Jundishapur Journal of Microbiology
Volume:8 Issue: 8, Aug 2015

Infections are considered as one of the main factors of neonatal mortality, especially in developing countries. Blood and urine infections are one of the most prevalent infectious factors among the infants. On the other hand, resistance against antimicrobial factors is one of the major problems in the world, and it is important to be informed about antibiotic resistance pattern of microorganisms for treatment of infections.. The aim of this study was to examine the bacterial strains causing blood and urinary tract infections in Neonatal Intensive Care Unit (NICU) and determine their antibiotic resistance pattern.. In this study, the microorganisms of 150 blood and urine samples of infants hospitalized in NICUs of Imam Hussein Hospital, Children Hospital Center and Bahrami Hospital in Tehran, Iran, were collected during seven months, and the antimicrobial resistance patterns of the isolates were studied by the Kirby-Bauer test.. During the seven-month study on 105 samples, including 85 (81%) urine samples and 20 (19%) blood samples, 81 samples (77.1%) were Gram-negative and 24 (22.9%) were Gram-positive organisms. Klebsiella pneumoniae (30.5%) was the most common Gram-negative microorganisms and Staphylococcus epidermidis (11.4%) was the most prevalent Gram-positive microorganisms. The most antimicrobial susceptibility in Gram-negative microorganisms was shown to ciprofloxacin (84.2%) and in Gram- positive ones was shown to vancomycin (83.3%).. This results of the study show that the most contamination in NICUs is from Gram-negative bacteria and ciprofloxacin is the most effective antibiotic for treatment. Thus, the control of infections in NICUs in hospitals is very important..

The etiology of morphea is still unknown. Borrelia spp. as a causative agent of morphea has been discussed since 1985, but the relationship remains uncertain. We aimed to find the frequency of Borrelia in morphea lesions by polymerase chain reaction (PCR) in northeast of Iran.Patients and Sixty six patients with morphea were prospectively included in the present study. For each patient, formalin-fixed, paraffin-embedded tissue blocks of skin lesion biopsies were examined for Borrelia spp. DNA using PCR.. No Borrelia DNA was detected by PCR in skin lesions of patients with morphea.. The result of this study showed no relationship between Borrelia infection and morphea lesions and in other word indicated that morphea, at least in Iran, is not caused by Borrelia spp

This study was performed in response to the rapid propagation of HIV/AIDS across Iran and its status in this region. Accordingly, an evidence-based program is required to combat this disease. The present study estimated the prevalence of HIV/AIDS in East Azerbaijan (population: 3,724,000). We created a database of all positive cases from 1987 to 2012. We also analyzed and described the epidemiological status of HIV/AIDS during a 25-year period by using SPSS. In East Azerbaijan, 371 HIV/AIDS cases have been reported, i.e. 1 case per 10,000 population. The vast majority of reported cases (91%, n =338) were men, whereas only 9% (n = 33) were women. The mean age of patients was 30.8 ± 12.3 years. Unsafe drug injection (59%, n = 219) and sexual interaction (13%, n = 48) were the two major modes of HIV transmission. In addition, 7% (n = 25) of patients have been diagnosed with HIV, hepatitis B Virus, and hepatitis C virus simultaneously. Moreover, 60% (n = 205) of men were infected via drug injection, while 82% (n = 27) of women were infected via unprotected sexual interaction (P < 0.001). The results indicate a rapid increase in the number of HIV/AIDS cases in East Azerbaijan, necessitating immediate attention and strategies to combat the rapid spread of the disease. Development of provincial and national HIV/AIDS strategies demands more accurate and comprehensive HIV/AIDS surveillance.

Staphylococcus aureus, an important human pathogen is one of the main causative agents of nosocomial infection. Virulence genes play a major role in the pathogenicity of this agent and its infections. Methicillin-Resistant Staphylococcus aureus (MRSA) isolates are major challenge among infectious agents that can cause severe infections and mortality. Methicillin-resistant S. aureus produces a unique type of Penicillin Binding Protein 2a (PBP2a) that has low affinity for β-lactam antibiotics. Most of the MRSA bacterial strains can also produce a leukotoxin as Panton-Valentine Leukocidin (PVL) that increases the virulence of MRSA strains and can cause severe necrotic pneumonia. The presence of pvl gene is a genetic marker for the MRSA populations. The aim of this study was to explore the association of pvl and mecA genes in clinical isolates of MRSA. Fifty MRSA isolates were collected from 200 clinical samples from three different educational hospitals in Ahvaz, Iran, and identified by biochemical tests including catalase, oxidase, tube coagulase, mannitol fermentation, and sensitivity to furazolidone, resistance to bacitracin, PYR test and Voges-Proskauer test. Their resistance to methicillin was evaluated using the disc diffusion method. DNA was extracted by boiling and then the presence of pvl and mecA genes was investigated by the polymerase chain reaction method using specific primers. The results revealed that mecA and pvl genes were positive for 15 (30%) and 3 (6%) of the isolates, respectively. None of mecA positive isolates was positive for pvl gene. It can be concluded from these results that fortunately the prevalence of pvl gene is low in MRSA isolates in this region and there is no association between the presence of pvl and mecA genes in these isolates.

It is often difficult for a physician to distinguish between viral and bacterial causes of respiratory infections and this may result in overuse of antibiotics. In many cases of community-acquired respiratory infections, clinicians treat patients empirically. The development of molecular methods for direct detection of viruses has been progressed recently. The objective of this study was recognizing the panel of respiratory RNA viruses by multiplex SYBR Green real-time polymerase chain reaction (PCR). Randomized 172 influenza-negative respiratory specimens of all age groups of hospitalized patients were collected. After RNA extraction, cDNA was synthesized. Three SYBR Green multiplex real-time PCR assays were developed for simultaneous detection of 12 respiratory RNA viruses. Each set of multiplex methods detected four viruses, the first set: respiratory syncytial virus, human metapneumovirus, rhinovirus, enterovirus; the second set: parainfluenza viruses 1 - 4 (PIV1-4); the third set: coronaviruses NL63, 229E, severe acute respiratory syndrome (SARS), and OC43. Application of the multiplex SYBR Green real-time PCR in clinical samples from 172 patients in a one-year study resulted in detection of 19 (11.04%) PIV3, 9 (5.23%) PIV4, and 1 (0.58%) coronavirus NL63. All the positive samples were detected during December to March (2011 - 2012). Multiplex SYBR Green real-time PCR is a rapid and relatively inexpensive method for detection of respiratory viruses.

Pseudomonas aeruginosa is a well-known opportunistic pathogen, which affects hospitalized patients in different wards due to its natural resistance to drugs. The purpose of the current study was to determine the antibiotic susceptibility profiles and genetic relatedness in P. aeruginosa isolated from patients admitted to a referral hospital in Isfahan, Iran. Out of 150 analyzed samples, 54 P. aeruginosa isolates were recovered and were subjected to antibiotic resistance patterns and genetic diversity determination by Kirby-Bauer’s disk diffusion method and RAPD-PCR, respectively. The highest percentage of resistance was observed against ceftazidime and imipenem with 30 (55.6%) isolates; meanwhile all isolates were sensitive to polymyxin B. Twenty-eight (51.8%) isolates revealed resistance to all applied antibiotics. RAPD-PCR (Random Amplified Polymorphic DNA- Polymerase Chain Reaction) results showed 54 unique genotypes, which were divided into 39 clusters. Although different source of P. aeruginosa may involve in patient colonization, genetically related strains were isolated from different wards and or the same ward of the hospital. Our results pointed to the restriction of currently used antibiotics in studied hospital. We hope that our results cast light on the control and transmission of the infection in the investigated hospital.

The emergence of multidrug-resistant Acinetobacter baumannii complicates the therapy of the related infections. Hospital isolates of A. baumannii are usually multidrug-resistant. The problem is compounded by increasing resistance to broad-spectrum antibiotics including carbapenems. The aim of this study was to determine antimicrobial susceptibility patterns and distribution of blaOXA-type carbapenemases genes among A. baumannii isolates from hospitalized patients in Shiraz, Southwest Iran. Two hundred A. baumannii isolates were recovered from different clinical specimens in four Shiraz teaching hospitals. Isolates were detected as A. baumannii by Microgen kit and PCR with specific primers of blaOXA-51-like gene. Antimicrobial susceptibility testing was determined by disk diffusion method for all the isolates. Multiplex PCR assays were performed for detection of blaOXA-23-like, blaOXA-24-like and blaOXA-58-like genes. All the isolates were susceptible to colistin and polymyxin B. Moreover, all of them were resistant to piperacillin, piperacillin-tazobactam, ampicillin, ceftazidime, cefoxitin and aztreonam. Eighty (40%) isolates had positive results for blaOXA-23-like, 14 (7%) for blaOXA-24-like and 1 (0.5%) isolate for blaOXA-58-like. The co-existence of studied genes was detected for blaOXA-23-like plus blaOXA-24-like in nine (4.5%) isolates. The prevalence of carbapenem resistant A. baumannii isolates in Shiraz hospitals is high. The blaOXA-23-like gene was the most frequent carbapenemase identified among resistant A. baumannii isolated in Shiraz hospitals. The increasing incidence of A. baumannii is a serious concern, therefore control of this pathogen and taking preventive measures are emphasized.

Garlic is considered a rich source of many compounds, which shows antimicrobial effects. The ability of microorganisms to adhere to both biotic and abiotic surfaces and to form biofilm is responsible for a number of diseases of chronic nature, demonstrating extremely high resistance to antibiotics. Bacterial biofilms are complex communities of sessile microorganisms, embedded in an extracellular matrix and irreversibly attached to various surfaces. The present study evaluated the antimicrobial activity of Allium sativum extract against the biofilms of six pathogenic bacteria and their free-living forms. The clinical isolates in this study had not been studied in any other studies, especially in regard to biofilm disruption and inhibition of biofilm cell metabolic activity. Antimicrobial activities of A. sativum L. extracts (methanol and ethanol extracts) against planktonic forms of bacteria were determined using the disc diffusion method. The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) values were evaluated by a macrobroth dilution technique. The anti-biofilm effects were assessed by microtiter plate method. The results showed that the A. sativum L. extract discs did not have any zone of inhibition for the tested bacteria. However, The MIC values of A. sativum L. extracts (0.078 - 2.5 mg/mL) confirmed the high ability of these extracts for inhibition of planktonic bacteria. A. sativum L. extracts were efficient to inhibit biofilm structures and the concentration of each extract had a direct relation with the inhibitory effect. Finally, it can be suggested that the extracts of this plant be applied as antimicrobial agents against these pathogens, particularly in biofilm forms.

Pseudomonas aeruginosa remains a leading cause of severe wound infection and mortality in burn patients. The current study aimed to determine the prevalence of Ambler class A and D β-lactamases among P. aeruginosa isolated from infected burn injuries in Tehran, Iran.Patients and Bacteriological samples were taken from burn patients with clinical symptoms of burn infection. Fifty Gram-negative, oxidase-positive, catalase- positive bacilli, grown at 42ºC and production of pigment on Mueller-Hinton agar were identified as P. aeruginosa. All of the 50 isolates were examined for antibiotic susceptibility via disk diffusion method, and production of Ambler class A and and D β-lactamases by phenotypic screening test. The presence of Ambler class A and D β-lactamases was confirmed by polymerase chain reaction technique. The results showed that the majority of isolates (88%) were multi-drug resistant. Out of these 50 imipenem resistant isolates, 7 (14%), 18 (36%), 18 (36%) and 18 (36%) strains were positive for blaPER, blaOXA-10, blaTEM and blaSHV genes alone or in combination, respectively. None of the isolates possessed blaKPC or blaGES genes. The current study highlights that the high level of resistance to many antibacterial agents and a gradual increase in the degree of PER, OXA-10, SHV and TEM ESBLs among the majority of imipenem resistant P. aeruginosa isolated from patients with burn infection is an enormous threat in burn centers in Iran.

Coagulase-negative staphylococci (CNS) are a common cause of nosocomial infections. In recent years, an increase in the incidence of methicillin-resistant coagulase-negative staphylococci (MRCNS) has led to the severity of the disease. The aim of this study was to isolate and identify MRCNS strains by oxacillin disk agar diffusion, oxacillin agar screening, and polymerase chain reaction (PCR) and to evaluate their antibacterial resistance patterns.Patients and Totally, 122 CNS isolates were collected from the clinical specimens of four hospitals in Iran. Susceptibility testing was performed by disk agar diffusion against 15 antimicrobial agents. Then, disk agar diffusion, agar screening, and PCR were applied to determine susceptibility to oxacillin. Out of the 122 isolates, 92 isolates were found to be MRCNS by PCR. The sensitivities and specificities of disk agar diffusion and agar screening were 89.2% and 69% and 93.8% and 96.3%, respectively. Also, 93 CNS isolates were resistant to Methicillin according to disk agar diffusion. Our results indicated that agar screening was superior to oxacillin disk agar diffusion. A comparison between the antibiotic sensitivity patterns of the MRCNS and the Methicillin-Susceptible Coagulase-Negative Staphylococci (MSCNS) showed that the MRCNS were predominantly multiple-drug resistant isolates as the simultaneous resistance rate to 4 or more antibiotics in the MRCNS and MSCNS was 93% and 56%, respectively.

Frog skin secretions have potentials against a wide spectrum of bacteria. Also, frog skin compositions have healing properties. The aim of this study was to investigate the antibacterial potentials along with healing properties of frog skin Rana ridibunda, a species which thoroughly lives in Iran marshes, as a biological dressing on wounds. In this study, excisional wounds, dressed with frog skin, were compared between experimental and control groups of guinea pigs. In the experimental groups, wounds were dressed with the dermal (FS) and epidermal (RFS) sides of fresh frog R. ridibunda skin, while only usual cotton gauze covered the wounds of the control group. Furthermore, microbial samples were taken on different days (0, 3, 5, and 7 days post injury) to count the number of the colony-forming units. Additionally, the microbial penetration test was performed on frog skin and then the progression of wound closure was evaluated. In the microbial studies, the bacterial load considerably declined in the wounds treated with FS and RFS compared with the control wounds. On day 7 post injury, the numbers of the colony-forming units for the FS, RFS, and control groups were 6.75, 105, and 375, respectively. In the penetration test, fresh frog skin showed to be a bacterial resistant dressing. The results revealed that the rate of wound closure in the experimental groups significantly was accelerated in comparison with that in the control group. Our results demonstrated the antimicrobial properties of frog skin as a wound dressing, which has antimicrobial effects per se. This biological dressing shows promise as an effective biological wound dressing insofar as not only is it capable of resisting microbes and accelerating wound healing but also it is cost-effective and easy to use..

In Streptococcus mutans, ComCDE, a peptide-induced two-component signal transduction system, forms a closed signal transduction, and even if difunctional ComE closes this signal at its headstream to avoid its infinite amplification, it is not enough for ComE to work in a concentration-dependent manner. CslAB has a chance to regulate ComCDE by controlling extracellular competence-stimulating peptide (CSP) concentration through its processing and secretion. To first confirm the binding properties of cslAB promoter (PcslAB) with ComE, then to uncover in vivo need of cslAB expression, and finally to unveil the role of CslAB. Electrophoretic mobility shift assay was used to confirm the binding properties of PcslAB with ComE. In vivo cslAB transcription was detected by β-galactosidase activity because its gene has been fused to cslAB operon, and finally the role of CslAB was reviewed. PcslAB is a weak promoter responding to ComE and its binding appears to be negative cooperative. Although PcslAB is partially controlled by ComCDE, it can respond to ComCDE regulation. Supported by the obtained molecular evidence, CslAB acts as a stabilizer of ComCDE signal on the patterns of its expression. PcslAB is partially controlled by ComCDE. CslAB is a stabilizer of ComCDE signal to ensure that ComE works in a concentration-dependent manner.

C-Phycocyanin (C-PC) from blue-green algae such as Spirulina has been reported to have various pharmacological characteristics, including anti-inflammatory and anti-tumor activities. Recombinant β-subunit of C-PC (C-PC/β) is an inhibitor of cell proliferation and an inducer of cancer cell apoptosis. Since C-PC/β has a big potential to be used as a promising cancer prevention or therapy agent, the purpose of this study was to clone and express Spirulina platensis cpcB gene in a bacterial expression system. This is a significant step for the production of this compound. The cpcB gene was amplified using specific primers and cloned in a bacterial expression vector, namely pET43.1a+. Gene expression of cpcB was analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and the dot blotting technique. The SDS-PAGE analysis and dot blotting confirmed the production of recombinant C-PC/β in the bacterial expression system. Over-expression of cpcB gene was optimized in induction by 1 mM Isopropyl-β-D-Thiogalactoside (IPTG), after four hours of inoculation at 30°C. Over-expression of the synthetic CPC/β protein in the bacterial system (Escherichia coli BL-21) showed that E. coli can be used as a basis for further research to produce this desired protein in large quantities.

Persistent Helicobacter pylori infection confers an increased risk for serious illnesses such as peptic ulcers and gastric cancer. Various cytokines are involved in the regulation of inflammatory immune response in H. pylori-infected gastric mucosa. The current study aimed to obtain evidence regarding the association between IL-17, IL-8 and IL-18 expression in peripheral blood and H. pylori infection in Mongolian gerbils. Mongolian gerbils were inoculated with H. pylori by a metal stomach catheter. After sacrifice, their gastric mucosae were examined in macroscopic, histological and electron microscopy levels. In addition, enzyme linked immunosorbent assay (ELISA) assay was performed on the IL-17, IL-8 and IL-18 cytokines in the blood samples. Serum levels of IL-17, IL-8 and IL-18 were remarkably up-regulated compared to those of the control group. There was an obvious correlation between the increase of IL-17 and the serious extent of gastritis in the current study. However, the serum levels of IL-8 and IL-18 without getting increasingly more for repetitive intragastric administration. There were plenty of neutrophils infiltrating in the infected group mucosal. Intestinal metaplasia and gastric ulcers were also founded in H. pylori infected animals after enhanced inoculation. The edema, degeneration and necrosis changes could be found in organelles by transmission electron microscopy. More serious pathological changes were detected in the enhanced inoculation groups compared to the cycle group. The serum levels of IL-17, but not IL-8 and IL-18 may serve as a potential biomarker for diagnosis and predicting the prognosis of gastritis caused by H. pylori.

Carcinogenesis is a multi-step process and the role of infectious agents in this progression has not been fully identified. Since human cytomegalovirus (HCMV) is frequently presented in the gingival sulcus fluid, we hypothesized that this virus would be important in the pathogenesis of oral squamous cell carcinoma (OSCC). The aim of this study was to investigate the presence of active HCMV in different histopathological grades of OSCC in southeast of Iran. Forty eight individual specimens were evaluated in this study. Serial sections were obtained from paraffin-embedded tissue samples of OSCC biopsies. The frequency of HCMV was investigated using the real-time polymerase change reaction method after DNA extraction from biopsies. The mean age of the patients (66.7% female and 33.3% male) was 58.6 years. Only three cases (6.3%) of the grade I, OSCC biopsies, were positive for active HCMV with average load of 57.7 × 103. According to the low prevalence of HCMV in OSCC, it seems that this virus plays a minor role in this kind of cancer at least in southeast of Iran. More comprehensive studies are needed to investigate the oncomodulatory effect of this virus on OSCC.

Tuberculosis (TB) is a contagious disease caused by Mycobacterium tuberculosis. Development of a new vaccine for tuberculosis requires immunogenic antigens capable of inducing suitable and long-lasting T cell immunity. The emergence of multidrugs and extensively drug-resistant strains of M. tuberculosis has made it a global public health concern. DNA vaccine is a straightforward method to introduce antigens to the host. In the present study, two immunodominant mycobacterial antigens (Mtb32C and HBHA) were isolated and cloned into pcDNA3.1 (+) to design and construct a new DNA vaccine. This vector is capable of producing new potent chimeric protein. Mtb32C (Rv0125) and heparin-binding haemagglutinin adhesion (HBHA) genes were amplified using polymerase chain reaction (PCR) of M. tuberculosis H37Rv genome and ligated into pcDNA3.1 (+). Colony-PCR and restriction enzyme analysis were used to confirm the accuracy of the cloning procedure. In the current study, recombinant pcDNA3.1 (+) vector containing Mtb32C and HBHA genes was successfully constructed. The desired size of DNA fragment was observed using single and double digestion methods. Mtb32C and HBHA genes were successfully isolated from H37Rv genome and cloned into an eukaryotic expression vector. This vector can be considered as a vaccine to evaluate immune responses in animal models.

Helicobacter pylori infection is associated with gastritis and marked infiltration of the gastric mucosa by several cytokines secreting inflammatory cells that contribute to sustained local inflammation. In this study, we sought to examine IL-6 expression in H. pylori-infected and uninfected gastric mucosa and elucidate the implication in the pathogenesis of H. pylori-associated gastritis in human. The current study aimed to determine mucosal IL-6 mRNA expression level and their correlation with virulence factors and the grade of chronic gastritis among H. pylori infected patients with chronic gastritis from Shahrekord, Iran.Patients and Mucosal IL-6 mRNA levels was measured by real-time PCR using endoscopic biopsies taken from the gastric antrum of 58 subjects infected with H. pylori and 44 uninfected subjects. Presence of vacA and cagA virulence factors was evaluated using PCR. The IL-6 mRNA expression levels were significantly more elevated in H. pylori-positive patients than uninfected individuals and expression of this cytokine was independent from the virulence factors. There was a correlation between IL-6 expression level and the grade of chronic gastritis.. Enhanced induction of IL-6 may be involved in the pathogenesis of H. pylori-associated gastritis..

Hepatitis B, hepatitis C and HIV infections constitute serious healthcare problems worldwide.. There are a limited number of studies regarding the prevalence of hepatitis B, hepatitis C and HIV infections among the drug addicts in Turkey; hence, the current study aimed to determine the frequency of these infections among 235 drug addicts treated in a drug addiction treatment centre/Elazig, Turkey.Patients and HBsAg, anti-HBs, anti-HCV and anti-HIV tests in 235 drug addicts were studied by ELISA technique. Urine samples obtained from drug addicts were analyzed for cannabis, opiate and cocaine metabolites.. All the 235 drug users were males, and their mean age was 30.69 ± 9.494 years; 112 (47.7%) of them were in the age group ranging 20 - 29 years (P < 0.05). Of 235 drug addicts, 113 (48.1%) and 115 (48.9%) were only cannabis and opiate users, respectively. In urine samples of seven (3%) drug addicts both cannabis and opiate metabolites were detected. Cocaine was detected in none of the urine samples. The frequencies of HBsAg, anti-HBs and anti-HCV among drug addicts were 2.6%, 38.3%, and 9.4%, respectively. None of the drug addicts was positive for HIV. Anti-HCV was more prevalent in opiate users than in cannabis users: 15.7% vs. 1.8% (P < 0.001).. The obtained results showed that HCV infection was an alarming problem among opiate users in the eastern part of Turkey. It is suggested to rapidly diagnose the infected persons; thus preventive measures and appropriate control may limit further transmission of these infections..

Pneumonia is the third most common cause of death in the world, and mortality is highest for patients who require hospitalization. This prospective observational study is an etiological survey of community-acquired pneumonia (CAP) over a 12-month period in the Iranian city of Mashhad. To our knowledge, this is one of the first prospective hospital-based studies to comprehensively evaluate the epidemiological, demographical, clinical, and prognostic factors of patients with CAP in Iran.Patients and We studied all adult patients (aged ≥ 16 years) with CAP admitted to Imam Reza Hospital, Mashhad, Iran, between February 2013 and January 2014. The etiological diagnosis of CAP was made through conventional culturing and staining of respiratory secretions (i.e. sputum and pleural fluid), standard BACTEC™ Plus Aerobic/F bottles for blood cultures, and the immunochromatographic assays BinaxNOW® Streptococcus pneumoniae antigen and BinaxNOW® Legionella pneumophila antigen for the detection of S. pneumoniae antigen and L. pneumophila serogroup 1 antigen, respectively. Among 120 patients with CAP, the most common etiology was S. pneumoniae (24.4%), followed by Mycobacterium tuberculosis (17.5%), S. aureus (6.7%), polymicrobial agents including anaerobes (4.2%), complicated hydatid cyst (2.5%), Influenza A virus (4.2%; including 2 cases of mixed Influenza A-bacterial infection), and Klebsiella pneumoniae, Brucella melitensis, Mucor, and varicella, each in 0.8% of the patients. The diagnosis of pneumonia remained unknown in 49 (40%) patients. Tuberculosis was an important cause of CAP in our region. Hence, it should be considered in all patients admitted with a CAP diagnosis.

Oseltamivir has been used as a drug of choice for the prophylaxis and treatment of human influenza A(H1N1)pdm09 infection across the world. However, the most frequently identified oseltamivir resistant virus, influenza A(H1N1)pdm09, exhibit the H275Y substitution in NA gene.. This study aimed to determine the prevalence and phylogenetic relationships of oseltamivir resistance in influenza A(H1N1)pdm09 viruses isolated in Shiraz, Iran..Patients and Throat swab samples were collected from 200 patients with influenza-like disease from December 2012 until February 2013. A total of 77 influenza A(H1N1)pdm09 positive strains were identified by real-time polymerase chain reaction (PCR). Oseltamivir resistance was detected using quantal assay and nested-PCR method. The NA gene sequencing was conducted to detect oseltamivir-resistant mutants and establish the phylogeny of the prevalent influenza variants. Our results revealed that A(H1N1)pdm09 viruses present in these samples were susceptible to oseltamivir, and contained 5 site specific mutations (V13G, V106I, V241I, N248D, and N369K) in NA gene. These mutations correlated with increasing expression and enzymatic activity of NA protein in the influenza A(H1N1)pdm09 viruses, which were closely related to a main influenza A(H1N1)pdm09 cluster isolated around the world.. A(H1N1)pdm09 viruses, identified in this study in Shiraz, Iran, contained 5 site specific mutations and were susceptible to oseltamivir..