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  Table of Contents  
Year : 2017  |  Volume : 35  |  Issue : 1  |  Page : 146-147

Prevalence of bi-component pore-forming toxin genotypes of Staphylococcus aureus causing skin and soft tissue infections

1 Department of Microbiology, Dr. ALM PG Institute of Basic Medical Sciences, University of Madras, Chennai, India
2 Department of Microbiology, Government Dharmapuri Medical College, Dharmapuri, Tamil Nadu, India

Date of Web Publication16-Mar-2017

Correspondence Address:
Padma Krishnan
Department of Microbiology, Dr. ALM PG Institute of Basic Medical Sciences, University of Madras, Chennai
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ijmm.IJMM_16_424

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How to cite this article:
Perumal N, Dass BS, Mani S, Krishnan P. Prevalence of bi-component pore-forming toxin genotypes of Staphylococcus aureus causing skin and soft tissue infections. Indian J Med Microbiol 2017;35:146-7

How to cite this URL:
Perumal N, Dass BS, Mani S, Krishnan P. Prevalence of bi-component pore-forming toxin genotypes of Staphylococcus aureus causing skin and soft tissue infections. Indian J Med Microbiol [serial online] 2017 [cited 2020 Apr 5];35:146-7. Available from:

Dear Editor,

Staphylococcus aureus is the most challenging human pathogen causing a wide range of diseases from skin and soft tissue infections (SSTIs) to life-threatening systemic infections and is a leading cause of hospital-associated (HA) and community-associated (CA) infections worldwide.[1] Staphylococci evade immune system, through the production of a huge array of membrane damaging toxins such as leukocidins and haemolysins.[2] Bi-component pore-forming toxins consist of two classes of proteins denoted as S and F subunits and have been classified into different families. This staphylococcal toxin family comprises well-known Panton-Valentine Leukocidin (PVL) (LukS-PV/LukF-PV) as well as the gamma haemolysin (Hlg) and the more recently described LukA/B, LukE/D and LukM/LukF-PV leukocidins. These toxins are the potent virulence factors of S. aureus causing SSTIs.[3],[4] Hence, the study was aimed to determine the prevalence of bi-component pore-forming toxins in S. aureus isolated from SSTIs. A total of 106 S. aureus isolates causing SSTIs obtained from tertiary care hospitals were included in this study. Screening of methicillin-resistant S. aureus (MRSA) was done using cefoxitin disc diffusion method and interpreted as per the CLSI guidelines (2015). DNA was extracted using QIAGEN DNeasy extraction kit (Qiagen, Germany) as per the manufacturer's protocol and using lysostaphin. A rapid triplex polymerase chain reaction (PCR; femA, mecA, lukS) was performed for the detection of MRSA and PVL gene.[5] Two different multiplex PCR procedures were employed to amplify gene fragments specific for LukE/LukD, LukM/LukF-PV and Hlg, respectively.[6],[7],[8]S. aureus MW2 and S. aureus NCTC 7428 were used as positive controls. Of the tested isolates, 46% (n = 49) were found to be methicillin resistant by both cefoxitin disc diffusion method and mecA PCR. Among MRSA, 59% (n = 29) isolates were CA-MRSA and 41% (n = 20) were HA-MRSA. All the tested leukocidin genes were found to be negative in 38.6% (n = 41) of tested S. aureus isolates. Distribution of staphylococcal toxin genes in inpatients and outpatients is given in [Table 1]. The gene lukS was the predominant leukocidin and was observed in 58.9% of MRSA and 41% of MSSA isolates. The incidence of infection with PVL-producing S. aureus was significantly higher in outpatients (69%) than from inpatients (17.3%). None of the isolates were positive for Hlg gene and lukM gene. The combined toxin profile of lukS+ lukE/D+ lukM hlg was seen in two CA methicillin-susceptible isolates. The present study highlights the trend of increasing methicillin resistance and the high prevalence of genotype lukS+ lukE/D lukM hlg among CA-MRSA isolates causing SSTIs.
Table 1: Distribution of staphylococcal bi.component pore.forming toxin genotypes among study isolates

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We acknowledge the Government Dharmapuri Medical College, Dharmapuri, Tamil Nadu for providing the isolates for the study. The authors would also like to acknowledge Mr. Suresh Jothi Kumar for his support.

Financial support and sponsorship

This work was partly funded by DST-PURSE and DST-INSPIRE fellowships awarded to Nagaraj Perumal and Betsy Sowndarya Dass, respectively.

Conflicts of interest

There are no conflicts of interest.

 ~ References Top

Lowy FD. Staphylococcus aureus infections. N Engl J Med 1998;339:520-32.  Back to cited text no. 1
Otto M. Staphylococcus aureus toxins. Curr Opin Microbiol 2014;17:32-7.  Back to cited text no. 2
Aman MJ, Adhikari RP. Staphylococcal bicomponent pore-forming toxins: Targets for prophylaxis and immunotherapy. Toxins (Basel) 2014;6:950-72.  Back to cited text no. 3
von Eiff C, Friedrich AW, Peters G, Becker K. Prevalence of genes encoding for members of the staphylococcal leukotoxin family among clinical isolates of Staphylococcus aureus. Diagn Microbiol Infect Dis 2004;49:157-62.  Back to cited text no. 4
Abimanyu N, Krishnan A, Murugesan S, Subramanian GK, Gurumurthy S, Krishnan P. Use of triplex PCR for rapid detection of PVL and differentiation of MRSA from methicillin resistant coagulase negative staphylococci. J Clin Diagn Res 2013;7:215-8.  Back to cited text no. 5
Shukla SK, Karow ME, Brady JM, Stemper ME, Kislow J, Moore N, et al. Virulence genes and genotypic associations in nasal carriage, community-associated methicillin-susceptible and methicillin-resistant USA400 Staphylococcus aureus isolates. J Clin Microbiol 2010;48:3582-92.  Back to cited text no. 6
Jarraud S, Mougel C, Thioulouse J, Lina G, Meugnier H, Forey F, et al. Relationships between Staphylococcus aureus genetic background, virulence factors, agr groups (alleles), and human disease. Infect Immun 2002;70:631-41.  Back to cited text no. 7
Jarraud S, Lyon GJ, Figueiredo AM, Lina G, Vandenesch F, Etienne J, et al. Exfoliatin-producing strains define a fourth agr specificity group in Staphylococcus aureus. J Bacteriol 2000;182:6517-22.  Back to cited text no. 8


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