Identification of Panton-Valentine leukocidin virulence gene in methicillin-resistant Staphylococcus aureus isolated from clinical specimens of burn patients in Zare Hospitals of Sari, Iran

Objective:To identify the pathogenic gene of Panton-Valentine leukocidin in methicillin-resistant Staphylococcus aureus strain isolated from clinical specimens of burn patients in Shaheed Zare Burn Hospital.Methods:A total of 104 samples of Staphylococcus were collected and 78 aureus samples were isolated from Zare Hospital patients from November 2016 to July 2017.All isolates were identified using a standard biochemical and laboratory methodology in accordance with CLSI principles,and disk agar diffusion antibiogram were performed to identify methicillin resistant colonies.Then the presence of the Panton-Valentine leukocidin gene was tested by PCR.Results:Of the methicillin-resistant Staphylococcus aureus samples,80%were negative for the Panton-Valentine leukocidin gene,and only 20%of the samples had Panton-Valentine leukocidin gene.Male and female patients showed no significant difference in the positivity rate of Panton-Valentine leukocidin gene(16.12%vs.33.33%)(P=0.25).Besides,there was no significant difference in bacterial resistance or susceptibility to antibiotics between samples with or without the Panton-Valentine leukocidin gene.Conclusions:In recent years,increased resistance has been a serious threat.The resistance or susceptibility of Staphylococcus aureus strains to different antibiotics is different in different geographical locations.

Identification of a T-cell epitope in the <i>Staphylococcus aureus</i>Panton-Valentine LukS-PV component

We previously observed the elicitation of a significant delayed-type hypersensitivity response to the Panton-Valentine leukocidin (PVL) LukS-PV subunit following subcutaneous immunization (Brown et al., Clinical Microbiology and Infection, 2009, 156: 156-164). A LukS-PV-specific cell line (LST) was screened for proliferative responses against a panel of 25 amino acid-long peptides spanning the length of LukS-PV (amino acids 29-312). This analysis demonstrated that stimulation of LST with LukS-PV resulted in significant proliferative responses and adoptive transfer of LST into na?ve mice conferred a LukS-PV-specific DTH response following challenge. Challenge of mice adoptively transferred with LST with peptides 7 (149-173), 8 (169-193) and 14 (289-312) also elicited a measurable DTH response suggesting that these peptides contained T cell epitopes.

Prevalence of Panton Valentine Leukocidin in Carriage and Infective Strains of <i>Staphylococcus aureus</i>at a Referral Hospital in Kenya

Panton valentine leukocidin (PVL) is a pore forming exotoxin that is expressed by some Staphylococcus aureus (S. aureus) strains and is thought to add to its virulence. The prevalence of PVL in carriage and disease causing strains varies considerably from region to region. This study compared the prevalence of the PVL gene in S. aureus isolates obtained from healthcare workers and from patients seen at the Aga Khan University Hospital Nairobi (AKUHN). S. aureus isolates obtained from healthcare workers and patients attended to at AKUHN between July 2010 and March 2011 were used for this study. Forty five S. aureus isolates from healthcare workers and 63 from clinical specimens obtained from 59 patients were analysed for the PVL gene. The prevalence of PVL in isolates from healthcare workers was 24.4% compared to 39.7% in the isolates causing infection (P = 0.098). PVL prevalence was 58.8% in S. aureus isolates obtained from skin and soft tissue infections (SSIs) compared to 25.0% in carriage isolates (P = 0.002, OR 4.29). Prevalence in isolates from invasive infections was 11.1%. Patients with PVL positive S. aureus were younger than those with PVL negative isolates (P = 0.082). The high prevalence of PVL is comparable with that reported in other African countries. The significance of the high prevalence of PVL in S.aureus isolates carried by health care workers at AKUHN is unclear at the moment. PVL prevalence is significantly higher in S. aureus isolates causing SSIs compared to carriage and invasive isolates.

Screening for Panton-Valentine Leukocidin Toxin Genes in Multi-Drug Resistant Methicillin-Resistant <i>Staphylococcus aureus</i>Nasal Isolates from Healthy School Children in Mariental, Namibia

Panton-Valentine leukocidin (PVL) is one of the toxins responsible for increased virulence of Staphylococcus aureus. In school settings where children are in close contact with each other, S. aureus strains, including those that may produce PVL, can be transmitted and spread in the community. Twenty-two multi-drug resistant MRSA nasal isolates from children enrolled in five schools in the town of Mariental and the multi-drug resistant American Type Culture Collection MRSA reference strain S. aureus ATCC 33591 (PVL-negative control) were used for molecular assays. Plasmid deoxyribonucleic acid (DNA) of isolates was amplified by polymerase chain reaction (PCR) and amplified PCR products were electrophoresed on a 2.5% (w/v) agarose gel containing 12 μl 0.5 μg/ml ethidium bromide and 1× TAE (Tris-acetate-EDTA) buffer at 90 volts for 50 minutes. The developed gel was viewed for the PVL-associated lukS and lukF genes that amplified at 151 bp and 406 bp, respectively. Our results indicated that seven nasal isolates had PVL toxin gene(s). From the seven isolates, three were tested positive for both lukS and lukFgenes, one tested positive for only lukS, and three tested positive for only lukF. Two of the isolates harbouring both lukS and lukF genes shared the same antibiotic resistance pattern and one of them could also produce enterotoxin A. One of the isolates with only lukF gene could produce enterotoxins B and C. These toxin-producing isolates can be expected to be more virulent than non-producers. Children should be educated on the importance of regular handwashing with soap and water to prevent the spread of potentially virulent staphylococci amongst them and the wider community. This work warrants a larger study to be carried out to investigate PVL toxin and its associated infections in Staphylococcus from school children in Namibia.

Molecular Diversity of <i>Staphylococcus aureus</i>from the Nares of Hospital Personnel, HIV-Positive and Diabetes Mellitus Patients in Yaounde Cameroon

Nasal carriage of Staphylococcus aureus has been identified as a risk factor for the development of staphylococcal infections caused by endogenous colonizing strains. Information on the genotypic diversity of Staphylococcus aureus is relevant for managing epidemiological and clinical challenges resulting from the evolutionary differences of this bacterium. The objective of this study was to determine and compare the molecular diversity of Staphylococcus aureus isolates from three high-risk populations in Yaounde, Cameroon. Molecular analysis confirmed that 95% of 100 tested isolates were S. aureus. The mecA and Panton Valentine-Leukocidin (PVL) genes (lukS/F-PV) were detected in 37% (35/95) and 43% (41/95) of isolates respectively and 18% (17/95) of the isolates harboured both the mecA and lukS/F-PV genes. A mixed distribution of both methicillin sensitive S. aureus (MSSA)/PVL and methicillin resistant S. aureus (MRSA)/PVL strains were detected within the study population. Community associated MRSA accounted for 94% (33/35) of the isolates, further classified into allotypes SCCmec type IV 54% (19/35) and SCCmec type V 40% (14/35), while two isolates were hospital associated SCCmec type II strains. A majority of the isolates harboured a single aggressive gene regulator allele agr type I. Pulsed Field Gel Electrophoresis (PFGE) generated 18 pulsotypes that grouped isolates irrespective of the study population. Multilocus Sequence Typing (MLST) of 12 selected isolates was assigned to six pandemic clonal complexes (CC): CC5 (ST5), CC8 [ST8, (n = 3)], CC15 (ST 15), CC25 (ST 25), CC72 [ST72 (n = 2)] and CC121 [ST 121 (n = 2)] and three atypical sequence types ST 508, ST 699 (CC45) and ST 1289 (CC 88). The study population represents an important reservoir for MRSA, MRSA-PVL and MSSA-PVL which could serve as focal point for further dissemination bringing about significant clinical and epidemiological implications. The predominance of SCCmec IV and agr types in this setting warrants further investigation. Isolates were genetically diverse with MLST indicating that pandemic ST8 was predominant. Detection of atypical STs has provided an insight into the necessity for constant monitoring.