Detection of panton valentine gene in some clinical isolates of methicillin resistant staphylococcus aureus; relation to disease severity

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

Phenotypic and molecular detection of TEM and SHV beta-lactamases produced by organisms of the family enterobacteriaceae; study on blood culture clinical isolates from intensive care unit

The increasing emergence of clinical isolates of the family Enterobacteriaceae with Extended-spectrum beta-lactamases [ESBLs] phenotypes remains a major reason for antimicrobial resistance problems, especially in intensive care units [ICUs]. ESBLs are enzymes produced by some species of Gram negative bacilli and have the ability to inactivate a wide range of beta-lactam antibiotics. The distinguishing feature of these enzymes is that they have extended substrate profiles that confer resistance to the expanded-spectrum cephalosporins [cefotaxime, ceftriaxone, ceftazidime, cefepime and others] and aztreonam. More than 150 different ESBLs have been characterized, and most of these are derived from point mutations affecting the TEM-1 and SHV-1 enzymes. The aim of this study was to evaluate the reliability of double disc diffusion method for the detection of ESBLs in several Enterobacteriaceae blood culture clinical isolates and to detect of point mutation in blaTEM and blaSHV genes in ESBLs producing strains. Eighty six blood culture specimens collected from septicaemic ICU patients admitted to the Internal Medicine Department of Alexandria Main University Hospital, during the period between February through November 2006. Out of 86 specimens, 37 gave positive results for different members of the family Enterobacteriaceae. Screening test for ESBLs was done to determine the sensitivity of the isolates to third generation cephalosporins [3GC]: ceftazidime, cefotaxime, and ceftriaxone each 30 micro g/disc. Double Disc Synergy test [DDST] was also done to determine synergy between a disc of augmentin [20 micro g amoxycillin and 10 micro g clavulanic acid] and 30 micro g disc of each 3GC antibiotics [cefotaxime and ceftazidime]. Fifteen isolates [40.5%] out of the 37 were suspected to be ESBLs producers by the screening test: E.coli 10/37 [27%], Klebsiella spp 4/37 [10.8%], Enterobacter spp. 1/37 [2.7%] and none of the Acinitobacter spp. 0/37 [0%]. By doing the DDST [confirmatory], 7/37 [18.9%] E.coli strains 3/37 [8.1%] Klebsiella spp. and 1/37 [2.7%] Enterobacter spp. gave positive results. Among the isolates positive by screening test; 2/10 [20%] E.coli strains gave positive PCR results for bla[TEM-1] gene and 2/10 [20%] gave positive result for bla[SHV-1] gene. One of these 2 strains showed positive results for both genes. Among the 4 Klebsiella spp., positive also by screening test, 1/4 [25%] strain gave positive result for bla[TEM-1] gene and 2/4 [50%] gave positive result for bla[SHV-1] gene. The Enterobacter spp. gave positive result for blaSHV-1 gene. The DNA sequence analysis of the bla[TEM-1] and bla[SHV-1] genes amplification products was performed. The sequencing of TEM gene of strain No.4 revealed that it encoded TEM-1 beta-lactamase. The sequencing of SHV gene of strain No.14 revealed the G to A nucleotide change that gives the glycine to serine substitution at position 238, denoting that it encoded SHV-2. ESBL producers are associated with increased morbidity and mortality, especially amongst patients on intensive care and high-dependency units. Accurate laboratory detection is important to avoid clinical failure due to inappropriate antimicrobial therapy

Detection of legionella pneumophila, mycoplasma pneumoniae and chlamydophila pneumoniae as aetiological agents of community - acquired pneumonia in holy Makkah, KSA

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

Detection of enterovirus genome in cerebrospinal fluid of children with aseptic meningitis; the relationship with interferon - gamma

Aseptic meningitis is one of the most common inflammatory disorders of the meninges. The most common viruses causing aseptic meningitis are the enteroviruses, which account for more than half the cases. We analyzed the combined diagnostic utility of reverse transcriptase polymerase chain reaction [RT- PCR] and the level of interferon gamma [IFN-gamma] in cerebrospinal fluid [CSF] specimens obtained from children with aseptic meningitis, for the diagnosis of enterovirus. Out of 33 CSF samples, 9 [27.2%] gave positive results for enterovirus RNA by RTPCR and 15 [45.4%] gave detectable level of IFN-gamma, ranging from 15.6 up to more than 1000 picogram/ ml. The mean CSF IFN-gamma concentration was 243.73 picogram/ml. which was significantly higher in CSF samples gave positive results for enterovirus genome by RT- PCR [384.3 picogram /ml] when compared with CSF samples gave negative results for enterovirus genome [56.6 picogram /ml],the results was statistically significant [p=0.0001]. Overall, data from previous reports and from the present study indicated that RT-PCR for enteroviral meningitis is an important tool in the diagnosis of children with aseptic meningitis and IFN-gamma is produced in the CSF in response to viral infection, and about half of the patients with aseptic meningitis contain IFN-gamma in the cerebrospinal fluids