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.

Current Issue

Vol 13 No 6 (2021)

Review Article(s)

  • XML | PDF | downloads: 78 | views: 110 | pages: 728-736

    Coronavirus disease 2019 (COVID-19), the first pandemic caused by a human infecting coronavirus, has drawn global attention from the first time it appeared in Wuhan city of China in late December 2019. Detection of the responsible viral pathogen, named as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by WHO, and its possible pathogenesis lead to the forming of many hypotheses about the factors that may affect the patients’ outcome.
    One of the SARS-CoV-2 infection concerns was the potential role of angiotensin-converting enzyme (ACE) inhibitors and angiotensin-receptor blockers (ARBs) in COVID-19 patients’ morbidity and mortality. Studies demonstrated that because SARS-CoV-2 uses human ACE2 cell receptors as an entry receptor to invade the cells, there might be an association between antihypertensive drugs such as RAAS inhibitors (specifically ACEIs and ARBs) and the COVID-19 disease. Data are scarce and conflicting regarding ACEI or ARB consumption and how it influences disease outcomes, and a single conclusion has not been reached yet.
    According to the literature review in our article, the most evidentially supported theory about the use of RAAS inhibitors in COVID-19 is that these medications, including ACEI/ARB, are not associated with the increased risk of infection, disease severity, and patient prognosis. However, further studies are needed to support the hypothesis.

  • XML | PDF | downloads: 50 | views: 98 | pages: 737-747

    Coronavirus disease 2019 (COVID-19), caused by the novel coronavirus, Severe Acute Respiratory Syndrome-Coronavirus-2 (SARS-CoV-2), led to the ongoing global public health crisis. Existing clinical data suggest that COVID-19 patients with acute respiratory distress syndrome (ARDS) have worse outcomes and increased risk of intensive care unit (ICU) admission. The rapid increase in the numbers of patients requiring ICU care may imply a sudden and major challenge for affected health care systems. In this narrative review, we aim to summarize current knowledge of pathophysiology, clinical and morphological characteristics of COVID-19-associated ARDS and ARDS caused by other factors (classical ARDS) as defined by Berlin criteria, and therefore to elucidate the differences, which can affect clinical management of COVID-19-associated ARDS. Fully understanding the characteristics of COVID-19-associated ARDS will help identify its early progression and tailor the treatment, leading to improved prognosis in severe cases and reduced mortality. The notable mechanisms of COVID-19-associated ARDS include severe pulmonary infiltration/edema and inflammation, leading to impaired alveolar homeostasis, alteration of pulmonary physiology resulting in pulmonary fibrosis, endothelial inflammation and vascular thrombosis. Despite some distinct differences between COVID-19-associated ARDS and classical ARDS as defined by Berlin criteria, general treatment principles, such as lung-protective ventilation and rehabilitation concepts should be applied whenever possible. At the same time, ventilatory settings for COVID-19-associated ARDS require to be adapted in individual cases, depending on respiratory mechanics, recruitability and presentation timing.

Original Article(s)

  • XML | PDF | downloads: 58 | views: 120 | pages: 748-756

    Background and Objectives: The entire globe is undergoing an unprecedented challenge of COVID-19. Considering the need of rapid and accurate diagnostic tests for SARS-CoV-2, this study was planned to evaluate the cost effective extraction free RT-PCR technique in comparison to the standard VTM based RT-qPCR method.
    Materials and Methods: Paired swabs from nasopharynx and oropharynx were collected for SARS-CoV-2 testing, from 211 adult patients (≥18 years) in VTM and plain sterile tubes (dry swabs). These samples were processed and RT-qPCR was carried out as per standard protocols.
    Results: 54.5% of the patients were females and 45.5% were males with sex ratio 1:1.19 (M: F). 38.86% were symptomatic, of which fever (86.59%), cough (79.23%) and breathlessness (46.34%) were the most common symptoms. The positivity by VTM based method and index method was 31.27% and 13.27% respectively. Of the 27 inconclusive results from index method, 37.04% were positive, 48.15% were negative by VTM based method. However, in 40 inconclusive results by VTM based method, 90% were negative and rest remained inconclusive by index method. The sensitivity and specificity of the index method were 39.39% and 85.71% respectively. The overall agreement between VTM based method and index method was 49.59% with estimated Kappa value of 0.19.
    Conclusion: VTM based method showed higher sensitivity compared to the index method. The higher positivity by VTM based method, suggests that VTM based method could plausibly be a better detection method of SARS-CoV-2. Still, the index method might add value in a resource limited setups for detection of SARS-CoV-2.

  • XML | PDF | downloads: 36 | views: 92 | pages: 757-763

    Background and Objectives: This study aimed to detect SARS-CoV-2 in conjunctival samples of COVID-19 patients to investigate the transmission route of COVID-19 and its correlation with laboratory indexes.
    Materials and Methods: In this cross-sectional study, 44 COVID-19 patients were tested for conjunctival PCR in Ayatollah Rouhani hospital of Babol, Iran, in January and February 2021. The conjunctival samples were collected using a conjunctival swab and suspended in a viral transport medium. After RNA extraction and cDNA synthesis, real-time PCR was performed to investigate the SARS-CoV-2 genome in samples. The ocular manifestations and laboratory indexes were evaluated for all patients.
    Results: Among 44 COVID-19 patients, 6 samples (13.63%) were positive in terms of conjunctival PCR. The mean ± SD age of conjunctival PCR-positive patients was 76.17 ± 16.61-year-old, while conjunctival PCR-negative COVID-19 patients were aged 57.54 ± 13.61-year-old (p <0.05). D-dimer serum level is significantly higher in conjunctival PCR-positive COVID-19 patients (4001.00 ± 3043.36 µg/ml) compared to normal individuals (496.80 ± 805.92 µg/ml, p <0.01).
    Conclusion: Our study showed that the conjunctiva and tear contain the SARS-CoV-2 in COVID-19 patients as a possible transmission route.

  • XML | PDF | downloads: 66 | views: 125 | pages: 764-768

    Background and Objectives: Nosocomial infections (NIs) are an important cause of mortality and morbidity in intensive care units (ICU). Pneumonia is the most common serious manifestation of infection in Covid-19 patients. The aim of this study was to investigate the prevalence of pneumonia in Covid-19 patients admitted to the ICU.
    Materials and Methods: In this cross-sectional study, 1240 Covid-19 patients admitted for more than 48 h in the ICUs of Imam Khomeini Complex Hospital (IKCH) in Tehran for seven months in 2020 were included in the study with initial diagnosis of Covid-19 (PCR test and chest imaging). Data were collected regarding severity of the illness, primary reason for ICU admission, presence of risk factors, presence of infection, length of ICU and hospital stay, microbial type and antibiotic resistance. In this study, the pattern of antibiotic resistance was determined using the disk difusion method.
    Results: In this study, 289 (23.3%) out of 1320 patients experienced NIs. 221 (76.4%) out of 289 patients had underlying diseases and the most common of which were hypertension, diabetes and heart disease, respectively. 163 patients (56.4%) were RT-PCR COVID-19 positive and 200 patients (69%) died. The majority of patients with NIs (71%) were over 55 years old. The most common type of nosocomial infection (66%) was ventilator-associated pneumonia (VAE). The most common microorganisms that cause pneumonia were Acinetobacter baumannii, Klebsiella pneumoniae and Pseudomonas aeruginosa, respectively.
    Conclusion: Pneumonia infection is high in Covid-19 patients admitted to the ICU, it needs to be planned with the diagnosis and measures related to the control and prevention of this infection.

  • XML | PDF | downloads: 64 | views: 143 | pages: 769-778

    Background and Objectives: The outbreak of COVID-19 has been challenging the global health systems. As one of the major associated concerns, microbial co-infections and antimicrobial resistance play critical roles in the prognosis of the disease. This study aims to evaluate co-infections in COVID-19 patients regarding drug resistance.
    Materials and Methods: A total number of 5530 Real Time PCR-confirmed COVID-19 cases, who were admitted to two major educational Hospitals in Zanjan, Iran, from February 2019 to February 2020 were included. Respiratory, blood and urine specimens were collected and cultured on selective media. Subsequently, isolates identification, disc diffusion susceptibility tests, and data analysis were carried out.
    Results: Bacterial and fungal co-infections were confirmed in 423 patients (8.1%). Co-infections were more prevalent among females (53.2%) than males (46.8%). Coinfected patients had a significantly higher mortality rate compared to those without co-infections (54.8% vs. 12.2%, P<0.001). Acinetobacter baumannii was the most prevalent bacteria isolated from respiratory tract (15.4%) and blood (2.1%). Escherichia coli (12.5%) was the most frequent bacteria in urine. Fungal co-infection was confirmed in 174 (3.36%) patients. Gram-negative bacteria were highly sensitive to colistin (97.85%) and widely resistant to cefixime (91.79%) and trimethoprim-sulfamethoxazole (89.64%). Gram-positive bacteria were considerably sensitive to vancomycin (68%) and nitrofurantoin (66%). Tetracycline and ampicillin were the least effective antibiotics for Gram-positive bacteria with respective resistance rates of 90.91% and 83.33%.
    Conclusion: Given the high incidence of bacterial co-infections in COVID-19 patients, it is important to develop rapid and efficient diagnostic, therapeutic and disinfection guidelines to control these infections in the hospitals.

  • XML | PDF | downloads: 37 | views: 106 | pages: 779-784

    Background and Objectives: Gardnerella vaginalis and Candida albicans are the most common causative agents of bacterial vaginosis, and infections with these pathogens lead to inflammation, endometritis, and pruritus. The aim of this retrospective study was to determine the trends of G. vaginalis infections based on real-time PCR data according to age and sex in patients with sexually transmitted diseases.
    Materials and Methods: A total of 59,381 specimens isolated at a clinical laboratory from September 2018 to December 2020 were subjected to real-time PCR for the detection of G. vaginalis DNA. Sample types included catheter, pus, tissue, swab, and urine samples.
    Results: Among 59,381 samples, 20,718 (34.8%) were positive for G. vaginalis. Of the positive samples, 13,186 (63.7%) were from male patients and 7,532 (36.3%) were from female patients. Average patient age was 39.1 years (the average age of male and female patients was 38.34 and 40.43 years, respectively). Female patients younger than 19 years exhibited the highest incidence of G. vaginalis, at 71.57%, followed by 68.46% incidence in those aged 20-29 years; the lowest incidence was in women aged 40-49 years. Further, among specimen types, the highest number of G. vaginalis-positive specimens was obtained by the swab sampling method.
    Conclusion: From 2018 to 2020 in Korea, the number of tests conducted for bacterial vaginosis has increased, while the incidence of G. vaginalis infections appears to have decreased. the finding that female adolescents have a high tendency to carry the pathogen is important. and for effective surveillance of BV, sampling by cotton swabs and detection by multiplex PCR might be a good approach.

  • XML | PDF | downloads: 40 | views: 98 | pages: 785-792

    Background and Objectives: Imipenem/relebactam (IMP/R) is a newly FDA approved β-lactam/β-lactamase inhibitor combination. Relebactam ability to restore IMP activity could differ according to the cause of imipenem non-susceptibility. Therefore, we investigated the in-vitro activity of IMP/R against Klebsiella pneumoniae with different mechanisms of imipenem non-susceptibility.
    Materials and Methods: Imipenem-nonsusceptible (IMP-NS) K. pneumoniae isolates were collected and characterized for β-lactamase encoding genes by multiplex PCR. For IMP-NS carbapenemase-negative isolates, study of Ompk35 & Ompk36 gene expression was performed by reverse transcription-PCR while efflux pump activity was studied by minimum inhibitory concentration (MIC) reduction assay using efflux pump inhibitor. Susceptibility testing of K. pneumoniae to IMP and IMP/R were achieved by broth microdilution (BMD) method.
    Results: During the study period, 140 isolates of IMP-NS K. pneumoniae were collected. BMD method showed that relebactam restored IMP susceptibility in 100%, 60% and 49% of isolates that only harbor AmpC, extended spectrum beta lactamase (ESBL) and carbapenemases, respectively. IMP/R was most potent against all blaKPC and 50% of blaOXA-48_producing isolates. No demonstrable activity of IMP/R against K. pneumoniae harboring metallo-β-lactamases (MBLs). Out of 18 isolates with IMP non-suceptibility due to porins loss with overproduction of ESBL and/or AmpC, 14 (77.7%) isolates were IMP/R susceptible. IMP/R showed no activity against isolates with only efflux pump hyperactivity.
    Conclusion: Relebactam could restore IPM activity in KPC or AmpC-producing IMP/NS K. pneumoniae but with no activity against MBL- producing isolates. Relebactam activity against isolates harbouring-blaOXA-48 or with altered Ompk35 & Ompk36 gene expression and efflux pump hyperactivity need further studies. Therefore, using IMP/R antibiotic in the treatment of infections caused by IMP/NS K. pneumoniae should be based on its molecular profile of IMP resistance to optimize the utility of IMP/R.

  • XML | PDF | downloads: 37 | views: 114 | pages: 793-800

    Background and Objectives: Due to the reduced susceptibility of clinical Clostridioides difficile strains in hospitals to various antimicrobial agents, the importance of antimicrobial susceptibility testing (ASTs) has increased. This study aimed to investigate the toxin gene profiles and the antimicrobial resistance of C. difficile isolated from hospitalized patients suspected of having Clostridioides difficile infection (CDI) in Tehran, Iran.
    Materials and Methods: The stool samples were obtained from a hospitalized patients. The samples were shocked by alcohol and the patients cultured on cycloserine-cefoxitin-fructose agar in anaerobic Conditions. Toxin assay was performed for detection of toxinogenic isolates. An antibiotic susceptibility test was done. Furthermore, their genome was extracted for PCR to confirm C. difficile and detect toxin gene profile.
    Results: Toxigenic C. difficile were identified in 21 of the 185 stool samples (11.3%). PCR detected seven toxin gene profiles; the highest prevalence was related to tcdA+B+, cdtA+B- toxin gene profile (57.1%). There were 14.3% and 28.6% resistant rates of the isolates towards vancomycin and metronidazole with the toxin gene profiles; tcdA+B+, cdtA±B+; and tcdA+B-, cdtA-B+. All resistant isolates to moxifloxacin, clindamycin, and tetracycline were belonged to the toxin gene profiles; tcdA+B+, cdtA+B+; tcdA+B+, cdtA+B-, and tcdA-B+, cdtA+B-.
    Conclusion: Relative high resistance was detected towards metronidazole and vancomycin, although, still have acceptable activity for CDI treatment. However, a proper plan for the use of antibiotics and more regular screening of C. difficile antibiotic resistance seems necessary.

  • XML | PDF | downloads: 35 | views: 102 | pages: 801-807

    Background and Objectives: Taking unnecessary or inappropriate prophylactic antibiotics can cause infections with resistant organisms. The present study aimed to investigate administration prophylactic antibiotics in surgery ward and its compliance with standard protocol in Imam Reza teaching hospital of Birjand, Iran.
    Materials and Methods: This descriptive-analytical study was performed to evaluate the pattern of prophylactic antibiotics on patients who underwent surgical operations from October to December 2019. A checklist including demographic information, type of prophylactic antibiotics, dose and duration of using drug, type of surgery, and compliance with standard protocol was used. The validity and reliability of the checklist were evaluated and confirmed prior to the study. All eligible patients were enrolled and the information of the prescribed drugs in the surgical wards was compared with the Schwartz’s principles of surgery as standard protocol.
    Results: Out of a total of 300 patients, 187 (62.3%) were male. Among the patients, 155 (51.7%) cases underwent general surgery, 119 (39.6%) cases orthopedic surgery, and 26 (8.7%) cases neurosurgery. The most popular prescribed antibiotics were cefazolin (170 cases) and ceftriaxone + metronidazole (67 cases). Furthermore, the maximum antibiotic administrations were two days (127 cases) and one day (93 cases). More importantly, 67.7% and 92.3% of the patients were in compliance with the standard protocol in terms of the type and time of administration, respectively.
    Conclusion: Our results showed that duration and route of administrating antibiotics were consistent with the standard protocol, but the type of drugs and indication did not match.

  • XML | PDF | downloads: 42 | views: 101 | pages: 808-816

    Background and Objectives: Antibiotics at sub-minimum inhibitory concentrations (sub-MIC) may alter bacterial virulence factors. The objective of this study was to investigate the effect of gentamicin at sub-MIC concentrations on the expression of genes involved in alginate production and biofilm formation of Pseudomonas aeruginosa.
    Materials and Methods: The broth microdilution method was used to determine the MIC of gentamicin for three P. aeruginosa clinical isolates (P1-P3) and standard strains (PAO1 and 8821M). Alginate production and biofilm formation of the bacteria in the presence and absence of sub-MIC concentrations of gentamicin were measured using microtiter plate and carbazole assay, respectively. The real-time PCR method was used to determine the effect of gentamicin at sub-MIC concentrations on the expression level of genes involved in biofilm formation (pelA and pslA) and alginate production (algD and algU).
    Results: Gentamicin at sub-MIC concentrations significantly reduced alginate production, biofilm formation, and the expression of alginate and biofilm-encoding genes in clinical isolate P1. This inhibitory effect was also observed on the alginate production of 8821M strain and biofilm formation of PAO1strain. In clinical isolates, P2 and P3, alginate production, biofilm formation, and the expression of alginate and biofilm-encoding genes were significantly increased in exposure to sub-MIC concentrations of gentamicin.
    Conclusion: This study showed that different phenotypic changes in clinical isolates and standard strains of P. aeruginosa in exposure to sub-MIC concentrations of gentamicin are associated with changes in the expression of virulence genes. Further researches are required to understand the mechanisms involved in regulating the expression of virulence genes after exposure to sub-MIC concentrations of antibiotics.

  • XML | PDF | downloads: 32 | views: 71 | pages: 817-823

    Background and Objectives: Recently, the rise of methicillin-resistant Staphylococcus aureus (MRSA) isolated from hospital healthcare workers (HCWs) and various infectious samples has become one of the main concerns in hospital settings. Therefore, epidemiological studies are necessary to monitor antibiotic resistance patterns in each region and to study the pathogenesis of this strain to control infections.
    Materials and Methods: In this cross-sectional study, a total of 100 S. aureus isolates, including 50 isolates obtained from the anterior nares of healthcare workers, as well as 50 other isolates cultured from the various clinical specimens from the referral hospitals in Khorramabad (West of Iran) were tested. All isolates were examined to determine antibiotic resistance pattern, and the presence of staphylococcal enterotoxin A (sea), staphylococcal enterotoxin B (seb) and mecA genes.
    Results: The mecA gene was found among 36% (18/50) of the clinical S. aureus isolates (CSIs) and 14% (7/50) of nasal S. aureus isolates (NSIs), with statistically significant difference (X2 = 6.53; p = 0.011). The difference between the frequency rate of sea gene among MRSA strains isolated from clinical specimens (46.6%, 7/15) was significant compared to strains isolated from nostrils (14.3%, 1/7) (X2 = 3.85; p = 0.049).
    Conclusion: The frequency of mecA, sea, and seb genes among the clinical samples was more than strains isolated from the nostrils of healthcare personnel.

  • XML | PDF | downloads: 54 | views: 95 | pages: 824-831

    Background and Objectives: Different types of antibiotics have been indicated to enhance the secretion of OMVs from Pseudomonas aeruginosa. We aimed to investigate the effect of meropenem and amikacin antibiotics on inducing the secretion of OMVs and immunologic features in P. aeruginosa.
    Materials and Methods: The OMVs were prepared from P. aeruginosa under hypervesiculation condition (treatment with amikacin and meropenem), and extraction was carried out by the sequential ultracentrifugation. Physicochemical features of extracted OMVs were evaluated by electron microscopy and SDS-PAGE. To quantify antibody synthesis and function after immunization with OMV, we used ELISA, serum bactericidal activity, and opsonophagocytosis. Production of cytokines from splenocytes of immunized mice was measured with ELISA.
    Results: Specific-antibody IgG production, particularly IgG1 subclass, increased in mice primed with hypervesiculation-derived OMVs compared to normal condition-derived OMVs. Serum bactericidal activity and opsonophagocytosis of secreted antibody was enhanced in mice primed with hypervesiculation-derived OMVs. Investigation of cytokine production showed the upregulation of IL-8, IL-12, IL-17, and TNF-α and downregulation of IL-10.
    Conclusion: Based on our findings, OMVs production can be increased by treating P. aeruginosa with amikacin and meropenem antibiotics. Moreover, hypervesiculation-derived OMV scan possibly activate the humoral and cellular immune response more than normal OMVs.

  • XML | PDF | downloads: 28 | views: 70 | pages: 832-838

    Background and Objectives: Epsilon toxin is the third hazardous bacterial toxin causing ABS enterotoxaemia in domestic animal. In addition, epsilon toxin is known as a biological warfare agent. The aim of this study was to produce the recombinant mature epsilon toxin to evaluate cell death impact on the kidney cell line.
    Materials and Methods: For this purpose, the sequence of mature epsilon toxin (46-328 aa) in pET28a was cloned and expressed in Escherichia coli BL21 (DE3) and purified by nickel-nitrilotriacetic acid (Ni-NTA) column and confirmed by western blot analysis using HRP conjugated anti-His antibody. Then, to assess the anti-proliferative effects of different concentrations of recombinant epsilon toxin, the MTT assay was done on the HEK293 cell line. The annexin V/PI staining was done to investigate the apoptotic and necrotic cell populations after exposure to epsilon toxin.
    Results: Induction by 1 mM IPTG for 4 h at 37°C was an optimized condition for expressing mature epsilon toxin in E. coli strain BL21 (DE3). Electrophoresis on SDS-PAGE 12% gel showed the desired band approximately at 38 KDa. Our results showed that recombinant epsilon toxin is mainly expressed as an inclusion body. Furthermore, 100, 150, and 200 µg/mL of mature epsilon toxin are significantly reduced the cell viability (P≤0.05). The considerable increase of necrotic cell percentage was shown after exposing to 100, 150, and 200 µg/mL of mature epsilon toxin (P≤0.05).
    Conclusion: The recombinant mature epsilon toxin had cytotoxic effects and could induce necrosis.

  • XML | PDF | downloads: 45 | views: 97 | pages: 839-847

    Background and Objectives: Secondary metabolites in the supernatants of probiotic microorganisms have shown anticancer effects. The present study was aimed to investigate the cytotoxicity of Bacillus coagulans supernatants and their role in apoptosis induction in MCF7 cancer cells.
    Materials and Methods: The inhibition of MCF7 cancer cells by Bacillus coagulans supernatants was assessed by MTT assay at three exposure times of 24, 48, and 72 h. Apoptosis induction was explored by flow cytometry while the expression levels of bax, caspase 3, caspase 9, and bcl2 were examined by real-time PCR and compared with normal HFF cells.
    Results: Bacillus coagulans supernatants exhibited inhibitory effects on MCF7 cells in a concentration-dependent and time-dependent manner; while lower cytotoxic effects were observed in normal HFF cells. The increase in the expression of bax, caspase 3, and caspase 9 genes and the decrease in the anti-apoptotic gene of bcl2, along with the flow cytometry results, confirmed the induction of apoptosis in the cancer cells.
    Conclusion: Regarding the cytotoxic influence of Bacillus coagulans supernatants against breast cancer cells, this bacterium can be considered as a potential candidate for a novel therapeutic strategy with lower side effects which of course requires further investigations.

  • XML | PDF | downloads: 29 | views: 78 | pages: 848-861

    Background and Objectives: Silver nanoparticles (AgNPs) have been found to have multiple uses as antibacterial, antifungal and anti-biofilm agents because of their biological activities and safety. The present study was aimed to analyze the antimicrobial and anti-biofilm activities as well as the cytotoxic effect of AgNPs against different human pathogens.
    Materials and Methods: AgNPs were synthesized using cell free supernatants of Escherichia coli (ATCC 25922), Enterococcus faecalis (ATCC 19433), Pseudomonas aeruginosa (ATCC 27856), Enterobacter cloacae (ATCC 13047) and Penicillium oxalicum strain, then were analyzed using UV/Vis Spectral Analysis, Transmission electron microscopy (TEM). Scanning Electron Microscope (SEM) and Energy Dispersive-X-ray Spectroscopy (EDX) analysis. Antimicrobial activities of biosynthesized AgNPs were assessed with selected antimicrobial agents against multidrug resistant bacteria and candida. Anti-biofilm and cytotoxicity assays of these biosynthesized AgNPs were also done.
    Results: The synthesis of AgNPs were confirmed through observed color change and monitoring UV-Vis spectrum which showed homogeneous (little agglomeration) distribution of silver nanoparticles. TEM and SEM have shown that the particle size ranged from 13 to 34 (nm) with spherical shape and a high signal with EDX analysis. Antibacterial and antifungal efficacy of antibiotics and fluconazole were increased in combination with biosynthesized AgNPs against resistant bacteria and candida. Significant reduction in biofilm formation was found better with Penicillium oxalicum AgNPs against biofilm forming bacteria.
    Conclusion: Penicillium oxalicum has the best effect towards synthesizing AgNPs, for antimicrobial activities against resistant bacteria and candida, in addition to anti-biofilm activities against biofilm forming Staphylococcus aureus and E. coli and the safest cytotoxicity effect on (MRC-5) cell line.

  • XML | PDF | downloads: 33 | views: 68 | pages: 862-870

    Background and Objectives: Silver nanoparticles (Ag-NPs) are potent antimicrobial agents, which have recently been used in dentistry. The aim of the current study was to optimize antimicrobial activity of Ag-NPs used in preparing irreversible hydrocolloid impressions against three microorganisms of Escherichia coli, Streptococcus mutans and Candida albicans.
    Materials and Methods: After assessing antimicrobial activity of the compound using disk diffusion method, three parameters of concentration of Ag-NPs (250-1000 ppm), ratio of hydrocolloid impression material powder to water (0.30-0.50) and time of mixing (20.0-60.0 s), affecting antimicrobial activity of irreversible hydrocolloid impression materials against the three microorganisms, were optimized. This combined process was successfully modeled and optimized using Box-Behnken design with response surface methodology (RSM). Decreases in colony number of E. coli, S. mutans and C. albicans were proposed as responses.
    Results: Qualitative antimicrobial assessments respectively showed average zone of inhibition (ZOI) of 3.7 mm for E. coli, 3.5 mm for S. mutans and 4 mm for C. albicans. For all responses, when the mixing duration and powder-to-water ratio increased, the circumstances (mixing duration of 59.38 s, powder-to-water ratio of 0.4 and Ag-NP concentration of 992 response) increased. Results showed that in optimum ppm, the proportion of decreases in colony numbers was maximum (89.03% for E. coli, 87.08% for S. mutans and 74.54% for C. albicans). Regression analysis illustrated a good fit of the experimental data to the predicted model as high correlation coefficients validated that the predicted model was well fitted with data. Values of R2Adj with R2Pred were associated to the accuracy of this model in all responses.
    Conclusion: Disinfection efficiency dramatically increased with increasing of Ag-NP concentration, powder-to-water ratio and mixing time.

  • XML | PDF | downloads: 33 | views: 67 | pages: 871-877

    Background and Objectives: Due to the widespread use of lipase enzymes in various industries, finding native lipase producing microorganisms is of great value and importance. In this study, screening of lipase-producing lactobacilli from native dairy products was performed.
    Materials and Methods: Qualitative evaluation of lipolytic activity of lipase-producing lactobacilli was performed in different media containing olive oil. A clear zone observation around the colonies indicated the lipolytic activity. The strain with the highest enzymatic activity was identified. Determination of optimal pH and temperature of lipase activity was measured by spectrophotometry using p-nitrophenyl acetate (ρ-NPA) substrate. Partial purification of lipase enzyme was performed using 20-90% saturation ammonium sulfate. Eventually, lipase was immobilized by physical adsorption on chitosan beads.
    Results: Among screened lipolytic bacterial strains, one sample (5c isolate) which showed the highest enzymatic activity (5329.18 U/ml) was close to Lactobacillus fermentum. During characterization, the enzyme showed maximum activity in Tris-HCl buffer with pH 7, while remaining active over a temperature range of 5°C to 40°C. The results of the quantitative assay demonstrated that the fraction precipitated in ammonium sulfate at 20% saturation has the highest amount of lipolytic activity, with a specific activity of 22.0425 ± 3.6 U/mg. Purification folds and yields were calculated as 8.73 and 44%, respectively. Eventually, the enzyme was immobilized by physical adsorption on chitosan beads with a yield of 56.21%.
    Conclusion: The high efficiency of enzyme immobilization on chitosan beads indicates the suitability of this method for long-term storage of new lipase from native 5c isolate.

  • XML | PDF | downloads: 30 | views: 84 | pages: 878-886

    Background and Objectives: Human immunodeficiency virus (HIV) has various transmission routes. Instant antiretroviral therapy (ART) is the recommended treatment for HIV infection. Highly active antiretroviral therapy (HAART) significantly decreases the acquired immunodeficiency syndrome (AIDS) and AIDS-related co-morbidities. Notwithstanding the suitability of HAART, the antiretrovirals (ARVs) have adverse effects and antiretroviral drug resistance mutations are reported among those who receive ARVs. In this survey, the abundance of HIV-1 infection in Iranians with high-risk behaviors, and detection of the surveillance drug-resistant mutations (SDRMs) were evaluated.
    Materials and Methods: This cross-sectional study was conducted on 250 individuals with high-risk behaviors from September 2014 to February 2020. HIV-1 Ag/Ab in plasma samples was detected using enzyme immunoassay (EIA) kits. The conserved region of HIV-1 was detected in the plasma samples by real-time polymerase chain reaction (PCR) assay. Furthermore, in individuals with positive HIV-1 RNA, HIV-1 viral load testing was performed. After amplification and sequencing of the HIV-1 protease, reverse transcriptase, and integrase genes, surveillance drug resistance mutation (SDRM) and phylogenetic analysis were determined.
    Results: Out of the 250 participants with high-risk behaviors, six (2.4%) were infected with HIV-1. According to the phylogenetic analysis, the CRF35_AD (83.3% or 5/6) was the dominant subtype, followed by CRF01_AE (16.7% or 1/6). In this research, in none of the HIV-1 infected patients, SDRM for protease inhibitors (PIs), nucleoside reverse transcriptase inhibitors (NRTIs), non-nucleoside reverse transcriptase inhibitors (NNRTIs), and integrase inhibitors (INs) were observed. Nevertheless, in one of the patients, V179L mutation was detected which is a rare non-polymorphic mutation and is listed as a rilpivirine (RPV) -associated resistance mutation.
    Conclusion: The results of the current survey revealed that 2.4% of people with high-risk behaviors are infected with HIV and the level of drug resistance mutations (DRMs) in these people is very low.

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