Mikrobiyoloji bulteni最新文献

Enterococcus faecalis is among the leading causes of hospital-acquired infections worldwide. This bacterium has both intrinsic and acquired resistance to various antibiotics. The continuous developmentof antibiotic resistance by pathogens poses a challenge that economically and technologically restrictsthe discovery of next-generation antibiotics. Therefore, many researchers aim to develop new strategies to combat this pathogen. The aim of this study was to evaluate the synergistic antimicrobial andantibiofilm effects of the combination of antimicrobial agents such as chlorhexidine (CHX), ethylenediaminetetraacetic acid (EDTA) and sodium hypochlorite (NaOCl) with nisin against clinical and foodisolates of E.faecalis. Nisin produced by wild-type and recombinant Lactococcus lactis strains was purifiedand their activities were evaluated in comparison with commercial nisin. The minimum inhibitory concentration (MIC) and minimum biofilm eradication concentration (MBEC) of the agents were determined using microplate dilution methods. Antibiofilm activities were visualized using scanning electronmicroscopy (SEM). The MIC values for CHX, EDTA, and NaOCl were determined as 0.0002%, 5 mM, and0.50%, respectively. The MIC values of nisin for all tested strains and isolates ranged from 12.5 to 100 IU/mL. Synergistic interactions of the antimicrobial agents were determined using the checkerboard method, revealing that the most effective combination was the combination of nisin and EDTA. Similarly, themost effective combination for eradicating 24-hour biofilms was nisin + EDTA (1000 IU/mL + 10 mM).The concentration of nisin in this combination was lower than its MBEC value (1500 IU/mL). While thecombination of nisin with CHX and NaOCl achieved complete eradication of biofilms, the agents alonewere ineffective in achieving such results. SEM images showed that although E.faecalis biofilms were notcompletely eradicated, they were significantly disrupted as a result of the combined application of nisinwith antimicrobial agents. These in vitro findings indicate that the combination of nisin and EDTA maybe effective against biofilm structures formed by clinical and food-derived E.faecalis isolates and demonstrate the potential of this combination for practical applications. Considering the different resistanceprofiles of clinical and food isolates, our study emphasizes the need to tailor treatment strategies according to the distinct characteristics of the bacterial strains involved. The results provide a scientific basis forfuture combination-based studies aimed at enhancing antibiofilm efficacy against E.faecalis.

Malaria is a severe infectious disease caused by Plasmodium parasites transmitted by infected femaleAnopheles mosquitoes. Plasmodium falciparum is the leading cause of malaria-related deaths worldwideand can lead to severe complications such as coma, metabolic acidosis and renal failure. In this report acase of high-parasitemia P.falciparum infection diagnosed and treated with intravenous (IV) artesunatewas presented. The patient was a 52-year-old male with a travel history to Liberia who was referredto a university hospital due to thrombocytopenia and hematochezia. Subsequently, the patient developed severe malaria symptoms, including metabolic acidosis and acute renal failure. Laboratory testsrevealed a leukocyte count of 9370/mm³, hemoglobin level of 18.3 g/dL, platelet count of 11000/μL,aspartate aminotransferase of 57 U/L, alanine aminotransferase of 28 U/L, gama-glutamyl transferaseof 160 U/L, lactate dehydrogenase of 629 U/L, total bilirubin of 8 mg/dL, direct bilirubin of 4.64 mg/dL, creatinine of 1.69 mg/dL, prothrombin time of 14.9 seconds, international normalized ratio of 1.27,and C-reactive protein level of 247.7 mg/L. Giemsa-stained thin blood smear preparations, the AbbottBioline™ Malaria Ag P.f/P.v rapid diagnostic test and real-time quantitative polymerase chain reactionconfirmed P.falciparum infection. Intravenous artesunate and meropenem for secondary infections wereadministered, resulting in a rapid response to treatment. Parasite density was regularly monitored duringtreatment, and the patient was transitioned to oral therapy. According to the treatment algorithms ofthe World Health Organization and the Turkish Public Health Directorate, IV artesunate is the first-linetreatment for severe malaria. In patients who have traveled to endemic regions and present with unexplained fever and flu-like symptoms, malaria should always be considered in the differential diagnosis andprompt diagnosis and treatment are crucial. Early diagnosis and the rapid action of artesunate significantly contribute to reducing morbidity and mortality rates. In this case, the rapid effect of artesunateand the significant decrease in parasitemia follow-up were clearly observed. In this case report, it wasevaluated that parasitemia monitoring plays a critical role in directing patient treatment and is an important guide for clinicians and microbiologists.

Vancomycin-variable enterococci (VVE) are Enterococcus strains that appear phenotypically susceptibleto vancomycin but harbor glycopeptide resistance genes, representing a significant diagnostic andtherapeutic challenge and posing a risk for therapeutic failure. These strains are often undetectable byconventional susceptibility methods but can be identified by molecular techniques. This study aimed toinvestigate the prevalence of vanA and vanB resistance genes in vancomycin- and teicoplanin-susceptibleEnterococcus faecalis and Enterococcus faecium clinical isolates using multiplex and monoplex polymerasechain reaction (PCR) techniques. A total of 251 clinical Enterococcus isolates phenotypically confirmedas susceptible to vancomycin by disc diffusion test, broth microdilution and gradient diffusion test(Etest®), were retrospectively analyzed. Multiplex PCR targeting vanA and vanB genes was performedon all isolates, followed by monoplex PCR for the confirmation of positive results. Among the 251isolates screened, only one E.faecalis isolate (0.4%) from a urinary sample of a 91-year-old female patientdetected as positive for the vanA gene in both multiplex and monoplex PCR. In contrast, vanB gene wasdetected as positive in 100 isolates (39.8%) by multiplex PCR, but none of these were confirmed bymonoplex PCR. The detection of a vanA-positive E.faecalis isolate that was phenotypically susceptible tovancomycin highlights the risk of missing vancomycin-variable enterococci (VVE) when relying solely onconventional testing. The high rate of false-positive vanB results obtained by multiplex PCR demonstratesthe limitations of this method and underscores the necessity of confirmatory testing within molecularworkflows. Integrating gene-specific PCR assays into standard diagnostic protocols may facilitate moreeffective detection of VVE strains and the development of appropriate antimicrobial managementstrategies, particularly in settings with high glycopeptide use or unexplained treatment failures.

Klebsiella pneumoniae is a major pathogen in ventilator-associated pneumonia (VAP) and poses asignificant challenge in healthcare-associated infections due to its multidrug resistance (MDR). Mobilegenetic elements such as integrons are key factors in the spread of resistance genes in pathogens likeK.pneumoniae. This study aimed to detect class 1 and class 2 integron gene cassettes in K.pneumoniaeisolates from VAP patients. A total of 22 isolates were collected between 2022 and 2023 from the intensive care unit of Kırşehir Training and Research Hospital. DNA was extracted using the boiling methodand integrons were amplified via polymerase chain reaction with specific primers. Amplified fragmentswere cloned into the pJET1.2/blunt vector and sequenced. Sequences were processed using BioEditand compared with the NCBI BLAST GenBank database to identify gene cassette contents. Identifiedsequences were submitted to GenBank and assigned accession numbers. Class 1 integrons were foundin five isolates (22.7%) and class 2 integrons in two isolates (9.1%). Class 1 integrons harboured dfrA12responsible for trimethoprim resistance and aadA which provides resistance to aminoglycoside group antibiotics. In class 2 integrons, dfrA1, sat2 and aadA1 were identified which confer resistance to trimethoprim, streptothricin and streptomycin/spectinomycin, respectively. The results of this study demonstratethat integrons play a significant role in the spread of hospital-acquired MDR K.pneumoniae isolates.Strengthening infection control measures and monitoring antibiotic resistance mechanisms are crucialfor controlling antibiotic-resistant isolates seen in hospitals. This study will contribute to understandingthe genetic makeup of VAP-related K.pneumoniae isolates, determining appropriate treatment approaches and controlling hospital-acquired infections.

Lichtheimia corymbifera (formerly known as Absidia corymbifera) is a mold fungus belonging to thefamily Mucorales. Mucormycosis caused by L.corymbifera is a newly recognized and rare opportunisticinfection in immunocompromised patients. Rapid diagnosis and treatment are crucial due to the highmortality rates, especially in patients with hematologic malignancies. Early clinical suspicion, surgicalremoval of necrotic tissue and appropriate antifungal chemotherapy constitute the main steps of treatment. Lipid formulations of Amphotericin B are the first-line treatment for mucormycosis. In this reporta case of fungal sinusitis and preseptal cellulitis caused by L.corymbifera in a 23-year-old male patientwho had been followed for eight years with a diagnosis of acute myeloid leukemia (AML) was presented.The patient, hospitalized due to relapsed AML, development of edema and discharge in the left eye andophthalmological evaluation revealed preseptal cellulitis. Despite treatment, no clinical improvementwas observed and contrast-enhanced orbital and paranasal sinus computed tomography revealed sinusitis. Direct microscopic examination of crusted lesions from the left nasal cavity showed the presenceof irregular aseptate hyphae. A panic notification was reported to the relevant clinic with a preliminarydiagnosis of mucormycosis. After the clinic and the patient interview, liposomal Amphotericin B treatment was started since the patient did not accept surgical debridement. The material was cultured ontwo Sabouraud’s Dextrose agar; one was incubated at 22 °C (room temperature) and the other at 37 °C(incubator). On the second day of incubation at 37 °C, colony morphology was observed as light whitewoolly surfaces with a dark white, non-pigmented base. In the preparations prepared with lactophenolcotton blue; fixed stolons ending in a pyriform funnel-shaped apophysis supporting the sporangiumwere observed. The agent grown in culture was named to species level with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) (MALDI Biotyper® Sirius System,Bruker, Germany) and diagnosed as L.corymbifera based on characteristic macroscopic and microscopicfeatures. Although the patient refused surgical debridement treatment, early presumptive diagnosis allowed for the administration of liposomal Amphotericin B, resulting in successful treatment In conclusion,rapid preliminary diagnosis is critical to prevent the aggressive clinical course of mucormycosis, improvesprognosis and increases survival rate.

Crimean-Congo hemorrhagic fever (CCHF) is a rare but severe viral hemorrhagic disease transmittedto humans through tick bites or contact with the blood, tissues or secretions of infected animals. CCHFcan lead to widespread endothelial damage and immune dysfunction, resulting in severe hemorrhagicmanifestations and various complications. Although the majority of patients recover without permanentsequelae, unexpected complications such as secondary bacterial infections may rarely occur during theacute phase or convalescence. In this report, the case of a 42-year-old female patient who developedspinal epidural abscess and lumbar spondylodiscitis following real-time polymerase chain reaction testingconfirmed CCHF was presented. On the seventh day of illness, the patient admitted to our emergencydepartment with persistent high fever, nausea, vomiting, anorexia, malaise, diffuse body pain, hematuria and vaginal bleeding. The patient’s past medical history was unremarkable except for a lumbar discherniation surgery 10 years ago. Following recovery from the acute viral illness, the patient developedsudden and severe lower back pain, recurrent high-grade fever and progressive motor weakness in plantar flexion of the right ankle. On the 10th day of hospitalization, spinal magnetic resonance imagingrevealed spondylodiscitis and a spinal epidural abscess at the L5-S1 level. The epidural abscess causedcompression of the S1 nerve roots, correlating with her neurological symptoms. The patient underwentsurgical intervention (abscess drainage and stabilization) by the department of neurosurgery. Growth ofStaphylococcus aureus in the blood culture confirmed that the infection was of bacterial origin but sincethe operation was performed while under 10 days of antibiotic treatment, there was no bacterial growthin the abscess material taken during the surgery. The patient was treated with intravenous cefazolin at adose of 1000 mg three times daily for six weeks. Clinical improvement was rapid and complete, with noresidual neurological deficits. This rare complication is thought to be related to immunoparalysis following a cytokine storm induced by CCHF, predisposing the patient to opportunistic bacterial infections.While leukopenia was observed during the immunosuppressive phase, a subsequent rise in leukocytecounts during recovery unmasked the signs of infection. Additionally, the patient’s history of prior spinalsurgery may have created a localized microvascular injury or hematoma, forming a favorable niche forbacterial proliferation. New symptoms in the convalescent phase of CCHF must be carefully evaluated.In patients presenting with spinal pain and progressive localized motor deficits, prompt imaging and advanced diagnostics are essential to ensure early recognition and treatment of rare but potentially seriouscomplications.

Mucormycosis is a rare, difficult-to-diagnose, angioinvasive fungal disease with high morbidity andmortality. It is classified into clinical categories based on the anatomical regions involved. The mostcommon clinical form is rhino-orbito-cerebral mucormycosis (ROCM). In this study, we aimed to identifythe risk factors for mortality in cases of rhino-orbito-cerebral mucormycosis (ROCM). We retrospectivelyevaluated histopathologically and/or microbiologically confirmed ROCM cases in patients over the ageof 18, diagnosed in our clinic between January 1, 2003, and December 31, 2024. A total of 49 patientswere diagnosed as ROCM, with a mean age of 56.6 ± 15.5 years, including 22 women (44.9%) and 27men (55.1%). Patients had diabetes mellitus (65.3%), hematological cancer (24.4%), hematopoieticstem cell transplantation (10.2%), chronic kidney failure (8.1%), solid organ transplantation (8.1%), andsolid organ cancer (8.1%). Predisposing factors among the patients included steroid treatment (32.6%),erythrocyte transfusion (26.5%), recent tooth extraction (20.4%), neutropenia (18.3%) and a recenthistory of coronavirus disease-2019 (12.2%). Periocular pain (81.6%), ophthalmoplegia (75.5%), periorbital cellulitis (69.3%) and ptosis (67.3%) were identified as the most common presenting symptomsand clinical findings. Although antifungal therapy (liposomal amphotericin B), functional endoscopicsinus surgery (FESS) and orbital exenteration were performed when necessary, 24 patients (48.9%) died.Binary logistic regression analysis revealed that the risk of mortality was significantly higher in patientswith hematological malignancy (8.2-fold), those receiving steroid therapy (5.2-fold), those undergoingchemotherapy or immunosuppressive treatment (10-fold) and those who received erythrocyte transfusion (9.8-fold). Additionally, patients presenting with orbital apex syndrome (3.5-fold), those withcerebral infarction (6.9-fold) and those whose duration from symptom onset to FESS exceeded 96 hours(4-fold) also had a significantly increased risk of death. As a result, underlying hematological malignancy,immunosuppressive therapy, steroid use, erythrocyte transfusion, the presence of orbital apex syndromeat admission, cerebral infarction and delayed surgical intervention were all found to increase the risk ofmortality.

The three step human immunodeficiency virus (HIV) testing algorithm used in Türkiye was updated and implemented in 2019 in accordance with the current HIV testing algorithm of the Centers forDisease Control and Prevention. In this study, it was aimed to obtain HIV test data with a multicenterand multidisciplinary approach in order to reveal the current situation in the diagnosis of HIV/acquiredimmunodeficiency syndrome in our country and to identify new algorithm applications and problemsencountered in HIV diagnosis. For this purpose, 12 HIV testing centers were asked about the HIV testingalgorithms they use, the problems they encountered in practice and their suggestions for solution with a57-question survey. The performance of the current algorithm and the current HIV status of the centerswere evaluated with the total number of three-year fourth generation HIV enzyme linked immunsorbentassay (ELISA) tests , the number of repeated reactive tests, the distribution of confirmatory test resultsand the number of HIV nucleic acid amplification tests (NAT) between 2018 and 2020. Between 2018and 2020, the total number of anti-HIV ELISA tests were 788261, 871299 and 835498, the repeatingreactivity rates were 0.48, 0.51 and 0.70, respectively, while the confirmed HIV test rates were 0.24, 0.25and 0.21 respectively. During this period the rates of Western Blot (WB) confirmatory test utilization were25.77%, 12.29% and 9.86%, respectively and are gradually decreasing. The utilization rates of HIV-1/2antibody differential rapid confirmatory tests recommended in the current algorithm were found to be25.72%, 38.76% and 45.78%, respectively and it is seen to replace WB. The rates of HIV-1 RNA studiedby year were 48.77%, 97.98% and 46.31% respectively. In our study, it has been observed that the useof the rapid HIV-1/2 antibody differential test, which is included in the new algorithm, is gradually increasing and is used more effectively in HIV diagnosis, while the use of HIV-1 NAT has decreased. This situation, which is associated with the shift of NAT opportunities to coronavirus diseases-2019 (COVID-19)polymerase chain reaction studies in the shadow of the COVID-19 pandemic, requires more detailedmonitoring in terms of possible changes in the HIV epidemic in our country.

Monitoring of viral load is of critical importance in the clinical management of patients at risk of cytomegalovirus (CMV)-related complications following transplantation. Quantitative real-time polymerasechain reaction (qRT-PCR) is one of the most commonly used methods for CMV DNA detection. For thispurpose, commercial test kits calibrated according to the International Standard of Quantitation (ISQ)defined by the World Health Organization (WHO) are used. However, measurement variability betweendifferent test systems still constitutes a significant problem. The aim of this study was to compare the testresults of two different commercial kits, CMV Cobas Ampliprep/Cobas Taqman (CMV-CAP/CTM) (RocheDiagnostics, Mannheim, Germany) and NeuMoDx CMV Quant Assay (Qiagen, Ann Arbor, USA) whichhave been calibrated with the WHO CMV IQS. The results of 478 plasma samples run simultaneouslywith the CMV-CAP/CTM and NeuMoDx CMV PCR tests were analyzed. Fully automated steps includingextraction, real-time amplification and result analysis were performed according to the manufacturer’srecommendations. CMV DNA was detected in 216 (45.18%) samples and not detected in 82 (17.15%)samples in both tests. A total of 180 (37.65%) samples had discordant results. Statistically, a moderatelevel of qualitative agreement was found between the qualitative results of both tests (kappa= 0.28, p<0.001). When the quantitative results obtained in the dynamic measurement range of both tests (n= 104)were examined, the median viral load values measured by CMV-CAP/CTM and NeuMoDx CMV tests werecalculated as 1598 IU/mL (range= 137.41-115570) and 2600 IU/mL (range= 55-220000), respectively.According to the correlation analysis, a very strong correlation was found in the comparison of the resultsof both tests (r= 0.83, p< 0.001). According to the Bland-Altman analysis; the average difference betweenthe CMV-CAP/CTM test and NeuMoDx CMV test values was found to be 0.296 log10 (standard deviation:0.412) IU/mL (the lowest difference was 0.005 and the highest difference was -1.559 log10 IU/mL), andthe CMV-CAP/CTM test gave lower measurements than the NeuMoDx CMV test. In 104 samples with results in the dynamic measurement range of both tests, for log10 IU/mL results, the measurement differencewas within ±0.5 log10 IU/mL in 71 (quantitative agreement: 68.3%) samples and the measurement difference was greater than ±0.5 log10 in 33 (31.7%) samples (median= 0.7 log10 IU/ml; range: 0.51-1.56).A measurement difference of more than ±1 log10 was detected in two samples (1.9%). As a result, in themeasurements made with CMV-CAP/CTM and NeuMoDx CMV PCR tests, a moderate level of agreementwas found for qualitative results in plasma samples, a strong correlation for quantitative values and a biologically significant viral load difference in one-third of the samples was detected. Our study shows thatthe measurement differences observed between CMV PCR test platforms do not com