title: Clonal complexes and virulence factors of Staphylococcus aureus from several cities in India.
abstract: BACKGROUND
  Diseases from Staphylococcus aureus are a major problem in Indian hospitals and recent studies point to infiltration of community associated methicillin resistant S. aureus (CA-MRSA) into hospitals. Although CA-MRSA are genetically different from nosocomial MRSA, the distinction between the two groups is blurring as CA-MRSA are showing multidrug resistance and are endemic in many hospitals. Our survey of samples collected from Indian hospitals between 2004 and 2006 had shown mainly hospital associated methicillin resistant Staphylococcus aureus (HA-MRSA) carrying staphylococcal cassette chromosome mec (SCCmec) type III and IIIA. But S. aureus isolates collected from 2007 onwards from community and hospital settings in India have shown SCCmec type IV and V cassettes while several variations of type IV SCCmec cassettes from IVa to IVj have been found in other parts of the world. In the present study, we have collected nasal swabs from rural and urban healthy carriers and pus, blood etc from in patients from hospitals to study the distribution of SCCmec elements and sequence types (STs) in the community and hospital environment. We performed molecular characterization of all the isolates to determine their lineage and microarray of select isolates from each sequence type to analyze their toxins, virulence and immune-evasion factors.
  
  
  RESULTS
  Molecular analyses of 68 S. aureus isolates from in and around Bengaluru and three other Indian cities have been carried out. The chosen isolates fall into fifteen STs with all major clonal complexes (CC) present along with some minor ones. The dominant MRSA clones are ST22 and ST772 among healthy carriers and patients. We are reporting three novel clones, two methicillin sensitive S. aureus (MSSA) isolates belonging to ST291 (related to ST398 which is live stock associated), and two MRSA clones, ST1208 (CC8), and ST672 as emerging clones in this study for the first time. Sixty nine percent of isolates carry Panton- Valentine Leucocidin genes (PVL) along with many other toxins. There is more diversity of STs among methicillin sensitive S. aureus than resistant ones. Microarray analysis of isolates belonging to different STs gives an insight into major toxins, virulence factors, adhesion and immune evasion factors present among the isolates in various parts of India.
  
  
  CONCLUSIONS
  S. aureus isolates reported in this study belong to a highly diverse group of STs and CC and we are reporting several new STs which have not been reported earlier along with factors influencing virulence and host pathogen interactions.
authors.affiliation: Society for Innovation and Development, Department of Microbiology, Indian Institute of Science, Bengaluru 560012, India.
authors.forename: Srikanth
authors.initials: S
authors.lastname: Shambat
authors.forename: Savitha
authors.initials: S
authors.lastname: Nadig
authors.forename: Sushma
authors.initials: S
authors.lastname: Prabhakara
authors.forename: Michele
authors.initials: M
authors.lastname: Bes
authors.forename: Jerome
authors.initials: J
authors.lastname: Etienne
authors.forename: Gayathri
authors.initials: G
authors.lastname: Arakere
mesh_terms: D002353:Carrier State / Q000453:epidemiology / Q000382:microbiology; D002947:Cities; D016000:Cluster Analysis; D017714:Community-Acquired Infections / Q000453:epidemiology / Q000382:microbiology; D003428:Cross Infection / Q000453:epidemiology / Q000382:microbiology; D005838:Genotype; D006801:Humans; D007194:India / Q000453:epidemiology; D046228:Microarray Analysis; D017720:Molecular Epidemiology; D058889:Molecular Typing; D017422:Sequence Analysis, DNA; D013203:Staphylococcal Infections / Q000453:epidemiology* / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity*; D037521:Virulence Factors / Q000235:genetics*
chemical_list: D037521:Virulence Factors