دو ماهنامه میکروب شناسی پزشکی ایران
سال هفتم شماره 3 (پاییز 1392)

Pertussis vaccination in this country has been going on for many years and active infection or vaccination will provide immunity in 85% of cases. However, every 2-5 years outbreaks in unprotected adults creates an epidemy for children and infants. Based on conserved genomic sequences, Real time PCR could be an easy, cost- benefit, fast and highly sensitive method for pertussis detection. A total of 170 nasopharyngeal swabs of infants with history of cough for more than 2 weeks were collected. In the first stage, Bordetella pertussis bacteria detection was performed by culture and followed by Real time PCR using a commercial kit and then repeated with newly designed primers. Performance of our home made primers for detecting pertussis using Real Time PCR in comparison with those by commercial kit was acceptable based on diagnostic classical guidance (WHO) and the (CDC). Real time PCR test with new primers in comparison with culture techniques is more suitable, high sensitivity and can provide more informative values for pertussis detection.

Salmonella contamination is a major problem in poultry and food industry. Lack of on-time diagnosis of the bacteria may cause irreparable economic loss. Speed, repeatability and cost-benefits are the most important parameters. Faster, easier and more economic monitoring of pathogens (e.g. Salmonella.) is essential in the whole process. Routine bacterial culture methods and Antibody-Enzyme Immunoassay (ELISA) are time consuming and costly. The aim of this study was to compare Polymixin Coated Polyester Cloth (P-CEIA) with culture and ELISA in identification and rapid diagnosis of different Salmonella serovars in dairy products. In order to compare Ab-EIA and P-CEIA, different dilutions of S. typhimorium Ra-30 were prepared in peptone water (BPW, pH=7.4). From the 20 samples of milk and cream, 10 suspicious slamonella contaminated samples had been surveyed by the two methods. The sensitivity of P-CEIA method was 106 cfu/ml while the sensitivity of ab-EIA was estimated to be 105 cfu/ml. The sensitivities of the two methods were equal following heat treatment in the presence of sodium deoxy-cholate. Ab-EIA detected 5 and 3 suspicious samples of milk and cream, respectively. PCEIA detected 3 and 6 of the contaminated samples. The first method required 14 hours less time than the other method. Our data shows that P-CEIA is a rapid, economic and sustainable method for Salmonella detection in dairy products.

Pseudomonas aeruginosa is an important opportunistic pathogen, particularly in immuno compromised patients and is one of the main bacteria that cause nosocomial infections. The aim of this study was to evaluate the antibiotic sensitivity and determine the MIC levels for clinical isolates of Pseudomonas aeruginosa to antibiotics commonly used. In this study, 100 Pseudomonas aeruginosa strains from different infections occurring in Hamadan city hospitals were isolated. Thirty one samples were selected based on antibiotic susceptibility testing by disk diffusion test for aminoglycoside antibiotics (gentamicin, tobramycin, amikacin, kanamycin), and quinolone (ciprofloxacin, levofloxacin and ofloxacin) and carbapenem (imipenem and meropenem). Microdilution tests were performed to determine the MIC levels towards ciprofloxacin, gentamicin and imipenem. Out of the 31 samples, the highest resistance was seen towards levofloxacin (61.2%) and the least to imipenem (9.6%). Two of the isolates (6.5%) were resistant to all of these eight antibiotics. The MIC results for the three antibiotics were as follows. Gentamicin: (58.06%) resistant, (25.8%) intermediate and (16.12%) sensitive. Ciprofloxacin: (90.32%) resistant and (9.67%) intermediate. Imipenem: (30.7%) resistant, (41.93%) intermediate and (19.35%) sensitive. In comparison with other studies, there were not any significant differences in antibiotic resistance rates which shows similar patterns in different regions. Imipenem was the most effective antibiotics against clinical isolates. Amikacin and ofloxacin was the most effective antibiotic in the next order.

Continuous appearance of antibiotic resistance bacteria can cause significant complications and mortality. In this regard, tracing for new antimicrobial agents is of great significance. During the past decades, many studies have documented isolation of Antimicrobial Peptides (AMPs) from different sources. These peptides which are responsible for hinnate immunity were purified from human, vertebrates, invertebrates, insects, venomous animals, and plants. This study aimed to extract antibacterial peptides from Iranian scorpion Hemiscorpius lepturus. Venom was obtained by electric stimulation and its quality examined by protein electrophoresis. The venom peptides were purified using Gel filtration chromatography and subsequently with Reverse Phase- High Performance Liquid Chromatography (RP-HPLC). The peptide fractions were evaluated for antibacterial activity against Pseudomonas aeruginosa ATCC 27853. Inhibitory activity was determined by disk diffusion method. Seven protein fractions were obtained from Sephadex-G50, among them only two fractions had peptides with less than 10 kDa. One FPLC purified fraction had anti-pseudomonas activity by disk diffusion method and was selected for further purification. Four major fractions were obtained by RP-HPLC ranging from 4 to 7 kDa. Subsequent tests showed that two fractions had bactericidal activity against pseudomonas. Natural compounds like antimicrobial peptides derived from venomous animals could be an effective solution to deal with multidrug-resistant pathogens. The results demonstrated that two peptide fractions of the scorpion venom had bactericidal activity against pseudomonas. This is the first report for isolation of antibacterial peptides from the Iranian scorpion Hemiscorpius lepturus.

The health benefits of lactic acid bacteria in human, especially their anti-pathogenic properties has been the focus of recent interests. The objective of this study was to investigate the antibacterial activity of lactic acid bacteria (LAB) isolated from traditional Kurdish cheese against a few bacterial pathogens. The cell free culture supernatant of LAB isolated from Kurdish cheese which was treated with heat and NaOH were tested for their antibacterial activity by Agar Disk Diffusion method. Moreover, Minimum Inhibition Concentration and Co-aggregation of LAB against pathogens were determined. Each test was repeated for three times. The LAB isolates, in comparison with commercial lactic acid bacteria, showed suitable antibacterial activity. Heating the bacterial supernatant eliminated its anti-bacterial property; however, alkali treatment did not have any effect. The Minimum Inhibition Concentration did not show significant differences between native and commercial lactic acid bacteria; however, the native LAB showed suitable co-aggregation with pathogens. Traditional lactic acid bacteria and their metabolites can inhibit growth of pathogens. This shows the positive role of LAB in human health which necessitates their increase usage as natural antimicrobial agent.

Ochratoxin A (OTA) is a mycotoxin that possess a risk to human health due to its nephrotoxic, immunotoxic, mutagenic, teratogenic and carcinogenic properties. This study was undertaken in order to determine the presence and levels of ochratoxin A in different types of bread consumed in Shahrekord city. Eighty six samples of different types of bread purchased in March 2012 from retail bakeshops in Shahrekord city were surveyed for the presence of ochratoxin A (OTA) using ELISA assay. Ochratoxin A was detected in 45 out of the 86 bread samples (52.3%). Levels of OTA in positive samples ranged between 0.19 and 10.37 ng/g and the average contamination of all positive samples was 3.04 ng/g. The highest frequency of positive samples was related to machinery Taftoon (88.8%) and Lavash bread (81.8%). The most contaminated sample (5.39 ng/g) was found in the Iranian Lavash bread. Fifteen of the positive samples exceed the maximum level of 5 ng/g set by European regulations for OTA in cereal and bread. The results of this study indicated that contamination levels of ochratoxin A were high in part of the samples (17.4%). Bread and cereals are considered to be the main and predominant ingredient of Iranian food; therefore, their contamination can have long-term negative impact on people's health.

Infection with hepatitis B virus is a major life threatening situation for more than two billion people throughout the world. Many people are chronic carriers and suffer from this fatal infection. The majority of these carriers live in South East of Asia. In Iran, 3 percentages of the people are carriers of this virus. Molecular methods can detect the virus in serum even though the HBsAg is negative. The current study was designed to evaluate the number of copy of the HBV DNA in serum and cerumen and its relation to some immunological parameters. Seventy chronic hepatitis B patients with at least one year history of the disease and aged 20-40 years were enrolled in this study. Serum and cerumen samples were taken from each participant and kept at -20 C. Diaplus Spine ELISA kit was used to measure some immunological parameters such as HBsAg, HBeAg and Anti HBe. In order to measure the copy number of HBV DNA, a quantitative Real Time PCR assay was performed using the BioRad detection PCR /USA)Tm CFX96system. Quantitative and qualitative parameters were compared using the Mann-Whitney U test and Pearson chi squared tests or Fisher's exact test, respectively. All cases were HBsAg positive. 22 out of the 70 patients (31.4%) were HBeAg positive. 48 (68.8%) were HBsAg negative, 37(53%) anti-HBe positive and 11(15.6%) were both anti-HBe and HBeAg negative. Patients who immunologically were Anti-HBe and HBeAg negative had the highest copy of HBV DNA among all CHB patients with different immunological properties compared to those who were either HBeAg positive, anti-HBe negative or HBeAg negative, anti-HBe positive with mean DNA copy of Mc=2.83 x107and 3.37x 108, respectively. The specificity of some immunological parameters such as HBeAg positive or negative, Anti-HBe positive or negative and simultaneous Anti-HBeAg and HBeAg negative in CHB patients can affect the mean HBV DNA copy number. This together with other parameters put the patients in different phases of the disease. Therefore, quantitative molecular methods performed on biological fluids like cerumen together with immunological parameters can help to manage the disease in CHB patients.