Genotyping of coa and aroA Genes of Methicillin-Resistant Staphylococcus aureus Strains Isolated From Nasal Samples in Western Iran

Effects of Staphylococcus aureus on stem cells and potential targeted treatment of inflammatory disorders

Due to the advanced studies on stem cells in developmental biology, the roles of stem cells in the body and their phenotypes in related diseases have not been covered clearly. Meanwhile, with the intensive research on the mechanisms of stem cells in regulating various diseases, stem cell therapy is increasingly being attention because of its effectiveness and safety. As one of the most widely used stem cell in stem cell therapies, hematopoietic stem cell transplantation shows huge advantage in treatment of leukemia and other blood-malignant diseases. Besides, due to the effect of anti-inflammatory and immunomodulatory, mesenchymal stem cells could be a potential therapeutic strategy for variety infectious diseases. In this review, we summarized the effects of Staphylococcus aureus (S. aureus) and its components on different types of adult stem cells and their downstream signaling pathways. Also, we reviewed the roles of different kinds of stem cells in various disease models caused by S. aureus, providing new insights for applying stem cell therapy to treat infectious diseases.

Staphylococcus aureus nasal colonization and susceptibility profile to antimicrobials in hemodialysis patients using a protocol of seven collections

BACKGROUND

Patients colonized with Staphylococcus aureus in their nasal passages have a higher risk of acquiring infection, especially if they are immunocompromised or have comorbidities such as chronic renal failure undergoing hemodialysis (HD).

OBJECTIVE

This study aimed to report the prevalence of nasal carriage of S. aureus among HD patients utilizing a seven-week sampling protocol and to assess the susceptibility of these isolates to various antimicrobial agents.

METHODS

Over seven consecutive weeks, nasal swab samples were collected from 47 HD patients, resulting in a total of 329 samples. The microorganisms were identified using biochemical methods and subjected to antimicrobial susceptibility testing via disk diffusion and microdilution techniques.

RESULTS

Out of all the patients analyzed, 25 individuals (53.19%) were found to be colonized by S. aureus, with 21 of them displaying intermittent colonization. Additionally, 38% showed positive results for S. aureus in only the 6th or 7th week of sampling. Within the 58 isolates, 17.2% (n=10) exhibited methicillin (oxacillin)-resistance and 25.86% (n=15) displayed elevated vancomycin MIC values (2 µg/ml). Based on the results, daptomycin and gentamicin were found to be effective treatment options. However, 31% of the isolates (n=18) exhibited a MIC of 1 µg/ml for daptomycin.

CONCLUSION

Over half of the patients were colonized by S. aureus, but mostly on an intermittent basis. The identification of oxacillin resistance and high vancomycin and daptomycin MICs serve as warnings for possible future complications in managing bacteremia caused by S. aureus in these patients.

Emerging Challenges in Staphylococcus aureus Bloodstream Infections: Insights from Coagulase Typing, Toxin Genes, and Antibiotic Resistance Patterns

Background

The incidence of complications and mortality associated with Staphylococcus aureus (S. aureus) bloodstream infections has been increasing significantly, particularly in developing countries where control strategies against this virulent pathogen and its resistance to antibacterial agents are insufficient. The aim of this study was to investigate coagulase typing, the prevalence of toxin genes, and the antibiotic resistance profile of S. aureus isolated from bloodstream infections.

Methods

Antibiotic susceptibility of the isolates was determined by the disk diffusion method. The prevalence of toxin genes was determined using the polymerase chain reaction (PCR) method. Genetic variability of isolates was determined using multiplex PCR based on coagulase gene polymorphism.

Results

Out of 120 strains, 55 (46%) were methicillin-resistant S. aureus (MRSA) and 65 (54%) were methicillin-sensitive S. aureus (MSSA). All isolates were susceptible to linezolid and teicoplanin but showed varying levels of resistance to other antibiotics. The highest resistance was observed for ampicillin (92.5%), gentamicin (69.2%), and amikacin (68.3%). Multidrug resistance was observed in all isolates. PCR analysis revealed a higher prevalence of toxin genes in MRSA (tst: 38%, pvl: 29.1%, eta: 10%, and etb: 4.1%) than that in MSSA. According to the coa typing, the most prevalent types were coa III (29.2%), coa II (26.7%), and coa VI (10%).

Conclusion

The presence of genetic variability and widespread multidrug resistance in our hospitals emphasizes the circulation of various coa types. Therefore, it is crucial to implement antimicrobial stewardship and infection control measures to prevent and control the spread of these strains.

Characterization of genotypes and antimicrobial resistance profiles of clinical isolates of Shigella from patients in the southern region of Iran

BACKGROUND

Shigella spp., which are facultative anaerobic bacilli within the Enterobacteriaceae family, present a significant public health burden due to their role as prominent contributors to diarrheal diseases worldwide. A molecular analysis can facilitate the identification and assessment of outbreaks involving this bacterium. So, we aimed to investigate the antibiotic susceptibility pattern and clonal relatedness of clinical Shigella spp. isolates obtained from patients with diarrhea in Hormozgan province, South of Iran.

METHODS

From 2019 to 2021, a cross-sectional investigation was conducted on 448 stool samples obtained from patients who were experiencing diarrhea, in the southern region of Iran. Shigella spp. isolates were identified based on biochemical and serological tests. All Shigella species were verified using species-specific polymerase chain reaction (PCR), followed by susceptibility testing to antimicrobial agents. Subsequently, genotyping of all Shigella species was conducted using ERIC-PCR.

RESULTS

Out of a total of 448 stool samples, the presence of Shigella was detected in 62 cases, accounting for a prevalence rate of 13.84%. Among the identified isolates, the majority were attributed to S. flexneri, representing 53.23% of the cases. This was followed by S. sonnei at 24.19% and S. boydii at 22.58%. Notably, no instances of S. dysenteriae were found. The highest prevalence of Shigella isolates was observed in infants and children under the age of five. A significant proportion of the identified isolates demonstrated resistance to various antibiotics. Specifically, high resistance rates were noted for ampicillin (90.78%), piperacillin-tazobactam (87.1%), cefixime (83.87%), trimethoprim-sulfamethoxazole (83.87%), cefotaxime (82.26%), and ceftriaxone (80.65%). In addition, a substantial number (87.1%) of the isolates exhibited a multidrug-resistant (MDR) phenotype. Using the ERIC-PCR method, a total of 11 clusters and 6 distinct single types were identified among all the Shigella isolates.

CONCLUSION

A notable occurrence of antibiotic-resistant Shigella species has been noted, with multi-drug resistant (MDR) strains presenting an increasing challenge for treating shigellosis worldwide, and this includes Iran. Techniques such as ERIC-PCR are useful for assessing the genetic variation and connections between Shigella strains, which indirectly contributes to understanding antimicrobial resistance patterns. Further research is needed to explore the specific correlation between resistance genes and ERIC genotyping patterns in Shigella strains.

Comparative Genotypic Analysis of RAPD and RFLP Markers for Molecular Variation Detection of Methicillin-Resistant Staphylococcus aureus Clinical Isolates

Background and Objectives: Methicillin-resistant Staphylococcus aureus (MRSA) isolates are associated with various diseases ranged from mild superficial impairments to invasive infections. This study aimed to evaluate the ability of polymerase chain reaction (PCR) based methods namely, restriction fragment length polymorphism (RFLP) of the coa gene and random amplified polymorphic DNA (RAPD), to determine the genetic diversity of MRSA isolates. Materials and Methods: A total of 37 MRSA isolates were conventionally identified depending on their biochemical and microbiological culture characteristics. Genotypic confirmation was based on detection of the associated mecA gene. The genetic variation amongst MRSA isolates was evaluated following the coa gene-based RFLP and RAPD fingerprints. Results: Results illustrated that, the species specific coa gene was detected in all MRSA isolates. The irregular bands intensity, number, and molecular sizes of the PCR amplicons demonstrated the coa gene polymorphism. The incompatible AluI digestion patterns of these amplicons classified the tested MRSA isolates into 20 RFLP patterns which confirm the coa gene polymorphism. Additionally, the PCR-based RAPD analysis showed variable bands number with size range of approximately 130 bp to 4 kbp, which indicated the genetic variation of the tested MRSA isolates as it created 36 variable RAPD banding profiles. Conclusions: coa gene AluI enzymatic restriction sites, amongst the tested MRSA isolates, certify their genetic variation on the basis of the accurate but complicated and relatively expensive coa gene-based RFLP. Conversely, the results verified the excellent ability of the simple and cost-effective PCR-based RAPD analysis to discriminate between MRSA isolates without any preface data about the genome.

Evaluation of aminoglycoside modifying enzymes, SCCmec, coagulase gene and PCR-RFLP coagulase gene typing of Staphylococcus aureus isolates from hospitals in Shiraz, southwest of Iran

Staphylococcus aureus is an important human pathogen that causes various infections. Aminoglycosides are broad-spectrum antibiotics used to treat methicillinresistant S. aureus (MRSA) infections. Typing of S. aureus isolates by coagulase gene typing and PCR-RFLP coa gene is a fast and suitable method for epidemiological studies. Aim of the present study was to evaluate the resistance to aminoglycosides, staphylococcal chromosomal cassette mec (SCCmec) types, coagulation typing and PCR-RFLP coa gene in clinical isolates of S. aureus. 192 S. aureus isolates were collected from Namazi and Shahid Faghihi hospitals. Antibiotic resistance was measured by disk diffusion method and MIC was determined for gentamicin. The presence of genes encoding aminoglycoside modifying enzymes (AME) and mecA gene were assessed by PCR. Also the coagulase typing, PCR-RFLP coa gene, and SCCmec typing were performed. Out of 192 isolated S. aureus isolates, 83 (43.2%) MRSA isolates were identified. In this study, a high resistance to streptomycin and gentamicin (98.7%) were observed. Among the AME genes, the aac (6′)-Ie-aph (2″) gene was the most common. Based on the SCCmec typing, it was determined that the prevalence of SCCmec type III (45.8%) was highest. From the amplification of the coa gene, 5 different types were obtained. Also, in digestion of coa gene products by HaeIII enzyme, 10 different RFLP patterns were observed. According to this study, aminoglycoside resistance is increasing among MRSA isolates. As a result, monitoring and control of aminoglycoside resistance can be effective in the treatment of MRSA isolates. Also, typing of S. aureus isolates based on coagulase gene polymorphism is a suitable method for epidemiological studies.

Mupirocin-Resistant Staphylococcus aureus in Iran: A Biofilm Production and Genetic Characteristics

The spread of mupirocin-resistant Staphylococcus aureus strains in hospitals and communities is a universal challenge. Limited data is available on the genetic features of high-level mupirocin resistant- (HLMUPR-) S. aureus isolates in Tehran. In the present research, we investigated 48 high-level mupirocin resistance S. aureus by antimicrobial activity, virulence analysis, biofilm formation, multilocus sequence typing (MLST), and staphylocoagulase (SC) typing. All the HLMUPR strains were positive for mupA gene. The frequency of multidrug resistance was 97.9%. Twenty-one (43.8%) were toxinogenic with 14 producing pvl (29.2%), 5 tst (10.4%), and two eta (4.2%). Among the HLMUPR isolates, biofilm production was detected in 45 (89.6%) isolates with complete dominance clfB, clfA genes, and a noticeably high frequency fnbA (95.8%), followed by fnbB (93.8%), eno and icaD (each 83.3%), sdrC (81.3%), ebps (79.2%), icaA (75%), sdrD (66.7%), fib (60.4%), sdrE (50%), cna (41.7%), and bap (4.2%). Coagulase typing distinguished isolates into four genotypic patterns including III (50%), II (27.1%), and type IVa (22.9%). A total of three clonal complexes (CCs) and 4 sequence types (STs) including CC/ST22 as the most prevalent (52.1%), CC8/ST239 (20.8%), CC/ST8 (16.7%), and CC/ST5 (10.4%) were identified in current work. According to our analysis, nonbiofilm producer isolates belonged to CC8/ST239 (6.3%) and CC/ST8 (4.2%). Fusidic acid-resistant isolates belonged to CC/ST45 (n = 3) and CC8/ST239 (n = 1). Observations highlighted the circulation of the CC/ST22 HLMUPR S. aureus strains with strong biofilm-production ability in our hospitals, indicating the possibility of transmission of this type between community and hospital.

Phylogenetic relationship, virulence factors, and biofilm formation ability of human, pet animals, and raw milk Staphylococcus aureus isolates

BACKGROUND

Identification of genotypic characteristics and pathogenicity of Staphylococcus aureus isolates is very important in the epidemiological study of its related diseases.

AIMS

The present study was done to compare the S. aureus isolates from different sources on the basis of virulence gene properties, biofilm production ability, and phylogenetic variations.

METHODS

Seventy S. aureus isolates (including 25 human, 25 raw milk, and 20 pet animal isolates) were subjected to slime production ability testing, polymerase chain reaction (PCR) detection of 14 different virulence genes, and DNA fingerprinting using restriction fragment length polymorphism (RFLP) of coa gene PCR products.

RESULTS

Among 70 S. aureus, 64 (91.4%) isolates were slime producers on Congo red agar (CRA) medium. The spa and icaD virulence genes were present in all isolates and the seD and etaA genes were not detected in any of the isolates. In total, 22 different virulence gene patterns and nine distinct clusters of coa-PCR-RFLP were identified among isolates.

CONCLUSION

According to the results, S. aureus strains of human origin showed a significant association with specific virulence gene profiles and genotypes. seB and seC were the most responsible genes for S. aureus enterotoxin among human and animal isolates, respectively. Coa-RFLP showed partially appropriate results in the classification and source detection of S. aureus isolates.

Emergence of CC8/ST239- SCCmec III/t421 tigecycline resistant and CC/ST22-SCCmec IV/t790 vancomycin resistant Staphylococcus aureus strains isolated from wound: A two-year multi-center study in Tehran, Iran

Staphylococcus aureus as an opportunistic bacterial pathogen with intrinsic and acquired resistance to many antibiotics is a worldwide problem. The current study was undertaken to evaluate the resistance pattern, and determine the genetic types of multidrug-resistant S. aureus isolated from wound. This cross-sectional study was conducted over the period of two years (from December 2018 to November 2020) at the hospitals affiliated to Shahid Beheshti University of Medical Sciences, Tehran, Iran. In present study, 75 multidrug-resistant S. aureus isolates collected from wound infections were investigated. Phenotypic resistance was assessed by Kirby-Bauer disk diffusion method. Conventional PCR was performed for the detection of virulence encoding genes. Genotyping of strains was performed based on coa gene polymorphism using multiplex-PCR assay. SCCmec typing, spa typing and MLST were also used to characterize the genotype of the mupirocin, tigecycline and vancomycin resistant multidrug-resistant S. aureus isolates. All 75 multidrug-resistant S. aureus isolates in the study were confirmed as MRSA. Coagulase typing distinguished isolates into five genotypic patterns including III (40%), I (24%), IVb (16%), V (10.7%) and type X (9.3%). Resistance to tigecycline was detected in 4% of MDR-MRSA isolates and all belonged to CC8/ST239- SCCmec III/t421 lineage. According to our analysis, one VRSA strain was identified that belonged to coa type V and CC/ST22-SCCmec IV/t790 lineage. Resistance to mupirocin was detected in 9.3% of strains. All 7 mupirocin resistant MDR-MRSA isolates exhibited resistance to mupirocin in high level. Of these, 4 isolates belonged to CC/ST8-SCCmec IV/t008 (57.1%), 2 isolates belonged to CC/ST8-SCCmec IV/t064 (28.6%) and one isolate to CC/ST22-SCCmec IV/t790 (14.3%). Altogether, current survey provides a snapshot of the characteristics of S. aureus strains isolated from patients. Our observations highlighted type III as predominant coa type among multidrug-resistant MDR strains indicating low heterogeneity of these isolates. Our study also indicates the importance of continuous monitoring of the genotypes of MDR-MRSA isolates to prevent nosocomial outbreaks and the spread of MDR isolates.

A retrospective cross-sectional survey on nosocomial bacterial infections and their antimicrobial susceptibility patterns in hospitalized patients in northwest of Iran

Objective

Nosocomial infections (NIs) are known as one of the remarkable problems in all countries. This study is aimed to estimate the prevalence rate of nosocomial bacterial agents with antimicrobial susceptibility pattern in hospitalized patients. This study was conducted from April 2017 to September 2018, on 4029 hospitalized patients. We set out to recognize the commonest bacterial infections and antimicrobial susceptibility patterns of nosocomial infection.

Results

Of the 4029 patients, 509 (12.6%) of them were culture positive. Of these Escherichia coli (E. coli) (98.3%) and Staphylococcus epidermidis (S. epidermidis) (37.5%) were the most abundant bacterial identified in the urinary tract and bloodstream cultures respectively, Moreover, Acinetobacter spp. (100%) and Pseudomonas aeruginosa (22.2%) were the most abundant organisms detected in the respiratory system. According to susceptibility testing results, 370 (80.5%) and 264 (57.3%) in Gram-negatives and 44 (91.7%) and 35 (72.9%) in gram positives isolated strains were classified as multidrug-resistant (MDR) and extensive drug-resistant (XDR) strain respectively. On account of the high prevalence of MDR and XDR bacterial species, there is a pressing need for the expansion of new strategies on antibiotic supervision and infection control to introduce new guideline on empirical antibiotic therapy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13104-021-05503-0.

Technological interventions and advances in the diagnosis of intramammary infections in animals with emphasis on bovine population-a review

Mastitis, an inflammation of the udder, is a challenging problem in dairy animals accounting for high economic losses. Disease complexity, degree of economic losses and increasing importance of the dairy industries along with public health concerns envisages devising appropriate diagnostics of mastitis, which can offer rapid, accurate and confirmatory diagnosis. The various diagnostic tests of mastitis have been divided into general or phenotypic and specific or genotypic tests. General or phenotypic tests are those that identify general alterations, which are not specific to any pathogen. Genotypic tests are specific, hence confirmatory for diagnosis of mastitis and include specific culture, polymerase chain reaction (PCR) and its various versions (e.g. qRT-PCR), loop-mediated isothermal amplification, lateral flow assays, nucleotide sequencing, matrix-assisted laser desorption ionization time-of-flight mass spectrometry, and other molecular diagnostic methods. However, for highly specific and confirmatory diagnosis, pure cultures still provide raw materials for more sophisticated diagnostic technological interventions like PCR and nucleotide sequencing. Diagnostic ability of like infra-red thermography (IRT) has been shown to be similar to California mastitis test and also differentiates clinical mastitis from subclinical mastitis cases. As such, IRT can become a convenient and portable diagnostic tool. Of note, magnetic nanoparticles-based colorimetric biosensor assay was developed by using for instance proteolytic activity of plasmin or anti-S. aureus antibody. Last but not least, microRNAs have been suggested to be potential biomarkers for diagnosing bovine mastitis. This review summarizes the various diagnostic tests available for detection of mastitis including diagnosis through general and specific technological interventions and advances.

Mesenchymal stem cells significantly improved treatment effects of Linezolid on severe pneumonia in a rabbit model

The present study aimed to investigate whether co-administration of mesenchymal stromal cells (MSC) and linezolid (LZD) into a rabbit model of methicillin-resistant Staphylococcus aureus (MRSA)-infected pneumonia would bring a synergistic therapeutic effect. Human umbilical cord-derived MSCs (hUMSCs) were isolated and characterized. A rabbit model of pneumonia was constructed by delivering 1 × 1010 CFU MRSA via a bronchoscope into the basal segment of lower lobe of right lung. Through analyzing vital sign, pulmonary auscultation, SpO2, chest imaging, bronchoscopic manifestations, pathology, neutrophil percentage, and inflammatory factors, we verified that a rabbit model of MRSA-induced pneumonia was successfully constructed. Individual treatment with LZD (50 mg/kg for two times/day) resulted in improvement of body weight, chest imaging, bronchoscopic manifestations, histological parameters, and IL-10 concentration in plasma (P<0.01), decreasing pulmonary auscultation, and reduction of IL-8, IL-6, CRP, and TNF-α concentrations in plasma (P<0.01) compared with the pneumonia model group at 48 and 168 h. Compared with LZD group, co-administration of hUMSCs (1 × 106/kg for two times at 6 and 72 h after MRSA instillation) and LZD further increased the body weight (P<0.05). The changes we observed from chest imaging, bronchoscopic manifestations and pathology revealed that co-administration of hUMSCs and LZD reduced lung inflammation more significantly than that of LZD group. The plasma levels of IL-8, IL-6, CRP, and TNF-α in combined group decreased dramatically compared with the LZD group (P<0.05). In conclusion, hUMSCs administration significantly improved therapeutic effects of LZD on pneumonia resulted from MRSA infection in a rabbit model.

Molecular biological tools applied for identification of mastitis causing pathogens

The molecular diagnostic tools became the gold standard of mastitis diagnosis in the last few years. They enable rapid, qualitative, quantitative and large scale diagnosis. In addition to their role in diagnosis, they can identify pathogens at the subspecies level which is necessary for the epidemiological studies. They are increasingly used in mastitis control programs through identification of suitable candidates for vaccine production and through the selection of mastitis resistant cattle breeds. The present molecular techniques are continuously improved and new techniques are developed in order to provide higher sensitivity and specificity and to minimize the costs. The present work aims to provide an overview of the modern molecular tools, discuss why they replaced the traditional tools and became the new gold standard in mastitis diagnosis through comparing both traditional and molecular tools, explore the prospective of the molecular diagnostic techniques in mastitis diagnosis and control and to explore new horizons of using molecular assays in near future.