Journal of Medical Microbiology and Infectious Diseases
Year:2024 | Volume:12 | Issue:1|Papers Count:8

The emergence and re-emergence of pathogenic fungi pose a significant challenge, fueled by factors like increased immunosuppression and climate changes. Despite the development of new antifungal drugs and therapies, controlling these infections remains a pressing issue. Candida auris, a multidrug-resistant yeast, has caused invasive infections with high mortality rates in hospitals worldwide, with Iran experiencing a particularly high burden of invasive C. auris infections. The identification of new at-risk groups, rising prevalence of resistant infections, and the emergence of novel multidrug-resistant pathogenic fungi highlight the need for novel therapeutic approaches and effective prevention strategies. This review explores the potential of nanotechnology, an emerging field, in combating emerging fungal infections, such as C. auris, and re-emerging infections caused by Fusarium and Rhizopus species. We conducted a literature review of studies exploring nanotechnology-based approaches to control or inhibit these emerging and re-emerging fungal pathogens with a particular focus on Iran and globally, where antimicrobial resistance is a growing concern. Nanotechnology revolutionizes antifungal strategies with novel solutions. Nanoparticles (NPs) and nanomaterials possess unique properties, such as enhanced solubility, targeted delivery, and ROS generation, which can disrupt fungal cell membranes, inhibit biofilm formation, and prevent sporulation. Their tailored sizes, high surface-to-volume ratios, and customizable surface chemistries make them game-changing solutions to combat drug-resistant fungal infections and improve treatment outcomes. Numerous studies have demonstrated the ability of various NPs, including silver, metal oxide, and carbon-based nanomaterials, to inhibit the growth and virulence factors of C. auris, Fusarium, and Rhizopus species. These nanomaterials exhibit potent antifungal activities through mechanisms such as disrupting cell membrane integrity, inducing oxidative stress, and inhibiting fungal metabolic pathways.

Introduction: Traditional chewing sticks from Vernonia amygdalina and Citropsis articulata have been used for oral hygiene in African rural communities. This study pioneers an eco-friendly approach to silver nanoparticle (AgNP) synthesis using stem extracts from these medicinal plants, addressing environmental concerns associated with conventional methods. The antibacterial properties of the AgNPs against oral bacterial strains are assessed, offering a sustainable solution for oral health care. Methods: AgNPs were synthesized using aqueous and ethanolic stem extracts of V. amygdalina and C. articulata. Characterization was performed using UV-visible and FTIR spectroscopy. Phytochemical analysis revealed a diverse profile of bioactive compounds, with ethanolic extracts showing greater diversity. The AgNPs were tested against 100 bacterial isolates from dental caries patients at the Federal Medical Center, Abeokuta. Results: Molecular identification revealed three prevalent bacterial isolates: Bacillus fungorum (strain CUAB-AKINTOLA01), Klebsiella pneumonia (strain CUAB-AKINTOLA02), and K. pneumonia (strain CUAB-AKINTOLA03). The extracts from V. amygdalina and C. articulata, as well as the biofabricated AgNPs, showed significant antibacterial activity against these oral pathogens. Notably, AgNPs from V. amygdalina exhibited higher zones of inhibition, with B. fungorum being the most susceptible. These findings suggest the potential of these eco-friendly AgNPs as an effective antibacterial agent against oral bacterial infections. Conclusion: This study highlights the potent antibacterial efficacy of V. amygdalina and C. articulata stem extracts, as well as the silver nanoparticles biosynthesized from these extracts, against oral bacterial pathogens. While these findings are promising, further investigations are necessary to fully elucidate the therapeutic potential of these eco-friendly agents in the prevention and treatment of dental plaque-associated diseases

Introduction: Vulvovaginal candidiasis (VVC) is a prevalent and often recurrent condition affecting an estimated 75% of women worldwide. Candida albicans is a primary fungal pathogen responsible for a significant proportion of VVC cases. This cross-sectional study investigated the expression levels of two critical virulence genes, ALS1 and HWP1, in C. albicans isolates from women diagnosed with VVC. Moreover, we examined the effect of copper nanoparticles on the expression of these genes, exploring their potential as a novel antifungal therapy for VVC treatment. Methods: This study recruited 30 patients diagnosed with VVC from Razi Hospital, Iran. We employed polymerase chain reaction (PCR) to confirm the presence of the ALS1 and HWP1 genes in C. albicans isolates. Subsequently, we extracted RNA from the isolates and assessed the effect of copper nanoparticles on the expression of ALS1 and HWP1 genes using quantitative real-time PCR (qRT-PCR). Results: Of the 30 C. albicans clinical isolates analyzed, 17 (56. 7%) harbored both HWP1 and ALS1 virulence genes. Copper nanoparticles significantly downregulated the expression of these genes. Notably, treatment with 8. 8 μg/mL copper nanoparticles resulted in a significant reduction of HWP1 gene expression, while 3. 23 μg/mL copper nanoparticles led to a significant decrease in ALS1 gene expression. Conclusion: This study identified the presence of ALS1 and HWP1 virulence genes in C. albicans isolates from women with VVC and demonstrated the potential of copper nanoparticles to downregulate their expression. These findings offer promising insights into the development of novel antifungal therapies for VVC treatment. However, further investigations with larger, more diverse cohorts and comprehensive analyses are necessary to fully understand the effects of copper nanoparticles on C. albicans gene expression and their potential clinical applications for VVC management

Introduction: Understanding the epidemiological and clinical characteristics of different tuberculosis strains is crucial for developing improved diagnostic tools, drugs, and vaccines for tuberculosis management. This study aimed to investigate the molecular epidemiology of Mycobacterium tuberculosis using spoligotyping, a widely used molecular typing method, to understand the genetic diversity and transmission dynamics of M. tuberculosis, on isolates obtained from patients with pulmonary tuberculosis in central Kerala. Methods: In a prospective study at a tertiary care hospital, 404 respiratory specimens from patients with symptoms suggestive of TB were collected. Specimens underwent Ziehl-Neelsen staining, culture in liquid (BD BACTEC™ MGIT™) and solid (Lowenstein-Jensen) media, and standard drug susceptibility testing with the MGIT system. Molecular analysis involved conventional PCR amplification of genomic DNA to generate sufficient genetic material for analysis, using species-specific and primers targeting the direct repeat region, followed by spoligotyping to assess the genetic diversity of the M. tuberculosis strains. Results: Out of 404 samples from individuals with suspected pulmonary TB, Mycobacteria were cultured from 48 [11. 9%] of the samples. Amongst the 48 culture-positive M. tuberculosis isolates, 20 (41. 66%) were sensitive to all five first-line anti-TB drugs, and 3 (6. 2%) were resistant to all five drugs. Spoligotyping of the 47 isolates showed that 36. 1% [n=17] of the isolates belonged to the M. tuberculosis EAI3 (East African-Indian) family, followed by 27. 6% (n=13) M. tuberculosis EAI5 and 21. 2% (n=10) M. tuberculosis CAS (Central Asia). Other families observed in this study, although less prevalent, were M. tuberculosis Beijing, 8. 5% (n=4), family 33, 4. 3% (n=2), and Mycobacterium bovis-BCG family, 2. 1% (n=1). Conclusion: This study explored the genetic diversity and distribution of circulating M. tuberculosis strains in central Kerala. Genotyping M. tuberculosis strains provides valuable insights into TB transmission and progression, which can inform the development of effective public health control strategies

Introduction: Colistin, a polymyxin antibiotic often reserved for treatment of multidrug-resistant Gram-negative infections, exhibits a narrow therapeutic index. Careful consideration of the pharmacokinetic (PK) and pharmacodynamic (PD) parameters of colistin is essential to maximize its efficacy and minimize toxicity. Both thrice-daily and twice-daily administration regimens have been employed, with critically ill patients posing unique challenges regarding colistin's PK/PD. Methods: This retrospective observational study compared the mortality rates, cure rates, length of hospital stay, nephrotoxicity, and readmission rates associated with thrice-daily and twice-daily administration of a fixed total daily dose of 9 million international units (MIU) of colistin in 151 critically ill patients with multidrug-resistant Gram-negative infections. Propensity score matching with a 1: 5 case-control ratio was performed using XLSTAT software (by Addinsoft), and outcomes were analysed using logistic regression analysis. Results: Thrice-daily dosing of colistin was recorded in 125 patients, and twice-daily dosing in 26 patients. A total of 73 patients were included in the final analysis after propensity score matching. The 28-day mortality rates, clinical cure rates, and microbiological failure rates were comparable between the two groups (Odds ratio (OR) [95% confidence-interval (CI)] = 0. 48 [0. 07-3. 46], P=0. 467,1. 67 [0. 31-8. 90], P=0. 548,0. 13 [0. 001-19. 5], P = 0. 428, respectively). Hospital readmission rates within 90 days (OR [95% CI] = 1. 05 [0. 12-9. 10], P=0. 964) and duration of hospital stay (Beta coefficient = 1. 55, P=0. 683) were also comparable between the two groups. The incidence of nephrotoxicity-related AKI events during Colistin therapy was significantly lower with the 4. 5 MIU twice-daily regimen (OR [95% CI] = 0. 04 [0. 004-0. 35], P=0. 004). Conclusion: Twice-daily colistin administration significantly reduces the risk of nephrotoxicity-related AKI events compared to thrice-daily administration in critically ill patients with multidrug-resistant Gram-negative infections

Introduction: Diarrheal disease is a major cause of morbidity and mortality among children under the age of 10 worldwide, particularly in low-and middle-income countries. Diarrheagenic Escherichia coli (DEC) is a common cause of gastroenteritis in children. This study investigated the frequency, virulence markers, and antibiotic resistance patterns of DEC in children below 10 years with acute diarrhea in Zahedan, Iran. Methods: In this cross-sectional study, 300 E. coli isolates were collected from stool samples of children aged below 10 years with diarrhea who presented to hospitals and clinical laboratories in Zahedan. DEC pathotypes were identified using multiplex PCR and confirmed by standard biochemical tests and polyvalent antisera. Results: Of the 300 E. coli isolates examined, 89 (29. 6%) were identified as diarrheagenic E. coli (DEC) using polyvalent antisera targeting known DEC pathotypes. Enteroaggregative E. coli (EAEC) was identified in 31 isolates (34. 83%) based on reaction with antiserum No. 1. Enterotoxigenic E. coli (ETEC) was identified in 35 isolates (39. 33%) based on reaction with antiserum No. 2. Enteropathogenic E. coli (EPEC) was identified in 23 isolates (25. 84%) based on reaction with antiserum No. 3 (anti-coli3). Multiplex PCR identified the most common pathotype as EAEC (37. 6%), followed by EPEC (21. 7%), ETEC (15. 9%), and EIEC (11. 5%). Statistical analysis revealed no significant correlation between the presence of specific virulence genes (e. g., eae, pcvd432, elt, est, and iaH) and antibiotic resistance patterns in the DEC isolates. Conclusion: Given the distribution of DEC pathotypes among children in Zahedan and their increased antibiotic resistance, antibiotic treatment should be guided by molecular typing and antimicrobial susceptibility testing of isolates, when appropriate

Introduction: Pneumocystis jirovecii pneumonia (PCP) remains a significant cause of pneumonia among immunocompromised individuals, despite a decline in prevalence with the advent of antiretroviral therapy (ART) for Human Immunodeficiency Virus (HIV). This study aimed to evaluate and compare the diagnostic accuracy of four distinct staining techniques for PCP in respiratory specimens. We assessed the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of these techniques against the gold standard Gomori Methenamine Silver stain (GMS), in order to identify the most effective method for diagnosing PCP. Methods: In a prospective observational study, we collected induced sputum (IS) and BAL samples from 100 immunocompromised patients and examined them microscopically for P. jirovecii cysts. We employed four staining methods for detection: Calcofluor White, Modified Toluidine Blue, Wright's stain, and Gomori Methenamine Silver stain. Results: The combination of Modified Toluidine Blue, Calcofluor White, and Wright's stains detected P. jirovecii cysts in 5% of the study population. The sensitivity of the staining methods was: 80% for Modified Toluidine Blue, 40% for Calcofluor White, and 20% for Wright's, compared to the Gomori Methenamine Silver (GMS) stain, which was used as the gold standard. All the staining methods exhibited equivalent specificity (100%). Conclusion: The Modified Toluidine Blue stain is a viable alternative to the Gomori Methenamine Silver stain due to its simplicity, speed, and applicability in resource-limited settings. The low prevalence of P. jirovecii in this study population suggests that routine cotrimoxazole prophylaxis may be effective in reducing the incidence of P. jirovecii pneumonia among HIV patients.

Introduction: Secondary bacterial and fungal infections are a significant concern in COVID-19 patients, particularly those critically ill and requiring intensive care. This retrospective study investigated the prevalence and spectrum of secondary infections among COVID-19 patients admitted to the intensive care unit (ICU) at a tertiary care hospital in Navi Mumbai. Additionally, we explored the association between secondary infections and patient comorbidities. Methods: We performed a single-center, retrospective cohort study of 3234 COVID-19 patients admitted to a tertiary care hospital in Navi Mumbai, India, between August 2020 and August 2021. Microbiological data from various clinical specimens, including blood, sputum, bronchoalveolar lavage (BAL) fluid, urine, and tissue cultures, were retrospectively analyzed. Patient demographics and comorbidities were extracted from medical records. We employed descriptive statistics and Pearson's Chi-square test for data analysis to identify associations between secondary infections and patient characteristics. Results: Among the 3234 COVID-19 patients, 195 (6. 02%) presented with clinical features suggestive of secondary infections. Microbiological analysis confirmed secondary infections in 98 patients (3. 03%), with a culture positivity rate of 50. 3%. Among bacterial isolates, Klebsiella pneumoniae was the most prevalent (43. 28%), followed by Acinetobacter baumannii (25. 37%). Aspergillus spp. emerged as the dominant fungal pathogen. Notably, Escherichia coli isolation was significantly associated with various specimen types (P < 0. 001). However, no significant correlation was found between secondary infection rates and patient comorbidities. Conclusion: Gram-negative bacteria, specifically K. pneumoniae and A. baumannii, were the primary pathogens responsible for secondary infections in our cohort of critically ill COVID-19 patients admitted to the ICU. These findings underscore the importance of ongoing surveillance and monitoring of secondary infection trends, including fungal pathogens, to inform and optimize management strategies in this high-risk population