Clonal complexes and virulence factors of Staphylococcus aureus from several cities in India

Abstract

BackgroundDiseases 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.ResultsMolecular 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.ConclusionsS. 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.

Panton-Valentine leukocidin-positive Staphylococcus aureus osteomyelitis of the tibia in a 10-year-old child

“…Further, a recent study in rural India has identified MRSA as replacing MSSA in causing many community-acquired soft-tissue infections, being responsible for 64.7% of community-acquired S. aureus infections in the series described [13]. One can only speculate about the significance of the insect bites in the current case, and, of note, the dominant sequence types identified in India have been ST22 and ST772, which are different from the organism identified here, although 69% PVL positivity is identified among strains in India [14]. The strain of MRSA described in our case report was characterized by spa typing (using the polymorphous X region of the protein A gene) rather than multilocus sequence typing, but spa t021 has been shown to correspond with ST030 on multilocus sequence typing [15].…”

Global epidemiology of community-associated methicillin resistant Staphylococcus aureus (CA-MRSA)

“…USA400 appears to be more virulent than USA300 [6 ], but is rarely isolated in the U.S. outside of the aforementioned regions. In recent years, ST772-V (Bengal Bay clone), a single locus variant of ST1 (differing by a single MLST allele), has emerged as a virulent and unusually resistant CA-MRSA strain in Bangladesh and India [31], and is increasingly reported in the U.K. and Europe [23 ,32].…”

High Prevalence of Ciprofloxacin Resistance in Community Associated <i>Staphylococcus aureus</i> in a Tertiary Care Indian Hospital

“…There has been no systematic analysis of ciprofloxacin resistance associated with particular genetic back grounds or diseases [10]. This study involves ciprofloxacin resistant MRSA and MSSA isolates, their genetic backgrounds and mutations important in causing the resistance as we have analyzed the clonal complexes present among Indian S. aureus isolates in an earlier study [11]. ST772 (single locus variant of ST1) is one of the prominent sequence types present among Indian community associated S. aureus, and there is not much information on resistance to this antibiotic and its mechanism [11][12][13].…”

“…This study involves ciprofloxacin resistant MRSA and MSSA isolates, their genetic backgrounds and mutations important in causing the resistance as we have analyzed the clonal complexes present among Indian S. aureus isolates in an earlier study [11]. ST772 (single locus variant of ST1) is one of the prominent sequence types present among Indian community associated S. aureus, and there is not much information on resistance to this antibiotic and its mechanism [11][12][13]. This work demonstrates that a high percentage of patients in this tertiary care hospital carry CA-MRSA which is highly resistant to ciprofloxacin and a single mutation in gyrA gene is responsible for high resistance in ST772.…”