فهرست مطالب

Jundishapur Journal of Microbiology
Volume:13 Issue: 11, Nov 2020

  • تاریخ انتشار: 1399/12/26
  • تعداد عناوین: 8
|
  • Yasaman Abdoli Oskouie, Masoumeh Abbassi, Ali Taghavi Zonouz, Fariba Pashazadeh, Shahram Abdoli Oskouie *, Hamed Ebrahimzadeh Leylabadlo Page 1

    Context:

     Evaluating the prevalence of Staphylococcus aureus nasal carriage and methicillin-resistant S. aureus (MRSA) that are sources of nosocomial infection among medical students.

    Evidence Acquisition:

     Electronic databases were searched by preferred subject headings and free-text keywords. After omitting duplicates, retrieved articles were screened by two independent reviewers in a three-step process based on inclusion criteria. Then, reviewers critically appraised the selected studies by JBI checklists and extracted the required data. Finally, the pooled prevalence rates of S. aureus nasal carriage and MRSA were meta-analyzed by Stata V.16 software. The heterogeneity of included studies was calculated by I2 and chi-square. Subgroup analysis was carried out according to study designs, as well as the continent origin of clinical and preclinical students.

    Results

     Of 858 retrieved studies, 15 were included in the meta-analysis. The results showed that the pooled prevalence of nasal S. aureus carriage was 28% [prevalence rate: 0.028, 95% CI: 0.21 - 0.34, P < 0.001, I2: 96.40%, chi2: 360.98 (df = 14)]. The prevalence of S. aureus among clinical students was 33% (pooled prevalence rate: 0.33, 95% CI: 0.18 - 0.47) whereas, in preclinical students, it was 25% (pooled prevalence rate: 0.25, 95% CI: 0.23 - 0.28). Also, in a subgroup analysis of continents, Australia (Oceania) had the highest prevalence rate. According to an evaluation of publication bias, the distribution of studies was very high. Moreover, pooled MRSA prevalence among medical students was 2% (prevalence rate: 0.02 95% CI: 0.01 - 0.03, P < 0.001).

    Conclusions

     In this meta-analysis, S. aureus and MRSA prevalence rates among medical students were estimated at 28% and 2%, respectively. More attention should be given to the prevention of MRSA colonization and screening strategies among medical students across the world.
     

    Keywords: Prevalence, Systematic Review S, taphylococcus aureus, Meta-analysis, Methicillin-Resistant
  • Feizollah Mansouri, Siavash Vaziri, Mandana Afsharian, MohammadHossein Zamanian, Nahid Madadi Goli, Zainab Mohseni Afshar, Ronak Miladi, Mohsen Bijari, Amirhossain Naghash Zargar, Fatemeh Nouri, Kamal Ahmadi, Mohsen Azizi * Page 2
    Background

     The main pathogen causing various nosocomial infections, especially in burn patients, is Staphylococcus aureus. An important virulence factor of this bacterium is leukocidin, which binds to white blood cells and leads to apoptosis and necrosis.

    Objectives

     In the present research, we aimed at investigating the prevalence of the panton-valentine leukocidin (PVL) and LucED genes in methicillin-susceptible and resistant isolates of S. aureus isolated from burn patients in Kermanshah, Iran.

    Methods

     Overall, 73 isolates of S. aureus were collected from burn wounds and identified by specific biochemical tests. After determining the susceptibility patterns of the isolates by the disc diffusion method, the frequencies of the PVL and LucED genes were assessed using specific primers and polymerase chain reactions.

    Results

     The rates of methicillin-resistant Staphylococcus aureus (MRSA) and Methicillin-susceptible Staphylococcus aureus (MSSA) isolates were 58.9% (43 isolates) and 41.1% (30 isolates), respectively. In MRSA isolates, the highest antibiotic resistance was to penicillin (100%) and gentamicin (81.4%). Moreover, the frequencies of the LucED and PVL genes were 76.7% (56 isolates) and 27.4% (20 isolates), respectively, and the highest frequency of the LucED and PVL genes was observed in MRSA (81.4%) and MSSA (40%) isolates, respectively.

    Conclusions

     Increased multidrug resistance pattern among S. aureus isolates with leukocidin production has led to treatment failure and severe infections. The development of infections can be prevented by the identification of isolates carrying the leukocidin gene, and early detection of MRSA isolates is feasible by using the PVL gene.
     

    Keywords: Staphylococcus aureus, Burn Wound, Leukocidin
  • Young Sam Yuk, Young Ki Lee, Ga Yeon Kim * Page 3
    Background

     Candida albicans is an yeast species that colonizes the vaginal and oral mucosa of healthy women. However, it exhibits pathogenicity when the balance between yeast and mucous membranes and host defense mechanisms is disrupted.

    Objectives

     To develop an auxiliary treatment for vaginitis, we evaluated the inhibitory effects of a probiotic bacterial strain isolated from kimchi on C. albicans.

    Methods

     Lactobacillus plantarum, which exhibits potent inhibitory activity against pathogenic bacteria and is resistant to broad-spectrum antibiotics, was isolated from commercially kimchi in Korea, and its antagonistic effects on C. albicans were examined in a mixed culture with ME-180 cervical carcinoma cells.

    Results

     Candida albicans caused extensive damage in ME-180 cells. In ME-180 cells inoculated with L. plantarum and then with C. albicans, the extent of cell damage increased as the concentration of the C. albicans culture increased. However, in ME-180 cells inoculated with L. plantarum at 106 CFU/mL or at a higher concentration, the extent of cell damage increased substantially with the concentration of C. albicans, indicating that L. plantarum inhibited the growth of C. albicans.

    Conclusions

     Lactobacillus plantarum did not directly inhibit the growth of C. albicans but may have inhibited biofilm development at an early stage, thereby preventing the growth and mucosal adhesion of C. albicans. Further investigation of the safety, side effects, and metabolism of L. plantarum and its potential infectivity in animals is required before the L. plantarum isolate can be used to treat vaginitis.

    Keywords: Probiotics, Candida albicans, Cervical Cancer, Vaginitis, Lactobacillus plantarum
  • Cuihua Bai, Huandong Tian * Page 4
    Background

     Patients with hepatitis virus C (HCV) infection have declined levels of forced expiratory volume (FEV), which is a prognostic marker for chronic obstructive pulmonary disease (COPD).

    Objectives

     The current study primarily aimed to investigate the incidence of subclinical HCV infection (clinical signs are absent but positive HCV RNA test performed by polymerase chain reaction) in patients with COPD of Zhejiang province, China, and its secondary aim was to investigate the clinical influence of HCV infection on COPD severity by body mass index, airflow obstruction, dyspnea, and exercise capacity (BODE) scoring index and pulmonary function tests (PFT).

    Methods

     A total of 252 patients with COPD (confirmed by routine lab tests, BODE index, and PFT) were included in a cross-sectional multicenter study. An anti-HCV antibody test was used to diagnose HCV infection. Hepatitis virus C RNA was tested for patients with a HCV antibody-positive test.

    Results

     Twelve patients had a positive anti-HCV antibody test. Of 12 anti-HCV antibody positive test patients, 10 were positive for the HCV RNA. The prevalence of anti-HCV antibody positivity and HCV RNA positivity was 12/ 252 and 10/ 252, respectively. The partial arterial pressure of oxygen was the same for patients with HCV RNA positive test compared to those with a negative anti-HCV antibody test (59.70 ± 5.50 mmHg vs. 63.84 ± 15.63 mmHg, P = 0.791). Patients with a positive HCV RNA test had a higher partial arterial pressure of carbon dioxide compared to those with a negative anti-HCV antibody test (43.70 ± 1.89 mmHg vs. 49.42 ± 7.33 mmHg, P = 0. 007). BODE index was higher for patients with HCV RNA positive test than those with anti-HCV antibody test negative (6 (3 - 7) vs. 4 (2 - 6), P < 0.0001). Among the variables of BODE index scoring, the values of distance walked in 6 min (P < 0.0001) and % predicted forced expiratory volume in 1 s (P < 0.0001) were fewer for patients with HCV RNA positive test than those with a negative anti-HCV antibody test.

    Conclusion

     This study demonstrated that subclinical HCV infection may be observed in COPD patients.
     

    Keywords: Chronic Obstructive Pulmonary Disease, Liver Diseases, Hepatitis C Virus Infection
  • Na Du, Shumin Liu, Jing Yao, Kai Yang, Yun Lin, Min Niu, Qingwen Zhang, Zhiping Yin, Huanqin Li, Yan Du * Page 5
    Background

     Carbapenem-resistant Enterobacteriaceae (CRE) has become a public health threat due to resistance to multiple antibiotics. The production of β-lactamase is the most important resistance mechanism of Enterobacteriaceae. Although isolates producing KPC-2 or NDM-1 enzymes have been reported widely, isolates co-producing KPC-2, NDM-1, TEM-1, TEM-95, SHV-66, and other β-lactamases have rarely been detected in the same strain, especially in Enterobacter cloacae.

    Objectives

     In this study, we identified and sequenced the genome of carbapenem-resistant E. cloacae ECL189 to in-depth analyze the resistance and transmission mechanisms of E. cloacae.

    Methods

     We investigated the antimicrobial susceptibility of ECL189 by a VITEK 2 system, E-test gradient strips, and K-B method. Whole-genome sequencing was used by the PacBio RS II platform and Illumina HiSeq 4000 platform. Antimicrobial resistance genes, virulence genes, non-coding RNA, and repeat sequences were predicted by biological information databases. A PCR was used to further confirm that the blaKPC-2, blaNDM-1, blaTEM-1, blaTEM-95, and blaSHV-66 genes existed in ECL189. A conjugation experiment was performed to determine the transferability of resistance. Molecular typing of ECL189 was done by multilocus sequence typing (MLST).

    Results

     Enterobacter cloacae ECL189 was resistant to 21 out of 23 tested antibiotics, but its transconjugant was resistant to eight out of 18 tested antibiotics. The genome of ECL189 consisted of a 5,026,406 bp chromosome and four circular plasmids. In total, 26 resistance genes and 58 resistance proteins were identified. In addition, 77 determinants associated with bacterial virulence were identified. A large number of resistance and virulence genes were located in the plasmids. The results of whole-genome sequencing were consistent with the β-lactamase genes. The MLST analysis revealed that this strain belonged to ST74.

    Conclusions

     This study further revealed the resistance, virulence, and transmission mechanisms of carbapenem-resistant E. cloacae. Resistance and virulence genes spread in bacteria by the horizontal transfer of plasmids, which should attract more attention in relevant departments.
     

    Keywords: Carbapenems, Enterobacter cloacae, Whole-Genome Sequencing, BlaKPC-2, BlaNDM-1
  • Maryam Moslem, Mahnaz Fatahinia, Neda Kiasat, Ali Zarei Mahmoudabadi * Page 6
    Background

     Cryptococcus neoformans is an encapsulated yeast pathogen with worldwide distribution, and the highest incidence of cryptococcosis was attributed to C. neoformans (var. grubii. The pathogenicity of Cryptococcus species is associated with several factors, including capsule and melanin production, growth at 37 ºC, and secretion of extracellular enzymes.

    Objectives

     The present study aimed to isolate and identify Cryptococcus species from pigeon guano in Ahvaz, Iran and investigate important virulence factors in the isolates.

    Methods

     Seventy-three isolates of C. neoformans var. grubii were identified based on classical and molecular microbiology methods. Capsule size was measured by the grow yeasts in the presence of 5% CO2. Specific media demonstrated the activity of extracellular enzymes (phospholipase, hemolysin, proteinase, esterase, urease, catalase, and gelatinase). Besides, melanin production was evaluated by the niger seed agar medium.

    Results

     Two hundred and seventeen samples were examined for the presence of Cryptococcus over 165 days in Ahvaz. All tested isolates were contained capsules with variable sizes under 5% CO2 concentration. Moreover, 100% of isolates were produced extracellular enzymes (urease, hemolysin, and catalase), whereas no proteinase and gelatinase activities were observed among isolates. Furthermore, most isolates had phospholipase (93.1%) and esterase activities (86.3%). Also, melanin was produced by all of the isolates.

    Conclusions

     Although two methods were used for recovery of Cryptococcus, only Cryptococcus was isolated from pigeon guano, and swabs from the cage walls were negative. Cryptococcus neoformans var. grubii was the only species from pigeon droppings from Ahvaz with more pathogenic factors. Owing to the high pathogenicity of the isolates, the frequency of the disease is expected to be higher.

    Keywords: Melanin, Capsule, Virulence Factors, Enzymes, Cryptococcus neoformans
  • Ensieh Lotfali, Behshad Valizadeh, Reza Ghasemi, Seyed AmirHossein Feghhi * Page 7
    Background

     The pathogenic and opportunistic fungal species cause life-threatening infections in immunocompromised patients. The ultraviolet (UV) germicidal irradiation is a well-known method for inactivating a significant number of microorganisms and has wide application for sterilization.

    Objectives

     This study aimed to investigate the effect of ultraviolet C (UV-C) irradiation on the antifungal susceptibility pattern of some filamentous fungi.

    Methods

     The effect of UV-C on the antifungal susceptibility pattern of itraconazole, voriconazole, fluconazole, and amphotericin B against filamentous fungi was examined. Changes in the morphological features of resistant strains following UV-C irradiation were also evaluated using scanning electron microscopy.

    Results

     The results revealed a significant decrease in the number of the surviving spores of strains with the prolongation of UV-C irradiation (0 - 10 to 20 min; P < 0.05). Concerning the morphology of resistant Aspergillus spp., the results of scanning electron microscopy showed a significant increase in the length of irradiated hyphae compared to the non-irradiated hyphae (P < 0.05). In addition, colony count showed a significant decrease (P < 0.05). The findings revealed that UV-C radiation exposure could alter the antifungal susceptibility pattern of Aspergillus spp., such as increasing the minimum inhibitory concentration.

    Conclusions

     Aspergillus spp. can cause systemic infections among lab technicians exposed to different doses of radiation. Moreover, this increase in susceptibility pattern can directly affect the duration of treatment.
     

    Keywords: Drug Resistance, Aspergillus, Ultraviolet Rays
  • Amir Azimian *, Mahsa Khosrojerdi, Abdollah Kebriaei, Hasan Namdar Ahmadabad, Reza Besharati Page 8
    Background

     Streptococcus pneumoniae is one of the common bacterial pathogens in pediatrics. In this study, we performed antimicrobial susceptibility testing, serotyping, and molecular typing of blood-isolated strains of pneumococci in Bojnurd.

    Objectives

     In the current study, blood-isolated, penicillin-nonsusceptible S. pneumoniae strains were subjected to antimicrobial susceptibility testing and typing of capsular polysaccharides using the quelling reaction and PCR method, as well as genotyping using the Multi Locus Sequence Typing (MLST) method.

    Methods

     In this study, 51 S. pneumoniae strains were isolated from blood samples of children less than five-years-old in 2014 - 2018. Antibiogram was performed using the Kirby-Bauer method. All of the isolates were serotyped by the Quelling reaction and PCR. The MLST method was applied to determine the molecular types.

    Results

     Our study revealed that the most common serotypes of blood-isolated pneumococci were 19A, 6A/B, 1, 23F, 19F, 14, 15B/C, and 15A, and the common serotypes in Penicillin-nonsusceptible pneumococci (PNSP) isolates were 19F, 19A, 23F, 14, and finally 15A, 6A/B, 1, and 15B/C. The MLST analysis of PNSP isolates revealed that three highly resistant isolates with MIC ≥ 16 belonged to Sweden15A-25-19A (ST63), Taiwan19F-14-1 (ST236), and Taiwan19F-14 (ST236) clones.

    Conclusions

     Regarding the common serotypes in this study, it seems that PCV-13 is a suitable choice for vaccination in this area. We also observed a high prevalence of PNSP and multi-drug resistant (MDR) strains between 2014 and 2018. It seems that the Taiwan19F-14 clone and its related STs played an essential role in the diffusion of antibiotic-resistant S. pneumoniae isolates in Bojnurd.

    Keywords: Genotype, Drug Resistance, Vaccines, Anti-bacterial Agents, Streptococcus pneumoniae, Serogroup