Iranian Journal of Microbiology最新文献

Background and objectives: Coagulase-negative staphylococci (CoNS), previously classified as normal bacterial flora, have recently been associated with serious infectious diseases. The clinical isolation rate of these bacteria has increased in parallel with a rising prevalence of antibiotic resistance. Therefore, this study aims to determine the prevalence and species diversity of CoNS and their antibiotic susceptibility patterns.

Materials and methods: Two hundred samples were collected from patients attending outpatient clinics. Bacterial genus, species, and antimicrobial susceptibility patterns were confirmed by the Vitek2 system. The mecA gene was then detected in all isolated bacteria using a polymerase chain reaction.

Results: The most frequently isolated bacterium was Staphylococcus haemolyticus accounting for 37.83% of the isolates and was identified in different specimens. The antibiotic susceptibility profile illustrated the highest resistance against cefoxitin, followed by erythromycin, tetracycline, gentamicin, levofloxacin, clindamycin, and tobramycin. The mecA gene was detected in 95.49%, and all isolates demonstrated resistance to one or more classes of antibiotics. The highest degree of multiple resistance involved six classes of antibiotics.

Conclusion: Methicillin resistance in coagulase-negative staphylococci is alarmingly high. Periodic surveillance of multidrug-resistant CoNS is essential to monitor changes in their antimicrobial susceptibility and to prevent their transition from opportunistic pathogens to regular pathogens.

Background and objectives: This study aimed to investigate the virulence factors and genes associated with biofilm and protease in Stenotrophomonas maltophilia in Bushehr, Iran.

Materials and methods: Eighty-seven S. maltophilia isolates (67 clinical and 20 environmental isolates) were studied. The isolates were assessed for the production of virulence factors including several enzymes and biofilm. To detect rmlA, rpfF, spgM, smf-1, StmPr1 868 bp, StmPr1 1621 bp, and StmPr2 genes, PCR and sequencing were performed.

Results: All isolates (100%) produced DNase, hemolysin, protease, lipase, and hyaluronidase. Seventy-eight (89.7%) isolates were gelatinase producers, and 85 (97.7%) isolates were lecithinase producers. All isolates were biofilm producers: 79 (90.8%) isolates produced strong biofilm, 5 (5.7%) isolates produced moderate biofilm, and 3 (3.5%) isolates produced weak biofilm. The frequency of smf-1, rmlA, rpfF, and spgM was 93.1%, 86.2%, 26.4%, and 59.8%, respectively. The frequency of protease genes including StmPr1 868 bp, StmPr1 1621 bp, and StmPr2 was 12.6%, 41.4%, and 18.4%, respectively.

Conclusion: Our findings revealed a high frequency of isolates that produce DNase, hemolysin, protease, gelatinase, lipase, lecithinase, hyaluronidase, and biofilm. All isolates that harbored spgM or rpfF or both genes were strong biofilm producers. Notably, the presence of isolates that lacked spgM and rpfF genes but produced strong biofilm indicates that in addition to these two genes, other genes or factors may play a role in the production of strong biofilm. Based on this research, S. maltophilia in our area possesses the capability to produce several factors that could play roles in pathogenicity.

Background and objectives: The ability of Candida albicans to produce biofilm is considered an important pathogenic factor. In addition, the low sensitivity of biofilms to antifungal drugs is a challenge for patients, clinicians, and laboratory workers. We aimed to investigate the effectiveness of luliconazole and caspofungin on the planktonic and biofilm types of C. albicans strains.

Materials and methods: Fifty C. albicans from vaginitis, candiduria, gastrointestinal candidiasis, and saliva were examined for antifungal susceptibility against caspofungin and luliconazole using the CLSI M27 guideline. Moreover, the susceptibility of biofilms was detected using 96 well microplates and the MTT method.

Results: The capacity of the isolates to produce biofilm within 2, 6, and 24 h was different, however, all tested isolates produced biofilm after 24 h. Vaginal and esophagitis isolates had a high and low ability for biofilm production during 24-hour incubation. In our study, 90% of isolates were sensitive to caspofungin, while 7.5 and 2.5% of them were intermediate and resistant. The MIC range of all isolates against luliconazole was 0.01562-1 μg/mL.

Conclusion: The MICs of biofilms were 15.6, and 171.3 higher than that of planktonic cells for caspofungin and luliconazole, respectively. Moreover, paradoxical and trailing effects occurred at 4 and 32 μg/mL of caspofungin and luliconazole, respectively.

Background and objectives: Human cytomegalovirus infection poses an important public health issue. This issue in India has not received enough attention. The majority of research workers have highlighted the seroprevalence of human cytomegalovirus. Hence this study was conducted to find out true magnitude of human cytomegalovirus disease.

Materials and methods: Samples from 181 patients with suspected human cytomegalovirus disease were analyzed for human cytomegalovirus. DNA extraction was followed by real-time PCR. Human cytomegalovirus DNA-specific probes, fluorophore FAM™ and fluorophore JOE™ were utilized to detect human cytomegalovirus specific DNA and internal control at the same time. After completion of the assay, fluorescent growth curves were examined, and the response growth curves passing the threshold line in less than 36 cycles were deemed to be positive. All relevant clinical, demographic, and epidemiological information of the patients was also recorded.

Results: The most common clinical presentation was meningitis/meningoencephalitis. Out of the total samples, human cytomegalovirus infection was detected in 21% of the samples. Most positive samples were from infants (18.2%), followed by post-renal transplant cases (2.7%). Human cytomegalovirus was detected in urine samples (17.1%) followed by serum (3.8%). Four out of the 14 CSF samples were tested for other viruses as well, and they were positive for EBV (n=1, 7%), enterovirus (n=2, 14%), and varicella zoster virus (n=1, 7%).

Conclusion: PCR has a significant role in the detection of human cytomegalovirus disease at an early stage to avoid irreversible sequelae of late diagnosis.

Background and objectives: Acinetobacter baumannii is considered a troublesome cause of infection in burn units, where its capability to form biofilm and resist antibiotics significantly hampers therapeutic success. This study explored the correlations between antimicrobial resistance profiles, biofilm-producing capacity, and genetic diversity of A. baumannii strains from patients with burn wound infection in Isfahan, Iran.

Materials and methods: Ninety-six isolates were analyzed for antibiotic resistance using the disk diffusion technique and for biofilm formation through the microtiter dish assay. The prevalence of ten biofilm-related genes was investigated using specific primers. Clonal relatedness among bacterial strains was defined by Enterobacterial Repetitive Intergenic Consensus-Polymerase Chain Reaction (ERIC-PCR).

Results: A vast majority of isolates (99%) exhibited resistance to meropenem, ciprofloxacin, ceftriaxone, cefotaxime, piperacillin-tazobactam, and imipenem, qualifying them as extensively drug-resistant (XDR). Twenty-five percent of the strains were strong biofilm formers, while 68% demonstrated moderate or weak biofilm formation. The most commonly identified biofilm-related genes included bfmR (100%), ompA (100%), and bap (99%). A significant association was found between the production of biofilm, resistance to aminoglycosides, and the presence of csuE and bap genes. ERIC-PCR typing showed the presence of 3 clonal types and 7 single types, with biofilm producers predominantly clustering to clonal type 2.

Conclusion: This work highlights a notable prevalence of biofilm-producing XDR A. baumannii in burn patients, underscoring the need for continuous surveillance and enhanced infection control strategies.

Background and objectives: Enteral feeding solutions (gavage) play a vital role in supporting ICU patients who cannot eat by mouth. However, their preparation is vulnerable to microbial contamination, posing serious health risks. This study aimed to assess and improve the microbial safety of enteral feeding solutions prepared at Imam Khomeini Hospital in Urmia, Iran.

Materials and methods: A three-phase intervention was conducted involving microbial and PCR analyses, source identification, and corrective measures. Initial testing revealed high contamination levels: coliform bacteria (>5×10³ CFU/mL), fungi (>3×10³ CFU/mL), and total mesophilic bacteria (>10⁴ CFU/mL). PCR analysis confirmed the absence of Escherichia coli and Klebsiella spp. Corrective actions-such as installing UV lighting, implementing enhanced cleaning protocols, and replacing the mixing device-were introduced.

Results: Post-intervention analyses showed complete elimination of detectable microbial contamination in the gavage solutions.

Conclusion: This study demonstrates that implementing a HACCP-based approach can effectively eliminate microbial contamination in enteral feeding solutions. The findings support the development of national guidelines and highlight the importance of standardized safety practices to improve patient care in hospital settings.

Background and objectives: Scrub typhus, caused by Orientia tsutsugamushi, is a significant zoonotic illness in the Asia-Pacific region. Timely diagnosis is crucial, but overlapping symptoms and limitations of traditional diagnostic methods pose challenges. This study evaluates the diagnostic accuracy and utility of IgM ELISA, RT-PCR, and Rapid Card test for Scrub typhus, focusing on sensitivity, specificity, and practical applicability in endemic regions.

Materials and methods: This cross-sectional study was conducted on 192 patients with suspected Scrub typhus at a tertiary care hospital from June to November 2024. Diagnostic tests included Rapid Card, IgM ELISA, and RT-PCR. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy were calculated, along with clinical and demographic data.

Results: IgM ELISA had the highest sensitivity (96.30%) and specificity (100%), followed by Rapid Card (sensitivity: 93.55%, specificity: 99.38%) and RT-PCR (sensitivity: 92.86%, specificity: 99.44%). Common symptoms included fever (99.4%) and headache (95.8%). Positive cases were mostly males (56.7%-64.3%) and individuals aged 21-40 years.

Conclusion: IgM ELISA shows high sensitivity and specificity for Scrub typhus, while RT-PCR aids early detection. The Rapid Card offers a quick field alternative. Combining molecular and serological methods can enhance diagnostic accuracy.

Fungal surgical site infections (SSIs) may be less common than bacterial SSIs but are a significant clinical issue due to their challenging diagnosis, higher morbidity, and rising incidence, particularly in immunocompromised patients. The epidemiology, risk factors, prevalent fungal pathogens, and prevention of SSIs caused by fungi are discussed in this narrative review. Systematic literature search for the period 2000 to 2024 was conducted on top databases using relevant MeSH keywords. The most frequent solitary pathogens were Candida spp., followed by Aspergillus and Mucor spp., especially in transplant, cardiac, and GI infections. The greatest challenge is extended length of hospital stay, broad-spectrum antibiotics, immunosuppression, and invasive interventions with prosthetic device or shunts. While it creates added burden, fungal SSIs go unnoticed by clinical practice and are rarely included in SSI prevention strategies. The review declares the significance of enhanced clinical vigilance and tailored antifungal prophylaxis in high-risk exposure surgical procedures. The review, based on the integration of existing information, provides clinicians and infection control practitioners with a framework of fungal SSIs so that they can be better equipped to assess risk, detect infection sooner, and focus prevention efforts.

Background and objectives: Carbapenem-resistant Enterobacterales (CRE) pose a major healthcare challenge due to high resistance rates and limited treatment options. This study characterized carbapenemase production among CRE isolates using phenotypic methods-Modified Carbapenem Inactivation Method (mCIM) and EDTA-Carbapenem Inactivation Method (eCIM)-as genotypic methods have limitations like restricted gene targets and mutations.

Materials and methods: This six-month study was conducted at Sher-i-Kashmir Institute of Medical Sciences (SKIMS). Samples including swabs, respiratory specimens, pus, body fluids, and blood were cultured on Blood Agar and MacConkey Agar (HiMedia, India). Enterobacterales were identified using conventional methods and screened for carbapenem resistance. CRE isolates underwent mCIM and eCIM testing per CLSI guidelines.

Results: Among 471 Enterobacterales isolates tested, 160 (33.9%) were carbapenem-resistant. Of these, 97 (60.6%) were mCIM positive, indicating carbapenemase production. eCIM further identified 83 (85.5%) as metallo-beta-lactamase (MBL) producers and 14 (14.4%) as serine carbapenemase producers. CRE prevalence was higher in ICU settings and among males. Isolates showed high cephalosporin resistance, with multi-drug resistance (MDR) common in both MBL and serine carbapenemase producers.

Conclusion: The prevalence of CRE was found to be 33.9%. The findings underscore the critical need for continuous surveillance and stringent infection control measures to manage the spread of CRE in healthcare settings.

Background and objectives: Staphylococcus aureus significantly contributes to healthcare-associated infections, with biofilm formation causing chronic, antibiotic-resistant cases. Because biofilms show high resistance to conventional antibiotics, endolysins have emerged as a promising alternative for treating antibiotic-resistant, biofilm-associated infections. This study evaluated the effects of four culture media and different incubation times on biofilm formation in methicillin-sensitive (MSSA) and methicillin-resistant (MRSA) S. aureus strains and assessed the anti-biofilm efficacy of a novel chimeric endolysin called ZAM-CS (catalytic domain of SAL-1 endolysin and binding domain of lysostaphin).

Materials and methods: Biofilms were grown for 24, 48, and 72 hours in Mueller-Hinton broth (MHB), Luria broth (LB), terrific broth (TB), and tryptic soy broth (TSB). The crystal violet assay was used to assess the biomass of the biofilm. The optimal biofilm conditions were then used to test ZAM-CS's activity at different concentrations.

Results: MSSA formed the strongest biofilms in TB. MRSA formed stable, high-biomass biofilms in TSB, TB, and LB, while MHB was the least supportive medium for both strains. ZAM-CS significantly reduced biofilm biomass in both MSSA and MRSA (up to 77%).

Conclusion: ZAM-CS's rapid and potent anti-biofilm activity at low concentrations highlights its potential as a promising treatment against antibiotic-resistant S. aureus biofilm infections.