Jundishapur Journal of Microbiology
Volume:14 Issue: 6, Jun 2021

Yeasts naturally colonize the mammalian digestive tract and play an important role in health and disease. This community is composed of commensal yeasts, mostly Candida and Saccharomyces described as a part of the intestinal mycobiome and could be associated with resident or transient flora.

The aim of our study was to perform the phenotypic and genotypic characterization of culturable Candida isolates present in stool specimens of healthy Tunisian individuals and to evaluate their antifungal susceptibility.

Yeasts were recovered from 46 stool samples cultured on Sabouraud dextrose agar at 37°C. Species were identified using conventional methods and ITS-PCR sequencing. Candida isolates were tested by exploring their tolerance to oxidative stress and extreme acidic conditions. In addition, their biofilm formation ability and in vitro resistance to antifungals was determined by the VITEK 2 system.

The identification by sequencing the ITS1-5.8S-ITS2 region of the 56 yeast strains isolated from 37 stool samples revealed that Candida was the dominant genus and was represented by Candida albicans (n = 21), C. parapsilosis (n = 10), C. glabrata (n = 9), and C. krusei (n = 9). In contrast, the other genera, including Trichosporon, Geotrichum, and Rhodotorula, were sporadically occurring. We found that mostCandida isolates were able to form biofilms under oxidative stress and extreme pH conditions. Regarding antifungal susceptibility, a higher resistance rate to fluconazole was revealed in comparison to caspofungin and micafungin. However, no resistance was revealed against voriconazole, amphotericin B, and 5-flucytosine.

This is the first work-generated data on cultivable yeasts from stool specimens of healthy individuals in Tunisia. Further metagenomic studies with a larger sample size are needed to better characterize the intestinal mycobiota.

Mutations in herpes simplex virus Thymidine kinase (TK, UL23) and DNA polymerase (pol, UL30) genes may confer resistance to acyclovir (ACV). Phenotypic resistancemust be determined along with genotypic resistance to achieve complete acyclovir susceptibility.

The present study aimed to characterize HSV-1 clinical isolates from outpatients and organ transplant recipients in terms of phenotypic ACV resistance. Moreover, genotypic resistance to ACV was assessed through sequencing the viral TK and pol genes amplified from virus-infected cell DNA.

Twenty-six HSV-1 clinical isolates collected between 2016 and 2019 were examined for drug susceptibility. The samples were collected from eyes, oropharyngeal, facial, and other skin parts of immunocompetent and immunocompromised individuals. Phenotypic susceptibility was determined by using three different concentrations of ACV. The results were expressed based on the ability of ACV in reducing viral plaques by 50%. Genotyping was carried out by polymerase chain reaction and sequencing of TK and pol genes.

All the strains were characterized as sensitive at 0.01 and 0.05µg.ml-1 concentrations to ACV. Seventy percent inhibition was observed at ≥ 0.1 µg.mL-1 of ACV for three isolates (two from patients who received transplants and one from an outpatient). Nine natural polymorphisms were detected in the TK gene and 31 in the Pol gene. Furthermore, four susceptible-associated mutations in the DNA pol gene were analyzed. A substitution was encoded in the conserved region of the pol Exo III motif (M553L), and nine amino acid substitutions in TK were detected. The phylogenetic analysis of partial genome sequences revealed high diversity in the TK and pol genes of HSV-1.

A higher number of mutations were observed in patients who received transplants and underwent long-term treatment compared with outpatients. The high genetic variability of HSV-1 TK and DNA pol was not associated with phenotypic resistance.

With the rapidly increasing incidence of the novel coronavirus disease 2019 (COVID-19) and the detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA in plasma, blood supply safety has become a main concern.

Due to some reports on the detection of RNAemia in SARS-CoV-2-infected blood donors, this study examined the presence of SARS-CoV-2 RNA in asymptomatic blood donors.

In this cross-sectional study, about 400 blood donors from the Tehran Blood Transfusion Center with negative results for viral serologicalmarkers of hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus (HIV) were included in the study. Moreover, all samples were tested for anti-SARS-CoV-2 ELISA (IgG) to detect antibodies against SARS-CoV-2. The Presence of SARS-CoV-2 RNA in blood donors was identified by targeting RNA-dependent, RNA polymerase (RdRp), and N (nucleocapsid protein) genes using Real-Time PCR. Furthermore, the RNase P gene was used as an internal control.

The SARS-CoV-2 ELISA test showed that 60 (15%) of blood donors had antibodies against SARS-CoV-2 nucleocapsid protein, and 340 (85%) of the participants have not been exposed to the virus. The cycle threshold (Ct) for positive control in the RT-PCR test for nucleocapsid (N) and RdRP SARS-CoV-2 genes was < 40 (CT = 20.37). Moreover, internal control (RNase P gene) in all samples had Ct < 40. The presence of SARS-CoV-2 RNA was detected in the blood sample of none of the blood donors. In this regard, there has been no report of SARS-CoV-2 transmission to blood recipients yet.

The blood-borne transmission of SARS-CoV-2 seems to be highly unlikely, and coronavirus RNA screening is unnecessary among blood donors. Preventive measures should be adopted to reduce the theoretical risk of transmitting SARS-CoV-2 by the blood from asymptomatic COVID-19 cases.

Acinetobacter baumannii has emerged as a critical pathogen with high morbidity and mortality in long-term hospitalized patients who stay in intensive care units. Carbapenemases and integrons are two critical DNA elements that contribute to the emergence of multidrug-resistant (MDR) A. baumannii.

The current study aimed at characterization and molecular detection of class 1, 2, and 3 integrons among carbapenemase-producing A. baumannii strains recovered from a clinical setting in Tehran, Iran.

A total of 65 non-replicated clinical strains were considered in this study. Class 1, 2, and 3 carbapenemase genes and clonal relatedness of the isolates were investigated by PCR assay.

The prevalence of carbapenemases was as follows: blaOXA23 (92.31%), blaVIM (69.23%), and blaNDM (1.54%). In addition, PCR sequencing confirmed the presence of gene cassette arrays consisting of aacA4-catB8-aadA1 (12/46, 26.09%), aadB-aadA1 (26.09%, 12/46), arr2-cm1A5 (30.43%, 14/46), and dfrA1-aadA1 (7.39%, 8/46) in class 1 integron and dfrA1-sat2 (52.94%, 9/17), and sat2-aadA1 (47.06%, 8/17) in class 2 integron. Sequence-based typing of both blaOXA-51-like and ampC revealed the following distribution of three different clone types among isolates: clonal complex (CC) 10 (46.15%, 30/65), CC2 (40%, 26/65), and CC3 (13.85%, 9/65). Statistical analysis showed that the presence of the intI1, blaOXA23, blaVIM, or blaNDM genes can significantly increase the acquiring MDR phenotypes in A. baumannii isolates.

High prevalence of carbapenemase-producing A. baumannii harboring integrons is alarming public health. It seems that class 1 integron can be served as a predictive biomarker for the presence of MDR phenotypes in the clinical setting. However, integrons do not carry carbapenemases in these strains.

Brucellosis is the most widespread zoonosis worldwide and one of the most neglected zoonotic diseases. At present, large-scale farms are growing rapidly, increasing the risk of disease transmission.

In this study, the propensity score matching (PSM) method was used to analyze the epidemiological characteristics of brucellosis and explore the risk factors of brucellosis infection in Hulunbuir, Inner Mongolia, China.

A questionnaire for brucellosis was designed based on general knowledge and the protection of key groups of brucellosis. Epidata 13.0 software was used to establish the questionnaire, and propensity score matching was used to select cases that met the requirements of case-controls.

A total of 152 cases and 456 controls were included. The results of the study show that feeding livestock, carrying lambs regularly, and raising livestock without protective measures can increase the risk of brucellosis infection.

Behavioral factors are the main risk factors for brucellosis, and livestock keepers should strengthen self-protection when working.

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) preferentially infects respiratory tract cells, but it has organotropism. Middle East respiratory syndrome coronavirus (MERS-CoV) is significantly distinct from common cold and SARS coronavirus. In past few years, the SARS-CoV-2 and MERS-CoV caused several deaths in South Korea. The aim of current study was to assess SARS-CoV-2 and MERS-CoV awareness and epidemic prevention ability in South Koreans.According to our results, out of 1500 participants, 98.8% and 64.3% were aware of SARS-CoV-2 and MERS-CoV, respectively. Moreover, 97% of the participants used masks for prevention of airborne diseases, while 65.3% of the participants reused the same mask for several days. In addition, 50% of the participants were not satisfied with the government support. Future viral epidemics can be prevented by disseminating advanced knowledge and awareness among general public.