Jundishapur Journal of Microbiology
Year:2012 | Volume:5 | Issue:1 (S.N. 15)|Papers Count:12

Background: For more than 2 decades, human immunodeficiency virus (HIV) infection has been known to cause significant morbidity and mortality. Difficulties in treating HIV-infected patients include adverse effects and drug resistance and continue to limit the use of conventional anti-retroviral therapies.Objectives: To find new anti-retroviral drugs from natural sources, we investigated the inhibitory effects and mechanism of action of HESA-A, a natural biological compound of herbal-marine origin, against HIV-1 replicationin vitro.Materials and Methods: In this study, we used a single-cycle replicable HIV-1 system in which co-transfection of human embryonic kidney (HEK) -293T cells with pmzNL4-3, psPAX2, and pM2G.2 plasmids was performed. Cytotoxicity and cytopathic protection assays were performed using the 2, 3-bis- (2-methoxy-4-nitro-5-sulfophenyl) - (2H) -tetrazolium-5-carboxanilide method. Inhibition of p24 antigen production was analyzed, and time-of-drug-addition assay was conducted using quantitative enzyme-linked immunosorbent assay (ELISA).Results: HESA-A inhibited HIV-1-induced cytopathic effect in MT2 and HEK293T cells, and the selectivity index values were 13.3 and 8, respectively. We performed quantitative p24 ELISA and added varying concentrations of HESA-A in cell culture supernatants at different times; we observed that HESA-A preserved its ability to inhibit viral replication even at 12 h post-infection.Conclusions: These results suggest that HESA-A has potent anti-HIV activity, and its mechanism of action likely involves interference during the late stages of viral replication, such as virus maturation.

Background: American cockroaches are found in association with human dwellings and hospitals. They have a worldwide distribution. These domestic pests affect human health in several ways. Their habits make them ideal mechanical carriers of different pathogenic microorganisms. Numerous bacteria of medical importance have been isolated from cockroaches.Objectives: The objective of this research was to determine the role of American cockroaches as carriers of pathogenic bacteria. This was accomplished through the isolation and identification of these microorganisms from the external surfaces of cockroaches captured in Health and Medical Services Centers and their surroundings.Materials and Methods: Seventy-three cockroaches were caught in Health and Medical Services Centers in Khorramshahr County, southwestern Iran, in 2006. The fluid used to wash the external surfaces of cockroaches was cultured to isolate and identify bacterial pathogens.Results: Pathogenic bacteria were isolated from the external surfaces of 100% of the American cockroaches examined. The following bacterial pathogens were recovered from their body surface: Klebsiella (47.9%), Pseudomonas (37%), Escherichia coli (30.1%), Staphylococcus (24.6%), Enterobacter (19.2%), Streptococcus (15.1%), Serratia (8.2%), Bacillus (4.1%), and Proteus(2.7%).Conclusions: The bacterial pathogenic flora isolated from this cockroach species indicate that domestic pests could pose a health problem to humans. Thus, we must control cockroaches, particularly in indoors, sewage and solid wastes.

Background: Asymptomatic bacteriuria can develop into symptomatic urinary tract infection.Objectives: This study investigated asymptomatic Escherichia coli bacteriuria among undergraduate students of Nasarawa State University, Keffi, Nigeria, and the antimicrobial susceptibility of bacterial isolates from these subjects.Patients and Methods: Four hundred urine samples were collected from consenting healthy male and female students. The bacterial load of each sample was determined by spread plate count on nutrient agar.E. coli was isolated and antimicrobial susceptibility of the isolates to common antibiotics was evaluated by the disc-diffusion method.Results: Of the urine samples, 80 (20%) showed significant bacteriuria, with a higher prevalence in females (25%) than in males (15%). While 60% of E. coli isolates from male samples were susceptible to pefloxacin or gentamicin, 3.3% were susceptible to amoxicillin/ clavulanic acid. Twenty-seven (90%) E. coli isolates from male samples had multiple antibiotic resistance (MAR), with 37% being resistant to 5 antibiotics and possessing MAR indices of 0.5. Forty-nine (98%) of the E. coli isolates from female samples had MAR, with 13 (26.5%) being resistant to 6 antimicrobial agents and possessing MAR indices of 0.6.Conclusions: Significant bacteriuria is observed among the students of Nasarawa State University, with a higher prevalence in females than in males. Pefloxacin, ofloxacin, and gentamicin are effective against E. coli isolates from the urine of these students.

Background: Staphylococcus aureusis the causative agent of a high percentage of nosocomially acquired infections and food-borne illnesses. Antimicrobial resistance of S. aureus, especially methicillin-resistant S. aureus (MRSA), continues to be a concern for clinicians worldwide.Objectives: The aim of this study was to investigate the effects of salt stress on the antimicrobial drug resistance and protein profile of S. aureus.Materials and Methods: Staphylococcus aureus (ATCC 25823) was grown in trypticase soy broth at 37oC. Cells in the exponential growth phase were gradually exposed to sub-lethal salt stress with concentrations ranging from 5% to 35% (wt/vol). There after, these cells were harvested and re-suspended in a tube containing 0.5mL of saline. To standardize the number of bacteria, the bacterial suspension was compared to the 0.5 Mc Farland standard suspension.Antibiotic susceptibility was determined using the disk diffusion method, and the method involved plating of cell suspensions with stressed cells and unstressed cells on Mueller-Hinton agar plates. The pooled proteins from each condition were analyzed using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE).Results: Compared to the unstressed cells, the cells exposed to salt showed significant changes in resistance to rifampicin (P=0.032), penicillin (P=0.02) and methicillin (P=0.001). Furthermore, SDS-PAGE analysis of pooled proteins from cells exposed to salt showed changes in the protein profile.Conclusions: We conclude that salt stress is responsible for the changes in protein profileand antimicrobial resistance ofS. aureus, especially to methicillin.

Background: The protist pathogen Toxoplasma gondii infects humans and other animals such as wild rats (Rattus rattus) worldwide. Wild rats are infected with T. gondii due to ingestion of food or water contaminated with oocysts and may play an important role in the transmission of T. gondii infection to humans.Objectives: The aim of the present study was to determine the seroprevalence of T. gondii among wild rats in Ahvaz district, southwestern Iran.Materials and Methods: We determined the seroprevalence of T. gondii among wild rats (R. rattus) in Ahvaz district between February 2008 and January 2011. Immunochromatographic assay (ICA) to detect serum antibodies against T. gondii was performed for 127 adult wild rats. The rats were captured in cages and brought alive to the Veterinary Hospital of Shahid Chamran University. The rats were classified according to sex and season and region of capture. The results were analyzed by Chi-square analysis and Fisher’s exact test.Results: Thirty-one of the 127 serum samples (24.41%) had antibodies against T. gondii (95% Confidence interval; 16.9–31.9%). Prevalence was higher in female rats (24.66%) than in male rats (24.07%). The rats caught during summer (34.48%) and in the east region of Ahvaz district (36.36%) showed high prevalence. However, the gender, season and region of collection did not significantly affect the prevalence of infection (P>0.05).Conclusions: Our study showed that the seroprevalence of T. gondii was relatively high (24.41%) among wild rats in the Ahvaz district of Iran. The high prevalence of T. gondii infection in rodents may be of epidemiological importance as infected rodents are a potential route for T. gondii transmission to Felidae via ingestion of tissue cysts.

Background: The incidence of opportunistic infections due to Candida albicans and other Candida spp. has been increasing. Rapid identification of candidiasis is important for the clinical management of immunocompromised patients. Polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) is a rapid, sensitive, and specific method for detection of clinically important fungi.Objectives: The purpose of this study was to identify Candida spp. isolated from the oral cavities of HIV-infected patients in southeastern Iran (Kerman), by using PCR-based restriction enzyme digestion.Patients and Methods: We identified 96 Candida isolates obtained from 139 Iranian patients infected with the human immunodeficiency virus (HIV), between April 2009 and April 2010, by using PCR-RFLP assay. Universal primers for the internal transcribed spacer (ITS) region (ITS1–ITS4) of the fungal rRNA genes were used for this assay.Results: We successfully identified the different Candida spp. by using the restriction enzyme MspI.C. albicans was the most commonly identified species (82.2%), followed by C.glabrata (7.29%), C. parapsilosis and C. kefyr (both 4.1%), and C. tropicalis (2%).Conclusions: PCR-RFLP is a highly sensitive, specific, and direct method for fungal detection and can be used for fungal epidemiological studies in HIV-positive and other immunocompromised patients.

Background: Emerging antibiotic resistance in pathogenic bacteria has driven the development of new assays for routine antibiotic testing.Objectives: The purpose of this study was to evaluate the effects of different organic solvents in preparing two-fold decreases in serial penicillin concentration coated onto 96-well plates to design a method for antibiotic susceptibility testing.Materials and Methods: Benzyl penicillin was dissolved in each solvent (sterile distilled water, PBS, diethyl alcohol, ethanol, butanol, chloroform, 2-propanol, and acetonitrile). Serial dilutions of each solution were loaded onto a 96-well microtiter plate and incubated at 37oC for 12 h. Next, 200 mL of sterilized Mueller-Hinton broth was added along with 50 mL of bacterial suspension at an adjusted concentration equivalent to 0.5 McFarland standards. The prepared plates were incubated at 37oC for 24 h. Optical density (OD) was measured at 540 nm.Results: When comparing the ODs of each sample in 96-well microtiter plates with positive and negative controls, significant antibacterial activity was observed. Most activities ranged from 50 to 200 units of penicillin in samples that were diluted with distilled water, PBS, or isobutyl alcohol as a solvent. Analysis of the results suggested that, when using the aforementioned solvents, the minimum inhibitory concentration of penicillin against a sensitive strain of Staphylococcus aureus was ³50 units of penicillin.Conclusions: The results revealed that the accuracy and feasibility of this method can greatly reduce the waiting period of antibacterial sensitivity tests. Additionally, this method is lowcost and could benefit patients who urgently require proper antibiotic therapy.

Background: Some species of yeast such as Yarrowia lipolytica produce citric acid, lipases, single-cell oil, etc.Y. lipolytica can degrade renewable, low-cost substrates to produce organic acids like citric acid, more efficiently than Aspergillus niger, and result in higher product yield and lesser waste production and toxicity.Objectives: The aim of this study was to isolate yeast strains with potential for use in biotechnological applications such as production of citric acid and lipase.Materials and Methods: For yeast strain screening, we isolated 179 yeast strains from meat and meat products that were prepared at the RAK and Pegah factories in Isfahan, Iran. Different media were used for screening of yeast colonies and for analyses of citric acid and lipase production; the production of these metabolites was assayed over time.Results: One of the yeast strains isolated from poultry produced 55.5 g/L of citric acid and 12.3 U/mL of lipase. Biochemical and molecular tests showed that this strain belonged to the species Y. lipolytica. Molecular identification was confirmed by DNA sequencing, and the strain was named Y. lipolytica M7 (Gen Bank accession number, HM011048).Conclusions: The results of this study suggest that meat and its products, especially poultry products, are suitable sources for isolation of yeast strains that produce two biotechnologically valuable products-citric acid and lipase. The yeast strainY. lipolytica M7 can be used for citric acid production in bioreactor.

Background: Acute gastroenteritis, which is one of the most common diseases in humans, is responsible for many illnesses in both children and adults. Group A rotaviruses are considered the main agents of gastroenteritis, and these are followed by calciviruses, adenoviruses, and astroviruses.Objectives: The aim of this study was to determine the rate of astrovirus and rotavirus coinfection among children up to 5 years of age who had gastroenteritis and who were referred to Ahvaz Aboozar Hospital.Patients and Methods: A total of 180 stool specimens, which were collected from children with gastroenteritis who were less than 5 years old and who were referred to Ahvaz Aboozar Hospital, were tested by enzyme-linked immunosorbent assay methods for the detection of rotavirus infections. Detection of astroviruses in positive rotavirus stool specimens was performed by reverse transcriptase-polymerase chain reaction (RT-PCR) methods.Results: Fifty-nine of the 180 samples were positive for rotavirus infection. These positive samples were subjected to RT-PCR to test forastrovirus. After RT-PCR with specific astrovirus primer sets, 8 samples were positive for astrovirus as well. Therefore, 13% of rotavirus-positive samples were also positive for astrovirus.Conclusions: Group A rotaviruses, in addition tocalciviruses, adenoviruses, and astroviruses, can cause acute gastroenteritis. Studies have shown that 2.5 million deaths occur every year from gastroenteritis. In this study, we found that the prevalence of rotavirus infections was very high and that of coinfections of rotavirus and astrovirus were considerable. In order to reduce the risk of infections and to eliminate viral gastroenteritis in this zone of the region, education, vaccinations, and improved personal hygiene must be improved.

Background: Noroviruses belong to the Norovirus genus in the Caliciviridae family. Noroviruses are the most common causes of gastroenteritis and have a great impact on public health. They have been identified as a common cause of acute gastroenteritis in children.Objectives: The aim of this study was to determine the prevalence of Norovirus in children suffering from gastroenteritis.Patients and Methods: Fecal samples (n=143) were collected from children under 5 years of age who were suffering from gastroenteritis. All the children were referred to Ahvaz Aboozar Hospital, located in southwestern Iran. Norovirus RNA was extracted by Trizol, and RNA was detected using nested reverse transcriptase polymerase chain reaction (nested-RT-PCR).Results: Norovirus infection was detected in 9 of the 143 collected samples (6.3%). All positive samples belonged to genogroup II. Five positive samples were obtained from male patients and 4 were obtained from female patients. Most of the positive cases were from patients between 3 and 5 yars of age (n=5, 56%). There was no relationship between gender and virus prevalence. The rate of infection peaked in winter (n=6, 66.9%), and we did not detect any positive cases in summer.Conclusions: The prevalence of this virus in Ahvaz is similar to that reported by other researchers.Because this virus is transmitted by contaminated food or water, we recommend adult education and improved personal hygiene to reduce the incidence of Norovirus infection in children. This study improves our epidemiological knowledge of the prevalence of this virus in Ahvaz and Iran.

Background: Gastroenteritis is a common cause of morbidity and mortality in humans all over the world, especially in infants under 5 years of age. Many microorganisms, including viruses, have been identified as the causative agents of gastroenteritis. Sapovirus is a major causative agent of acute viral diarrhea that occurs mostly in children under 5 years of age.Objectives: The aim of this study was to determine the prevalence of Sapovirus infection among children under 5 years of age who had gastroenteritis and were referred to Aboozar Hospital, Ahvaz, Iran.Patients and Methods: All fecal specimens were collected from children with acute gastroenteritis, Sapovirus RNA was extracted using TRIzol and detected by reverse transcriptasepolymerase chain reaction (RT-PCR) followed by sequencing of the positive samples.Results: Of the 200 clinical stool samples collected, 6 (3%; 5 samples from male patients and 1 from a female patient) were found to be positive for Sapovirus by the RT-PCR method.The identityof the PCR products was confirmed by sequencing. Sapoviruses belonging to genogroup II were identified as the dominant type causing gastroenteritis in children. The incidence of Sapovirus infection was the highest during the coldest months.Conclusions: Sapovirus prevalence in children under the age of 5 years with acute gastroenteritis was 3%, and genogroupІІ was the dominant type.

We report the first case of Microsporum persicolor being isolated from an Iranian patient.An 8-year-old girl was examined for tinea corporis. Microscopic examination of the skin scraping performed using 15% KOH revealed hyaline septate branching mycelium and arthroconidia. Cultures of the clinical material yieldedM. persicolor after 2 weeks of incubation.The isolate was identified on the basis of gross morphological characteristics of the fungal colony on Mycobiotic agar and peptone agar, microscopic characterization of slide culture, and biochemical reactions.