Staphylococcus epidermidis is a major opportunistic pathogen primarily recovered from device-associated healthcare associated infections (DA-HAIs). Although S. epidermidis and other coagulase-negative staphylococci (CoNS) are less virulent than Staphylococcus aureus, these bacteria are an important reservoir of antimicrobial resistance genes and resistance-associated mobile genetic elements that can be transferred between staphylococcal species. We report a whole genome sequence of a multidrug resistant S. epidermidis (strain G6_2) representing multilocus sequence type (ST) 59 and isolated from an environmental sampling of a hotel room in London, UK. The genome of S. epidermidis G6_2 comprises of a 2408357 bp chromosome and six plasmids, with an average G+C content of 32%. The strain displayed a multi-drug resistance phenotype which was associated with carriage of 7 antibiotic resistance genes (blaZ, mecA, msrA, mphC, fosB, aacA-aphD, tetK) as well as resistance-conferring mutations in fusA and ileS Antibiotic resistance genes were located on plasmids and chromosome. Comparative genomic analysis revealed that antibiotic resistance gene composition found in G6_2 was partly preserved across the ST59 lineage.

Staphylococcus aureus colonization in the nares of patients undergoing elective orthopedic surgery increases the potential risk of surgical site infections. Methicillin-resistant S. aureus (MRSA) has gained recognition as a pathogen that is no longer only just a hospital-acquired pathogen. Patients positive for MRSA are associated with higher rates of morbidity and mortality following infection. MRSA is commonly found in the nares, and methicillin-sensitive S. aureus (MSSA) is even more prevalent. Recently, studies have determined that screening for this pathogen prior to surgery and diminishing staphylococcal infections at the surgical site will dramatically reduce surgical site infections. A nasal mupirocin treatment is shown to significantly reduce the colonization of the pathogen. However, this treatment is expensive and is currently not available in China. Thus, in this study, we first sought to determine the prevalence of MSSA/MSRA in patients undergoing elective orthopedic surgery in northern China, and then, we treated the positive patients with a nasal povidone-iodine swab. Here, we demonstrate a successful reduction in the colonization of S. aureus. We propose that this treatment could serve as a cost-effective means of eradicating this pathogen in patients undergoing elective orthopedic surgery, which might reduce the rate of surgical site infections.

Macrolides, lincosamides, and streptogramins (MLS) resistance genes are responsible for resistance to these antibiotics in Staphylococcus infections. The purpose of the study was to analyze the distribution of the MLS resistance genes in community- and hospital-acquired Staphylococcus isolates. The MLS resistance phenotypes [constitutive resistance to macrolide-lincosamide-streptogramin B (cMLSb), inducible resistance to macrolide-lincosamide-streptogramin B (iMLSb), resistance to macrolide/macrolide-streptogramin B (M/MSb), and resistance to lincosamide-streptogramin A/streptogramin B (LSa/b)] were determined by double-disc diffusion method. The presence of the MLS resistance genes (ermA, ermB, ermC, msrA/B, lnuA, lnuB, and lsaA) were determined by end-point polymerase chain reaction in 179 isolates of staphylococci collected during 1-year period at the Center for Microbiology of Public Health Institute in Vranje. The most frequent MLS phenotype among staphylococcal isolates, both community-acquired and hospital-acquired, was iMLSb (33.4%). The second most frequent was M/MSb (17.6%) with statistically significantly higher number of hospital-acquired staphylococcal isolates (p < 0.05). MLS resistance was mostly determined by the presence of msrA/B (35.0%) and ermC (20.8%) genes. Examined phenotypes were mostly determined by the presence of one gene, especially by msrA/B (26.3%) and ermC (14.5%), but 15.6% was determined by a combination of two or more genes. M/MSb phenotype was the most frequently encoded by msrA/B (95.6%) gene, LSa/b phenotype by lnuA (56.3%) gene, and iMLSb phenotype by ermC (29.4%) and ermA (25.5%) genes. Although cMLSb phenotype was mostly determined by the presence of ermC (28.9%), combinations of two or more genes have been present too. This pattern was particularly recorded in methicillin-resistant Staphylococcus aureus (MRSA) (58.3%) and methicillin-resistant coagulase-negative staphylococci (MRCNS) (90.9%) isolates with cMLSB phenotype. The msrA/B gene and M/MSb phenotype were statistically significantly higher in hospital-acquired than community-acquired staphylococci strains (p < 0.05). There are no statistically significant differences between staphylococci harboring the rest of MLS resistance genes acquired in community and hospital settings (p > 0.05). The prevalence of iMLSb phenotypes may change over time, so it is necessary to perform periodic survey of MLS resistance phenotypes, particularly where the D-test is not performed routinely.

The aim of the study was molecular analysis of coagulase-positive isolates of Staphylococcus bacteria obtained from wild animals and evaluation of their resistance to antimicrobial agents. A total of 76 rectal swabs were taken from wild animals. The species of the Staphylococcus isolates was determined by MALDI TOF MS, susceptibility to antimicrobials was evaluated by phenotypic and molecular methods, epidemiological analysis (ADSRRS-fingerprinting) was also carried out. MRSA isolate was typed by MLST and spa-typing. The animals tested, were carriers (n=38) of coagulase-positive Staphylococcus (S. aureus, S. pseudintermedius and S. delphini B). Analyzed isolates were resistant to 1 or 2 antimicrobials, which was confirmed by the presence of genes (blaZ, ermA, ermB, msrA, tetK and tetM). A multi-drug resistant and methicillin-resistant isolate of S. aureus was obtained as well (MRSA, ST8, t1635, PVL-positive and ACME-negative). The ADSRRS-fingerprinting method enabled interspecific and intraspecific differentiation of coagulase-positive Staphylococcus isolates, revealing a certain degree of correlation between the species of the isolate, and the degree of similarity between the isolates. The presence of resistance genes in 13% (5/38) of the isolates obtained from wild animals, including one methicillin-resistant isolate, is relatively small in comparison to the degree of colonization by resistant strains in humans, livestock or pets. Nevertheless, due to the possibility of contact between wild animals, domestic animals and humans, transmission of resistant strains is possible, as suggested by our isolation of a MRSA strain typed as ST8 and specific spa type t1635, which had previously been isolated exclusively from humans.

We studied Staphylococcus aureus and Streptococcus pneumoniae carriage among elderly adults in Jakarta, Indonesia. Nasopharyngeal swabs were collected from 149 adults aged 60-97 years. Both S. aureus and S. pneumoniae were identified by conventional and molecular methods. Methicillin-resistant Staphylococcus aureus (MSRA) was determined by PCR and antibiotic susceptibility using the disk diffusion method. Pneumococcal serotyping was performed with sequential multiplex PCR. We found S. aureus and S. pneumoniae present in 42 and 4 elderly adults respectively, and MRSA prevalence of 6%. Serotypes 3, 6A/B, 15B/C and 35F were identified among the four pneumococcal isolates. The majority of S. aureus isolates were susceptible to chloramphenicol (93%) and sulfamethoxazole/trimethoprim (93%), followed by gentamicin (88%), erythromycin (83%), penicillin (79%) and tetracycline (74%). Thus S. aureus prevalence is higher than that of S. pneumoniae, and a high frequency of MRSA carried by elderly adults in Jakarta, Indonesia.

Staphylococcus aureus is one of the most common cause of both community and healthcare-associated infections. As staphylococci have developed resistance to various antibiotics, initially to penicillins then to methicillin and glycopeptides and have the ability to cause epidemics, they continue to be a major problem from past to present. Methicillin resistance gave rise to the use of alternative antibiotics such as macrolides, however worldwide development of macrolide resistance limited the use of these antibiotics. Macrolide resistance occurs either through target site modification (MLS(B) phenotype, encoded by erm genes), efflux pumps (MS phenotype, encoded by msrA/B genes) or decreased cell wall permeability. The aim of this study was to investigate the MLS(B) resistance of clinical S.aureus strains with phenotypic and genotypic methods. A total of 404 S.aureus strains isolated from different clinical samples (50% wound, 15% tracheal aspirate and 35% other samples) of inpatients (93.3%) and outpatients (6.7%) were included in the study. Double disc synergy test (D-test) was used for the phenotypical research and PCR was used for the genotypical research of MLS(B) resistance of isolates. One hundred fifty eight (39.1%) of the S.aureus isolates were methicillin-resistant (MRSA), and 246 (60.9%) were methicillin-susceptible (MSSA). By the use of D-test, constitutive (cMLS(B)) and inducible (iMLS(B)) clindamycin resistance were detected in 19 and 111 isolates, respectively, while five isolates were MS phenotype and 268 isolates were S phenotype (susceptible to erythromycin and clindamycin). The resistance genes of 136 isolates with MLS(B) resistance phenotype were determined genotypically and among 111 isolates showing iMLS(B) phenotype ermA gene was found in 81.9% (83 MRSA, 8 MSSA), ermC gene in 10.8% (7 MRSA, 5 MSSA), msrA gene in 10.8% (11 MRSA, 1 MSSA), msrB gene in 1.8% (2 MRSA) and ermB gene in 0.9% (1 MRSA). Among 19 strains with cMLS(B) phenotype, ermA was found in 57.9% (10 MRSA, 1 MSSA), ermC in 36.8% (6 MRSA, 1 MSSA) and ermB in 15.8% (3 MRSA). Among five strains with MS phenotype, ermA was found in 80% (2 MRSA, 2 MSSA), msrA in 75% (3 MSSA), msrB in 50% (2 MSSA) and ermC in 25% (1 MSSA) of the isolates. ErmA and ermC genes were detected together in 14 isolates, ermA, ermC and msrA genes in one isolate, ermA and msrA genes in 11 isolates, ermA, msrA and msrB genes in three isolates and ermA and ermB genes in three isolates, respectively. In this study, two MRSA isolates with MS phenotype and negative D-test had only ermA gene and among two MSSA strains, erm genes were also determined in addition to msr genes. In our study RAPD-PCR method was used to investigate the clonal similarity, however no dominance of one or a number of clonal type was observed among the isolates in which the resistance genes were identified. In conclusion, the detection of MLS(B) resistance in S.aureus isolates is likely to influence the selection of antibiotics in the treatment of the infections caused by this bacteria.

Staphylococcus aureus is a major human pathogen and emergence of antibiotic resistance in clinical staphylococcal isolates raises concerns about our ability to control these infections. Cell wall-active antibiotics cause elevated synthesis of methionine sulfoxide reductases (Msrs: MsrA1 and MsrB) in S. aureus. MsrA and MsrB enzymes reduce S-epimers and R-epimers of methionine sulfoxide, respectively, that are generated under oxidative stress. In the S. aureus chromosome, there are three msrA genes (msrA1, msrA2 and msrA3) and one msrB gene. To understand the precise physiological roles of Msr proteins in S. aureus, mutations in msrA1, msrA2 and msrA3 and msrB genes were created by site-directed mutagenesis. These mutants were combined to create a triple msrA (msrA1, msrA2 and msrA3) and a quadruple msrAB (msrA1, msrA2, msrA3, msrB) mutant. These mutants were used to determine the roles of Msr proteins in staphylococcal growth, antibiotic resistance, adherence to human lung epithelial cells, pigment production, and survival in mice relative to the wild-type strains. MsrA1-deficient strains were sensitive to oxidative stress conditions, less pigmented and less adherent to human lung epithelial cells, and showed reduced survival in mouse tissues. In contrast, MsrB-deficient strains were resistant to oxidants and were highly pigmented. Lack of MsrA2 and MsrA3 caused no apparent growth defect in S. aureus. In complementation experiments with the triple and quadruple mutants, it was MsrA1 and not MsrB that was determined to be critical for adherence and phagocytic resistance of S. aureus. Overall, the data suggests that MsrA1 may be an important virulence factor and MsrB probably plays a balancing act to counter the effect of MsrA1 in S. aureus.