جستجوی مقالات مرتبط با کلیدواژه « virulence factors » در نشریات گروه « پزشکی »

The consumption of contaminated poultry meat is considered as a significant route of campy- lobacteriosis transmission. Lactic acid is a disinfectant agent with bactericidal effects on Campylobacter spp. The purpose of this study was to assess the low concentrations of lactic acid effect and different temperatures on the transcriptomic responses of Campylobacter jejuni (C. jejuni) adhesion and virulence-associated genes including peb4, ciaB, cdtA, cdtB, and cdtC.

The samples were incubated at 10°C and 22°C for 48 h upon exposure to 30% and 60% lactic acid. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of lactic acid was also determined. Then, gene expression was assessed using real-time polymerase chain reaction (RT-PCR).

Lactic acid had lower MIC and MBC levels at lower temperature. The utilization of both levels of lactic acid signifi- cantly reduced the expression of peb4, ciaB, cdtB, and cdtC genes over 48 h of incubation at 22°C. However, no significant difference was found in the expression of the cdtA gene between 10 and 22°C at 30% lactic acid.

These results highlight the potential of low-concentration lactic acid in the downregulation of adhesion and virulence-associated genes as well as reduction of C. jejuni pathogenicity.

Multi-drug-resistant pathogens pose a significant threat as they can rapidly spread, leading to severe healthcare-associated invasive infections. In developing countries, diarrheagenic Escherichia coli (DEC) is a major bacterial pathogen responsible for causing diarrhea. However, the outbreak of resistant strains has made the treatment of DEC infections much more challenging. This study aimed to investigate the relationship between antibiotic resistance genes and other virulence categories in E. coli strains that cause diarrhea, particularly DEC.

The phylogenetic grouping was defined using PCR and multi-locus sequence type (MLST) methods.

Among the isolates analyzed, 14 were identified as resistant and were classified into eight distinct sequence types: ST3, ST53, ST77, ST483, ST512, ST636, ST833, and ST774, indicating genetic diversity among the resistant strains. Certain sequence types, notably ST512 and ST636, were found to be associated with multiple antibiotic resistance in DEC. Regarding antibiotic susceptibility, strains showed the highest resistance to amoxicillin, suggesting that this antibiotic may not be effective in treating DEC infections. On the other hand, the isolates demonstrated susceptibility to amikacin and chloramphenicol, implying that these antibiotics could be more suitable treatment options for DEC infections.

The findings underscore the importance of promptly identifying antibiotic resistance patterns and their correlation with specific pathogenic virulence categories, as this knowledge can aid in selecting the most appropriate antibiotics for treating DEC infections. Considering the antibiotic resistance profiles and associated resistance genes is crucial in managing and containing diarrheal outbreaks and in selecting effective antibiotic therapies for DEC infections.

 Staphylococcus aureus is one of the most common hospital- and community-acquired pathogens. This bacterium has different virulence factors, and today’s reports show that the prevalence of methicillin resistance in S. aureus is increasing in different regions of the world.

 This cross-sectional descriptive study was performed on 60 hospital samples. First, biochemical tests were conducted on the samples to separate and confirm the genus of S. aureus. After the enrichment and isolation of bacteria and extraction of the DNA of mec-A and lukS/F-PV genes, they were evaluated by multiplex polymerase chain reactions (PCR).

 In this study, 20 isolates of S. aureus were obtained from a total of 60 samples. In these 20 S. aureus isolates, the frequency of the lukS/F-PV gene was reported in 12 isolates, and the frequency of the mecA gene was reported in 8 isolates, of which 4 isolates had both genes.

 According to the results, the identification of genes related to the severity of the disease and antibiotic resistance can play an effective role in the identification of the antibiotic-resistant population and subsequent planning to deal with antibiotic resistance. In addition, multiplex PCR, as a low-cost and specific method, was used to identify infectious agents of pathogens related to their virulence.

Salmonella species (spp) are the most prevalent zoonotic pathogens that cause outbreaks of gastroenteritis worldwide. Therefore evaluation of the profile of antibiotic resistance, virulence factors, and plasmid replicon types in these bacteria is necessary to control and prevent the spread of potentially pathogenic and drug-resistant strains.

This study was performed on 39 Salmonella spp. The antibacterial susceptibility of isolates to various antibiotic agents was determined using disk diffusion test. β-lactamases (bla) including ESBLs, AmpC, MBLs, and virulence genes were detected by PCR methods. Plasmid incompatibility groups among the isolates were identified using PCR-based replicon typing (PBRT).

The most prevalent virulent gene was phoP/Q (84.6%). slyA, sopB, and stn were identified in 79.4% (n=31), 69.2% (n=27), and 2.5% (n=1) of the isolates, respectively. The antibiotic susceptibility testing showed that 30.7% of the isolates were ESBL-producing. bla TEM (41%; n=16) was the most frequent β-lactamase gene among the isolates followed by bla NDM-1 (15.4%; n=6), bla DHA (7.7%; n=3), and bla CTX-M (1.5%; n=1). Six different plasmid replicon types, including IncP (n=9; 23%), IncFIC (n=3; 7.70%), IncY (n=3; 7.70%), IncI1-Iγ (n=2; 5.12%), IncFIIAs (n=1; 2.56%), and IncN (n=1; 2.56%) were ob- served among the isolates.

Our study showed the emergence of carbapenem-resistant and bla NDM-1 among Salmonella spp. for the first time in Kerman, Iran. Since Salmonella spp. plays an important role in the transmission of resistance genes in livestock and humans in the food chains, so more stringent control policies are recommended to prevent the circulation of drug-resistant and potentially pathogenic strains from animals to humans.

“Salmonella species can cause various infections in humans and animals. The presence of certain genes determines the virulence of a Salmonella serotype”.

The current research endeavor was undertaken to assess the virulence characteristics and genotypic traits of Salmonella serotypes extracted from various sources within the geographical boundaries of Iran.

Salmonella isolates, previously retrieved and preserved in the veterinary microbiology laboratory, underwent serotyping and polymerase chain reaction (PCR) identification of nine virulence-associated genes. Genotyping was carried out using random amplified polymorphic DNA-PCR (RAPD-PCR).

All Salmonella isolates showed the presence of invA, sdiA, hilA, and iroB virulence genes. There were a total of 17 different virulence gene patterns among Salmonella serotypes. The presence of fliC and sefA genes and their related patterns were significant among S. typhimurium and S. enteritidis serotypes, respectively (P < 0.05). In the RAPD-PCR fingerprinting, 11 distinct clusters were obtained, and 16 isolates (26.66%) were classified as untypeable strains. There was a significant association between RAPD genotypes and Salmonella serotypes (P < 0.05), while the association between these RAPD patterns and the source of the isolates was not significant (P > 0.05).

According to the results, Salmonella serotypes from non-human sources carry significant virulence determinants and show similar genotypic patterns with human isolates. These findings provide valuable insights into the virulence properties and genetic diversity of Salmonella serotypes in Iran, which could inform the development of effective control and prevention strategies for salmonellosis in the region.

 In hospitals and communities, Methicillin-resistant Staphylococcus aureus (MRSA) plays a critical role due to its ability to acquire resistance against several antibiotics and play a role in the spread of diseases.

 This research aimed to investigate the pattern of antibiotic resistance in MRSA isolates and perform molecular typing of MRSA isolates using various elements, including SCCmec type, ccr type, prophage type, and gene toxin profiles.

 The research spanned 20 months at Al-Zahra Hospital in Isfahan and involved 148 isolates from various anatomical sites. The isolates were evaluated for their antibiotic susceptibility patterns. They were characterized by screening for SCCmec typing, ccr typing, phage typing, and PCR profiling of pvl, hlb, sak, eta, and tst toxin genes.

 From 148 total S. aureus isolates, 42% (n = 62) were methicillin-resistant. The MRSA isolates demonstrated substantial resistance to penicillin and ciprofloxacin, and 90.3% of MRSA isolates were multiple-drug resistant. Also, SCCmec types III, I, and IV were identified in 45.16%, 35.48%, and 19.35% of MRSA isolates, respectively. Also, seven prophage patterns and 15 toxin patterns were detected among MRSA isolates.

 Multi-drug resistance is common among MRSA isolates. The only effective drug among the investigated antibiotics was chloramphenicol. The MRSA isolates can be controlled by changing the prescribing procedure of antibiotics and applying infection control strategies. The studied MRSA isolates can cause a wide range of diseases due to having several bacteriophages that encode virulence factors. Identification of different types of prophages may be useful in predicting such pathogenic agents.

 The adhesin gene (FimH) of uropathogenic Escherichia coli (UPEC) plays a critical role in mediating the first contact of UPEC bacterial strains with uroepithelial cells, leading to colonization and invasion of host cells.

 This study aimed to determine the prevalence of FimH in UPEC strains isolated from patients with urinary tract infections (UTIs) in North Lebanon and characterize the resistance profile of UPEC isolates.

 A total of 881 urine samples were collected from UTI-symptomatic patients admitted to different hospitals and laboratories in North Lebanon. Seventy UPEC isolates were identified and transferred to the Biomedical Laboratory of Beirut Arab University (BAU) for further analysis. All UPEC isolates were subjected to antimicrobial susceptibility testing, phenotypic assays for ESBL detection, and PCR to detect the FimH gene.

 The prevalence of UTIs reached 42% (370/881), with UPEC representing 19% (70/370) of the detected uropathogens. The highest and the lowest resistance among UPEC isolates were reported against Ampicillin (80%; 56/70) and carbapenem (0%; 0/70), respectively. A high prevalence of MDR (68%; 48/70) and ESBL (64%; 45/70) was reported. Molecular analysis revealed that most of the tested UPEC (98.6%; 69/70) harbored the FimH gene. A significant correlation was found between FimH and the antimicrobial resistance properties of UPEC (P < 0.05).

 This study highlighted the high prevalence of the FimH adhesin gene among UPEC isolates, revealing its crucial role in enhancing the resistance of these bacteria to antimicrobial agents.

The resistance of Pseudomonas aeruginosa to antibiotics offers a significant challenge in the treatment of patients. This study aimed to investigate the antimicrobial resistance profile, biofilm-specific antimicrobial resistance genes, and genetic diversity of P. aeruginosa recovered from clinical samples.

Totally 47 non-duplicate isolates of P. aeruginosa were recovered from various clinical samples. toxA, algD, ndvB, and tssC1 genes were detected in biofilm-producing isolates. The DNA sequences of the toxA and tssC1 genes were analyzed, by creating phylogenetic trees.

The findings revealed that 30 (63.8%) of the isolates tested positive for Extended spectrum β-lactamase (ESBL), whereas 31 (65.9%) tested positive for Metallo-β-lactamase (MBL) and all of the isolates presented the toxA genes, and 19.1%,17%, 6.3% presented by algD, ndvB and tssC1 genes. Besides, the phylogenetic trees of the toxA and tssC1 gene isolates suggested a genotype that was closely aligned with others. Gene sequencing similarity revealed 99% identity with other isolates deposited in GenBank.

The occurrence of toxA was most prevalent. One isolate was recorded as a novel isolate in the global gene bank as a locally isolated strain from the city of Erbil that has never been identified in global isolates due to genetic variation.

Staphylococcus aureus causes problems in hospitals and it has emerged as a serious agent acquired from the environment in recent years. One of the capabilities of S. aureus is the formation of biofilms, in which bacteria can exchange antibiotic-resistance genes among themselves and increase the virulence of other strains of this species (S. aureus). A surface protein attached to the cell wall in S. aureus clumping factor A is a virulence factor in various staphylococcal infections.

In this study, after the Urea Analysis (UA) test, the urea culture test was applied to the blood agar and Baird-Parker Agar culture media from the infectious urine samples in Imam Hospital, Tehran, to identify S. aureus isolates. Finally, a molecular method was used for the confirmation of identified isolates. The microliter plate method was performed to determine the biofilm formation ability. The disk diffusion method was also used for profiling the antibiotic resistance of the isolates.

In the results of this study, 45 out of 160 urinary clinical samples were positive for S. aureus, among which 42 isolates expressed the clfA gene. Moreover, 39 isolates had the ability to form biofilms in vitro. Among these 42 isolates, the highest (88%) and the lowest (16%) rates of antibiotic resistance were observed against penicillin and cefoxitin, respectively. Data analysis with SPSS software and chi-square indicated a significant relationship between gene expression and biofilm production with antibiotic resistance (P < 0.05).

The resistance of S. aureus bacteria is increasing strongly due to the repeated use of antibiotics such as beta-lactams, especially in respiratory infections and pharyngitis. Moreover, biofilm formation and virulence factors, such as clfA and clfB, cause concerns to the World Health Organization for treatment, especially for people with sepsis or toxemia.

Helicobacter pylori isa universal pathogen that causes gastric diseases and cancers in humans. In recent years, several virulence genes have been detected in this microorganism. Thus, we aimed to investigate the frequency of Helicobacter pylori strains with cytotoxin-associated gene A(cagA) and outer membrane inflammatory protein A(oipA) genotypes among children and adult patients in Tehran, Iran, and evaluatetheir relation to themanifestations of different clinical symptoms.  

In this cross-sectional study, biopsy specimens were obtained from patients with gastrointestinal symptomsand evaluated for Helicobacter pylori infectionand its genotypes (cagA/oipA) througha polymerase chain reaction PCR assay. Clinical findings and demographic data of patients were documented and analyzed.  

A total of 80 patients with Helicobacter pylori infection were included in the study (34 children and 46 adults). The cagA and oipA genotypes of Helicobacter pylori were identified in 22 (64.7%) and 24 (70.5%) children and in 31 (67.3%) and 34 (73.9%) adults, respectively. These differences were not statistically significant between the 2 studied groups. In addition, the frequency of cagA-positive strains of Helicobacter pylori was found more among patients with gastric ulcers rather than other clinical outcomes.  

Our findings demonstrate a highfrequency of Helicobacter pylori strains with oipA and cagA genotypes among children and adults in this region. Although we could not find a significant relationship between virulence genes and clinical outcomes in the patients, further studies are suggested to evaluate these factors in patients and assess their potential roles in the presence of antibiotic-resistant strains.

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the main causes of high mor- tality and morbidity in hospitals. This study was aimed to examine virulence factors, molecular typing, and the antibiotic resistance pattern of MRSA isolates in hemodialysis patients and healthy communities.

Total of 231 and 400 nasal samples were obtained from hemodialysis patients and healthy com- munities, respectively. Virulence factors profile was examined in two groups by PCR reaction. Enterobacterial Repetitive Intergenic Consensus (ERIC-PCR) was used as a molecular typing approach.

Overall, 35.49% (82/231) of hemodialysis patients were positive for S. aureus, and 47.56% (39/82) of isolates were positive for mecA. In a healthy community, 15% (60/400) of samples were positive for S. aureus, and 36.66% (22/60) were positive for mecA. The frequency of MDR was significantly higher in patients group (p-value < 0.00001). The frequency of pvl (p.value = 0.003932, P<0.05) and tsst-1 (p.value = 0.003173, p < .05) were significantly higher in patients group. The highest frequency virulence factors in healthy individuals were related to hla (68.33%, 41/60), hlb (53.33%, 32/60), and Acme/arcA (46.66%) genes. Two groups were clustered by the ERIC-PCR method into 7 clusters and 2 single isolate with a 0.74 similarity index. Based on the results, each cluster was combination with healthy and patient isolates.

Our findings indicate a notable variation in the frequency of virulence factors between S. aureus isolates ob- tained from dialysis patients and the healthy community.

 Uropathogenic Escherichia coli (UPEC) is the most prevalent causative agent of urinary tract infections (UTIs) in both community and hospital settings. Annually about 150 million people globally develop UTIs, resulting in increased healthcare costs. The current study examined the identification and the frequency distribution of virulence factors among fluoroquinolones-resistant (FQs-R) and fluoroquinolones-susceptible (FQs-S) UPEC strains in Hamadan hospitals, west of Iran.

 One hundred-seventy urine samples were collected consecutively from inpatients at three hospitals in Hamadan from March to September 2018. The UPEC isolates were identified using biochemical tests and polymerase chain reaction (PCR). The disk diffusion and the broth microdilution methods determined the antimicrobial susceptibility and the minimum inhibitory concentration (MIC) of Ciprofloxacin. The multiplex-PCR method investigated the prevalence of pap, aer, and hly genes.

Among 170 urine samples collected from inpatients, E. coli was the most common isolate, with a frequency of 125 (73.5%). Resistance to Nalidixic acid and fluoroquinolones, including Ciprofloxacin, Norfloxacin, and Ofloxacin, was detected in 88.8%, 71.2%, 70.4%, and 68.8% of UPEC isolates, respectively. The prevalence of hly and pap genes in FQs-R strains was significantly lower than in FQs-S strains.

 The high-level antibiotic resistance to quinolones & fluoroquinolones and heterogeneity of virulence genes among clinical UPEC isolates need strong attention.

Honey is one of the oldest traditional remedies that has been widely utilized to cure a variety of human ailments. The objective of this research was to test and compare the antibacterial activity of Sidr honey (SH) and Tualang honey (TH) to that of Manuka honey (MH) against Staphylococcus aureus.

The antibacterial activity of MH, SH and TH against S. aureus was investigated by agar well diffusion, Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC), time-kill curve, microtiter plate and RT-qPCR analysis.

Agar inhibition assay showed that MH possess highest total antibacterial activity against S. aureus with an inhibition zone 25.1 mm compared with that of SH (22.2 mm) and TH (21.3 mm). The findings showed that when compared to SH and TH (MIC: 25% and MBC: 50%), MH honey had the lowest MIC (12.5%) and MBC (25%). After S. aureus was exposed to MH, SH, and TH, there was a decrease in colony-forming unit as seen by the time-kill curve. The lowest concentration 20% of MH, SH and TH was significantly found to inhibit S. aureus biofilm. The RT-qPCR results revealed that all the selected genes in S. aureus were downregulated in gene expression following exposure to each of the tested honeys. Comparing the total antibacterial, antibiofilm, and antivirulence activities of all the tested honeys, MH demonstrated the greatest levels of these properties.

According to this study, various types of each evaluated honey have the capacity to effectively suppress and modify the virulence of S. aureus via a variety of molecular targets.

Dermatophytes are keratinophilic fungi that affect the stratum corneum of the skin and keratinous structures. Violent factors play a vital role in the pathogenesis and antifungal resistance of dermatophytes. 

This study aims to evaluate the activity of extracellular enzymatic and biofilm formation as virulence factors of dermatophyte isolates.

Fifty-eight dermatophyte isolates belonged to 27 Trichophyton. rubrum (46.6%), 19 T. mentagrophytes (32.8%), and 12 Microsporum. canis (20.7%) for evaluating the activity of phospholipase, hemolysin, proteinase, and biofilm formation were examined. The biofilm formed was analyzed by scanning electron microscopy (SEM).

Evaluation of extracellular enzymes production revealed that 86.2%, 77.6 %, and 57% of dermatophyte strains were shown to be phospholipase, hemolysin, and proteinase producers, respectively. Furthermore, all isolates of T. rubrum and M. canis can produce phospholipase and hemolysin, respectively. There was a statistically significant difference between phospholipase activity and dermatophyte strains (P<0.05). In addition, biofilm formation ability was observed in 41.5% of dermatophyte isolates. The highest level of biofilm production was found in 93% of dermatophytes isolated from nail chips. A significant difference between biofilm formation with dermatophyte isolates and different body sites was observed (P <0.05).

The activity of hydrolytic enzymes and biofilm formation as important pathogenic factors may play a role in the persistence of dermatophytosis infections. Our results showed that dermatophyte isolates have enzymatic activity and biofilm production at different levels. Therefore, understanding the function of these factors is essential to controlling the spread of dermatophytosis infection.

 Vancomycin-resistant enterococci (VRE) are recognized as nosocomial pathogens with increased importance in recent years. These bacteria are frequently isolated from patients admitted to intensive care units (ICUs). Enterococcal pathogenicity is enhanced by different antibiotic resistance and virulence determinants.

 The present study aimed to assess the prevalence of genes encoding resistance to antibiotics and virulence factors in intestinal VRE isolates from ICU patients.

 In this study, 23 VREs were investigated. Minimum inhibitory concentrations (MICs) to nine antimicrobial agents were examined using E-test. Genes encoding vancomycin resistance (vanABCDMN), aminoglycoside-modifying enzymes (aac(6')-Ie-aph(2")-Ia, aph(2")-Ib, aph(2")-Ic, aph(2")-Id, aph(3')-IIIa, ant(3')-Ia, ant(4')-Ia, ant(6')-Ia), together with genes for various virulence factor (ace/acm, asa1, cylA, efaA, esp, gelE and hyl), were detected using multiplex PCR.

 The species distribution of the tested VRE was as follows: Nine Enterococcus casseliflavus, seven E. gallinarum, and seven E. faecium. The vanA gene was found in all E. faecium, in six of which the classical VanA phenotype was observed. The vancomycin (vanC) phenotype was associated with the presence of vanC1 gene in E. gallinarum and the vanC2 gene in E. casseliflavus isolates. The aac(6')-Ie-aph(2")-Ia gene was encoding high-level gentamicin resistance (HLGR) in the studied VRE. All E. faecium were positive for acm and esp, while acm in combination with esp or hyl was detected in 2 vanC enterococci.

 According to the findings, there was a correlation between the phenotype and the genotype of glycopeptide resistance in the tested VRE. HLGR was more prevalent in E. faecium because of the presence of aac(6')-Ie-aph(2")-Ia. The higher prevalence of virulence determinants was confirmed in vanA isolates compared to the studied vanC-carrying enterococci.

Uropathogenic Escherichia coli (UPEC) is divided into different phylogenetic groups that differ in their antibiotic resistance patterns, serogroups and pathogenicity. This study aimed to investigate the prevalence of phylogenetic groups of UPEC isolates and their relationship with serogroups and virulence factors in patients with UTIs.

Of the 412 urine samples tested a total of 150 UPEC were isolated and confirmed with PCR using 16S rRNA gene. Antibiotic resistance of the isolates was tested using disk diffusion method and the isolates were divided into phylogenetic groups by the quadruplex PCR method. The prevalence of serogroups and virulence genes were investigated using multiplex PCR.

87 (58%) of the isolates belonged to phylogroup B2. Virulence genes fimH (95.3%), aer (49.3%) and serogroups O8 (22.3%), O25 (21.5%) showed the highest prevalence. The lowest drug resistance was observed against imipenem (4.6%) and meropenem (3.3%). The prevalence of multidrug-resistant and extended-spectrum beta-lactamases isolates were 60% and 61.3%, respectively. We also found a significant relationship between phylogenetic groups, serogroups and virulence factors among our isolates.

The high abundance of phylogenetic group B2, serogroups O8 and O25, and virulence genes fimH and aer indicate their importance in the pathogenesis of UPEC in this country.

Gastrointestinal (GI) cancers are considered among the most important causes of mortality and morbidity. Helicobacter pylori infection has been proven to be highly associated with the development of a variety of gastric diseases such as chronic gastritis, peptic ulcer disease (PUD), mucosa-associated lymphoid tissue (MALT), and gastric cancer (GC). To date, the exact role of the virulence factors in gastric diseases and other diseases remains elusive and controversial.

The present study is a classic systematic review (expert opinion), in which articles published in English and Persian languages derived from Web of Science, Scopus, PubMed, and Iranian databases, including Magiran, IranMede, and scientific information database (SID) without any time limitation were explored using standardized keywords of H. pylori, virulence factors, gastric cancer, a combination of the above words, and other synonymous keywords. Finally, the information and obtained results were collected and interpreted.

In total, 14 of the 172 articles reviewed had inclusion criteria with the approval of the responsible author. According to the results, the development of chronic bacterial inflammation due to pathogenic mechanisms and factors, especially the role of cagA and vacA genes in gastric cancer, remains an important medical problem.

Each of the H. pylori virulence factors can have a role in cancer development, and it appears that on-time H. pylori treatment is one of the best methods to prevent gastric cancer. Therefore, targeting Pathogenic factors of H. pylori to induce apoptosis and stimulate the immune system will be a promising, attractive, and helpful method for cancer prevention.