ST9 MRSA strains carrying a variant of type IX SCCmec identified in the Thai community.

BACKGROUND: Infections caused by methicillin-resistant Staphylococcus aureus (MRSA) in Thailand occur most frequently in healthcare facilities. However, reports of community-associated MRSA are limited. METHODS: We characterized 14 MRSA isolates from outpatients (O-1 to O-14) by phenotypic and genotypic methods and compared them with 5 isolates from inpatients (I-1 to I-5). Thai MRSA isolates from a healthcare worker (N-1) and a pig (P-1) were also included as ST9 MRSA strains from other sources. RESULTS: All MRSA isolates from the outpatients and inpatients were multidrug-resistant (resistant to ≥3 classes of antimicrobials). All of them except strains O-2 and I-3 carried type III SCCmec and belonged to agrI, coagulase IV, spa type t037 or t233, which related to ST239. The strain O-2 (JCSC6690) carried type IX SCCmec and belonged to agrII, coagulaseXIc, spa type t337 and ST9, whereas the strain I-3 carried a type III SCCmec and belonged to ST1429. Nucleotide sequence determination revealed that the type IX SCCmec element in strain O-2 was distinct from that in a Thai ST398 strain (JCSC6943) previously identified in 2011; nucleotide identities of ccrA and ccrB were 93 and 91%, respectively and several open reading frames (ORFs) at the joining regions were different. PCR experiments suggested that strain O-2 and N-1 carried similar SCCmec element, whereas that of strain P-1 was different, suggesting that distinct ST9-MRSA-IX clones might be spreading in this province. CONCLUSIONS: The SCCmecIX-ST9 MRSA clones of distinct SCCmec subtypes might have emerged in the Thai community and might also have disseminated into the hospital.

Epidemiological and molecular characterization of Staphylococcus haemolyticus strains, from a hematology ward, with decreased susceptibility to glycopeptides.

In the present study, we report on the reduced susceptibility to teicoplanin among clinical isolates of Staphylococcus haemolyticus in a hematology ward of a teaching hospital. The molecular characterization of 17 S. haemolyticus strains was performed using mec gene complex classification, pulsed-field gel electrophoresis analysis, and minimum inhibitory concentration examination. Pulsotype A strains carrying a class C2 mec gene complex were the most prevalent strains, at 64.7%. In vivo selection of stepwise increase in resistance to vancomycin and teicoplanin was observed in three S. haemolyticus strains serially isolated from a case patient. The results of the present study suggest the regional spread of certain S. haemolyticus clones with diminished susceptibility to glycopeptides, emphasizing the need for continuous monitoring of minimum inhibitory concentration levels of vancomycin and teicoplanin in S. haemolyticus strains, and the importance of infection control practices to prevent its transmission.

[Effects of Streptococcus pneumoniae on the ultrastructure of alveolar epithelial cells type â ¡ in the lung tissues of mice and children].

OBJECTIVE: To explore the possible mechanisms of lung necrosis by examining the effects of Streptoccus pneumoniae (S.p) on the ultrastructure of alveolar epithelial cells type Ⅱ(AEC-Ⅱ) in the lung tissues of mice and children. METHODS: The suspended solutions of S.p strains cultured from the blood of a child with pneumococcal necrotizing pneumonia (PNP) (0.3 mL, CFU: 1×108/L) were instilled into the trachea of pathogen-free mice to prepare PNP model. The same amount of normal saline was given for the control group (10 mice). The samples (1 mm3) from the lower lobe of right lung of the mice were obtained 92 hrs later and fixed in 2.5% glutaraldehyde. Normal and abnormal lung tissues (1 mm3) were obtained while operation for the left lower lobe pulmonary cavity excision in the child with PNP. The specimens were fixed in 2.5% glutaraldehyde and stored at 4℃. A transmission electron microscope was employed for the examination of the ultrastructure of AEC-Ⅱ in the lung tissues. RESULTS: Quantitative reduction and exfoliation of microvilli in S.p-infected AEC-Ⅱ were observed in both mice and this child compared with the control. Enlarged size, enhanced evacuation and reduced density of the lamellar bodies were also presented. The number of mitochondria was obviously reduced. The nucleolus chromatin concentrated and showed an inhomogeneous distribution. CONCLUSIONS: S.p infection results in comparable damage to the ultrastructure of AEC-Ⅱ in mice and children that may represent one of the primary causes responsible for S.p-induced lung tissue necrosis.

[Water Pollution Characteristics and Source Apportionment in Rapid Urbanization Region of the Lower Yangtze River: Considering the Qinhuai River Catchment].

Clarifying the current situation of regional water pollutants and the relationship between pollutants and pollution sources is considered essential for managing the water environment. Water quality identification index (WQI), cluster analysis (CA), positive matrix factorization (PMF), and stable isotope analysis in R (SIAR) were employed to interpret a large and complex water quality data set of the Qinhuai River catchment generated during 2015 to 2019 to monitor of 11 parameters at 29 different sampling sites. WQI analysis indicated that water quality in Qinhuai River catchment is considered to have "moderate pollution," and an improving trend of water quality was observed at the interannual scale. TN was the most deteriorated of all pollution parameters. CA and PMF results on the spatial scale revealed that sampling sites located at downtown of Nanjing and Lishui District or Jangling University town were highly polluted due to the sewage from domestic sewage and business service sewage (28.88%) as well as industrial wastewater (27.43%), while sampling sites located at Hushu Street Administrative District, Ergan River, and Sangan River were slightly polluted by rural domestic wastewater and garbage (28.79%), and agricultural non-point source pollution (24.3%). The middle-lower reaches (Jiangning Development Zone and Moling Street) and middle reaches (Lukou Street Administrative District) were moderately polluted by industrial wastewater (27.25%), sewage from domestic wastewater and business service wastewater (31.62%) as well as inner sources (24.76%). The SIAR results showed that NO3--N was the main nitrogen form, and the NO3--N mainly originated from sewage (61%) and soil (34%) in the Yuntaishan River sub-catchment. These results will aid in the development of measures required to control water pollution in river catchments.

Do foreign direct investment and environmental regulation improve green technology innovation? An empirical analysis based on panel data from the Chinese manufacturing industry.

The environmental regulation and foreign direct investment (FDI) inflow have an important impact on the progress of green technology. This study analyzes the impacts of environmental regulation and FDI on green technology innovation (GTI) based on the panel data of 13 Chinese manufacturing sectors. The results of static panel regression show that the environmental regulation has a positive impact on GTI, while the FDI has a negative impact. The results of the panel threshold model reveal that the effect of environmental regulation on GTI presents a nonlinear shape. The negative effect of FDI on GTI is strengthened when the environmental regulation exceeds its threshold. Increasing FDI inflow can inhibit the effect of environmental regulation. Meanwhile, a strict environmental regulation can enhance the inhibiting effect of FDI on GTI. The FDI inflow into high-tech manufacturing sectors has a less negative impact on GTI than the FDI inflow into low-tech sectors in the case of the enhancement of environmental regulation. This study provides some implications for the formulation of environmental regulation and the FDI inflow into China to improve the GTI.

Identification of a novel variant of staphylococcal cassette chromosome mec, type II.5, and Its truncated form by insertion of putative conjugative transposon Tn6012.

We identified two novel staphylococcal cassette chromosome mec (SCCmec) elements in sequence type 8 methicillin-resistant Staphylococcus aureus strains isolated in Japan: type II.5 SCCmec, whose J1 region was highly homologous to that of type I.2 SCCmec of strain PL72 (previously isolated in Poland), and its J1 region variant caused by the deletion/insertion of putative conjugative transposon Tn6012, identified in four S. aureus genomes.

Genetic diversity of methicillin-resistant Staphylococcus aureus carrying type IV SCCmec in Orebro County and the western region of Sweden.

BACKGROUND: Recent studies have shown a predominance of type IV SCCmec among the methicillin-resistant Staphylococcus aureus (MRSA) isolated in the low endemic areas of Orebro County and the western region of Sweden. However, many of these isolates were not possible to classify as existing subtypes IVa, IVb, IVc or IVd. METHODS: We analysed 16 such MRSA isolates by multilocus sequence typing, spa typing, staphylocoagulase (SC) typing and detection of type IVg and IVh SCCmec. MRSA that remained as unknown type IV SCCmec were investigated by long-range PCR covering the J1 region; however, only two isolates were possible to amplify by PCR. The nucleotide sequences of the entire SCCmec of these two MRSA were determined. In addition, isolates that had unknown SC types were investigated by nucleotide sequencing of the coa genes. RESULTS: Five of 16 isolates were classified as type IVg SCCmec, and four isolates had type IVh SCCmec. Two subtypes of type IV SCCmec shared J1 regions previously identified in other types of SCCmec, types I.2 and II.2. The novel elements were designated as type IVi and IVj SCCmec. In addition, the genetic backgrounds of these Swedish MRSA were diverse and constituted at least nine sequence types and eight SC types, including four new types of SC. CONCLUSIONS: Type IV SCCmec is occurring in heterogeneous clones of MRSA in Sweden, and the majority of the type IV SCCmec were identified in community-acquired MRSA. We describe two novel subtypes of type IV SCCmec with common J1 regions shared by other types of SCCmec, which indicate that J1 regions occurred as primordial SCC.

Novel type of staphylococcal cassette chromosome mec in a methicillin-resistant Staphylococcus aureus strain isolated in Sweden.

We identified a novel type of staphylococcal cassette chromosome mec (SCCmec) element carried by methicillin-resistant Staphylococcus aureus (MRSA) strain JCSC6082 isolated in Sweden. The SCCmec element was demarcated by characteristic nucleotide sequences at both ends and was integrated at the 3' end of orfX. The element carried a novel combination of a type 5 ccr gene complex and class C1 mec gene complex. The J regions of the element were homologous to those of the SCCmercury element of S. aureus strain 85/2082, with nucleotide identity greater than 99%. However, the novel SCCmec element from JCSC6082 did not carry the mer operon nor Tn554, suggesting that evolution to SCCmec could have been from a common ancestor by acquisition of the class C1 mec gene complex. The novel SCCmec element from JCSC6082 was flanked by a novel SCC-like chromosome cassette (CC6082), which was demarcated by two direct repeats and could be excised from the chromosome independently of the SCCmec element. Our data suggest that novel SCCmec elements can be generated on the staphylococcal chromosome through the recombination between extant SCC elements and mec gene complexes.

Two different Panton-Valentine leukocidin phage lineages predominate in Japan.

We determined the entire nucleotide sequence of phiSa2958-carrying Panton-Valentine leukocidin (PVL) gene, which was lysogenized in a sequence type 5 staphylococcal cassette chromosome mec (SCCmec) type II strain of methicillin-resistant Staphylococcus aureus (MRSA). Based on the nucleotide sequences of PVL phages, we developed PCRs to discriminate among five PVL phages, with a preliminary classification into two morphological groups (elongated-head type and icosahedral-head type) with four PCRs, including two PCRs for identifying the gene lineage between lukS-PV and the tail gene. The phages were then classified into five types by four PCRs identifying each phage-specific structure. With these PCRs, we examined the PVL phage types of 67 MRSA strains isolated in Japan from 1979 through 1985 and since 2000 and found that two morphologically distinct phages were predominant in Japan. The icosahedral-head-type phage, represented by the phi108PVL type, was identified for 39 of 53 strains isolated from 1979 through 1985. Of 26 other Japanese isolates, 25 belonged either definitively or presumably to elongated-head types as follows: 3 belonged to the phiSa2958 type; 8 were determined to belong to an elongated-head type, but a determination of greater specificity was not made; and 14 belonged to a phiSa2958-like phage of unknown type. We induced prophages by treatment with mitomycin C from six strains of the phiSa2958 type or of phiSa2958-like unknown-type phages; five of six strains carried intact PVL-carrying phages, which can infect other S. aureus strains and might generate novel PVL-positive strains of S. aureus. That various SCCmec elements were carried by different strains of the same phage type suggests that S. aureus strains might independently acquire PVL phages before they acquire various SCCmec elements.

Phenotypic and Molecular Characterisation of Staphylococcus Aureus with Reduced Vancomycin Susceptibility Derivated in Vitro.

Vancomycin has been the primary agent used to treat serious Methicillin-resistant Staphylococcus aureus (MRSA) infection for many years. However, the rise of MRSA infection rates and the extensive use of vancomycin have led to the emergence of reduced vancomycin susceptibility. Therefore, four typical Staphylococcus aureus (S. aureus) strains from different clinical specimens were derivated by vancomycin in vitro to better clarify their phenotypic and molecular characteristics. Some experiments, such as stepwise selection of vancomycin-resistant strains, pulsed-field gel electrophoresis (PFGE), antimicrobial susceptibility test, population analysis profile-area under the curve (PAP-AUC), molecular typing, transmission electron microscopy, δ-hemolysin expression, autolysis assay, biofilm assay and quantitative real-time polymerase chain reaction (qPCR) for gene expression were carried out to compare the derivated bacteria with their parental strains. Results showed that the observed phenotypes of vancomycin-resistant strains such as hemolysin, autolysis and biofilm significantly reduced, which were associated with vancomycin resistance capability of the selected strain. The changes of phenotype and regulatory genes expression were inversely proportional to the vancomycin minimum inhibitory concentration (MICvan). Most heterogeneous vancomycin intermediate Staphylococcus aureus (hVISA) or VISA strains belonged to spa type t570 and agr group II. In summary, the clinical isolated vancomycin susceptible Staphylococcus aureus (VSSA), hVISA and VISA could be derivated into high vancomycin-resistant VISA in vitro, but it was difficult for them to develop into vancomycin resistant Staphylococcus aureus (VRSA). VISA and hVISA could gradually adapt to the environment with the vancomycin concentration that continuously elevates.

[Spatio-temporal characteristics and source identification of water pollutants in Wenruitang River watershed].

Identifying the temp-spatial distribution and sources of water pollutants is of great significance for efficient water quality management pollution control in Wenruitang River watershed, China. A total of twelve water quality parameters, including temperature, pH, dissolved oxygen (DO), total nitrogen (TN), ammonia nitrogen (NH4+ -N), electrical conductivity (EC), turbidity (Turb), nitrite-N (NO2-), nitrate-N(NO3-), phosphate-P(PO4(3-), total organic carbon (TOC) and silicate (SiO3(2-)), were analyzed from September, 2008 to October, 2009. Geographic information system(GIS) and principal component analysis(PCA) were used to determine the spatial distribution and to apportion the sources of pollutants. The results demonstrated that TN, NH4+ -N, PO4(3-) were the main pollutants during flow period, wet period, dry period, respectively, which was mainly caused by urban point sources and agricultural and rural non-point sources. In spatial terms, the order of pollution was tertiary river > secondary river > primary river, while the water quality was worse in city zones than in the suburb and wetland zone regardless of the river classification. In temporal terms, the order of pollution was dry period > wet period > flow period. Population density, land use type and water transfer affected the water quality in Wenruitang River.

[Progress of pattern recognition receptors of molluscs].

Molluscs have established complete innate immunity to defense against pathogens. The pattern recognition receptors (PRRs) are the sensory receptors of molluscs to resist outside invaders, as the first reactor to initiate the innate immune response. Some PRRs have been identified in several molluscs, including Toll-like receptors (TLRs) , C-type lectins, galectins, lipopolysaccharide-ß-1,3-glucan binding protein (LGBP), Clq domain-containing protein (ClqDC), and peptidoglycan recognition protein (PGRP). PRRs have various biological activities and play important roles in the defense system of molluscs. This paper reviews the research progress of PRRs in molluscs.

Reduced vancomycin susceptibility found in methicillin-resistant and methicillin-sensitive Staphylococcus aureus clinical isolates in Northeast China.

BACKGROUND: Strains of Staphylococcus aureus with an intermediate level of resistance to vancomycin (vancomycin-intermediate S. aureus, or VISA) or which contain subpopulations of mixed susceptibility (heterogeneous VISA, or hVISA) have been reported worldwide. However, the prevalence of VISA and hVISA infections in Northeast China is unknown. From 2007 through 2010, we surveyed the vancomycin susceptibility of methicillin-resistant and methicillin-sensitive S. aureus (MRSA and MSSA, respectively) clinical isolates in Northeast China. METHODS: S. aureus clinical isolates (369 MRSA and 388 MSSA) were screened for hVISA and VISA on brain heart infusion agar containing 3 µg/mL vancomycin, and their identity confirmed using a modified population analysis profile-area under the curve method and broth microdilution. All hVISA and VISA isolates were characterized genotypically and phenotypically. RESULTS: Ten percent and 0.5 percent of the isolates were hVISA and VISA, respectively. The proportion of hVISA among MSSA isolates for the entire study period was 4.1%, but increased significantly year-by-year, from 1.2% in 2007 to 7.2% in 2010. The predominant sources of hVISA and VISA isolates were sputum (56.3%), pus (18.8%), and blood (8.8%). Molecular typing of hVISA and VISA strains revealed that, taken together, 80% contained the accessory gene regulator (agr) group II, and of these, 85.7% of the MR-hVISA and MR-VISA strains were staphylococcal cassette chromosome mec (SCCmec) type II. The adherence ability of all hVISA and VISA strains was reduced compared with that of vancomycin-susceptible strains, shown by biofilm assay. CONCLUSIONS: The percentage of hVISA strains was high and increased each year. The proportion of hVISA among MSSA specifically also increased significantly each year. In isolates collected from diverse infection sites, hVISA and VISA strains were found predominantly in sputum, pus, and blood, in descending order. Testing for vancomycin susceptibility should include both MRSA and MSSA isolates collected from different clinical sites.

Epidemiological and molecular characterization of community and hospital acquired Staphylococcus aureus strains prevailing in Shenyang, Northeastern China.

In order to obtain adequate information for the treatment of methicillin resistant Staphylococcus aureus (MRSA) infections, it is crucial to identify trends in epidemiological and antimicrobial resistance patterns of local S. aureus strains. Community and hospital acquired S. aureus isolates (n=202) were characterized using staphylococcal cassette chromosome mec (SCCmec) typing, pulse field gel electrophoresis (PFGE) analysis, spa typing and minimal inhibitory concentration (MIC) determination. The prevalence of the Panton-Valentine leukocidine (pvl) and several antibiotic resistance genes among the isolates were also detected by PCR. All of the S. aureus isolates were susceptible to vancomycin, daptomycin and linezolid. Three hospital isolates were resistant to teicoplanin while 14 showed intermediate resistance to teicoplanin. The resistance patterns of community-acquired MRSA (CA-MRSA) isolates to other antimicrobials were similar to those of hospital-acquired MRSA (HA-MRSA) isolates except for clindamycin and gentamicin. There was excellent correlation between phenotypes and genotypes in the determination of S. aureus resistance to erythromycin, gentamicin, and tetracycline. The SCCmec type II and SCCmec type IV were the predominant types detected in hospital and community isolates, respectively. The most frequently encountered spa types were t002 and t030 both in HA- and CA-MRSA isolates. Pulsotype A was the most predominant pulsotype identified among the isolates tested, followed by pulsotype B. Seventy-two hospital isolates (19 HA-MRSA and 53 HA-MSSA) and 10 CA-MRSA were positive for the pvl gene. This study shows that the combination of susceptibility testing and various molecular methods has provided useful information on the antibiotic resistance and molecular diversity of S. aureus in a specific region of China. The high proportion of pvl positive MSSA and MRSA isolates observed in this study indicates that adequate measures are needed to curtail the spread of those MRSA and MSSA clones prevailing both in hospital and the community.

[Distribution of Staphylococcus aureus strains colonized in healthy community population and molecular epidemiological characteristics for MRSA strains].

OBJECTIVE: To investigate the nasal colonization of Staphylococcus (S.) aureus strains among medical university students in Shenyang and to study the molecular epidemiological characteristics of methicillin resistant S. aureus (MRSA) strains. METHODS: Sterilized nasal swabs were used to collect nasal bacteria from both nares of the students. Nasal specimens were further identified as S. aureus strains, sensitive or resistant to methicillin through a series of tests. Molecular related methods including staphylococcal cassette chromosome mec (SCCmec) typing, pulsed- field gel electrophoresis (PFGE), coagulase isotyping and minimum inhibitory concentration (MIC) determination etc. were used to characterize the isolates. Prevalence of the panton-valentine leukocidin (pvl) genes (lukS and F-PV) among the isolates was also assessed. RESULTS: Staphylococci were found in 488 specimens from 977 participants through the surveillance program, conducted in 2009. Of the 488 specimens being tested, 364 were identified as coagulase-negative staphylococci (CoNS) and 124 as S. aureus. MRSA strain among the S. aureus isolates was accounted for 3.4%. In the surveillance program conducted in 2010, staphylococci grew in 310 specimens from 657 participants. Of the 310 specimens tested, 195 were identified as CoNS and 115 as S. aureus. The percentage of MRSA strains among the S. aureus isolates was 7.7%. In total, 239 students carried S. aureus, and the percentage of MRSA carriers among the total specimens tested in this study was 5.1%. Most of the MRSA strains could be classified into one of the five types of SCCmec elements. Type IV a SCCmec strains were most frequent seen overall (10 isolates). A total of 11 pulsotype were identified among the MRSA strains and were classified into 7 major groups (A to G) by the mutual correlations of their banding patterns. Ten MRSA strains were identified as pvl positive strains. CONCLUSION: An MRSA clone (IV a SCCmec pulsotype A) carrying pvl toxin gene was found to be prevalent in the nares of the healthy university students.

Antibiotic susceptibility of coagulase-negative staphylococci (CoNS): emergence of teicoplanin-non-susceptible CoNS strains with inducible resistance to vancomycin.

Coagulase-negative staphylococci (CoNS) have become increasingly recognized as important agents of nosocomial infection. One of the characteristics of CoNS is their resistance to multiple antimicrobial agents commonly used for the treatment of staphylococcal infections. CoNS strains (n = 745) isolated from a university teaching hospital in China between 2004 and 2009 were tested for antibiotic resistance. The antibiotics were placed into three categories based on resistance levels of the CoNS strains to these antibiotics: high resistance (resistance rate >70 %), including penicillin G, oxacillin and erythromycin; medium resistance (resistance rate between 30 and 70 %), including tetracycline, clindamycin, ciprofloxacin, trimethoprim/sulfamethoxazole and chloramphenicol; and low resistance (resistance rate <30 %), including rifampicin, ceftizoxime and gentamicin. We also found that the prevalence of strains non-susceptible to teicoplanin increased from 4.5 to 6.7 % between 2008 and 2009. A one-step vancomycin agar selection experiment and subsequent population analysis revealed potentially vancomycin-resistant subpopulations that have been selected from the teicoplanin-non-susceptible strains. Vigilant surveillance of nosocomial isolates of CoNS is needed to determine their resistance to glycopeptides.

Ionic parachor and its application in acetic acid ionic liquid homologue 1-alkyl-3-methylimidazolium acetate {[C(n)mim][OAc](n = 2,3,4,5,6)}.

Five acetic acid ionic liquids (AcAILs) [C(n)mim][OAc](n = 2,3,4,5,6) (1-alkyl-3-methylimidazolium acetate) were prepared by the neutralization method and characterized by (1)HNMR spectroscopy and differential scanning calorimetry (DSC). The values of their density and surface tension were measured at 298.15 ± 0.05 K. Since the AcAILs can strongly form hydrogen bonds with water, the small amounts of water are difficult to remove from the AcAILs by common methods. In order to eliminate the effect of the trace water, the standard addition method (SAM) was applied to these measurements. As a new concept, ionic parachor was put forward. [OAc](-) was seen as a reference ion, and its individual value of ionic parachor was determined in terms of two extrathermodynamic assumptions. Then, the values of ionic parachors of a number of anions, [NTf(2)](-), [Ala](-), [AlCl(4)](-), and [GaCl(4)](-), were obtained by using the value of the ionic parachor of the reference ion; the parachor and surface tension of the investigated ionic liquids in literature were estimated. In comparison, the estimated values correlate quite well with their matching experimental values.

Nasal carriage of methicillin-resistant Staphylococcus aureus among preclinical medical students: epidemiologic and molecular characteristics of methicillin-resistant S. aureus clones.

Between May 2008 and October 2009, a total of 2103 interns were randomly tested for nasal colonization of S. aureus and methicillin-resistant Staphylococcus aureus (MRSA). The prevalence of S. aureus among staphylococci specimens was 23.1%, and among the total S. aureus the MRSA prevalence was 9.4%. MRSA isolates were further subtyped using genetic element staphylococcal cassette chromosome mec (SCCmec) typing, pulsed-field gel electrophoresis (PFGE) band pattern, and multilocus sequence typing. SCCmec type IVa was the most prevalent strain, at 45.4 %. Eleven PFGE patterns were identified in MRSA strains, with 1 predominant (pulsotype A, 45.5%). Eight strains which belonged to clonal complex 78 carried type IVa SCCmec and produced type 3 coagulase. Panton-Valentine leukocidin (PVL) genes (lukS and F-PV) were identified in 10 (45.4%) MRSA strains; these predominately carried ϕSa2958type and ϕSa108PVL-like type PVL phages. After inducing prophages, 8 strains infected other S. aureus isolates and could generate novel PVL-positive strains of S. aureus. The present study demonstrates that interns can carry certain MRSA strains asymptomatically and contribute to the spread of MRSA between the community and hospital.

A novel type-III staphylococcal cassette chromosome mec (SCCmec) variant among Indian isolates of methicillin-resistant Staphylococcus aureus.

We identified a novel type-III staphylococcal cassette chromosome mec (SCCmec) element carried by eight methicillin-resistant Staphylococcus aureus (MRSA) strains from different wards and patients in an Indian hospital. Although the pulsed-field gel electrophoresis pattern and spa types of eight strains were identical and clonally related to other nosocomial Indian isolates that belonged to sequence type (ST) 239 and spa type t037, the minimum inhibitory concentration (MIC) of these eight variants was noticeably low compared with the typical type-III isolates from the same hospital, and we were unable to identify ccrC and hsdR by multiplex PCR, although mer operon and transposases A, B, and C of Tn554 were amplified. By amplifying the entire SCCmec region by long-range PCR and determining parts of the nucleotide sequences of one isolate (V14), we found that the strain carried a novel SCCmec element containing a 422 bp sequence, which is highly homologous to that identified in strain CCR1-9583, mer operon and plasmid pT181 integrated in tandem via IS431 in the J3 region. It also carried a cassette chromosome, previously reported to be an SCC-like element, downstream of type-III SCCmec. Because PCR amplification of representative genes showed that these eight strains carried the same genetic elements, they belong to a novel MRSA clone that differs from most nosocomial clones carrying type-III SCCmec and SCCmercury, despite belonging to the ST239 genotype.

Epidemiological and molecular characterization of community and hospital acquired Staphylococcus aureus strains prevailing in Shenyang, Northeastern China

In order to obtain adequate information for the treatment of methicillin resistant Staphylococcus aureus (MRSA) infections, it is crucial to identify trends in epidemiological and antimicrobial resistance patterns of local S. aureus strains. Community and hospital acquired S. aureus isolates (n = 202) were characterized using staphylococcal cassette chromosome mec (SCCmec) typing, pulse field gel electrophoresis (PFGE) analysis, spa typing and minimal inhibitory concentration (MIC) determination. The prevalence of the Panton-Valentine leukocidine (pvl) and several antibiotic resistance genes among the isolates were also detected by PCR. All of the S. aureus isolates were susceptible to vancomycin, daptomycin and linezolid. Three hospital isolates were resistant to teicoplanin while 14 showed intermediate resistance to teicoplanin. The resistance patterns of community-acquired MRSA (CA-MRSA) isolates to other antimicrobials were similar to those of hospital-acquired MRSA (HA-MRSA) isolates except for clindamycin and gentamicin. There was excellent correlation between phenotypes and genotypes in the determination of S. aureus resistance to erythromycin, gentamicin, and tetracycline. The SCCmec type II and SCCmec type IV were the predominant types detected in hospital and community isolates, respectively. The most frequently encountered spa types were t002 and t030 both in HA-and CA-MRSA isolates. Pulsotype A was the most predominant pulsotype identified among the isolates tested, followed by pulsotype B. Seventy-two hospital isolates (19 HA-MRSA and 53 HA-MSSA) and 10 CA-MRSA were positive for the pvl gene. This study shows that the combination of susceptibility testing and various molecular methods has provided useful information on the antibiotic resistance and molecular diversity of S. aureus in a specific region of China. The high proportion of pvl positive MSSA and MRSA isolates observed in this study indicates that adequate measures are needed to curtail the spread of those MRSA and MSSA clones prevailing both in hospital and the community.