The Iranian Journal of Microbiology (IJM) is the offi­cial scientific quarterly publication of the Iranian Society of Microbiology which is published by Tehran University of Medical Sciences.  The areas that are covered by IJM are medical, veterinary, food and water, applied and  environmental microbiology. It ac­cepts Original Papers, Review Articles, Short Communications and Let­ters to the Editor in the fields of Microbiology.

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Current Issue

Vol 16 No 3 (2024)

Original Article(s)

  • XML | PDF | downloads: 74 | views: 70 | pages: 285-292

    Background and Objectives: Bloodstream infection (BSI) is defined by the presence of viable microorganisms in the bloodstream. BSI is one of the major causes of sepsis and subsequent adverse clinical outcomes all across the globe. The present study was undertaken to identify clinico-epidemio-microbiological variables associated with 30-day mortality in patients having BSI with WHO priority pathogens.
    Materials and Methods: The study was conducted at a public sector tertiary care institute in central India from April 2019 to March 2021. Blood samples collected from patients with clinical suspicion of sepsis, were processed by automated bacterial culture system and interpreted as per CLSI guidelines. Calculated sample size was 150. Data was analyzed by R software.
    Results: Respiratory tract infection was the most common source (43.3%) of BSI, followed by the gastrointestinal (20%) and urinary tract (18.7%). Among the patients, 33% required invasive mechanical ventilation, and 31% required inotropes. Diabetes mellitus (DM) was the most common co-morbidity (34%). The incidence of multi-drug resistant organisms (MDRO) was 59.3%. Escherichia coli was the most commonly (24%) isolated organism, followed by Klebsiella pneumoniae (17.3%) and Acinetobacter baumannii (16%).
    Conclusion: Higher age, higher qSOFA score / SIRS score / mean SOFA score at presentation had higher mortality. Use of mechanical ventilation and inotropes during treatment and isolation of critical category organisms of WPP and multi drug resistant organisms were independent 30-day mortality predictors.

  • XML | PDF | downloads: 41 | views: 37 | pages: 293-298

    Background and Objectives: To explore the prevalence and characteristics of secondary bacterial infections among patients suffering from mucormycosis following COVID-19 infection.
    Materials and Methods: We conducted a cross-sectional, retrospective analysis from March 2020 to April 2022 at Imam Khomeini Hospital Complex in Tehran. The study included patients with histopathologically confirmed mucormycosis and documented secondary bacterial infections. We extracted and analyzed data from hospital records using SPSS software, version 26.
    Results: The study comprised 27 patients, with a predominance of females (70.4%) and an average age of 56 years. The majority of these patients (63%) had pre-existing diabetes mellitus. The severity of their COVID-19 infections varied. Treatment regimens included immunosuppressive drugs and antibiotics. Rhinocerebral mucormycosis was the most common form observed. The predominant secondary infections involved the urinary tract, respiratory system, bloodstream (bacteremia), and soft tissues, with resistant strains of Acinetobacter baumannii, Escherichia coli, and Klebsiella pneumoniae being the most frequently identified microorganisms. Notably, cases of bacteremia and pneumonia exhibited a higher mortality rate. Ultimately, 55.6% of patients were discharged, while 44.4% succumbed to their infections.
    Conclusion: Patients recovering from COVID-19 with mucormycosis are significantly susceptible to secondary bacterial infections, particularly those with diabetes mellitus or those undergoing immunosuppressive therapy. Such infections compound the morbidity and mortality risks in this vulnerable patient cohort.

  • XML | PDF | downloads: 52 | views: 45 | pages: 299-305

    Background and Objectives: Pseudomonas aeruginosa, drug-resistant, causes health infections. Resistance to the preferred therapy meropenem is a serious threat. This study aimed to analyze changes in meropenem minimum inhibitory concentration (MIC), changes in ampC, mexA, and oprD gene expression, and the correlation between MIC and ampC, mexA, and oprD gene expression after meropenem exposure.
    Materials and Methods: Ten isolates of P. aeruginosa from the Clinical Microbiology Department, Faculty of Medicine, Universitas Indonesia were used. After the bacteria were shown to be sensitive to meropenem phenotypically, intrinsic resistance genes were detected using PCR. After meropenem exposure on Days 5 and 12, sensitivity testing was carried out with the concentration gradient method and RNA was detected using real-time RT-PCR.
    Results: All P. aeruginosa isolates that were phenotypically sensitive to meropenem had the ampC, mexA, and oprD genes. An increase in MIC, an increase in ampC and mexA gene expression, and a decrease in oprD gene expression were observed after meropenem exposure. There was a very strong and significant correlation (p ≤ 0.05) between MIC and oprD gene expression after Day 12 of meropenem exposure.
    Conclusion: Although there were no significant differences in MIC and ampC, mexA, and oprD gene expression between Day 5 and Day 12, there was a very strong and significant correlation between MIC and oprD gene expression on Day 12 (p ≤ 0.05). This indicates that decreasing oprD gene expression has the potential to increase meropenem resistance in Pseudomonas aeruginosa.

  • XML | PDF | downloads: 43 | views: 39 | pages: 306-313

    Background and Objectives: Klebsiella pneumoniae is a healthcare-associated infections agent and could be an extended spectrum β-lactamase (ESBL) producer. Understanding the transmission of this bacterium in a hospital setting needs accurate typing methods. An antibiogram is used to detect the resistance pattern of the isolates. Random Amplified Polymorphic DNA (RAPD) and Enterobacterial Repetitive Intergenic Consensus (ERIC)-PCR are rapid, technically simple, and easy-to-interpret DNA typing methods. This study aimed to evaluate the use of antibiotyping, RAPD-, and ERIC-PCR to investigate the heterogeneity of K. pneumoniae isolated from clinical specimens.
    Materials and Methods: The antibiograms of 46 K. pneumoniae clinical isolates were determined by Vitek® 2 Compact. All isolates underwent RAPD-PCR using AP4 primer and ERIC-PCR using ERIC-2 primer. The dendrogram was generated using the GelJ software and analyzed to determine its similarity. The analysis of antibiogram and the molecular typing diversity index was calculated using the formula of the Simpson’s diversity index.
    Results: About 71.7% of the isolates were ESBL-producers, and more than 80% of isolates were susceptible to amikacin, ertapenem, and meropenem. The antibiotyping produced 32 diverse types with DI = 0.964. In Conclusion: Antibiotyping, RAPD- and ERIC-PCR showed powerful discrimination power among the isolates, supported the diversity of K. pneumoniae isolates in current study. These combination could be promising tools for clonal relationship determination, including in tracking the transmission of the outbreak’s agent in hospital setting.

  • XML | PDF | downloads: 46 | views: 52 | pages: 314-322

    Background and Objectives: During the coronavirus pandemic, the overuse of antibiotics to reduce coinfections and mortality may be contributing to the rise of antimicrobial resistance. In this study, we aim to investigate the antibiotic resistance changes of Acinetobacter baumannii post-COVID-19 pandemic in Northern Iran.
    Materials and Methods: The current study is a cross-sectional study. Between 2022 and 2023, 2190 clinical samples were collected from patients with healthcare-associated infections (HAIs) at four hospitals in Sari, which served as corona centers after the COVID-19 pandemic. Antimicrobial sensitivity was determined using standard broth macro-dilution, and resistance genes were detected using multiplex PCR.
    Results: Based on the results co-amoxiclav had a resistance rate of 100%, while piperacillin/tazobactam showed the least resistance rate of 29.82%. In terms of GM MIC values, colistin was the most potent against multi-drug resistant isolates. The frequency of blaOXA-51, ampC, aphA6, and blaNDM genes were 100%, 99.12%, 90.35%, and 69.30% respectively.
    Conclusion: Our study revealed high multi-drug resistance rates. Piperacillin/tazobactam recommended for treating multidrug resistant Acinetobacter baumannii infections in Northern Iran.

  • XML | PDF | downloads: 35 | views: 31 | pages: 323-328

    Background and Objectives: Leptospirosis is a zoonotic disease caused by pathogenic Leptospira serovars. The genus Leptospira cannot differentiated by conventional techniques. However, identity determination of pathogenic serovar is precious of public health problems and epidemiological studies. Pulsed-field gel electrophoresis facilitates rapid identification of Leptospires to the serovar levels.
    Materials and Methods: In this study, we employed PFGE to evaluate 28 Leptospira isolates, with animal, human and environmental origin, obtained from Razi Vaccine and Serum Research Institute of Karaj, Iran. PFGE patterns of 28 Leptospira serovars were generated using the Not I restriction enzyme in comparison with the lambda ladder.
    Results: Out of 28 serovars evaluated, we identified 22 different pulsed types, designated P1- P22. Out of 22 pulse groups, 3 were found to be a common type, but others were a single Type. Groups consisting of the common type were P3, P9, P14, and P16. The results showed that the discriminatory index of PFGE by Not I enzyme was 0.99, demonstrating heterogeneous differentiation among serovar members.
    Conclusion: The PFGE methodology used in this study showed excellent interlaboratory report usability, rapid, reliable, enabling standardization and data sharing between laboratories.

  • XML | PDF | downloads: 26 | views: 34 | pages: 329-336

    Background and Objectives: Escherichia coli O157: H7 is one of the most important causes of hemorrhagic colitis, and hemolytic uremic syndrome. The present study aimed to isolate E. coli O157: H7 from foods and patients with hemorrhagic colitis, and identify Shiga toxin genes, phylogenetic comparison, and antibiotic resistance of the isolates.
    Materials and Methods: In total 400 samples, including patients stool and food were taken in Isfahan-Iran province. Phenotypic tests and PCR were performed to identify Shiga toxin-producing E. coli. The isolated strains were compared phylogenetically by PFGE. Agar disk diffusion was performed to identify the antibiotic resistance of the isolates.
    Results: Totally, 5 isolates of fecal samples were E. coli O157, but only 2 isolates carried H7 gene. Also, 9 isolates of E. coli O157 were isolated from food samples that 3 isolates were E. coli O157: H7. The isolates carried stx1, stx2, hlyA and eaeA genes. Also, E. coli non-O157: H7 identified from samples that contained stx1, stx2, hlyA genes. The highest susceptibility to imipenem and the highest resistance to ampicillin and ciprofloxacin were observed. There was a similarity of 100% between the E. coli O157: H7 strains isolated from patients and raw milk and minced beef samples.
    Conclusion: Serotypes other than the O157 of E. coli are more prevalent in patients and food. The E. coli O157: H7 isolates from patients had 100% genetic similarity with minced meat and cow milk isolates, which indicates cattle are the most important reservoir of this bacterium in Iran.

  • XML | PDF | downloads: 31 | views: 31 | pages: 337-341

    Background and Objectives: Enterococcus faecalis is known as common pathogen for endodontic infections and cause secondary and refractory pulp periapical periodontitis. The bacteria can opportunistically colonize periodontal pockets and presents a possibility of infection developing in other organs. This research will investigate the dissemination of E. faecalis from the gingival tissue to the heart and kidney.
    Materials and Methods: Three groups were formed, consisting of twelve male Sprague Dawley rats: a control group designated as 0-day, and experimental groups labeled as 7-days and 14-days. Periodontitis induced by concurrent infection with sterile wire 0.2 mm insertion and E. faecalis inoculation is performed into the gingival sulcus located between the maxillary right 1st and 2nd molar teeth area. After euthanasia, tissue samples around the maxillary gingiva, maxillary jaw samples, kidney and heart tissues were obtained for quantitative Real-Time PCR assay and histopathological analysis.
    Results: Results showed at 7-days, there was an upregulation of E. faecalis gene expression in the gingiva, heart, and kidney samples as well as infiltration of the inflammatory cells at 7-days post induction, which consequently decreased at 14-days.
    Conclusion: Thus, the study suggests dissemination of E. faecalis from gingival tissue to the heart, kidney which could be probable link between periodontal disease, heart, and kidney disease.

  • XML | PDF | downloads: 44 | views: 54 | pages: 342-350

    Background and Objectives: TB infection is one of the most challengeable epidemiological issues. Complex interactions between microbiota and TB infection have been demonstrated. Alteration in microbial population during TB infection may act as a useful biomarker. The present study examined the microbiota patterns of blood and sputum samples collected from Afghan immigrants and Iranian patients with active TB.
    Materials and Methods: Sixty active pulmonary TB patients were enrolled in the study. Blood and sputum samples were collected. To detect phylum bacterial composition in the blood and sputum samples, bacterial 16S rRNA quantification by Real-Time qPCR was performed.
    Results: A significant decrease in Bacteroidetes in Iranian sputum and blood samples of Afghan immigrants and Iranian TB active subjects were seen. While, sputum samples of Afghan immigrants showed no significant differences in Bacteroidetes abundance among TB active and control. Firmicutes were also presented no significant difference between sputum samples of the two races. Actinobacteria showed a significant increase in Iranian and Afghan sputum samples while this phylum showed no significant abundance in Iranian and Afghan TB positive blood samples. Proteobacteria also showed an increase in sputum and blood samples of the two races.
    Conclusion: An imbalance in Bacteroidetes and Firmicutes abundance may cause an alteration in the microbiota composition, resulting in dysregulated immune responses and resulting in the augmentation of opportunistic pathogens during TB infection, notably Proteobacteria and Actinobacteria. Evaluation of human microbiota under different conditions of TB infection can be critical to a deeper understanding of the disease control.

  • XML | PDF | downloads: 27 | views: 47 | pages: 351-356

    Background and Objectives: Lipoarabinomannan is one of the components of the significant structural cell surfaces of mycobacteria and serves as an immunostimulatory factor. TNF-α and IL-12 are two examples of the anti-bacterial inflammatory cytokines that are activated and induced during infection.
    Materials and Methods: In this study, mannan was extracted and processed, and then Bulb/c female mice were used in three groups, one group was given BCG vaccine, the other group was given BCG vaccine with mannan adjuvant, and a non-injected group was used as a control group. Inflammatory factors interleukin-12, TNF-α, IgG and IgM were measured in mouse serum.
    Results: The levels of the inflammatory factors interleukin-12 and TNF-α in the serum isolated from mice receiving the BCG vaccine with mannan adjuvant showed a significant difference compared to the group that received only the BCG vaccine and the control group [IL-12] and , with P≤0.05.The examination of the level of IgG immune factors in these three groups revealed a significant difference. The group that received the BCG vaccine with mannan adjuvant showed a marked contrast compared to the group that received only the BCG vaccine and the control group, with P≤0.05. The level of IgM was higher in the group that received the BCG vaccine alone compared to the adjuvant vaccine group and the control group, with P≤0.05.
    Conclusion: Our results indicated that mice receiving the BCG vaccine with mannan adjuvant had significantly higher serum levels of IL-12, TNF-α, and IgG than the group receiving BCG alone.

  • XML | PDF | downloads: 31 | views: 31 | pages: 357-365

    Background and Objectives: Helicobacter pylori is known as the main cause of gastrointestinal diseases including gastritis, gastric ulcer and stomach cancer. Serodiagnosis of H. pylori infection is a noninvasive and rapid method but the efficiency of this method is highly dependent to the antigens used. This study evaluated the efficacy of recombinant UreB-Omp18 and FliD for serodiagnosis of H. pylori infection.
    Materials and Methods: The genes encoding for fliD, ureB, and omp18 was amplified by PCR and cloned into pET-22b and pET-28a vectors. The constructs were expressed in E. coli BL21 and purified by affinity chromatography. The antigenic properties and diagnostic potential of the recombinant proteins were analysed by immunoblotting and ELISA, respectively.
    Results: The recombinant UreB-Omp18 and FliD with molecular weights of 48 kDa and 25 kDa were observed on SDS-PAGE and purified by the Ni-NTA column. The ELISA results showed that the sensitivity and specificity of recombinant UreB-Omp18 protein in serodiagnosis of H. pylori infection were 89% and 83%, respectively. Also, the sensitivity and specificity of the recombinant FliD protein were calculated to be 91% and 76%, respectively.
    Conclusion: The results indicated that the recombinant UreB-Omp18 and FliD could diagnose H. pylori infection with high sensitivity and specificity.

  • XML | PDF | downloads: 46 | views: 53 | pages: 366-375

    Background and Objectives: Methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of nosocomial and community acquired infections. Nanoparticles are considered as proper tools to overcome the therapeutic problem of antimicrobial-resistant infections because of the drug concentration increment at the desired location and protection from enzymatic degradation. The goal of this study was to evaluate the effect of the antibacterial and antibiofilm activities of zingerone and niosome containing zingerone against pre-formed biofilm of MRSA isolates.
    Materials and Methods: 62 MRSA isolates cultured from patients with diabetic ulcers were investigated. Niosomes were synthesized and characterized by X- ray diffraction, zeta potential and scanning electron microscopy (SEM). The size of niosomal particles measured by SEM and zetasizer.
    Results: The surface charge of prepared niosomes was about -37 mV. The effect of the zingerone and noisome containing zingerone was evaluated against biofilms of MRSA isolates. Also, the antibiofilm activity of prepared niosomes on gene expression of MRSA biofilms was evaluated using Real Time PCR. Our results demonstrated that the niosome containing zingerone had a diameter of 196.1 nm and a -37.3-mV zeta potential. Zingerone removed one and three-day old biofilms of MRSA at the concentration of 1000 µg/ml, while the zingerone-laoded niosomes removed 1, 3- and 5-days old biofilms at the concentration of 250 µg/ml, 250 µg/ml, and 500 µg/ml.
    Conclusion: The results indicated that niosome containing zingerone eliminated MRSA and its biofilms faster compared with free zingerone and it suggested that zingerone-encapsulated niosomes could be considered as a promising treatment against MRSA and its biofilms.

  • XML | PDF | downloads: 25 | views: 41 | pages: 376-388

    Background and Objectives: The main cause of mortality in burn patients is infection from burns. Drug-resistant bacteria are the main causes of wound infection, so alternative antibiotic therapies hold significant importance. The objective of this study was to examine the impact of a collagen hydrogel that contains a nanoemulsion of Lavandula essential oil on the healing process of infected burn wounds.
    Materials and Methods: In this experimental study, 20 rats were randomly divided after applying burns with a 10 mm diameter hot plate and infecting the wounds with multidrug-resistant Pseudomonas aeruginosa into four groups, including a positive control, a negative control, the first experiment (collagen hydrogel), and the second experiment (collagen hydrogel containing Lavandula essential oil nanoemulsion). On the 4th, 11th, and 18th days, tissue samples were taken for pathology studies. The important parameters in burn wound healing with hematoxylin and eosin and Masson's trichrome staining methods were investigated and scored according to Abramov’s method.
    Results: Based on the pathology findings, experimental groups 1 and 2 compared to the negative and positive control groups were effective in rat infection wound healing. The hydrogel scaffold in the experimental groups increased fibroblasts and angiogenesis compared to the control groups. Epithelization was noticed only in the hydrogel group containing nanoemulsion.
    Conclusion: The study findings suggest that the use of collagen hydrogel with Lavandula essential oil nanoemulsion has potential as a wound dressing. This is because it has the potential to effectively promote healing and act as an antibacterial agent to prevent infections.

  • XML | PDF | downloads: 31 | views: 34 | pages: 389-400

    Background and Objectives: Rumen microbiologists are looking for new probiotics to improve the digestibility of livestock diets. This study intended to screen and evaluate the ruminal cellulolytic bacteria (CBs) and their potential application as probiotics.
    Materials and Methods: Microbial culture and molecular techniques performed to isolate CBs from the rumen of camels, deer and rams. Their antibacterial and antibiogram tests were done using disc diffusion method. Their potential to degrade cellulose, starch, tannin and protein were investigated using clear zone halo, and spectrophotometric techniques. Bilious, saline, and acidic broth media were used to study the resistance of isolates in intestinal conditions.
    Results: The phylogenetic analysis revealed that the strains belonged to Firmicutes and Proteobacteria phyla, Citrobacter murliniae, Ornithinibacillus bavariensis, C. braakii, and Bacillus subtilis. The highest cellulase (CAS) activity was recorded by C. murliniae Dez wildlife13A (2.98 UmL-1), whereas C. braakii Loot desert 111A (1.14 Uml-1) was produced the lowest enzyme. The isolates were highly resistant to synthetic conditions of intestine (pH 2.5-3.5, bile 0.3-2%), as well as tolerated higher concentrations of NaCl (up to 10%). They effectively inhibited standard pathogen strains, and showed sensitivity to the used antibiotics.
    Conclusion: This study reports the cellulolytic O. bavariensis Tabbas desert 32A for the first time from the rumen, which will have potential biotechnological applications.

  • XML | PDF | downloads: 27 | views: 30 | pages: 401-410

    Background and Objectives: Rotavirus and Hepatitis A virus are responsible for causing gastroenteritis and jaundice. The current vaccination approaches have proven insufficient, especially in low-income countries. In this study, we presented a novel dual-vaccine candidate that combines the rotavirus VP8 protein and the hepatitis A virus VP1.
    Materials and Methods: The VP8*-rotavirus+AAY+HAV-VP1 fusion protein was produced using an Escherichia coli expression system. The recombinant protein had a molecular weight of approximately 45.5 kDa and was purified through affinity chromatography. BALB/c mice were injected subcutaneously with the recombinant protein, VP1, VP8 and vaccines for rotavirus and hepatitis A virus, both with and without ALUM and M720 adjuvants. ELISA assays were used to measure total IgG, IgG1, IgG2, and short-term and long-term IL-5 and IFN-γ responses.
    Results: The fusion protein, when combined with adjuvants, elicited significantly higher total IgG, IgG1, and IgG2 responses compared to VP1 and VP8 alone, as well as the rotavirus and hepatitis A vaccines. Furthermore, it induced a higher short-term IL-5 and IFN-γ response while demonstrating a higher long-term IL-5 response compared to the rotavirus and hepatitis A vaccines.
    Conclusion: This study demonstrates that the VP8*-rotavirus+AAY+HAV-VP1 fusion protein is a promising dual vaccine candidate for immunization against hepatitis A and rotaviruses.

  • XML | PDF | downloads: 36 | views: 44 | pages: 411-420

    Background and Objectives: The pediatric population worldwide bears a significant morbidity and death burden due to acute respiratory infections (ARIs). Human Orthopneumovirus, sometimes referred to as the Human Respiratory Syncytial Virus (HRSV), is one of the main causes of ARIs in infants. The main goal of this study was to identify the genetic diversity of HRSV strains that were circulating in the Iranian population at a certain time of year.
    Materials and Methods: Two hundred youngsters less than 12 years old with acute respiratory infections had samples taken from their throat and pharynx secretions. Then, external and hemi-nested PCR were employed, using specific primers targeting the G gene region to detect HRSV. Subsequently, nine randomly selected positive samples were subjected to sequencing. The results were then compared with reference strains cataloged in GeneBank, and phylogenetic tree was constructed using Chromes and MEGA7.
    Results: Out of 200 samples, 34 were identified as containing HRSV. Subgroup A was predominant, accounting for 61.76% of cases, followed by subgroup BA (35.29%) and subgroup B (2.94%). Phylogenetic analysis revealed five samples associated with subtype B and four with genotype A. Genomic analysis showed three samples under the GA2 subgroup and one under GA1 for subtype A, and four samples in subgroup BA and one in GB2 for subtype B.
    Conclusion: In this study, subgroup A strains, particularly genotype GA2, exhibited a higher prevalence compared to subgroup B strains during the specific period under investigation, shedding light on the genetic landscape of HRSV in this region.

  • XML | PDF | downloads: 33 | views: 23 | pages: 421-427

    Background and Objectives: Although several studies have been achieved on the frequency of the HPV types among women with cervical cancer in Iran, HPV-positive samples were in some cases directed to specific-primer genotyping of HPV 16 and 18. Therefore, the other HPV types are underestimated. Several studies have also reported a greater prevalence of HPV 16 in cervical cancer in Iran than in the world. To clarify these subjects, the distribution of HPV types in women referred for colposcopy in Tehran was investigated.
    Materials and Methods: In this cross-sectional study, a total of 148 cervical samples from women with normal, atypical squamous cells of undetermined significance, cervical intraepithelial neoplasia I-III, and invasive cervical cancer histopathology were included. HPV was detected by PCR assay and all HPV-positive specimens were subjected to direct nucleotide sequencing.
    Results: Our results demonstrated that the total prevalence of HPV was 92.5%. The five most common HPV types were HPV 16 (49.3%), 18 (14.8%), 6 (7.4%), 31 (4.1%), and 11 (2.7%). About the histopathological stage, HPV 16 and 18 were dominant in all studied groups. In cervical cancer, HPV 16 and 18 were detected in 60% and 20% of cases, respectively.
    Conclusion: HPV 16 and 18 were the most common in cervical cancer in Iran.

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