ReviewPrevalence and genotype distribution of methicillin-resistant Staphylococcus aureus (MRSA) in India
Introduction
Staphylococcus aureus is a highly versatile and adaptive pathogen that causes a wide spectrum of diseases ranging from minor local infections to fatal systemic syndromes [1]. The success of S. aureus as a pathogen is due to its ability to express various types of virulence factors and to form biofilm. These determinants not only help S. aureus to invade the host but also to resist the action of antimicrobials and host defence mechanisms, facilitating the establishment of persistent and recurring infections [2], [3], [4]. These properties make S. aureus a resilient pathogen and, not surprisingly, methicillin-resistant S. aureus (MRSA) has become one of the most significant nosocomial pathogens worldwide today. The first description of MRSA was in the UK in 1961, and this was followed soon thereafter by reports elsewhere—in Europe in 1965, in Australia in 1966, in the USA in 1968 and in Asia in the 1970s [5], [6].
MRSA can be genotyped by one or more of several molecular techniques [7], including pulsed-field gel electrophoresis (PFGE) [8], multilocus sequence typing (MLST) [9] (http://saureus.mlst.net), staphylococcal protein A (spa) typing [10] (http://spaserver.ridom.de) and staphylococcal cassette chromosome mec (SCCmec) typing [11]. The different typing techniques are employed for different purposes. PFGE and spa typing are very useful for short-term epidemiological studies, whereas MLST, which can be applied to phylogenetic analyses, can be used for longitudinal and long-term studies. PFGE is a PCR-independent technique where chromosomal DNA is subjected to restriction digestion followed by electrophoresis under an alternating voltage gradient. PFGE used to be the gold standard to investigate MRSA outbreaks in hospitals as well as to probe hospital-to-hospital transmission. However, in addition to poor extrapolation between laboratories, some studies have reported that PFGE is less reproducible and therefore less useful for long-term surveillance [12]. These drawbacks can be overcome by MLST, which involves PCR amplification and sequencing of seven housekeeping genes followed by allelic profiling and assigning of sequence types (STs) to each strain. Further, groups of STs in which every ST shares at least five of seven identical alleles with at least one other ST in the group are referred to as clonal complexes (CCs). Although laborious, MLST has been reported to be a useful tool for studying the phylogenetic relationship and evolutionary biology of isolates. Discrimination between strains and extrapolation of data between laboratories can also be achieved by spa typing, which involves PCR and sequencing for the single locus of spa as opposed to seven loci for MLST. MRSA can also be classified by SCCmec typing, which involves PCR for one or more of the mec, ccr, cch and ccu loci. As of 28 June 2016, 3112 STs (http://saureus.mlst.net/sql/sthtml.asp), 16 071 spa types (http://www.spaserver.ridom.de/) and 11 SCCmec types (I through XI, some further subclassified into A, B, C1, C2 and E) (http://www.sccmec.org/Pages/SCC_TypesEN.html) have been identified.
Outbreak strains of MRSA, which can cause a sudden rise in the incidence of infections, can be grouped into hospital/healthcare-associated (HA) or community-associated (CA) MRSA. Traditionally, HA-MRSA is considered to be of nosocomial origin and usually causes infections upon prolonged hospitalisation or in patients with indwelling devices, or those undergoing dialysis, surgery, or antimicrobial or immunosuppressive therapy [13]. By contrast, CA-MRSA strains originate from healthy individuals with no risk factors or previous healthcare contact and constitute a major proportion of skin and soft-tissue infections (SSTIs) [14]. CA-MRSA is typically susceptible to most antibiotics except methicillin and β-lactams [15]. Genotypically, HA-MRSA mainly carry SCCmec types I, II and III (1B, 2A and 3A in the newly proposed nomenclature), whilst CA-MRSA generally carry SCCmec types IV and V (2B and 5C2) [16].
A vast amount of information is available from several countries on the prevalence of MRSA. It has been observed that several clones have circulated or have been circulating in different parts of the world. These include the USA (100, 200, 300, etc.), the epidemic MRSA (EMRSA-1, −15, −16, etc.), the Western Australia (WA) and the Canadian MRSA (CMRSA) series as well as other clones, each of which harbour a few characteristic genetic loci [17].
Remarkably, a restricted number of genotypes appear to dominate specific outbreaks, sometimes in particular geographical areas. Of late, however, some of the clones have spread beyond their initial geographic boundaries [17]. It would be interesting and important to map and characterise the global distribution of genotypes in order to not only elucidate evolutionary relationships and movement of clones from one place to another, but also to design potential intervention strategies. However, data from developing and resource-constrained countries are scarce. This review presents the current knowledge about genotype and sequence characteristics of MRSA in India.
Section snippets
Literature search
PubMed, Medline and Google Scholar were mined for the search terms ‘MRSA’, ‘genotype’, ‘prevalence’ and/or ‘India’ and 361 abstracts and 205 manuscripts published between 1990 and 2016 were identified for inclusion in this review. After reviewing all of the relevant abstracts and articles, 86 full-length articles containing unambiguous genotyping information based on at least one of the methodologies described above were considered for discussion.
Conclusions
It is becoming clear that MRSA is as pervasive in India as it is worldwide and that both HA-MRSA and CA-MRSA are prevalent. Although certain spa types may be more frequent, MRSA from India are distributed among all of the SCCmec types. The majority of HA-MRSA belong to SCCmec III ST239, whereas CA-MRSA mostly belong to SCCmec IV ST22, SCCmec V ST772 and SCCmec V ST672 genotypes (Table 2). Similar to trends globally, CA-MRSA infections as well as vancomycin resistance appear to be on the rise in
Conflicts of interest
The authors certify that they have no affiliations with or involvement in any organization or entity with any interest, financial or non-financial, in the subject matter or materials discussed in this manuscript.
Funding
None.
Ethical approval
Not required.
References (86)
- et al.
Staphylococcus aureus virulence factors in evasion from innate immune defenses in human and animal diseases
Immunol Lett
(2013) Staphylococcus aureus toxins
Curr Opin Microbiol
(2014)- et al.
Typing of methicillin resistant Staphylococcus aureus: a technical review
Indian J Med Microbiol
(2012) - et al.
Health care-associated MRSA versus community-associated MRSA
Dis Mon
(2008) Community-associated MRSA: what makes them special?
Int J Med Microbiol
(2013)- et al.
Global epidemiology of community-associated methicillin resistant Staphylococcus aureus (CA-MRSA)
Curr Opin Microbiol
(2012) - et al.
Nasal carriage of methicillin-resistant Staphylococcus aureus in medical students
J Hosp Infect
(2008) - et al.
Screening for methicillin-resistant Staphylococcus aureus carriers among patients and health care workers of a tertiary care hospital in South India
Indian J Med Microbiol
(2009) - et al.
New epidemiology of Staphylococcus aureus in Asia
Clin Microbiol Infect
(2014) - et al.
Nasal carriage of methicillin-resistant Staphylococcus aureus among healthy population of Kashmir, India
Indian J Med Microbiol
(2014)
Emergence of methicillin-resistant, vancomycin-intermediate Staphylococcus aureus among patients associated with group A streptococcal pharyngitis infection in southern India
Infect Genet Evol
Genotype-specific prevalence of heterogeneous vancomycin-intermediate Staphylococcus aureus in Asian countries
Int J Antimicrob Agents
Strain relatedness of endemic MRSA isolates in a burns unit in South India—a five-year study
J Hosp Infect
Clinical and molecular characteristics of nosocomial methicillin-resistant Staphylococcus aureus skin and soft tissue isolates from three Indian hospitals
J Hosp Infect
Epidemiology of Staphylococcus aureus in Bangalore, India: emergence of the ST217 clone and high rate of resistance to erythromycin and ciprofloxacin in the community
New Microbes New Infect
Genotyping of community-associated methicillin resistant Staphylococcus aureus (CA-MRSA) in a tertiary care centre in Mysore, South India: ST2371-SCCmec IV emerges as the major clone
Infect Genet Evol
Livestock-associated meticillin-resistant Staphylococcus aureus in Asia: an emerging issue?
Int J Antimicrob Agents
Livestock-associated Staphylococcus aureus CC398: animal reservoirs and human infections
Infect Genet Evol
Molecular surveillance of putative virulence factors and antibiotic resistance in Staphylococcus aureus isolates recovered from intra-mammary infections of river buffaloes
Microb Pathog
Staphylococcus aureus infections
N Engl J Med
Staphylococcal infections: mechanisms of biofilm maturation and detachment as critical determinants of pathogenicity
Annu Rev Med
‘Celbenin’-resistant staphylococci
Br Med J
The global spread of healthcare-associated multidrug-resistant bacteria: a perspective from Asia
Clin Infect Dis
Interpreting chromosomal DNA restriction patterns produced by pulsed-field gel electrophoresis: criteria for bacterial strain typing
J Clin Microbiol
Multilocus sequence typing for characterization of methicillin-resistant and methicillin-susceptible clones of Staphylococcus aureus
J Clin Microbiol
Molecular typing of methicillin-resistant Staphylococcus aureus on the basis of protein A gene polymorphism
Eur J Clin Microbiol Infect Dis
Multiplex PCR strategy for rapid identification of structural types and variants of the mec element in methicillin-resistant Staphylococcus aureus
Antimicrob Agents Chemother
Methicillin-resistant Staphylococcus aureus: site of acquisition and strain variation in high-risk nursing home residents with indwelling devices
Infect Control Hosp Epidemiol
Guidelines for reporting novel mecA gene homologues
Antimicrob Agents Chemother
Prevalence of methicillin-resistant Staphylococcus aureus colonization among healthcare workers and healthy community residents
J Health Popul Nutr
Molecular epidemiology of clinical and carrier strains of methicillin resistant Staphylococcus aureus (MRSA) in the hospital settings of North India
Ann Clin Microbiol Antimicrob
Nasal carriage of methicillin-resistant Staphylococcus aureus among surgical unit staff
Jpn J Infect Dis
An increased incidence of biofilm-producing multidrug-resistant methicillin-resistant Staphylococcus aureus in a tertiary care hospital from India: a 2-year study
Am J Infect Control
Prevalence of methicillin resistant Staphylococcus aureus carriage amongst health care workers of critical care units in Kasturba Medical College, Hospital, Mangalore, India
J Clin Diagn Res
The prevalence of nasal carriage of Staphylococcus aureus among healthcare workers at a tertiary care hospital in Assam with special reference to MRSA
J Clin Diagn Res
Methicillin resistant Staphylococcus aureus carriage among the health care workers in a tertiary care hospital
J Clin Diagn Res
Methicillin resistant Staphylococcus aureus (MRSA) in India: prevalence and susceptibility
Indian J Med Res
Methicillin resistant Staphylococcus aureus (MRSA) in skin isolates from hospital acquired infections
Indian J Dermatol Venereol Leprol
Growing problem of methicillin resistant staphylococci—Indian scenario
Indian J Med Sci
A pilot programme of MRSA surveillance in India (MRSA Surveillance Study Group)
J Postgrad Med
Drug resistance pattern of methicillin resistant Staphylococcus aureus
Indian Pediatr
The spectrum of antimicrobial resistance among methicillin resistant Staphylococcus aureus (MRSA) in a tertiary care centre in India
Indian J Med Res
A community-based study on nasal carriage of Staphylococcus aureus
Indian J Med Res
Cited by (0)
- 1
Present address: Center for Immunology and Microbial Diseases, MS-251, Albany Medical College, 47 New Scotland Avenue, Albany, NY 12208, USA.