The authors summarize information on the basic aspects of MRSA infections. Special attention is concentrated on the epidemiology of these infections, risk factors facilitating their transmission and spread in hospitals. Furthermore, this paper attempts to evaluate methods used to reduce their occurrence and pays attention to the procedures aimed at identifying the sources of infection, including carriers and patients. This study also deals with organizational procedures used to control transmission of MSRA infections in hospitals. Lastly, procedures of infection control practices applied abroad are compared with those implemented in our hospitals.

The objective of this study was to determine the expression and transferability of tetracycline and erythromycin resistance among 188 MRSA strains from a Malaysian tertiary hospital. The minimum inhibitory concentrations (MICs) for oxacillin, erythromycin, tetracycline and ciprofloxacin ranged from 4 to 512 μg/ml, 0.25 to 256 μg/ml, 0.5 to 256 μg/ml and 0.5 to 512 μg/ml, respectively. Tetracycline-resistant strains showed co-resistance towards ciprofloxacin and erythromycin. There was a significant increase (P<0.05) of high-level tetracycline (≥MIC 256 μg/ml) and erythromycin (≥MIC 128 μg/ml) resistant strains in between the years 2003 and 2008. All erythromycin-resistant strains harboured ermA or ermC gene and all tetracycline-resistant strains harboured tetM or tetK gene. The blaZ was detected in all MRSA strains, whereas ermA, tetM, ermC, tetK and msrA genes were detected in 157 (84%), 92 (49%), 40 (21%), 39 (21%) and 4 (2%) MRSA strains, respectively. The blaZ, tetM, ermC and tetK genes were plasmid-encoded, with ermC gene being easily transmissible. Tn5801-like transposon was present in 78 tetM-positive strains. ermA and tetM genes were the most prevalent erythromycin and tetracycline resistance determinants, respectively, in MRSA strains. The association of resistance genes with mobile genetic elements possibly enhances the spread of resistant traits in MRSA.

Macrolide-lincosamide-streptogramin B (MLSB) group antibiotics are recommended as first choice in the treatment of staphylococcal infections. All of those drugs bind to the 50S subunit of bacterial ribosomes, thus cross-resistance is a major concern in this group of drugs. The mechanisms associated to resistance are (a) ribosomal methylation due to the methylases encoded by erm genes, (b) active drug efflux due to msrA, msrB, vga, vgb gene activity, (c) enzymatic inactivation of the drug due to the activity of linA, vat, vatB genes. While the most common resistance genes are ermA, ermB, ermC, msrA and msrB genes; linA, vga, vgb, vat and vatB genes have also been found in some studies. In this study it was aimed to investigate the presence of the rare MLSB resistance genes and their coexistence with erm and msr genes in 454 clinical isolates of coagulase-negative staphylococci (CNS). Of them 46.5% (n= 211) were S.hominis, 30.8% (n= 140) were S.epidermidis, 12.1% (n= 55) were S.haemolyticus, 3.5% (n= 16) were S.warnerii and 7% (n= 32) were the other coagulase-negative staphylococcal species. Resistance phenotypes were determined by using D-test method according to the recommendation of Clinical and Laboratory Standards Institute (CLSI). With the D-test 107 (23.6%) strains were determined as M phenotype (resistant to erythromycin and inducible clindamycin resistance was not detected), 92 (20.3%) were iMLSB phenotype (inducible clindamycin resistance was detected by the D-test) and 110 (24.2%) were cMLSB phenotype (constitutive erythromycin and clindamycin resistance was detected). linA, vga, vgb, vat, vatB, ermA, ermB, ermC, msrA, msrB genes were investigated by polymerase chain reaction in all strains showing iMLSB (n= 92) and cMLSB (n= 110) phenotypes and 46 randomly selected strains among 107 strains exhibiting the M phenotype. linA gene was found in 91 (20%) strains as single gene or in combination with erm or msr genes, and vga gene was found in 19 (4.2%) strains. linA gene was found in 52% of iMLSB phenotype, in 26% of cMLSB phenotype and 13% of M phenotype while vga gene was found in 5.4% of iMLSB phenotype, in 12% of cMLSB phenotype and in 0.9% of M phenotype. The most common resistance gene among iMLSB and cMLSB phenotypes was ermC (32.6% and 42.7%, respectively), followed by ermC + linA gene combination (31.5% and 14.5%, respectively). The most frequent gene combination was msrA and msrB in M phenotype (34.8%) and it was followed by a combination of msrA + msrB + linA genes (19.1%). None of the strains revealed presence of vgb, vat and vatB genes. There were no previous reports about the rarely detected resistance genes against MLSB antibiotics in our country. This was the first study which reported the frequency of linA, vga, vgb, vat and vatB genes in MLSB resistant CNS. In conclusion, since linA and vga genes were detected in high frequency in MLSB resistant CNS in this study, it was thought that the investigation of these genes should be included in the further related epidemiologic gene research.

This study was carried out to evaluate the association between the antibiotic susceptibility patterns and the antibiotic resistance genes in staphylococcal isolates obtained from various clinical samples of patients attending a teaching hospital in Hatay, Turkey.A total of 298 staphylococci clinical isolates were subjected to antimicrobial susceptibility testing. The genes implicated in resistance to oxacillin (mecA), gentamicin (aac(6')/aph(2''), aph(3')-IIIa, ant(4')-Ia), erythromycin (ermA, ermB, ermC, and msrA), tetracyclin (tetK, tetM), and penicillin (blaZ) were amplified using multiplex PCR method.Methicillin resistance rate among 139 Staphlococcus aureus isolates was 16.5 and 25.9 per cent of S. aureus carried mecA gene. Of the 159 CoNS isolates, methicillin resistance rate was 18.9 and 29.6 per cent carried mecA gene. Ninety four isolates identified as gentamicin resistant phenotypically, contained at least one of the gentamicin resistance genes [aac(6')/aph(2''), aph(3')-IIIa, ant(4')-Ia], 17 gentamicin-susceptible isolates were found as positive in terms of one or more resistance genes [aac(6')/aph(2''), aph(3')-IIIa, ant(4')-Ia] by multiplex PCR. A total of 165 isolates were resistant to erythromycin, and contained at least one of the erythromycin resistance genes (ermA, ermB, ermC and msrA). Phenotypically, 106 staphylococcal isolates were resistant to tetracycline, 121 isolates carried either tetK or tetM or both resistance genes. The majority of staphylococci tested possessed the blaZ gene (89.9%).The present results showed that the phenotypic antibiotic susceptibility patterns were not similar to those obtained by genotyping done by multiplex PCR. Rapid and reliable methods for antibiotic susceptibility are important to determine the appropriate therapy decisions. Multiplex PCR can be used for confirmation of the results obtained by conventional phenotypic methods, when needed.

Staphylococcus aureus is the most prevalent pathogen in dermatology causing a broad array of pyogenic, community-acquired (CA) and health care-associated (HA), acute and chronic, superficial and deep skin infections which can progress to life-threatening systemic infections. The pathogen causes also toxin-mediated diseases with cutaneous symptoms. Methicillin-resistant S. aureus (MRSA) strains are not sensitive to the beta-lactam antibiotics available in Germany. Even though they cause the same skin infections as methicillin -sensitive strains, they are associated with greater morbidity and mortality because of their resistance to therapy. In addition to HA-MSRA in hospitalized patients with well-known and defined risk factors, there are new CA-MSRA strains which arise in the community or from, animal husbandry sources. These MSRA strains are also a problem in hospitals today. CA-MRSA strains often have special virulence factors, such as Panton Valentine leukocidin), and are often associated with specific often recurrent skin and soft tissue infections (furuncles, abscesses, necrotizing entities).

Staphylococcal food poisoning, one of the most common food-borne diseases, results from ingestion of one or more staphylococcal enterotoxins (SEs) produced by Staphylococcus aureus in foods. In the present study, 64 S. aureus isolates recovered from foods and food handlers, associated or not associated with food-poisoning outbreaks in Spain, were investigated. They were assigned to 31 strains by spa typing, multilocus sequence typing (MLST), exotoxin gene content, and antimicrobial resistance. The strains belonged to 10 clonal complexes (CCs): CC5 (29.0%), CC30 (25.8%), CC45 (16.1%), CC8, CC15 (two strains each), CC1, CC22, CC25, CC59, and CC121 (one strain each). They contained hemolysin genes (90.3%); lukED (77.4%); exfoliatin genes eta, etd (6.5% each), and etb (3.2%); tst (25.8%); and the following enterotoxin or enterotoxin-like genes or clusters: sea (38.7%), seb (12.9%), sec (16.1%), sed-selj with or without ser (22.9%), selk-selq (6.5%), seh, sell, selp (9.7% each), egc1 (32.3%), and egc2 (48.4%). The number of se and sel genes ranged from zero to 12. All isolates carrying tst, and most isolates with genes encoding classical enterotoxins (SEA, SEB, SEC, and SED), expressed the corresponding toxin(s). Two CC5 isolates from hamburgers (spa type t002, sequence type 5 [ST5]; spa type t2173, ST5) were methicillin resistant and harbored staphylococcal cassette chromosome mec (SCCmec) IVd. Six (19.4%) were mupirocin resistant, and one (spa type t120, ST15) from a food handler carried mupA (MIC, 1,250 μg/ml). Resistance to ampicillin (blaZ) (61.3%), erythromycin (ermA-ermC or ermC) (25.8%), clindamycin (msrA-msrB or msrB) (16.1%), tetracycline (tetK) (3.2%), and amikacin-gentamicin-kanamycin-tobramycin (aphA with aacA plus aphD or aadD) (6.5%) was also observed. The presence of S. aureus strains with an important repertoire of virulence and resistance determinants in the food chain represents a potential health hazard for consumers and merits further observation.

Staphylococcus aureus is an important human pathogen that is responsible for the vast majority of bacterial skin and soft tissue infections in humans. S. aureus can also become more invasive and cause life-threatening infections such as bacteremia, pneumonia, abscesses of various organs, meningitis, osteomyelitis, endocarditis, and sepsis. These infections represent a major public health threat due to the enormous numbers of these infections and the widespread emergence of methicillin-resistant S. aureus (MRSA) strains. MSRA is endemic in hospitals worldwide and is rapidly spreading throughout the normal human population in the community. The increasing frequency of MRSA infections has complicated treatment as these strains are more virulent and are increasingly becoming resistant to multiple different classes of antibiotics. The important role of the immune response against S. aureus infections cannot be overemphasized as humans with certain genetic and acquired immunodeficiency disorders are at an increased risk for infection. Understanding the cutaneous immune responses against S. aureus is essential as most of these infections occur or originate from a site of infection or colonization of the skin and mucosa. This review will summarize the innate immune responses against S. aureus skin infections, including antimicrobial peptides that have direct antimicrobial activity against S. aureus as well as pattern recognition receptors and proinflammatory cytokines that promote neutrophil abscess formation in the skin, which is required for bacterial clearance. Finally, we will discuss the recent discoveries involving IL-17-mediated responses, which provide a key link between cutaneous innate and adaptive immune responses against S. aureus skin infections.

Infections due to Staphylococcus aureus have become increasingly common among burn patients. The antibiotic resistance profile of S. aureus isolates and inducible resistance against clindamycin were investigated in this study. The presence of mecA gene, mupA gene and macrolide resistance genes were detected using PCR and multiplex-PCR. The resistance rate to methicillin, erythromycin and mupirocin were 58.5%, 58% and 40%, respectively. The prevalence of constitutive and inducible resistance among macrolide resistant isolates was 75% and 25%, respectively. Ninety five percent of the isolates were positive for one or more erm genes. The most common genes were ermA (75%), ermC (72%) and ermB (69%), respectively. The ermA gene predominated in the strains with the inducible phenotype, while ermC was more common in the isolates with the constitutive phenotype. The msrA gene was only found in one MRSA isolate with the constitutive phenotype. A total of 27 isolates (25%) carried the mupA gene. All the mupirocin resistant isolates and almost all the erythromycin resistant isolates were also resistant against methicillin which may indicate an outbreak of MRSA isolates with high-level mupirocin and erythromycin resistance in the burn unit assessed.

Recent news in the field of bloodstream infection and sepsis relevant for the practitioner include the recommendation in the newly revised German sepsis guideline to introduce selective intestinal decontamination with non-absorbable antimicrobial substances for the prevention of secondary infections in ventilated patients. This intervention, however, remains controversial because there are indications of unfavourable effects (increased development of resistance), and because the effect size has been rather low. Other news indicate not only that procalcitonin can be reasonably used as an aid to determine the duration of antibiotic treatment in community-acquired respiratory infection and pneumonia. A procalcitonin-based algorithm can also be used in critical care patients to shorten the duration of antibiotic administration without worsening outcomes. Recent data indicate that E. coli and S. aureus continue to be the most frequent pathogens isolated in bloodstream infection. The proportion of E. coli strains producing extended-spectrum beta lactamase (ESBL) is increasing. New epidemiologic evidence shows that infections with this pathogen, resistant to many standard antibiotics, are associated with an increased mortality rate, similar to infections due to methicillin-resistant Staphylococcus aureus (MSRA). The incidence of MRSA bacteraemia in Germany can now be estimated better as it has become a notifiable infection.