Iranian Journal of Microbiology最新文献

Background and objectives: Salmonellosis is among the most common food-born infections, caused by Salmonella spp. bacteria. Present study has investigated the frequency and antibiotic resistance pattern of Salmonella spp. isolated from traditional dairy products and raw milk supplied in Yazd, Iran.

Materials and methods: In a cross-sectional study, 350 samples of raw milk and traditional dairy products were randomly collected from July to September 2018. Following culturing the samples, isolates went through biochemical tests for phenotypic identification. Results were confirmed through PCR technique by targeting invA gene. Antimicrobial susceptibility test was conducted by means of disk diffusion method.

Results: The rate of contamination with Salmonella bacteria was 6.57% in all samples. The PCR assay of all isolates showed that 23 isolates (100%) carried the invA gene. No significant association between the frequency of salmonella spp. and types of dairy and their origin was reported (P>0.05). The highest antibiotic resistance rate among the isolates belonged to tetracycline (34.8%) and the highest sensitivity was seen to imipenem, cefepime, and cefotaxime (each 91.3%).

Conclusion: According to our results there has been a rise in multiple drug resistance and contamination rate in traditional dairy products in Yazd province.

Background and objectives: The most common cause of severe foodborne salmonellosis is S. Typhimurium. Its interaction with intestinal epithelial cells is little known. Lactic acid bacteria (LAB) were recognized as a prominent probiotic gastrointestinal microbiota of humans and animals that confer health-promoting and protective effects. This study aims to determine the anti-invasion and antibacterial effects of heat-killed LAB (HK-LAB) isolates against S. Typhimurium towards human intestinal cells.

Materials and methods: 12 HK-LAB isolates from 3 sources of origin (stingless bee, plant, and food) were tested to determine the adhesion of HK-LAB to Caco-2 cells, anti-invasion and antibacterial activities against S. Typhimurium, the adhesion and invasion pattern of S. Typhimurium on intestinal epithelial cells (Caco-2) and assessing the effect of LAB on the S. Typhimurium-host cell interaction.

Results: Tairu isolates from food have the highest adhesion rate with 19 ± 1.32/10 Caco-2 cells followed by HK-LAB R-isolate from plant 17 ± 0.70/10 Caco-2 cells, which is similar to the control (Lactobacillus casei). In the anti-invasion assay, the two HK-LAB isolates that had the strongest adherence to Caco-2 cells, Tairu-isolate inhibited at 78.1 ± 3.06% and R-isolate inhibited at 64.76 ± 9.02% compared to the positive control (63.81 ± 1.15%), which led to increased suppression of S. Typhimurium accordingly. Tairu and R isolates were tested for their antibacterial ability against S. Typhimurium. Both R and Tairu isolates displayed strong inhibition zones (27 ± 0.06 mm, 23 ± 0.06 mm) respectively.

Conclusion: These findings suggest that the anti-invasion activities of HK-LAB R and Tairu may correlate to their bactericidal effects that serve to protect the host from infection.

Background and objectives: The incidence of multidrug-resistant, Gram-negative organisms, isolated as the etiological agents of infections is ascending. The advent of novel antibiotics poses significant challenges, necessitating the optimization and utilization of extant antimicrobial agents. Cefoperazone, a third-generation cephalosporin and β-lactam antimicrobial, when combined with sulbactam, an irreversible β-lactamase inhibitor, mitigates the vulnerability of cefoperazone to β-lactamase-producing organisms. Nonetheless, regional data on the susceptibility patterns for this pharmacological combination remains scarce. The primary objective of this investigation was to assess the efficacy of the cefoperazone-sulbactam combination against prevalent Gram-negative bacteria isolated from blood cultures.

Materials and methods: A total of 700 Gram-negative isolates, comprising Escherichia coli, Klebsiella pneumoniae, Acinetobacter species, and Pseudomonas aeruginosa, were procured using the BacT/Alert 3D system. The identification and susceptibility testing for cefoperazone-sulbactam were performed using the VITEK Compact ID and AST system. Comparative analysis was conducted against other tested antibiotics.

Results: The study revealed that cefoperazone-sulbactam exhibited commendable in-vitro activity against Gram-negative pathogens isolated from blood, surpassed only by colistin and tigecycline.

Conclusion: Cefoperazone-sulbactam demonstrates robust activity against the most frequently encountered clinical pathogens, suggesting its potential as an efficacious therapeutic agent. The findings underscore the imperative for ongoing surveillance of resistance patterns and trends among commonly used antimicrobials.

Background and objectives: Nosocomial pneumonia caused by multidrug-resistant gram-negative bacteria presents a significant challenge for healthcare systems, as there are limited effective treatments available. This systematic review and meta-analysis aim to investigate the outcomes of colistin plus meropenem combination therapy on nosocomial pneumonia.

Materials and methods: An exhaustive search of PubMed, Scopus, Web of Science (WOS), and Embase databases was conducted, resulting in the extraction of 5 studies for qualitative assessment and meta-analysis. The study sample included 991 patients admitted with nosocomial pneumonia. The outcomes evaluated were clinical improvement, microbiological response, mortality, Sequential Organ Failure Assessment (SOFA) score, Acute Physiology and Chronic Health Evaluation (APACHE II) score, Charlson Comorbidity Index (CCI), Clinical Pulmonary Infection Score (CPIS), C-reactive protein (CRP) levels, procalcitonin (PCT) levels, and intensive care unit (ICU) duration.

Results: The results demonstrated that colistin plus meropenem combination therapy significantly improved clinical outcomes (OR = 1.37, 95% CI = 1.04-1.81, p = 0.027), reduced SOFA scores (OR = -0.28, 95% CI = -0.44 to -0.11, p = 0.001), and increased CCI scores (OR = 0.16, 95% CI = 0.02-0.29, p = 0.021) compared to other medications. However, other evaluated parameters did not show significant differences.

Conclusion: This meta-analysis indicates that colistin-meropenem combination therapy is superior to other colistin-based treatments for nosocomial pneumonia in terms of clinical improvement, SOFA score reduction, and CCI score increase. Nevertheless, other variables assessed did not exhibit remarkable differences between the treatment regimens.

Background and objectives: The study aimed to investigate the epidemiology and clinical therapy of candidemia in burn patients hospitalized in Velayat Hospital, Rasht, Iran.

Materials and methods: The blood samples of suspected patients were cultured and PCR-sequencing was performed. Antifungal susceptibility testing was done by the CLSI M27-A4 document.

Results: Four blood samples were identified as positive. Candida parapsilosis complex (3 out of 4, 75%) was the predominant leading cause of candidemia. MIC values showed that all isolates were susceptible to itraconazole, amphotericin B, and 5-flucytosine.

Conclusion: It seems necessary to pay attention to Candida non-albicans species in antifungal therapy.

Background and objectives: Vitamin D deficiency in viral infection associated with autoimmune diseases is well documented. This study assessed the prevalence of JC virus in patients with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE), and its correlation with vitamin D level.

Materials and methods: Serum and urine samples were collected from 50 patients with RA and SLE. DNA was extracted and subjected to PCR test. Positive PCR products were sequenced, phylogenetic tree was constructed to determine the JC virus genotype. The patient's vitamin D level was evaluated.

Results: Of 50 patients, 19 (38%) were diagnosed as RA, and 31 (62%) were identified as SLE. JC virus DNA was detected in 17 (34%) patients' urine samples including 5 (26.3%) RA and 12 (38.7%) SLE cases. JC virus DNA was detected 2 (4%) in patients' serum samples (one RA. and one SLE). JC virus genotype 3A was dominant. Interestingly, the SLE patients with positive JC virus showed lowered vitamin D compared to patients with negative JC virus (P<0.005).

Conclusion: Given the high rate of JC virus, DNA detection and susceptibility of patients for PML development, it is recommended that detection of JC virus DNA and vitamin D level should be implemented for patients with RA/SLE prior to treatment.

Background and objectives: Brucellosis, a zoonotic bacterial disease caused by Brucella, affects humans and domestic animals, leading to significant economic loss. This study examined suspected cases in North Khorasan, Iran, to understand the prevalence of infection and its characteristics in this region.

Materials and methods: Blood specimens were collected from 200 patients suspected of brucellosis after obtaining informed consent. Serum samples were tested using RBPT, Wright, and 2-ME agglutination tests. Blood samples were cultured on Brucella agar, and positive cultures underwent biotyping and PCR assays. A questionnaire identified correlated risk factors.

Results: RBPT, Wright, and 2-ME tests showed 25% brucellosis seroprevalence in symptomatic patients. In contrast, the prevalence was 2.5% among those with positive blood cultures. Notably, all culture-positive patients were also serologically positive, with titers exceeding 1:320 in Wright and 2-ME tests. Most positive cases were in people in their 30s, with B. melitensis biovar 1 identified as the causative agent, and the results were confirmed by multiplex PCR. Significant risk factors include contact with livestock and consumption of raw milk (P < 0.0001).

Conclusion: The findings highlighted the importance of comprehensive diagnostic approaches for accurate identification of brucellosis. Furthermore, education regarding close contact with animals and pasteurization of dairy products is essential for controlling human brucellosis.

Background and objectives: The biofilm formation has been widely recognized as one of the main mechanisms of antimicrobial resistance development in microorganisms. However, few studies are focusing on this phenomenon in Candida spp. in clinical settings, especially on immuno-compromised patients.

Materials and methods: In this study, both the rate of biofilm formation in those patients and its drug susceptibility in initial and mature biofilm were assessed using crystal violet assay and dilution method.

Results: The results demonstrated that the biofilm formation rate was similar between albicans and non-albicans Candida. However, the biofilm formation capacity was more pronounced in non-albicans Candida, especially, C. glabrata. As expected, there was a significant relationship between biofilm formation and drug resistance. In addition, our study reconfirmed that the age of high concentration of antifungal agents only affected Candida before its biofilm formation regardless of its biofilm formation capacity. In the contrary, once the biofilm was formed even elevated drug concentrations did not show sufficient efficacy, highlighting a need for high dosage at the early stage of treatment for those patients.

Conclusion: The results of this study highlighted the importance of using appropriate antifungal agents for Candida treatment before the formation of biofilm.

Background and objectives: The rapid spread of Newcastle disease (ND), driven by extensive commercial exchange in the poultry industry, necessitates urgent preventive measures. Although effective vaccines against the Newcastle disease virus (NDV) have been used since 1940, recent outbreaks and the limitations of current vaccines highlight the need for improved solutions. Advances in synthetic biology, reverse vaccinology, molecular biology, and recombinant DNA technology over the past 20 years have led to the development of recombinant vaccines, which offer enhanced protection and broader immunogenic coverage against NDV. This study aimed to express the immunogenic domains of Hemagglutinin Neuraminidase (HN) and Fusion (F) glycoproteins, linked to the heat-labile enterotoxin B subunit (LTB) bio-adjuvant, to develop an effective and reliable recombinant vaccine for NDV.

Materials and methods: In this study, the L(HN)2F protein, composed of the LTB bio-adjuvant and the immunogenic regions of the doubled Hemagglutinin Neuraminidase (HN-HN) and Fusion (F) epitope, was expressed in Escherichia coli. Subcutaneous injection was used to evaluate the humoral immune response in mice and the result was compared with B1 vaccine.

Results: The induction of strong humoral immune responses proved the strong immunoreactivity of the recombinant protein.

Conclusion: The IgG elicited by the recombinant proteins was comparable to that of the commercial B1 vaccine against NDV, indicating its potential as a viable candidate for further development and evaluation as a recombinant vaccine against NDV.