Iranian Journal of Microbiology
Volume:2 Issue: 2, Jun 2010

Extra-intestinal pathogenic Escherichia coli (ExPEC) strains are divided into uropathogenic E. coli (UPEC), strains causing neonatal meningitis and septicaemic E. coli. The most common pathotype of ExPEC is found among patients with urinary tract infection (UTI), defined as UPEC. These bacteria are responsible for >90% of cases of UTI and are often found amongst the faecal flora of the same host. E.coli strains are classified into four phylogenetic groups, A, B1, B2, and D. Groups A and B1 are commensal strains and carry few virulence-associated genes (VGs) while pathogenic group B2 and D usually possess VGs which enhance colonic persistence and adhesion in the urinary tract (UT). The gastrointestinal (GI) tract is widely accepted as a reservoir for UPEC and is believed that healthy humans have a reservoir of UPEC strains, belonging to phylogenetic group B2, and to a lesser extent, group D. These strains have superior ability to survive and persist in the gut of humans and can spread to cause extra-intestinal infections. ExPEC trains possess a range of VGs which are involved in their pathogenesis. These include adhesins, toxins, iron-acquisition systems (e.g. siderophores), and capsules. Evolutionary influences on the acquisition and main role of VGs amongst E. coli are widely debated, with some research holding that the prevalence of strains with VGs increases the likelihood of infections, whereas others believe that VGs provide a selective advantage for infection of extra-intestinal sites. This review is intended to present our existing knowledge and gaps in this area.

Rapid clinical manifestation/progression of the meningococcal meningitis and lacunae in conventional bacteriological test often encourages indiscriminate use of antibiotics much before the etiology is established. This study was planned to evaluate ctrA PCR for rapid molecular detection. In addition, multiplex PCR and sequencing was done for serogroup prediction to provide essential epidemiological and laboratory evidence for decision makers of health department of the country for choosing appropriate vaccine and phylogenetic analysis to establish lineage. 73 CSF samples, collected from equal number of suspected cases, were investigated by both bacteriological (microscopy, culture, LA and drug sensitivity testing) as well as molecular tests i.e. PCR targeting conserved ctrA gene, multiplex PCR for serogroup characterization and DNA sequencing. ctrA PCR revealed sensitivity, specificity, positive predictive value and negative predictive values of 93.15%, 100%,100%, and 88.23% respectively. Multiplex PCR based genogrouping followed by DNA sequencing, BLAST and phylogenetic analysis revealed complete homology with earlier submitted Neisseria meningitidis serogroup A strain Z2491 to suggest the sole involvement of only serogroup A in the outbreak. Two strains showed resistance to cefuroxime, ciprofloxacin, nalidixic acid. Only one strain showed resistance to ciprofloxacin, emphasizing the need for a constant surveillance system. These diagnostic molecular tools are of paramount importance in establishing etiology, serogrouping, and epidemiological surveillance especially in developing countries like India.

Bartonella species are being recognized as increasingly important bacterial pathogens in veterinary and human medicine. These organisms can be transmitted by an arthropod vector or alternatively by animal scratches or bites. The objectives of this study were to identify contamination of cat's saliva and nail with B. henselae as a causative role to infect human in a sample of the cat population in Iran. Blood, saliva and nail samples were collected from 140 domestic cats (stray and pet) from Tehran and Shahrekord and analyzed for the presence of B. henselae with cultural and polymerase chain reaction (PCR) methods and DNA sequencing. In this study B. henselae was detected in 10.9% of saliva samples (12/110) from pet cats. B. henselae was not detected in nail samples of pet cats (n=110), and in any feral cat's saliva and nail samples (n=30). Our data suggest that pet cats are more likely than stray cats to infect human with B. henselae after a bite and also stray cats can play a role as a reservoir for this bacteria. This is the first report that investigates the presence of B. henselae in cats oral cavity in Iran.

300 Pseudomonas aeruginosa strains were isolated from hospitalized patients in Iran. Using international antigenic typing system (IATS) antibodies, all strains were classified into 16 serotypes while serotype 14 was not identified among the 17 known serotypes. To evaluate the rate of cross-reactivity between O- antigenic determinants, monospecific polyclonal antibodies were made against whole-killed-cells and live cells of each serotype. Each antiserum was challenged against homologous and heterologous antigens using slide agglutination test. The degree of agglutination reaction is shown by -ve, 1+ve, 2+ve, 3+ve and 4ve for 0, 25%, 50%, 75% and 100% agglutination respectively. Then, the results were tabulated for further study. The rate of cross-reactivity between O-antigenic determinants demonstrated that strains 10.55 and 15.14 had the highest agglutination reaction with serum of all the homologous and heterologous serotypes. Evaluation of the results obtained from the present study can be applied in production of reliable vaccines and antisera as therapeutic agents or as diagnostic kits.

In Iran, anaplasmosis is normally diagnosed with traditional Giemsa staining method. This is not applicable for identification of the carrier animals. The aim of this study was to compare the detection of Anaplasma marginale in two different numbers of microscopic fields (50 and 100) using conventional Giemsa staining method compared with the PCR-RFLP technique. In this study, examinations were performed on 150 blood samples from cattle without clinical signs. Sensitivity and specificity of two microscopic fields (50 and 100 fields) were compared with A. marginale specific PCR-RFLP. The degree of agreement between PCR-RFLP and the two microscopic tests was determined by Kappa (κ) values with 95% confidence intervals. PCR-RFLP showed that 58 samples were A. marginale, while routine microscopy showed erythrocytes harboring Anaplasma like structures in 16 and 75 blood samples determined in 50 and 100 microscopic fields respectively. Examination of 50 and 100 microscopic fields showed 25.8% and 91.4% sensitivity and 99% and 76.1% specificity compared to 100% sensitivity and specificity by PCR-RFLP. The Kappa coefficient between PCR-RFLP and Microscopy (50 fields) indicated a fair level of agreement (0.29). The Kappa coefficient between PCR-RFLP and Microscopy (100 fields) indicated a good level of agreement (0.64) Our results showed that the microscopic examination remains the convenient technique for day-to-day diagnosis of clinical cases in the laboratory but for the detection of carrier animal with low bacteremia, microscopy with 100 fields is preferable to Microscopy with 50 fields and molecular methods such as PCR-RFLP can be used as a safe method for identifying cattle persistently infected with A. marginale.

Allergic fungal sinusitis (AFS) has been recognized as an important cause of chronic sinusitis commonly caused by Aspergillus spp. and various dematiaceous fungi like Bipolaris, Alternaria, Curvalaria, and etc. Ulocladium botrytis is a non pathogenic environmental dematiaceous fungi, which has been recently described as a human pathogen. Ulocladium has never been associated with allergic fungal sinusitis but it was identified as an etiological agent of AFS in a 35 year old immunocompetent female patient presenting with chronic nasal obstruction of several months duration to our hospital. The patient underwent FESS and the excised polyps revealed Ulocladium as the causative fungal agent.

Probiotics including strains of Lactobacillus spp. are living microorganisms including which are beneficial to human and animals health. In this study, Lactobacillus has been isolated from corn silage in a cold region of Iran by anaerobic culture. The bacteriological and biochemical standard methods were used for identification and phenotypic characterization of isolated organism. To increase the stability of organism in the environment, we used microencapsulation technique using stabilizer polymers (Alginate and Chitosan). The isolated Lactobacillus spp. was able to ferment tested carbohydrates and grow at 10°C -50°C. Using microencapsulation, the stability and survival of this bacterium increased. microencapsulation of lactic acid bacteria with alginate and chitosan coating offers an effective way of delivering viable bacterial cells to the colon and maintaining their survival during refrigerated storage.

Halophilic bacteria produce a variety of pigments, which function as immune modulators and have prophylactic action against cancers. In this study, colorful halophilic bacteria were isolated from solar salt lake and their pigments was extracted in optimal environmental conditions and compared with the pigments of Halorubrum sodomense ATCC 33755. Water samples from the solar salt lake in Imam Khomeini port in southwest of Iran were used as a source for isolation of pigment-producing bacteria. Halorubrum sodomense ATCC 33755 was used as control for pigment production. The conditions for optimum growth and pigment production were established for the isolated bacteria. Pigment were analyzed by spectrophotometer, TLC and NMR assay. The 16S rRNA genes were sequenced and results were used to differentiate haloarchaea from halophilic bacterial strains. Among the isolated strains, YS and OS strains and Halorubrum sodomense were recognized as moderate and extremely halophile with maximum growth in the presence of 15% and 30% NaCl concentrations, respectively. Experiments conducted to find out the optimum conditions for growth and pigment production temperature at 25ºC, pH = 7.2 and shaking conditions at 120 rpm for three strains. Without shaking, little growth with no pigment production was observed. Total pigment produced by red, yellow and orange strains was measured at 240, 880 and 560 mg per dry cell weight respectively. Amplification yielded bands of to isolated strains only observed with bacteria primers. This result suggesting the YS and OS strains were not haloarchaea. The isolated halophilic bacteria produced much higher amounts of pigments than Halorubrum sodomense. Photo intermediates including metarhodopsin II (meta II, λmax=380 nm) were determined as major pigment in Halorubrum sodomense.