[Detection of biocide resistance genes, qac A/B and smr, among isolated Staphylococcus aureus from clinical and non-clinical sources]

Extensive use of biocides containing quaternary ammonium compounds [QACs] have led to the emergence of QACs resistant strains of staphylococci. The aim of the present study was to detect two biocide resistance genes, qac A/B and smr and to study their association with the presence of antibiotic resistance genes in isolated S. aureus from different sources. Forty two S. aureus from clinical sources, 11 from unpasteurized diaries, and 32 from nasal swabs out of 150 collected samples were isolated. Susceptibility of the isolates to biocide QACs containing didecyl dimethyl ammonium chloride was determined by the colorimetric broth microdilution test. Polymerase chain reaction was done for detection of qac A/B, smr, bla Z, and mec A genes. Fifty percent of clinical isolates, 36.36% of isolates from unpasteurized diaries and 15.6% of nasal isolates of S. aureus with the MIC range between 1.95-7.81 micro g/ml were resistant to QACs. The frequency of qac A/B and smr genes among clinical isolates was 19.4% and 45.2%, respectively, which was significantly higher than their frequency in other samples [2.3% and 20.9%, respectively] [p<0.05]. The smr gene with frequency of 15.6% was the dominant gene among the nasal isolates of S. aureus. There was a significant correlation between the presence of at least one of the biocide resistance genes and bla Z in clinical [p=0.04] and food-related isolates [p=0.024] but there wasn't any significant association between the presence of biocide resistance genes and mec A. It is for the first time that not only the prevalence of qac A/B and smr genes for Iranian S. aureus strains is reported but also to the best of our knowledge is the first time that the presence of smr gene with the frequency of 15.6% is reported for nasal isolates of S. aureus. The present study confirms the previous findings that there is a close relationship between QACs resistance and penicillin resistance. However the presence of qac genes in the S. aureus population and their ability to develop biological resistance or co-resistance with antibiotics highlights the importance of effective infection control strategies

Comparative molecular and microbiologic diagnosis of vaginal colonization by group B streptococcus in pregnant women during labor

Rapid tests for detection of Streptococcus agalactiae or Group B Streptococci [CGS] at the onset of labor are needed to permit early intrapartum antibiotic prophylaxis. This study aimed to evaluate the PCR assays targeting the 16S ribosomal RNA gene [16S rDNA] for detection of the GBS in comparison with a specific culture method. Two swabs were used to obtain vaginal specimens from the 330 pregnant women attended delivery room at Hedayat hospital, Tehran, Iran. One swab was analyzed by direct plating onto selective GBS agar medium [ISLAM] and the other swab was used for a PCR assay, which amplified the 16S rDNA of S.agalactiae. Comparative study between the selective culture and the PCR assay was done among the 330 tested women. The GBS colonization rate based on the culture results was 20.6% [68/330]. Both culture and PCR methods were positive for 56 and negative for 253 women. The culture method was positive and PCR was negative in 12 women. The culture was negative and the PCR positive for 9 women. Sensitivity of the PCR assay was 82.3% and specificity was 96.5%. The positive predictive value was 86.15% and negative predictive value was 95.4%. ISLAM diagnostic procedure and PCR are rapid and reliable analyzing methods, which might be useful for accurate diagnosis of GBS colonization in pregnant women at the time of delivery

Cloning, expression and purification of truncated Chlamydia trachomatis outer membrane protein 2 [Omp2] and its application in an ELISA assay

Although a simple and direct method does not exist for the detection of chlamydial infections, there are situations in which reliable serological tests, with sensitivity related to a specific antigen, could be helpful. The aim of this study was to clone the first 1100 bp of the C. trachomatis outer membrane protein 2 [omp2] gene in order to prepare a recombinant protein for use in an ELISA system designed to recognize the anti- C. trachomatis antibody in patient sera. The PCR product of the chlamydial omp2 gene was cloned in pBluescript and its first 1100 bp was subcloned in the pQE-30 expression vector and induced by IPTG. The recombinant protein was purified by affinity chromatography and its purity was confirmed by SDS-PAGE, gel diffusion and western blot analyses. The purified protein was coated onto a polystyrene microplate and tested by ELISA using patient serum. We have cloned, over-expressed and purified biologically functional recombinant truncated Omp2 from C. trachomatis for use, as a species-specific recognition antigen, in an ELISA system. In this study we determined a cut-off value of 0.345 for this ELISA system using 55 negative sera and measured six positive sera at dilutions of 1:20-1:2560. As a species-specific recognition antigen, the over-expressed and purified recombinant truncated Omp2 from C. trachomatis performed well in an ELISA system

Using recombinant chlamydia major outer membrane protein [MOMP] in ELISA diagnostic Kit

Chlamydia trachomatis is one of the main causes of Sexually Transmitted Diseases [STDs] such as prostatitis and epididymitis in men and cervicitis, endometriosis, vaginitis and ureogenital tract infections in women. Serological tests with sensitivities related to specific antigens are commonly used as routine laboratory tests for diagnosis of Chlamydia. In this research the Chlamydia Major Outer Membrane Protein gene was coloned in order to prepare a specific recombinant protein for use in the ELISA diagnostic kit. DNA was extracted from cultured C. tachomatis. PCR reaction was carried out and the resulting PCR product was cloned into the pGemex-1 expression vector and induced by IPTG [Isopropyl beta-DThiogalactopyrano side]. Recombinant protein was confirmed by gel diffusion, dot blot and western blot, using patient's serum. The use of recombinant protein for diagnosis of Chlamydia by ELISA is therefore recommended

Assessment of anti-streptokinase antibody in patients with heart diseases and normal subjects

Background: Streptokinase, which is injected intravenously with a standard dose of 1.5 MIU, is the most widely used thrombolytic agent around the world. What is so important about this bioproduct is the level of anti-streptokinase [anti-sk] antibody in the population, which is directly correlated to the incidence of streptococcal infections in that population

Objectives: Since Iran is an endemic area for streptococcal infections, this study was conducted to assess the anti-sk level in an Iranian population

Materials and Methods: 97 males and 47 females referred to Modarress Hospital of Tehran for coronary angiography and cardiac catheterization were included. 10 ml of venous blood was taken before angiographies from each patient. According to the angiography reports, the patients were divided into three groups: Coronary Artery Diseases [CAD, n=95], Rheumatic Heart Disease [RHD, n=19] and normal coronaries [n=30]. The anti-sk antibody level was assessed in the serum samples of all patients using Enzyme Linked Immunosorbant Assay

Results: In 23.2% of patients with CAD, 40% of normal coronaries and 73.7% of patients with RHD, the serum samples contained more than 2 arbitrary units [AU] of anti-SK antibody which regarded as high levels. There was no significant difference between the anti-sk level of patients with CAD and normal coronaries [2.03 +/- 3.02 AUs vs. 2.52 +/- 2.23 AU], but the level of antibody in RHD group [8.16 +/- 10.1 AU] was significantly higher than other groups [p<0.05]. No significant correlation was observed between antibody levels and the age or gender of patients

Conclusion: We concluded that the level of anti-sk antibody is high in Iranian population as compared to other endemic areas for streptococcal infections. Also we found no relation between the level of antibody and sex and age of patients. This study accentuated the necessity of assessment of drug efficacy in endemic areas for streptococcal infections especially in those patients with valvular heart disease