[Methicillin-sensitive Staphylococcus aureus isolates related to USA300 clone: Origin of community-genotype MRSA in Colombia?] (original) (raw)
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Characterisation of Staphylococcus aureus bacteraemia at Tygerberg hospital
The Southern African journal of epidemiology & infection: official journal of the Sexually Transmitted Diseases, Infectious Diseases and Epidemiological Societies of Southern Africa
To elucidate the local epidemiology of Staphylococcus aureus bacteraemia, we characterised blood culture isolates using molecular methods and prospectively collected clinical data to determine the occurrence of community-acquired, methicillin resistant S. aureus (MRSA). Consecutive S. aureus blood culture isolates were collected over a one-year period from patients who were admitted to Tygerberg Academic Hospital in the Western Cape. A multiplex polymerase chain reaction (PCR) was used for the detection of spa, mecA and lukS/F-PV genes. Strain typing was performed using spa typing. Multiplex PCR for staphylococcal cassette chromosome mec (SCCmec) typing was also performed, as well as multilocus sequence typing (MLST) on selected isolates. Cases were categorised by clinical data as either hospital-acquired, healthcare-associated or community-acquired. One hundred and thirteen S. aureus isolates (30% MRSA) were collected from 104 cases of bacteraemia. According to clinical data, all c...
European Journal of Clinical Microbiology & Infectious Diseases, 2005
Heterogeneous methicillin-resistant Staphylococcus aureus (MRSA) strains, including community-acquired MRSA strains, have been observed in Central Europe. The purpose of this study was to characterize by molecular methods MRSA isolated during the period 2002–2003 at the Otto-von-Guericke University Hospital in Magdeburg, Germany, and at a nearby chronic care facility. Strains were analyzed for their resistance phenotype. Selected isolates were typed by multilocus sequence typing (MLST), by a multiplex polymerase chain reaction (PCR) for the staphylococcal cassette chromosome mec (SCCmec), by an allele-specific PCR for the staphylococcal accessory gene regulator (agr), and by PCR for the presence of toxin genes (sea–sej, tsst-1, hlgA, C, and B, lukE/D, and luk-pvl). Of the 2,731 S. aureus isolates studied, 199 (7.3%) were MRSA, with a prevalence of 21.6%, 19.6%, and 12% in the department of dermatology, the chronic care facility, and the intensive care units. Six different sequence types (ST247, ST228, ST22, ST22a, ST225, and ST45) were observed. Of these, ST22, ST22a, and ST45 dominated (>50%) in the department of dermatology and the chronic care facility. Strains with these sequence types were usually not resistant to gentamicin and were associated with agr group I, the SCCmec type IV element, and the presence of the sec and sed toxin genes. ST228 strains were found mainly in the intensive care units and had a broader resistance phenotype and were associated with agr group II and the SCCmec type I element. All luk-pvl-positive MRSA isolates (n=8) belonged to agr group I and were typed as ST22 or ST45 and contained the SCCmec type I (n=1), type III (n=1), or type IV (n=6) element. The main observations of this study are in concordance with previously reported findings showing dissemination of MRSA in Central Europe. Through the multitude of applied methods, the data from this study contribute to a more precise knowledge about the heterogeneity of MRSA in a clinical setting. Rapid dissemination of MRSA clones at a university hospital was demonstrated, indicating that dissemination may depend on the environmental conditions within the individual departments.
Periodic monitoring of Staphylococcus aureus characteristics in a locality is imperative as their drug-resistant variants cause treatment problem. In this study, antibiograms, prevalence of toxin genes (sea-see, seg-ser, seu, tsst-1, eta, etb, and etd), PFGE types, accessory gene regulator (agr) groups, and ability to form biofilm of 92 S. aureus Thailand clinical isolates were investigated. They were classified into 10 drug groups: groups 1-7 (56 isolates) were methicillin resistant (MRSA) and 8-10 (36 isolates) were methicillin sensitive (MSSA). One isolate did not have any toxin gene, 4 isolates carried one toxin gene (seq), and 87 isolates had two or more toxin genes. No isolate had see, etb, or tsst-1; six isolates had eta or etd. Combined seg-sei-sem-sen-seo of the highly prevalent egc locus was 26.1%. The seb, sec, sel, seu, and eta associated significantly with MSSA; sek was more in MRSA. The sek-seq association was 52.17% while combined sed-sej was not found. Twenty-three PFGE types were revealed, no association of toxin genes with PFGE types. All four agr groups were present; agr group 1 was predominant (58.70%) but agr group 2 strains carried more toxin genes and were more frequent toxin producers. Biofilm formation was found in 72.83% of the isolates but there was no association with antibiograms. This study provides insight information on molecular and phenotypic markers of Thailand S. aureus clinical isolates which should be useful for future active surveillance that aimed to control a spread of existing antimicrobial resistant bacteria and early recognition of a newly emerged variant. BioMed Research International cytokines and T-cell stimulating factors leading to toxic shock syndrome which may be fatal [8, 9]. The enterotoxicity and superantigenicity are distinct properties of the toxin molecule [6]. SEs are classified into two types based on their emetic activity in the toxin fed modeled primate. Toxins that induce vomiting in the primate are placed in the classical SE type while those that lack the emetic activity or have not been tested are allocated in the SE-like (SEls) type [10, 11]. Members of the classical SEs are SEA-SEE and the more recently recognized SEG, SEH, SEI, SER, SES, and SET. The SEls members include SElJ, SElK, SElL, SElM, SElN, SElO, SElP, SElQ, SElU, SElU2 or SEW, and SElV [11]. The staphylococcal enterotoxin F (SEF) which lacks emetic activity but is associated with toxic shock syndrome is presently called toxic shock syndrome toxin-1 (TSST-1) [12]. The SEs and the TSST-1 as well as the bacterial resistance to drugs are encoded by genes on the mobile genetic elements including prophages, plasmids, pathogenicity islands, genomic islands, and antibiotic resistance cassette [13]; thus they are transmitted horizontally rather easily. Expression of S. aureus virulence factors and metabolism of metabolic pathways during growth are coordinated/regulated by a quorumsensing operon named accessory gene regulator (agr) [14, 15]. Based on the amino acid sequence polymorphisms of the agr-encoding autoinducing peptides and their responding receptors, S. aureus strains can be divided into four major agr groups (groups 1-4) [16]. During the last five decades, S. aureus clones that resist methicillin (methicillin-resistant S. aureus, MRSA) disseminated and caused medical and public health problem worldwide [17, 18]. These strains are not only resistant to methicillin, but also resistant to all other-lactams, such as cephalosporin [18, 19]. In Thailand, MRSA infections were reported from 23 hospitals from 1988 to 1998 [20, 21]. The proportions of MRSA to MSSA in the northeast, central, and southern regions of the country during the studied period increased from 11 to 23.4%, 16 to 30.5%, and 21 to 30.3%, respectively [22]. Moreover, methicillin-resistant S. aureus with reduced susceptibility to vancomycin was recognized [23]. However, data on genotypic characteristics and other attributes of the S. aureus isolates in Thailand are relatively rare. Therefore, this study investigated the prevalence of virulence toxin genes coding for enterotoxins (sea-see, seg-ser, and seu), toxic shock syndrome toxin-1 (tsst-1), and exfoliative toxins (eta, etb, and etd) among S. aureus Thailand clinical isolates. Molecular diversity of the isolates regarding their endonuclease-restricted patterns of genomic DNA (PFGE), agr types, and antimicrobial susceptibility as well as their ability to produce biofilm were also investigated.
Tropical Medicine and International Health, 1998
Staphylococcus aureus is a major cause of nosocomial infections and a risk in patients who have either undergone surgery or are on haemodialysis. The S. aureus infections in patients admitted to the clinical departments of Al-Makased Charitable Hospital in Jerusalem during a period of one year were investigated. Isolates included were from blood, surgical wounds, or other nonsuperficial sites. Of 63 isolates available for analysis, 46 (73.0%) expressed type 8 capsular polysaccharide; 13 (20.7%), type 5 capsular polysaccharide; only 4 isolates (6.3%) did not express type 5 or type 8 antibodies. The strains fitted in 7 different antibiogram types, with the type showing resistance only to penicillin and ampicillin prevalent in 34 out of 63 isolates (54.0%). Of the 12 methicillin-resistant S. aureus (MRSA) isolates (19.1%), 8(66.7%) possessed the type 8 capsule and 4(33.7%) the type 5 capsule. Pulsed-field gel electrophoresis of all isolates with the restrictionendonuclease enzymes Sma I revealed 34 patterns demonstrating that no single methicillin-sensitive S. aureus strain was endemic in the hospital. However, all MRSA isolates with a type 8 capsule showed identical PFGE patterns using the 2 restriction-endonuclease enzymes Sma I and SST II. Moreover, type 5 isolates showed identical patterns (one isolate differed from the rest with one band only). These data suggest and confirm the clonality of type 5 and type 8 MRSA isolates. Analysing the results of the capsular and antibiogram typing schemes in conjunction proved useful and suggested that such an analysis can be employed as a helpful epidemiological tool in hospitals with limited resources.
Staphylococcus aureusNasal Carriage Among Patients and Health Care Workers in São Tomé and Príncipe
Microbial Drug Resistance, 2014
Methicillin-resistant Staphylococcus aureus (MRSA) is a major human pathogen worldwide. However, data on MRSA prevalence in the African continent are scarce and nonexistent for Sã o Tomé and Príncipe. In November 2010 and April 2012, a total of 332 individuals (258 patients and 74 health care workers [HCW]) from Hospital Dr. Ayres Menezes in Sã o Tomé and Príncipe, were screened for S. aureus and MRSA carriage. Fifty-two persons (15.7%) were S. aureus nasal carriers out of which 14 (26.9%) were colonized with MRSA. MRSA isolates belonged to three clonal complexes: CC8 (PFGE type B-ST8-t064/t451-IVg/V), CC88 (PFGE E-ST88-t186/t786-IVa), and CC5 (PFGE K-ST5-t105-IVa/PFGE K-ST105-t002-II). A higher genetic diversity was found among methicillin-susceptible S. aureus (MSSA) isolates where 58.5% (n = 24) belonged to four major lineages: PFGE type A-ST15-t084; PFGE C-ST508-t861 or related; PFGE D-ST152-t355 or related; and PFGE G-ST121-t159/t2304. Despite the common nonmultiresistant profile, 98% of the isolates harbored two or more virulence factors. Panton-Valentine leukocidine was detected in 36% of the isolates, all MSSA. S. aureus cross-transmission between HCW and patients in the pediatric and medicine wards and the detection of identical MRSA strains among patients in two different wards evidenced the need of implementation of additional infection control measures in this hospital.
Advances in Microbiology, 2014
(MRSA) has also become a serious problem in Brazilian HI. The aim of this study was to characterize the pathogenicity of methicillin-resistant S. aureus (MRSA) and methicillin-sensitive Staphylococcus aureus (MSSA) isolated in public hospitals. The clinical isolates were obtained from intensive care unit. The MRSA and MSSA strains were genotyped by PCR for detection genes related to virulence factors. Moreover, the strains were tested for biofilm formation and cytokine induction in macrophages. Three strains of MRSA (9.68%) expressed the Sea gene, one (3.23%) Seb, 17 (54.84%) Spa and seven (22.58%) had PVL. Two MSSA strains (2.98%) expressed the Sea gene, three (4.48%) Seb, 18 (26.87%) Spa and 11 (16.42%) showed positive results for the PVL gene. There was no expression of Sec and CflA between MRSA and MSSA strains. Among MRSA and MSSA isolates, none statistical differences were observed in biofilm production. The analysis of cytokine induction in the inflammatory response of J774 macrophages by MRSA and MSSA isolates did not show statistical difference. Understanding the mechanisms of pathogenesis of S. aureus could provide important clues for both preventing and treating infection caused by these organisms.
Clinical Microbiology and Infection, 2013
Studies reporting on the population structure of Staphylococcus aureus in South Africa have focused only on methicillin-resistant S. aureus (MRSA). This study describes the population structure of S. aureus, including methicillin-susceptible S. aureus (MSSA) isolated from patients at Tygerberg Academic Hospital, Western Cape province. Pulsed-field gel electrophoresis (PFGE), detection of Panton-Valentine leukocidin (PVL), spa typing, multilocus sequence typing (MLST), agr typing and SCCmec typing were used to characterize strains. Of 367 non-repetitive S. aureus isolates collected over a period of 1 year, 56 (15.3%) were MRSA. Skin and soft tissue infections were the most frequent source (54.8%), followed by bone and joint (15.3%) and respiratory tract infections (7.7%). For strain typing, PFGE was the most discriminative method, and resulted in 31 pulsotypes (n = 345, 94.0%), as compared with 16 spa clonal complexes (CCs) (n = 344, 93.4%).