. This study provides baseline data to support clonal dissemination of CNS between cows, humans and manure, and indicates the possible transmission of the mecC gene to humans in contact with cows and manure.

The increasing resistance to macrolide, lincosamide, and streptogramin B agents among methicillin-resistant Staphylococcus aureus (MRSA) is a worldwide problem for the health community. This study aimed to investigate the prevalence of ermA, ermB, ermC, and msrA in MRSA strains isolated from burn patients in Ahvaz, southwest of Iran. A total of 76 isolates of S. aureus were collected from January to May 2017 from Taleghani Burn Hospital in Ahvaz. Among 76 S. aureus strains collected, 60 (78.9%) isolates were MRSA. The antimicrobial susceptibility testing for MRSA showed extreme high resistance rate to clarithromycin (100%) and azithromycin (100%), followed by erythromycin (98.3%). The PCR assay revealed that the frequency rates of msrA, ermA, and ermC genes were 23 (38.3%), 28 (46.7%), and 22 (36.7%), respectively. In addition, none of the MRSA isolates had the ermB gene. Because of the high prevalence of macrolide and lincosamide resistance found in MRSA isolates from infections of burn patients in Ahvaz, southwest of Iran, it is recommended that local periodic survey be performed for controlling the dissemination of antimicrobial resistance.

Staphylococcus species, categorized into Staphylococcus aureus and non-aureus staphylococci (NAS), are frequent causes of mastitis in dairy cattle around the world. Current treatments using antimicrobials are under increasing scrutiny due to rising prevalence of multi-drug resistance in S. aureus. Objectives of this study were to determine: (1) genetic diversity of Staphylococcus species isolated from clinical mastitis in cows from large Chinese dairy farms; and (2) prevalence and distribution of antimicrobial resistance genes (ARG) in these isolates. Staphylococcus aureus (n = 96) were isolated from 26 herds located in 12 provinces of China, whereas NAS (n = 112) were isolated from 59 herds located in 18 provinces of China. The NAS were identified at the species level using a partial 16S rRNA sequencing method, whereas random amplification of polymorphic DNA (RAPD) PCR was done to determine genetic relationships of isolates. Finally, PCR was used to detect resistance and biofilm formation genes. Staphylococcus chromogenes (33%) was the most common NAS species, followed by Staphylococcus sciuri (17%) and Staphylococcus epidermidis (8%). Staphylococcus aureus was grouped in 12 genotypes, of which 2 types represented 56% of isolates. Staphylococcus chromogenes (n = 37) clustered into 8 RAPD types, with 2 prevalent types containing 73% of isolates. The most prevalent ARG in S. aureus isolates was blaZ (95%), followed by tetM (33%), tetK (31%), ermT (26%), and aacA-aphD (23%). The mecA and vanA were detected in 16 and 4% of isolates, respectively. In NAS, blaZ (100%), mecA (73%), tetK (79%), tetM (96%), mphC (63%), and msrA (54%) were frequently detected. Antimicrobial resistance genes mecA, tetK, tetL, tetM, dfrG, ermB, msrA, mphC, aadD, and aphA3 were more commonly detected in NAS than in S. aureus. Biofilm formation genes (icaA and icaD) were frequently detected in staphylococci isolated from bovine clinical mastitis. The existence of predominant RAPD types in S. aureus and S. chromogenes isolates across Chinese dairy farms indicated that specific genotypes had disseminated within herds and become more udder-adapted. High prevalence of ARG, especially in NAS, highlighted the risk of selection of multi-drug resistant staphylococci with potential as a reservoir of ARG.