Advances in diagnosis and treatment of Helicobacter pylori infection.

Helicobacter pylori is a Gram-negative motile bacterium causative agent of acute and chronic digestive and extra-digestive human infections. According to different reports worldwide, H. pylori symptomatic and asymptomatic infections are a global problem. The statistical investigations show a percentage of 50 for people who are involved in H. pylori acute/chronic digestive and/or extra-digestive infections around the world. This review focuses on digestive and extra-digestive diseases caused by H. pylori, the related virulence factors, diagnostic techniques including non-invasive and invasive diagnostics and treatment. There is an abundance of diagnostics for detection and identification of H. pylori. The availability, cost, and the condition of test performance may differ from place to place. To increase the level of reliability in association with diagnostic tools for detecting H. pylori, several techniques must be applied at once as multi-diagnostic technique. Furthermore, there are several pharmacotherapies which can be used for complete eradication of H. pylori infection.

High efficacy of gemifloxacin-containing therapy in Helicobacter Pylori eradication: A pilot empirical second-line rescue therapy.

BACKGROUND: Helicobacter pylori (H pylori) is a common gastric pathogen which is associated with chronic gastritis, peptic ulcer, and gastric cancer. It has worldwide distribution with higher incidence in developing countries. Gemifloxacin is a fluoroquinolone antibiotic with documented in vitro activity against H pylori. Considering that there is no clinical data to verify gemifloxacin efficacy in H pylori eradication, this pilot clinical trial was designed. METHODS: This prospective pilot study was performed during February 2014 to February 2015. A regimen of gemifloxacin (320 mg single dose) plus twice daily doses of amoxicillin1g, bismuth 240 mg, and omeprazole 20 mg for 14 days were prescribed for H pylori infected patients in whom a first-line standard quadruple therapy (clarithromycin-amoxicillin-bismuth-omeprazole) had failed. To confirm H pylori eradication a 13C-urea breath test was performed 4 weeks after treatment.Compliance and incidence of adverse effects were evaluated by questionnaires. RESULTS: A total of 120 patients were enrolled consecutively; out of which 106 patients achieved H pylori eradication; per-protocol and intention-to-treat eradication rates were 91.4% (95% CI: 85.5-97.6) and 88.3% (95% CI: 75.4-92.4) respectively. Three patients (2.5%) failed to take at least 80% of the drugs and excluded from the final analysis. Adverse effects were reported in 42% of patients, most commonly including nausea (15%) and diarrhea (13.3%), which was intense in 1 patient and led to the discontinuation of treatment. In total, 96.7% (116/120) of the patients took the medications correctly. CONCLUSION: This study revealed that gemifloxacin-containing quadruple therapy provides high H pylori eradication rate (≥90% PP cure rate), and this agent can be included in the list of second-line H pylori therapeutic regimens.

Genotyping of the Helicobacter pylori cagA Gene Isolated From Gastric Biopsies in Shiraz, Southern Iran: A PCR-RFLP and Sequence Analysis Approach.

BACKGROUND: Cytotoxin-associated gene A (cagA) is an important virulence factor in the pathogenesis of Helicobacter pylori. OBJECTIVES: The aim of this study was to genotype the H. pylori cagA gene isolated from antral biopsies of patients with stomach symptoms, using a PCR-restriction fragment length polymorphism (PCR-RFLP) analysis. PATIENTS AND METHODS: A total of 161 gastric biopsies were collected from patients with stomach symptoms. After isolation of H. pylori from the biopsy culture, the cagA gene was assessed using PCR. The PCR products were then digested by the HinfI restriction endonuclease enzyme. A sample of each genotype was also subjected to direct sequencing for further analysis. RESULTS: From 161 antral biopsies, 61 (37.9%) were positive for H. pylori in culture. Overall, 24 cagA-positives were detected in the isolates. RFLP indicated three different genotypes (I, II, and III) of cagA with a frequency of 62.5%, 25%, and 12.5% among the isolates, respectively. Genotypes I and II of cagA were predominant in patients who had gastritis. However, genotype III was found in three patients with duodenitis and duodenal ulcers. Alignment of the nucleotide sequences of the three isolated genotypes, with H. pylori 26695 as a reference strain, revealed 12 inserted nucleotides in genotype III. When the sequence of genotype III was aligned with 15 additional H. pylori strains available in GenBank, the same inserted nucleotides were detected in six of them. CONCLUSIONS: Using the PCR-RFLP method, three distinctive H. pylori cagA genotypes were detected in antral biopsies. Genotype I, which was predominant among the isolates, was significantly associated with gastritis. However, the data showed that cagA genotype III may play a role in duodenitis and duodenal ulcers in patients infected with H. pylori.

Molecular Genotyping of Shigella sonnei Strains Isolated From Children With Bloody Diarrhea Using Pulsed Field Gel Electrophoresis on the Total Genome and PCR-RFLP of IpaH and IpaBCD Genes.

BACKGROUND: Identification, understanding of antibiotic sensitivity patterns and molecular characterization of genetic elements of Shigella species are important because of both epidemiological and clinical indications in developing countries. OBJECTIVES: The aim of this study was to analyze molecular epidemiology of Shigella isolates recovered from children with diarrhea in Shiraz (Southern Iran), using IpaH and IpaBCD PCR-restriction fragment length polymorphism (RFLP), and to determine pulsed field gel electrophoresis (PFGE) patterns of total DNA of the S. sonnei isolates to find the clonality among these strains. PATIENTS AND METHODS: A total of 82 clinical strains of Shigella spp., S. sonnei (n = 61), S. flexneri (n = 16), Shigella boydii (n = 3) and S. dysenteriae (n = 2) isolated from the stool samples of 719 patients, aged two months to 14 years, with positive occult blood (OB) test were characterized based on their IpaH and IpaBCD genes PCR-RFLP patterns. Genomic DNAs of S. sonnei strains were analyzed by PFGE. RESULTS: All Shigella isolates were positive for both invasive genes and showed homogeneous profiles for such genes except for two S. sonnei strains, which had IpaH bands with different sizes and PCR-RFLP profiles. Forty palsotypes were determined among the 41 S. sonnei strains. Sample patterns were divided into two groups based on the drawn dendrogram with a similarity range of 70% to 100%. CONCLUSIONS: The results revealed that the strains under study could be epidemically related. It seems that an alternative subtyping method is needed to study the relationship among clinical S. sonnei strains and their transmission. Here, we reported for the first time, two strains of S. sonnei with a different PCR-RFLP pattern for IpaH gene.

Characteristics of 26 kDa antigen of H. Pylori by Monoclonal Antibody.

Alkylhydroperoxide reductase (AhpC, the 26 kDa antigen) is one of the abundant antioxidant enzymes in Helicobacter pylori and seems to have a good potential for use in development of immunoassays to detect H. pylori infection in clinical specimens. This study aimed to investigate some properties of this antigen by the produced monoclonal antibodies. Five established hybridoma cell lines secreting monoclonal antibodies (MAbs) against 26 kDa antigen of H. pylori were cultivated and MAbs were purified by affinity chromatography. Subsequently, MAbs were conjugated with biotin, and different combinations of capture and tracer antibodies used in sandwich ELISA. Immunoblotting of bacterial extracts were performed to estimate aggregation status of the antigen. Release of antigen from the cultivated bacteria on solid media was examined by sandwich ELISA, and also, existence of interference in fecal extract was investigated by immunoblotting and sandwich ELISA. Our findings showed that the MAbs against 26 kDa antigen of H. pylori could recognize three bands of nearly 25 kDa, 50 kDa, and 75 kDa in immunoblotting. This study also indicated presence of more antigens in the culture medium around the bacteria than the bacterial extract itself. The results of sandwich ELISA and immunoblotting on fecal extracts suggest the presence of interfering agents that prevent detection of antigen by antibody in ELISA but not in immunoblotting. In this study the oligomerization of the 26 kDa antigen, presence of interfering agents in stool matrix, and release of antigen to outside of bacteria, were demonstrated.

Antibiotic Susceptibility Patterns and Molecular Epidemiology of Metallo-ß-Lactamase Producing Pseudomonas Aeruginosa Strains Isolated From Burn Patients.

BACKGROUND: Failure in the treatment of burn patients infected with Pseudomonas aeruginosa could happen as a result of the acquisition of antibiotic resistance, including carbapenems. OBJECTIVES: The aim of the present study was to investigate the phenotypic and genotypic characteristics of the Pseudomonas aeruginosa strains, isolated from burn patients. PATIENTS AND METHODS: During a 12 month period, in this cross-sectional study, two hundred seventy strains of Pseudomonas aeruginosa were isolated from the burn patients in Ghotbeddin Burn Hospital, Shiraz, Iran. Screening for the carbapenem resistance in the isolates was carried out by the E test method. Sensitivity patterns of metallo-ß-lactamase (MßLs) producing strains of pseudomonas to eleven antibiotics were determined by the mentioned method. The epidemiological associations of these strains were determined by Pulsed-field gel electrophoresis (PFGE). RESULTS: Of the 270 strains, 60 (22.2%) were resistant to imipenem and meropenem, classified as MßLs producing. MßLs producing strains of pseudomonas were completely resistant to five tested antibiotics while their sensitivities to the three most effective antibiotics including ceftazidime, amikacin and ciprofloxacin were 23.4%, 6.7 % and 1.7%, respectively. In PFGE, 37 patterns from the genome of Pseudomonas aeruginosa were observed. Majority of the strains (43; 71.6%) exhibited more than 80% similarity, based on the drawn dendrogram. CONCLUSIONS: According to the results, none of the tested antibiotics is safe to prescribe. As PFGE revealed, a limited number of Pseudomonas aeruginosa types are predominant in the hospitals which infect the burn patients.

Use of TaqMan® real-time PCR for rapid detection of Salmonella enterica serovar Typhi.

We evaluated the performances of a newly designed real-time polymerase chain reaction (PCR) assay using TaqMan® probes to detect Salmonella Typhi. TaqMan® real-time PCR assays were performed by designed primers and probe based on the staG gene for detecting S. Typhi. The specificity of the assay was evaluated on 15 Salmonella serovars. The analytical specificity was evaluated on 20 non-Salmonella microorganisms. The analytical sensitivity was assessed using decreasing DNA quantities of S. Typhi ATCC 19430. Finally the detection capability of the TaqMan® real-time PCR assay on isolates recovered from patients with Salmonella infections was compared to the conventional PCR assay. Only S. Typhi strain had positive results when subjected to the assay using Typhi-specific real-time PCR. No amplification products were observed in real-time PCR with any of the non-Salmonella microorganisms tested. The TaqMan® real-time PCR was more sensitive than the conventional PCR. In conclusion, we found that the easy-to-use real-time PCR assays were faster than conventional PCR systems. The staG-based TaqMan® real-time PCR assay showed to be specific and sensitive method for the safe and rapid detection of the S. Typhi.

Typing methods used in the molecular epidemiology of microbial pathogens: a how-to guide.

Microbial typing is often employed to determine the source and routes of infections, confirm or rule out outbreaks, trace cross-transmission of healthcare-associated pathogens, recognize virulent strains and evaluate the effectiveness of control measures. Conventional microbial typing methods have occasionally been useful in describing the epidemiology of infectious diseases. However, these methods are generally considered too variable, labour intensive and time-consuming to be of practical value in epidemiological investigations. Moreover, these approaches have proved to be insufficiently discriminatory and poorly reproducible. DNA-based typing methods rely on the analysis of the genetic material of a microorganism. In recent years, several methods have been introduced and developed for investigation of the molecular epidemiology of microbial pathogens. Each of them has advantages and limitations that make them useful in some studies and restrictive in others. The choice of a molecular typing method therefore will depend on the skill level and resources of the laboratory and the aim and scale of the investigation. This study reviews the most popular DNA-based molecular typing methods used in the epidemiology of bacterial pathogens together with their advantages and limitations.

Novel cassette array in a class 1 integron in clinical isolates of Acinetobacter baumannii from central Iran.

Antibiotic resistance in Acinetobacter baumannii is a major problem in the hospital and outbreaks caused by this organism have been reported frequently. The present study aimed at determining the antibiotic susceptibility patterns, the prevalence of different classes of integrons and the characterization of integron class 1 gene cassettes in Iranian A. baumannii isolates. A total of 63 non-duplicate A. baumannii isolates were collected from clinical and environmental specimens in the Vali-Asr hospital in the central province of Iran (March to September, 2011). The antimicrobial susceptibility for 15 antibiotics which are used conventionally was determined by disk diffusion. The presence of different integron classes was investigated by PCR and the size of gene cassettes in class 1 integrons was then determined by PCR as well. Moreover, integron cassette arrays of isolates were delineated by RFLP and sequencing amplicons with different lengths. Of 63 isolates 62 (98.4%) carried a class 1 integron. The prevalence of IntI2 was 15.9% and the length of the amplicons ranged from 500 bp to 3 kb. Sequencing of integrons of class 1 revealed the presence of many resistance genes (aadA, aacA, aacC, dfrA, bla(GES) and bla(IMP)). We identified a completely new gene cassette which contained aacA7-qacF-aadA5-bla(IMP), this cassette has not been reported previously in A. baumannii.

The occurrence of extended-spectrum ß-lactamase producing Shigella spp. in Tehran, Iran.

BACKGROUND AND OBJECTIVES: The emergence of extended-spectrum ß-lactamase (ESBL)-producing Shigella spp. is of increasing clinical concern specially in children worldwide. The aim of this study was to investigate the occurrence of extended-spectrum ß-lactamase producing Shigella spp. in Tehran, Iran. MATERIALS AND METHODS: The study included all Shigella isolates recovered from pediatric patients aged less than 12 years admitted to a major pediatric hospital in Tehran, Iran, from 2008 to 2010. Bacterial identification, antimicrobial susceptibility testing, extended spectrum ß-lactamases (ESBLs) screening and confirmatory tests were performed according to the standard guidelines. Conjugal transfer experiments and plasmid analysis were also carried out. Polymerase chain reaction and sequencing were used to identify the genetic determinants responsible for ESBL production. RESULTS: Four out of 55 Shigella isolates, including three S. sonnei and one S. flexneri, showed an ESBL-positive phenotype. Plasmid transfer of the ESBL phenotype was successful for the S. flexneri isolate only. By PCR and sequencing, one S. sonnei isolate tested positive for the CMY-59 gene, while the other two S. sonnei and the S. flexneri isolates tested positive for the bla TEM-1 and bla CTX-M-15 genes. CONCLUSION: We found the prevalence of ESBL producing Shigella isolates was higher than detection rates observed in many other countries. Our finding raise concerns about the dissemination of ESBL among the strains of endemic S. sonnei throughout the country, because this species is now the most frequently isolated Shigella species in Iran and shigellosis by such strains in the community can pose a significant threat to patients and presents a challenge for disease management.

New immunological investigations on Helicobacter pylori-induced gastric ulcer in patients.

Although Helicobacter pylori (Hp) plays an important role in the pathogenesis of chronic gastritis and gastric ulcer, little is known about the probable mechanisms of these types of gastrointestinal damage. To determine the precise mechanisms involved in ulcer formation, immune responses in patients with gastric ulcer (GUP) caused by Hp infection (Hp(+)) were compared with those of other gastritis patients (GP). The sensitivity and proliferation of peripheral blood mononuclear cells (PBMNCs) obtained from patients were evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay against exposure with complex Hp crude antigen (HPCA) and mitogen (phytohemagglutinin, PHA). Production of inflammatory cytokines, including interleukin (IL)-1ß and IL-8, in serum and supernatants of PBMNCs were then measured by ELISA. It was found that, after stimulation with PHA, both IL-8 and IL-1ß concentrations in sera and supernatants as well as proliferation and sensitivity were statistically greater in GUP Hp(+) than GP Hp(-) . Furthermore, HPCA inhibited the proliferation of PBMNCs dose-dependently; however, it stimulated IL-8 and IL-1ß production in supernatants of mononuclear cells. Therefore, the up-regulated concentrations of IL-8 and IL-1ß may have been caused by increase in the size of mononuclear cell subpopulations or in their cytokine secretory activity, indicating the greatest cell responsiveness in GUP Hp(+) patients. These results suggest that tissue damage and ulcers occur in patients who produce more IL-8 and IL-1ß than patients who do not develop ulcers; the former consequently have more activated immune cells at the site of infection. Therefore, both host responses and Hp virulence factors may be involved in the development of gastric ulcers.

Molecular evaluations of extended spectrum ß-lactamase producing strains of Serratia isolated from blood samples of the patients in Namazi Hospital, Shiraz, Southern Iran.

BACKGROUND AND OBJECTIVE: Nowadays, the presence of extended-spectrum ß-lactamases (ESBLs) producing strains in Serratia genus causes the emergence of resistance to many antibiotics. So, the lack of proper diagnosis of ESBLs strains can lead to failure in the treatment. The objective of the present study was to investigate ESBLs production in Serratia strains isolated from the clinical blood samples in Shiraz, Iran. MATERIALS AND METHODS: In this study, 39 Serratia strains isolated from the patients referred to Namazi Hospital, during a 2 year period were tested. The antimicrobial resistance of the isolates to 21 antibiotics was evaluated using Kirby-Bauer disk diffusion method. Combination disk method was used to determine the ESBL phenotype among the isolates. PCR was performed to investigate the presence of ESBL genes of SHV, OXA and TEM types. RESULTS: The lowest antibiotic resistance rates belonged to meropenem (7.69%) and imipenem (5.12%). Overall, positive ESBL phenotype was identified in 69% (n = 27) of the isolates, 70.37% (n = 19) for S. marcescens and 29.62% (n = 8) for S. liquefaciens. Results obtained by PCR showed that only 20.51% carried OXA gene and 15.38% carried SHV-1 gene. TEM gene was detected in none of the isolates. CONCLUSION: This study showed a high prevalence of the emerging ESBL producing strains among clinical isolates of Serratia that could lead to an increase in antibiotic resistance. However, ESBLs genes other than those tested here may be more responsible for the emergence of ESBL phenotype among Serratia clinical isolates in our region.

Validation of an in-house made rapid urease test kit against the commercial CLO-test in detecting Helicobacter pylori infection in the patients with gastric disorders.

BACKGROUND: H. pylori is a urease positive organism, and this activity in a gastric biopsy could be considered as a proof of the presence of H. pylori. For the reasons of high price and difficult accessibility to the commercial CLO-test in Iran, we designed an affordable equivalent test with high specificity, accuracy and availability. METHODS: Biopsy samples from 80 symptomatic patients with gastrointestinal problems were included in this study. The results of our in-house made rapid urease kit were compared with the commercial CLO-test up to 3 hours and 24 hours after inoculation of the biopsy samples. Culture results and gram staining were proposed as gold standard. RESULTS: Helicobacter pylori was isolated from 36 patients (45.0%) after cultivation of biopsy samples. After 3 hours, 33 (91.6%) cases of positive samples for H. pylori, showed urease positive reaction using both, in-house made and CLO-test kits. However, 2 (5.5%) cases showed urease reaction at 24 hours using both the kits. The specificity of 100% was determined for both, in-house made and commercial CLO-test kits after 3 hours. The sensitivity for both the kits was estimated at 97.1% after 3hours. However, after 24 hours, sensitivity and specificity of 97.1% and 88.64% was estimated for the in-house and 97.2 % and 95.4% for the commercial CLO-test kits, respectively. CONCLUSION: Specificity and sensitivity of 100% and 97.1 % for up to 3 hours follow biopsy sampling, could be considered as an advantage for our in-house rapid urease kit. Moreover, the rapid urease agar media designed in our lab is cost-effective with adequate sensitivity and specificity levels for the detection of H. pylori, compared with the commercial CLO-test.

Immunodot blot assay to detect Helicobacter pylori using monoclonal antibodies against the 26 kDa protein.

Development of a specific immunoassay to detect Helicobacter pylori infection in stool samples requires monoclonal antibody against the specific antigen. The aims of this study were to establish monoclonal antibodies against the 26 kDa protein of H. pylori and develop an immunodot blot for their application to recognize H. pylori infection using stool samples. Mice were immunized intraperitoneally with homogenized gel containing the 26 kDa band of cell surface proteins of H. pylori in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The monoclonal antibodies were produced using the hybridoma technique. Reactivity of monoclonal antibodies was tested with the purified 26 kDa antigen and cell surface proteins from cultured H. pylori by ELISA. Furthermore reactivity of monoclonal antibodies was tested on negative and positive stool samples for H. pylori and suspensions of several major bacteria in stool by immunodot blot assay. Five stable hybridoma monoclones were obtained. The concordant reactivity of the monoclonal antibodies with H. pylori present in the stool samples, which had been tested previously using an ACON ELISA kit for H. pylori stool antigen testing, and unreactivity with several different major fecal bacteria in immunodot blotting indicates high specificity of the immunodot blot based on the reaction of produced monoclonal antibodies with the H. pylori antigen in stools. The findings indicate that the novel immunodot blot developed based on new monoclonal antibodies for stool antigens would be useful as a noninvasive method of diagnosing H. pylori infection.

Antifungal susceptibility of the aspergillus species by Etest and CLSI reference methods.

BACKGROUND: Because resistance to antifungal drugs is seen in patients, susceptibility testing of these drugs aids in choosing the appropriate drug and respective epidemiology. This study has investigated and compared susceptibility patterns of the Aspergillus species isolated from patients by the Clinical and Laboratory Standards Institute (CLSI) reference broth microdilution (MD) assay and Etest method. METHODS: The minimum inhibitory concentrations (MICs) of various antifungal agents (amphotericin B, ketoconazole, itraconazole, and voriconazole) for 108 Aspergillus species isolated from patients were determined by CLSI M38-A broth MD and Etest. The isolates were obtained from clinical samples that included tissues, sputum, bronchoalveolar lavage, abdominal tap, and cerebrospinal fluid. RESULTS: As revealed by the MD method, 63.9% of the isolates were sensitive to amphotericin B and 36.1% were resistant.Etest revealed that 61.1% were sensitive to amphotericin B and 38.9% were resistant. As for ketoconazole, 108 isolates (100%) were shown to be sensitive through the MD method; while the Etest revealedan 88.9% sensitivity and 11.1% were resistant. All species were susceptible to voriconazole, according to both methods. The measure of agreement (Kappa Index) for these three drugs was satisfactory (≥0.6). According to the MD method, 69.4% of the species were susceptible to itraconazole, whereas 30.6% were not.For this drug, the Etest showed 86.1% susceptible and 13.9% resistant. CONCLUSION: Voriconazole was the most effective agent against isolates. Using RPMI agar, we found the Etest to be helpful, readily available, and easy to use for determining invitro susceptibilities of Aspergillus species to voriconazole, amphotericin B, ketoconazole, and itraconazole in the region of this study.

Two cases of bacteremia due to an unusual pathogen, Comamonas testosteroni in Iran and a review literature.

Here we describe two cases of bacteremia caused by Comamonas testosteroni in two malignant patients, a 10-year-old boy with brain medulloblastoma and a 19-year-old girl with osteosarcoma admitted in the same hospital at short intervals. This is the first report in Iran on this low inherent virulence organism as a human pathogen.

Microbial susceptibility, virulence factors, and plasmid profiles of uropathogenic Escherichia coli strains isolated from children in Jahrom, Iran.

BACKGROUND: Urinary tract infections (UTIs), including cystitis and pyelonephritis, are the most common infectious diseases in childhood. Escherichia coli (E. coli) accounts for as much as 90% of the community-acquired and 50% of nosocomial UTIs. Therefore, identification of E. coli strains is important for both clinical and epidemiological implications. Understanding antibiotic resistance patterns and molecular characterization of plasmids and other genetic elements is also epidemiologically useful. METHODS: To characterize uropathogenic strains of E. coli, we studied 96 E. coli strains recovered from urine samples of children aged 1 month to 14 years with community-acquired UTIs in Jahrom, Iran. We assessed virulence factors (VFs), drug sensitivities, and plasmid profiles. RESULTS: Drug sensitivities of the isolates were: 19.8% (ampicillin), 24% (trimethoprim-sulfamethoxazole), 29.2% ( tetracycline), 75.5% (nalidixic acid), 80.4% (cefixime), 84.6% (gentamicin), 91.4% (ciprofloxacin), 96.8% (nitrofurantoin), 96.8% (amikacin) and 100% (imipenem). Totally, 76 isolates harbored plasmids with an average of 5.5 plasmids (range: 1-10) in each strain. Plasmid profiling distinguished 22 different E. coli genotypes in all isolates that ranged in similarity from 50% to 100%. PCR showed that the prevalence of virulence genes ranged from 15.62% for hly to 30.2% for pap. CONCLUSION: These data mandate local monitoring of drug resistance and its consideration in empirical therapy of E. coli infections. Plasmid analysis of representative E. coli isolates also demonstrates the presence of a wide range of plasmid sizes, with no consistent relationship between plasmid profiles and resistance phenotypes. Plasmid profiles distinguished more strains than did the antimicrobial susceptibility pattern.

Characterization of Pseudomonas aeruginosa strains isolated from burned patients hospitalized in a major burn center in Tehran, Iran.

Pseudomonas aeruginosa is an important life-threatening nosocomial pathogen and plays a prominent role in serious infections in burned patients. The current study was undertaken to characterize P. aeruginosa strains isolated from burned patients in Tehran, Iran. The study was conducted in a major burn center in Tehran, Iran in 2007. A total of seventy specimens obtained from different clinical origin with positive culture results for P. aeruginosa were included in the study. Antimicrobial susceptibility test was performed according to the standard CLSI guideline. The relationship between the strains was also determined using antimicrobial drug resistance pattern analysis and plasmid profiling. All strains were multi drug resistant. The percentage of resistance to tested antibiotics was: imipenem 97.5%, amikacin 90%, piperacillin 87.5%, ceftizoxime 72.7%, gentamicin 67.5%, ciprofloxacin 65%, ceftriaxone 60%, and ceftazidime 57.5%. Thirteen resistant phenotypes were recognized, R3 (TET, IPM, AMK, CIP, PIP, GM, CAZ, CRO, CT) was the predominant resistance pattern seen in 27.5% of isolates. Results obtained from E-test showed that 100% of P. aeruginosa strains were resistant to cefoxitin, 97% to cefotetan, 93% to ticarcillin, 89% to ticarcillin/clav, 76% to gentamicin and imipenem, 63% to piperacillin, 49% to tetracycline, and 20% to meropenem. Nine different plasmid profiles were observed among the strains. The current study showed an increase rate of resistance for some antibiotics tested among P. aeruginosa strains isolated from burned patients in Tehran. A combination of antibiotic susceptibility testing and profile plasmid analysis, which are relatively cheap and available methods, showed to be useful to characterize the clinical strains of P. aeruginosa isolated from burned patients in Iran.

An improvement in isolation and preservation of clinical strains of Helicobacter pylori.

BACKGROUND AND AIM: Isolation of H. pylori from gastric mucosal biopsy specimens is a prerequisite for further studies addressing drug susceptibility testing, analysis and characterization of virulence factors, molecular epidemiology studying or other comparative studies. In this study, we used a modified enriched culture medium with short incubation time to improve the isolation rate of H. pylori from the clinical specimens. METHODS: Between October 2008 and October 2009, 266 dyspeptic patients attending the endoscopy ward of Motahhary Clinic of Shiraz University of Medical Sciences, were investigated. The biopsy samples were cultured on two selective media called M1, which we used in our previous studies, and a modified medium called M2. The cultures were kept in a microaerophilic atmosphere at 37 degrees C. The plates were inspected first on day 1, and then on daily basis for a total of 10 days. The isolates were confirmed as H. pylori by colony morphology and positive oxidase, catalase and rapid urease tests. We used the same media and culture conditions to subculture the isolates for several times. Specimens were considered to be H. pylori positive if either the culture or two of the three diagnostic methods yielded positive results. RESULTS: The isolation rate of H. pylori strains from the samples was significantly higher on M2 in comparison with M1 medium (p<0.05). The bacterial growth on M2 was observed after a significantly shorter time (p<0.05), i.e., after incubation for about 24 hrs. Following these procedures, the preservation time could be extended beyond 6 months without a significant loss of viability. CONCLUSION: The modified culture technique enabled a shorter incubation time and a higher isolation rate for H.pylori obtained from clinical samples.