Infection, Epidemiology And Medicine
Volume:8 Issue: 2, Spring 2022

Listeria monocytogenes is an opportunistic pathogen causing listeriosis, its pathogenicity is due to the presence of virulence factors including InlA, InlB, PlcA, PlcB, ActA, Iap, and Hly. The purpose of this study was to evaluate the formation of biofilm and its association with serotypes and virulence factors in L. monocytogenes isolates.

In this study, 51 L. monocytogenes isolates were collected from blood, urine, feces, placenta, rectum, and vagina samples as well as livestock and food samples. Biofilm production was measured using microtiter plate assay, and virulence genes were identified by PCR method.

Out of 51 isolates, 27 (52.9%) were non-biofilm producers, 17 (33.3%) were weak biofilm producers, four (7.8%) were medium biofilm producers, and three (5.9%) were strong biofilm producers. According to this study results, different L. monocytogenes strains could form biofilm with various intensities. The actA, flaA, inlJ, inlA, and plcB genes were observed in all the isolates. The frequency of the hlyA, plcA, iap, inlB, and inlC genes among the isolates was 90.2, 94.1, 98, 88.2, and 82.4%, respectively. There was no significant correlation between the presence/absence of virulence genes in biofilm producing and non-biofilm forming isolates, except for the inlC and iap genes, which showed a significant correlation with the ability to form biofilm.

Due to the high prevalence rate of biofilm formation among the isolates and the importance of biofilm production in medical surfaces and food industries, eradication of biofilm-forming isolates is important.

Uropathogenic Escherichia coli is one of the most important etiological agents of UTI. The aim of this study was to investigate the antibacterial effects of zinc oxide nanoparticles (ZnONPs) on aminoglycoside-resistant E. coli isolates from patients with UTI.

After identifying E. coli strains in 100 out of 250 urine samples, antibiotic susceptibility was evaluated against six antibiotic classes (with emphasis on aminoglycosides) by disk diffusion method according to CLSI-2020 guidelines. The presence of aac (6')-Ie-aph (2'') gene in isolates was investigated by PCR. Antibacterial properties and minimum inhibitory concentration (MIC) of zinc oxide nanoparticles were evaluated by agar well diffusion and broth microdilution assays, respectively.

Among 100 E. coli isolates, the highest and lowest antibiotic resistance rates were observed against tetracycline (70%) and ofloxacin (10%), respectively. Of 30 gentamicin-resistant E. coli isolates, 17 (56.5%) isolates harbored the aac (6')-Ie-aph (2'') gene. In agar well diffusion assay, 22 (74%) gentamicin-resistant isolates were eliminated by zinc oxide nanoparticles at a concentration of 150 mg/L, while ZnONPs at 300 mg/L could eliminate all gentamicin-resistant isolates. Furthermore, ZnONPs could inhibit all bacteria at a concentration of 200 μg/mL (MIC90 ≥ 100).

Spread of the aac(6')-Ie-aph(2'') gene could increase gentamicin resistance among E. coli strains causing UTI. Given the favorable antibacterial effects of zinc oxide nanoparticles in vitro, the clinical application of these nanoparticles in the treatment of UTIs caused by multidrug-resistant E. coli could be investigated in future studies.

Arcobacter is an emerging bacterium that may cause watery diarrhea and septicemia in humans. This study aimed to investigate the prevalence of Arcobacter spp. in diarrheal stool specimens using culture and molecular methods, their genetic diversity, and their resistance to different antibiotics in patients referring to clinical centers in Arak, Iran.

In this descriptive cross-sectional study, diarrheal stool specimens were collected from 230 patients over a two-month period from July to September 2016. The samples were tested for the presence of Arcobacter species. Suspected colonies were subjected to biochemical tests and identified by phenotypic methods. In addition, antimicrobial susceptibility testing was performed using the disk diffusion method. Arcobacter spp. were also directly detected  by multiplex-PCR.

Out of 230 samples, 20 samples (8.69%) were positive in culture method, and 44 samples (19.13%) were positive in PCR method, all culture-positive samples were also positive in PCR method. Rep-PCR indicated 14 different rep types among Arcobacter spp. isolated from patients with gastroenteritis. All Arcobacter isolates were resistant to cefazolin, ceftazidime, and nalidixic acid. The isolates showed high susceptibility to tetracycline, gentamicin, ampicillin, amikacin, meropenem, erythromycin, and ciprofloxacin.

To the best of our knowledge, this is the first study conducted in Iran to isolate Arcobacter spp. from patients with gastroenteritis. The results indicate that Arcobacter spp. are one of the main causes of acute diarrhea in humans. The research outcomes show that Arcobacter spp. could be considered as the etiology of gastrointestinal infections in humans.

Bacteriophage therapy could be an alternative strategy for the treatment of antibiotic-resistant bacteria. This study aimed to evaluate the antibacterial activities of isolated bacteriophages against methicillin-resistant Staphylococcus aureus (MRSA) isolates. 

A total of 16 clinical isolates of MRSA were collected from medical diagnostic laboratories in Tehran, Iran. A specific bacteriophage was isolated from hospital sewage using double-layer agar. Phage morphology was evaluated by transmission electron microscopy (TEM). Different bacteria were selected to determine the bacteriophage host range using spot test. Phage susceptibility to temperature and pH was evaluated by double-layer agar method.  In vitro assay was carried out on human epithelial type 2 (HEp-2) cells to investigate the effect of bacteriophage on the adhesion of MRSA to human epithelial cells. 

TEM suggested the Myoviridae family for the isolated phage. The effective titer of bacteriophages was 1.8×107 PFU/mL. The isolated bacteriophage was stable at 4 ˚C and pH=8. The isolated bacteriophage was specific for all clinical isolates of MRSA and had no lytic activity against other pathogenic bacteria. In evaluating the binding and invasion of MRSA to the HEp-2 cell line, as expected, the lytic activity of specific bacteriophages was observed following inoculation.

The specificity and lytic activity of this phage on MRSA and MRSA-infected HEp-2 cell line emphasized that the isolated bacteriophage may serve as an effective prophylactic and alternative therapeutic agent in hospital settings.

In recent years, Enterococcus species have emerged as a leading cause of nosocomial infections worldwide. The aim of this study was to determine the virulence biomarkers and antibiotic resistance profiles of Enterococcus spp. collected from a main tertiary teaching hospital in Bandar Abbas, Iran.

A total of 71 Enterococcus were isolated from clinical specimens of patients in different wards of a hospital. Enterococcus spp. were verified by detecting ddl gene using PCR-based method. Virulence-encoding genes including gelE and cylA were detected using PCR. Antibiotic resistance was assessed using the disk diffusion assay, and vancomycin resistance was identified using the E-test method.

Among Enterococcus isolates, 50 and 21 isolates were identified as E. faecalis and E. faecium, respectively. Most of the Enterococcus species were isolated from urine, followed by wound samples. The most prevalent virulence genes among E. faecalis isolates were cylA (60%) and gelE (30%); also, 19 and 14% of E. faecium isolates were positive for cylA and gelE genes, respectively. Many isolates of E. faecalis (84%) and E. faecium (76%) were resistant to one or more antibiotics and showed high resistance to gentamicin and ciprofloxacin.

This study revealed a high prevalence of ciprofloxacin and gentamicin resistance and a high frequency of virulence genes among E. faecalis isolates. Due to the high prevalence of MDR Enterococcus strains, control measures are necessary to prevent the emergence and transmission of these strains in different hospital wards.

Group B Streptococcus (GBS) is an important opportunistic bacterial pathogen that could cause serious infections, especially in neonates, adults, and the elderly. In GBS isolates, a macrolide resistance phenotype that confers constitutive resistance to macrolide-lincosamide-streptogramin B antibiotics (cMLSB phenotype) has become a global concern. On the other hand, little is known about the genetic relatedness and diversity of GBS isolates isolated from various patients in Iran. Hence, this study aimed to determine the genetic relatedness and molecular typing of cMLSB-GBS isolates using enterobacterial repetitive intergenic consensus-PCR (ERIC- PCR) technique.

A total of 100 GBS isolates were collected from patients with urinary tract infections (UTI).  Among them, 52 erythromycin-resistant GBS isolates were selected, and double-disc diffusion (D-zone) technique was applied to determine the MLSB phenotype among the isolates based on CLSI criteria. Then the genetic relatedness of MLSB-GBS isolates was assessed using ERIC-PCR fingerprinting method.

Among 52 erythromycin-resistant GBS isolates, 38 isolates were identified with cMLSB phenotype, nine isolates with M phenotype, and five isolates with iMLSB phenotype. The analysis of ERIC-PCR patterns revealed eight different ERIC types that were divided into seven clusters (A-G) and one single type. Also, four isolates were non-typeable. ERIC type A/ serotype Ib was the most prevalent clone among the isolates.

The current study findings showed a high level of diversity and multiclonal spread of the cMLSB phenotype in Isfahan. ERIC type A/ serotype Ib is the predominant clone circulating among erythromycin-resistant GBS strains.

Allium cepa L. as a traditional medicine is a rich source of beneficial bioactive metabolites. In the present study, the effect of A. cepa ethanolic extract (EAC) was studied on Aspergillus fumigatus growth, ergosterol synthesis, gliotoxin production, and gliP gene expression.

The minimum inhibitory concentration (MIC) of EAC (125-4000 µg/mL) was determined against A. fumigatus isolates according to Clinical and Laboratory Standards Institute (CLSI) guidelines (M-38). Protease activity, gliotoxin production, cell membrane ergosterol content, ultrastructure, and gliP gene expression were evaluated in the fungus exposed to 0.5× MIC concentrations of EAC (1000 μg/mL) and fluconazole (FCZ: 64 μg/mL).

Ergosterol content was significantly reduced to 0.53 and 0.45 µg/mg in FCZ- and EAC-treated fungal cells, respectively (p< .001). The protease activity was significantly inhibited in both EAC- and FCZ-treated groups. The gliotoxin production was inhibited by 51.55 and 68.75% in the treated groups with FCZ and EAC, respectively. The expression of gliP in both EAC- and FCZ-treated A. fumigatus groups was significantly reduced by 0.40 and 0.53-fold, respectively (p< .05).

This study finding revealed that A. cepa ethanolic extract (EAC) effectively suppressed the growth and virulence factors of A. fumigatus, which could be attributed in part to its bioactive metabolites. Further studies are recommended to isolate and identify these metabolites as potential candidates for the development of antifungal drugs.

Green synthesis of nanoparticles (NPs) is a simple, fast, and eco-friendly method which could be performed by various microorganisms or plant extracts. Silver NPs are well-known as antimicrobial and anti-fungal materials. They play an essential role in the control of tumors via their cytotoxic effects. Therefore, they have attracted significant attention for developing an effective treatment solution for cancer cells. This study aimed to investigate the potential of Penicillium chrysogenum for the synthesis of silver NPs and to evaluate their toxicity on liver cancer cell line (HepG2).

After synthesis of NPs using P. chrysogenum, characterization of the synthesized NPs was performed by UV–Vis spectroscopy, X-ray diffraction (XRD), and transmission electron microscopy (TEM). Fourier transform infrared spectroscopy (FTIR) was carried out to detect biomolecules that may be responsible for the synthesis and stabilization of NPs. The cytotoxic activity of the synthesized AgclNPs on HepG2 cell line was evaluated using MTT assay.

UV–Vis spectroscopy and XRD analysis confirmed the synthesis of AgclNPs using P. chrysogenum. TEM analysis revealed the spherical shape of AgclNPs with an average crystalline size of 15 to 45 nm. FTIR spectroscopy indicated the possible functional groups that could be responsible for the reduction of metal ions and the capping process. These nanoparticles showed a dose-dependent anticancer activity against HepG2 cells.

The results suggest that biosynthesized silver chloride nanoparticles could offer potential applications in cancer therapy.

Candida albicans (C. albicans) as a fungal pathogen is part of the normal flora of the human body, which could cause various infections in patients with defective immune systems. Nowadays, there is a need to design and synthesis new drug formulations to overcome drug resistance in this genus. Thymoquinone (TQ) is the main ingredient in Nigella sativa, which has considerable antifungal properties. The aim of this study was to investigate the inhibitory effects of thymoquinone-zein nanoparticles (TQ-ZNPs) on C. albicans.

In the current study, TQ was encapsulated in zein (as a biodegradable carrier) and polyethylene glycol (PEG). The antifungal activity of TQ-ZNPs against C. albicans (ATCC 10231; standard strain) and their inhibitory effects on biofilm formation were examined using standardized broth microdilution and MTT assays, respectively. The total oxidant status (TOS) of C. albicans was assessed using colorimetric method, and the toxic effect of nanoparticles on peripheral blood mononuclear cells (PBMCs) was evaluated by MTT assay.

The minimum inhibitory concentration (MIC) of TQ-ZNPs was significantly reduced compared to that of free TQ. MIC values of TQ-ZNPs and free TQ were determined to be 7.4 and 50 µg/mL, respectively. Biofilm formation was inhibited, and oxidant production by fungal cells was increased. The findings of this study showed that TQ-ZNPs had no toxic effect on PBMCs.

This study results revealed that the synthesized nanoparticles had a good antifungal activity without any toxicity. The results demonstrated the superior efficiency of TQ-ZNPs over free TQ. Hence, this structure could be used to load hydrophobic drugs. However, more studies are needed to evaluate the beneficial properties of TQ-ZNPs.

Plasmodium vivax is one of the leading causes of malaria as a severe and death disease. Malaria has always been a major challenge for human health. The study of the genetic diversity of genes in malaria-causing agents has always been a concern for researchers. One of these genes is SERA, which plays a key role in parasite escape from the immune system.

DNA was extracted from 40 blood samples taken from symptomatic malaria patients infected with P. vivax in southern and southwestern Iran using a DNA extraction kit. Then PCR was performed with specific primers, and the data were analyzed by sequencing and recording genes.

In this study, 14 different isolates were identified among all samples, which were recorded in the World Gene Bank. The number of haplotypes among the 14 samples was 12. Also, there were 25 polymorphic nucleotide positions out of about 400 nucleotide sites. The ratio of non-synonymous to synonymous mutations (1.87094) and the amount of Tajima’s D (-0.57671) indicated the positive effect of natural selection on the genetic diversity of C-terminal region in the SERA5 gene.

Considering the safety and relative immunogenicity of vaccines, in addition to performing clinical trials, a regional vaccine should be developed to overcome genetic variation and antigenic changes in proteins.