دو ماهنامه میکروب شناسی پزشکی ایران
سال شانزدهم شماره 4 (امرداد و شهریور 1401)

Coronavirus disease 2019, caused by severe acute respiratory syndrome coronavirus 2, has recently become the number one problem affecting global health. Coronavirus disease 2019 is principally recognized by its respiratory manifestations; however, recent studies have shown an increasing number of patients with gastrointestinal complaints like diarrhea, nausea, vomiting, and abdominal discomfort. Severe acute respiratory syndrome coronavirus 2 infects the gastrointestinal tract via the angiotensin-converting enzyme II receptor, expressed on the ileum and colon enterocytes. Usually, gastrointestinal symptoms manifest later than respiratory symptoms. Concern for fecal-oral transmission has been raised following the detection of severe acute respiratory syndrome coronavirus 2 RNA in fecal samples for prolonged periods, even after respiratory clearance. In this review, we summarize the effects of severe acute respiratory syndrome coronavirus 2 on the gastrointestinal system.

 As the most important human food source, milk and dairy products may lead to infectious diseases due to non-compliance with health standards. Brucellosis is one of the critical zoonotic diseases that affect the human population. Humans are usually infected by Brucella spp. via contaminated milk and dairy products and direct contact with infected animals.

 This study was conducted to determine the Brucella spp. contamination rate of milk and dairy products in the rural and urban areas in the city of Hamadan, west of Iran, in 2018-2019. In this descriptive-analytical study, 291 samples of nonboiling milk (227), fresh cheese (43), and cream (21) were collected from dairy products suppliers in the urban (No=103), rural areas (No=162), and industrial regions (No=26). We collected 72 samples from sheep and goats and 219 specimens from cattle. Samples were randomly selected from the target centers.

The overall contamination rate of collected samples with Brucella spp. found to be 4.1%. The milk and dairy products contamination in urban areas was 0.9%, rural 6.6%, and industrial regions 0%. Furthermore, the contamination rate varied from 9.7% to 2.5% for small ruminants and large ruminants, respectively, which was significant (P=0.01).

Given the importance of dairy consumption in the human diet and higher contamination of milk and dairy products taken from cattle, sheep, and goats with Brucella species, it is recommended that control and prevention programs in sheep and goats must be taken more seriously.

 Hepatitis A virus (HAV) and hepatitis E virus (HEV) are both transmitted by the fecal-oral route and are known as leading causes of acute viral hepatitis in the world, especially in developing countries. There is a lack of updated data on HAV and HEV seroprevalence in the north of Iran. This study aimed to determine the seroprevalence of HAV and HEV among blood donors in Babol, Iran.

 A cross-sectional study was performed in 2018 on 491 blood donors referred to the Babol Blood Transfusion Center. The serum samples were tested for anti-HAV and anti-HEV IgG using the enzyme-linked immunosorbent assay (ELISA).

The mean age of blood donors was 40.92 ± 9.86 years. An anti-HAV antibody was found in 385 (78.4%), and an anti-HEV antibody was detected in 8 (1.6%) blood donors. The seroprevalence of HAV was a significant correlation to age, marital and educational status (P<0.001). But there was no significant correlation between anti-HEV and all of our study's information factors (P>0.05).

 This study showed that the incidence of HAV in the age group of <33 years is low, and the incidence of HEV has not changed compared to the past and HEV was lower than in other regions in Iran, and it needs more investigation in the north of Iran to obtain detailed information in anti-HEV seroprevalence.

 Malignant otitis externa is a rare but potentially fatal infection. It tends to affect the elderly as well as patients with diabetes and immunocompromised status. We aimed to identify the epidemiological, clinical, therapeutic, and evolutionary features of malignant otitis externa.

 We conducted a retrospective study including patients hospitalized in the infectious diseases department in Sfax (South of Tunisia) for malignant otitis externa between 1994 and 2020. Non-documented cases were excluded from the study at enrolment.

We encountered 82 patients, among whom 45 were male (54.9%). The mean age was 62 ±14 years. Seventy-four patients had diabetes mellitus (90.2%). The most common clinical symptoms were otalgia (86.5%) and otorrhea (69.5%). Pseudomonas aeruginosa was the most common organism (56%). The first-line antimicrobial used on admission was a combination of ciprofloxacin (65.8%) and ceftazidime (51.2%). The median duration of treatment was 6 weeks [4-32 weeks]. The disease evolution was favorable in 67 cases (81.8%). According to the length of hospital stay, patients hospitalized for ≥ 21 days consulted after significantly longer duration of complaints (49 days vs. 36 days; P=0.01) and had significantly more frequent complications (35.3% vs. 10.4%; P<0.001), while the recovery was significantly more frequent in patients hospitalized less than 21 days (89.6% vs. 70.6%; P=0.02).

 Despite advancements in treatment and the variability of imaging modalities, malignant otitis externa remains a fatal disease. The diagnostic delay may worsen the disease outcome, requiring a longer duration of treatment and referral to surgery.

 Salmonellosis is an important infectious zoonotic disease that makes it even more significant to identify and control the causative strains. Molecular methods, especially polymerase chain reaction (PCR), for virulence genes can help to quickly and accurately identify Salmonella strains. Accordingly, the purpose of this study was molecular identification based on sivH, hilA and sefA genes and serotyping of Salmonella strains isolated from livestock in Alborz province, Iran.

 The present study was conducted on 30 Salmonella strains isolated from livestock in Alborz province. Salmonella strains were isolated using morphological identification and differential and selective culture media. DNA was then extracted by boiling, and PCR was performed to detect the virulence genes of hilA, sivH, and sefA. The sensitivity and specificity of the primers used were determined using PCR.

The PCR findings showed that 27 (90%) isolates had the hilA gene, 10 (33.3%) isolates had the sefA gene, and 24 (80%) isolates had the sivH gene. Moreover, the highest frequency among serotypes was related to Salmonella typhimurium (10%). The sensitivity of ST11-ST15, hilA, sefA, and sivH primers were estimated at 0.0001, 1, 0.1, and 0.001 ng/mol, respectively. The specificity of primers for Salmonella strains was also confirmed.

 Identifying livestock with salmonellosis and isolating pathogenic strains from other livestock are of the most important methods capable of reducing the prevalence of foodborne infection in consumers. This can be achieved by the PCR technique for virulence genes, especially hilA, which is more prevalent among Salmonella strains.

 This study was carried out to isolate lytic bacteriophages against Pseudomonas aeruginosa and analyze their biological characteristics and antibacterial effects on other clinical isolates of bacteria.

 Isolating two lytic bacteriophages against two strains of P. aeruginosa was carried out using the double-layer agar method. After investigating the antibacterial potential of the phages, the morphology of both phages was studied. The absorption rate and one-step growth curve of each phage were also determined. The survival rate of isolated phages was evaluated against different physical conditions, chemicals, and organic solvents. Then, the antibacterial potential of phages against clinical multidrug-resistant isolates of P. aeruginosa, Staphylococcus aureus, Escherichia coli, and Klebsiella pneuminiae, as well as standard strains of P. aeruginosa ATCC 27853, P. aeruginosa ATCC 9027, K. pneumonia ATCC 1290, S. aureus ATCC 25923, and Salmonella enterica ATCC 19430 and E. coli ATCC 8739, was determined.

One of the phages showed antibacterial effects on 50% of P. aeruginosa. Both phages had a high absorption rate, short latent period, and high burst size. Isolated bacteriophages belonged to the Cystoviridae family, and the highest stability of phages (PPaMa3/19 and PPaMa4/19) was observed at pH= 7 and a temperature of 4°C. The organic solvents and ionic detergents used in this study decreased the titers of both phages. Also, the highest anti-phage activity belonged to ethanol and acetone. PPaMa4/19 phage, unlike PPaMa3/19, was also lethal against E. coli (40%) and S. aureus (20%) bacteria.

 Phage PPaMa4/19 had high antibacterial potential against P. aeruginosa, S. aureus, and E. coli bacteria. What's more, it can be used for therapeutic purposes after more analysis. It is essential to consider the biological characteristics of phage stability and its resistance to infection treatment.

 The majority of bacterial infections are now treatable using different classes of antibiotics. However, the world has faced a challenge called antimicrobial resistance that will diminish most antibiotics' beneficial impacts. A valuable strategy to prevent this adverse phenomenon is to increase the antibacterial effects of antibiotics using various materials as antibiotic enhancers. The aim of this project was to investigate the synergistic effects of gold nanoparticles (with a concentration of 100-200 µg/mL, a size of 16 nm, and an average zeta potential of -54.4 mV) and different antibiotics against some gram-positive cocci.

 Standard Kirby-Bauer methods were used to test the antimicrobial properties of different concentrations of gold nanoparticles mixed with MIC levels of gentamycin, erythromycin, clindamycin, bacitracin, and polymyxin B against ATTC strains of S. aureus, S. saprophyticus, S. epidermidis, E. faecium, and E. faecalis.

It was indicated that the 25:75 ratio of AuNPs with gentamicin led to a larger zone of inhibition against S. aureus, S. epidermidis, and E. faecalis compared with pure antibiotics. Moreover, this increase was found against E. faecalis when applying 25:75, 50:50, and 75:25 ratios of AuNPs with clindamycin. Similarly, an increase in the diameter of the zone of inhibition against S. epidermidis was observed when using 25 μL AuNPs with 75 μL bacitracin. Additionally, a synergistic antibacterial effect against S. saprophyticus was found when using AuNPs and polymyxin B with a ratio of 50:50.

 It was concluded that suitable concentrations of gold nanoparticles could enhance the antibacterial activities of antibiotics.

 The evaluation of the publishing trend of articles in various scientific fields provides an insight into the efforts of researchers in the field of knowledge. Accordingly, the present study has evaluated and analyzed the scientific publications on brucellosis conducted by Iranian researchers using scientometrics methods and analysis of social networks.

 The present study is practical research that has been performed using the scientometric method and analysis of social networks. All Iranian scientific publications on brucellosis published until 2020 were extracted from the Scopus citation database. Excel, VOSviewer, and Gephi software were applied to analyze the data.

A total of 816 scientific publications on brucellosis conducted by Iranian researchers were extracted from the Scopus citation database. Keramat F. and Mirnejad R. have the highest degree centrality of 16 among other authors of Iranian scientific publications on brucellosis. Mirnejad has the highest closeness centrality and betweenness centrality, equal to 0.43 and 1153.61, respectively. The United States with 22 documents, the United Kingdom with 9 documents, and Germany with 7 documents had the most scientific collaborations in Iranian scientific publications. The prevalence, diagnosis, and treatment are three main topic clusters in this field.

 The present study results revealed the topical and content structure and scientific collaborations of the authors in Iranian publications and scientific productions on brucellosis. Accordingly, authors and researchers can develop a network of scientific collaborations in the region and the world to collaborate in producing new knowledge, solve problems, and provide appropriate solutions.

 Systemic sclerosis is an autoimmune disorder with orofacial manifestations, including tooth decay. Lactobacilli can inhibit biofilm formation and growth of cariogenic pathogens, such as Streptococcus mutans. We aimed to assess the salivary levels of S. mutans and Lactobacilli as indicators of dental caries development in patients with systemic sclerosis.

 In this cross-sectional study, 80 patients with systemic sclerosis were assigned into 2 groups, anti-centromere antibody (ACA) positive (n=42) and ACA-negative (n=38). Besides, 80 age- and gender-matched healthy individuals were enrolled as control. Unstimulated saliva was collected in sterile tubes. Blood agar and tomato juice agar were used to cultivate S. mutans and Lactobacilli. The number of colony-forming units per milliliter (CFU/mL) was calculated and compared between the groups.

 S. mutans in patients (median=1.6×107 CFU/mL; interquartile range (IQR): 1.1–3.1 ×107 CFU/mL) was significantly higher than control group (median=5.1×106 CFU/mL; IQR: 5.1–7.9 ×106 CFU/mL) (P<0.0001, Mann-Whitney U-test); however, the median Lactobacilli levels was similar between these groups (3.4×106 vs. 2.2×106 CFU/mL; P=0.095). The median concentrations of S. mutans (1.3×107 vs. 2.4×107 CFU/mL; P=0.342) and Lactobacilli (4.1×106 CFU/mL vs. 3.1×106 CFU/mL; P=0.515) in the ACA-positive and ACA-negative patients had no significant differences. There were no significant correlation coefficients between S. mutans and Lactobacilli levels in the study groups (P>0.05).

 Our findings suggest the higher levels of salivary S. mutans in patients with systemic sclerosis might increase the likelihood of dental caries over time; however, it was not affected by the ACA status.

 Today, one of the problems of health systems is the presence of cockroaches in hospitals as insects that move freely in and out of the hospitals and are infected with pathogenic bacteria. The aim of this study was to identify carbapenem resistance genes in Escherichia coli isolated from Blattella germanica by dot blot assay in Hamadan hospitals in the west of Iran.

 A total of 109 B. germanica from April to September 2018 were collected from ICUs of different hospitals in the Hamadan province, located in western Iran. The B. germanica were identified using reliable taxonomic keys by an expert in the Department of Entomology, insectarium Hamadan University of Medical Sciences, Iran. The antimicrobial susceptibility test was determined by disk diffusion. The dot blot assay was used to identify resistance genes in E. coli isolated from B. germanica.

Out of 109 B. germanica samples collected from ICUs of different hospitals in Hamadan, 31 samples (28.44%) were positive for E. coli. The highest frequency of antibiotic resistance against ampicillin (100%) and the lowest resistance to imipenem was observed in two isolates (6.45%). The frequency of genes among E. coli isolates in B. germanica was as follows: bla NDM (4 isolates: 3.66%), bla OXA-48 (one isolate: 0.92%), and other studied genes were not observed in any of the strains.

 Cockroaches are an important factor in transmitting Enterobacterales and multidrug-resistant (MDR) strains. Therefore, effective preventive and control measures are needed to reduce vector-borne diseases.

 Undetected coinfections in COVID-19 patients may have serious clinical consequences, including increased hospitalization and mortality. The current study was conducted on 455 patients diagnosed with the new epidemic coronavirus disease who were admitted to quarantine halls in Diwaniyah in Iraq for one month, from February 2021 to March 2021. The aim of the study was to investigate secondary bacterial infections associated with the virus and the effect of using some commonly used antibiotics such as azithromycin, Beta-lactam, ciprofloxacin, and ceftriaxone.

 Sputum samples were collected from all patients who tested positive for COVID-19 (Real-Time PCR) seven days after confirming the infection with the virus. The samples were streaked on a group of culture media, then transferred to pure cultures and diagnosed, and their sensitivity to antibiotics was determined using the Vitek -2 compact system technique.

 According to the findings, the two strains of methicillin-resistant and Staphylococcus aureus sensitive were the most common isolated species with a percentage of 85%, followed by Pseudomonas aeruginosa 78%, in addition to Streptococcus pneumonia 60%, Acinetobacter baumannii 64%, and Legionella pneumophila 60%. Also, many fungi were observed. Most isolated strains were resistant to antibiotics used in the study.

 The study concluded that these antibiotics have no role in treating the infection. Still, it may contribute to the emergence of new, multi-drug resistant MDR species, resulting in increased mortality rates. Also, excessive use of antibiotics may lead to increased mortality.