ABSTRACT
Staphylococcus aureus is recognized as one of the major causes of infections in humans occurring in both, the community and the hospitals. Community-acquired methicillin-resistant Staphylococcus aureus [CA-MRSA] appears to be a new emerging pathogen, which can cause fatal necrotizing pneumonia, skin, and soft tissue infections. Common features of these CA-MRSA strains are the presence of the Panton-Valentine leucocidin [PVL] genes. The aim of this study was to assess the prevalence of Panton-Valentine leucocidin [PVL] encoding genes lukF and lukS among Methicillin-resistant Staphylococcus aureus [MRSA] clinical isolates, and to investigate its association with various types of staphylococcal diseases. Forty seven MRSA isolates were recovered from unique patient clinical specimens: skin and soft tissue infections [SSTI], n=18; bronchoalveolar lavage [BAL] from clinically diagnosed cases of pneumonia, n=20 ; surgical site infections [SSI], n=7; and central venous line [CVL] catheter tip, n=2. Specimens were collected during the period between June 2005 through May 2006. All isolates were tested for the presence of mecA and PVL genes [lukS/F] by single target polymerase chain reaction [PCR]. All isolates were mecA gene positive. The PVL genes were detected in 8[17.02%] of the 47 MRSA isolates included in the study. The prevalence of PVL genes varies with the type of specimen from which MRSA isolates were recovered; 27.8% [5/18] among isolates associated with SSTI, 15% [3/20] among isolates from cases of pneumonia all of them were found to be community-acquired pneumonia; one of them was recovered from a case of acute necrotizing pneumonia. No PVL genes were detected from MRSA isolates recovered from cases of hospital acquired infections including SSI or CVL catheter tips. PVL genes are prevalent among community- acquired MRSA strains with no prevalence among hospital acquired strains. The presence of PVL genes is related to disease severity especially acute necrotizing pneumonia. Close surveillance of these strains is essential to monitor their spread, antimicrobial resistance profiles, and association with disease severity
ABSTRACT
Atypical organisms such as Mycoplasma pneumoniae, Chlamydia pneumoniae, and Legionella pneumophila are implicated in up to 40 percent of cases of community-acquired pneumonia. Culture is labor-intensive, takes several days to weeks for growth, and can be very insensitive for the detection of some of these organisms. Antibiotic treatment is empiric and includes coverage for both typical and atypical organisms.In the present study we investigate the occurrence Mycoplasma pneumoniae, Chlamydia pneumoniae, and Legionella pneumophila as atypical pathogens responsible for considerable cases of atypical pneumonia.Among 71 bronchoalveolar lavage specimens taken from patients presented clinically with community-acquired pneumonia admitted to Al-noor specialist Hospital Holly Makkah, KSA., PCR results showed that 14 cases [19.7%] gave positive results for Mycoplasma pneumoniae,16 cases [22.5%] gave positive results for Chlamydia pneumoniae and only 4 [5.6%] cases gave positive results for Legionella pneumophila. All our patients were living in an air conditioned atmosphere due to high temperature in the holly Makkah city. Two[2.8%] mortality cases from Legionella pneumophila were reported. Because of the non-specificity in clinical presentation of atypical pneumonia, specialized laboratory tests are necessary to establish the diagnosis. The PCR method is a rapid, sensitive and specific technique that has been applied to the detection of many infectious pathogens. Different PCR-based assays for the detection of Mycoplasma pneumoniae, Chlamydia pneumoniae, and Legionella pneumophila in clinical specimens have been described