Species Distribution and Antifungal Susceptibilities of Candida Species Isolated From Blood Culture

Introduction Candida species (spp.) are among the leading agents of bloodstream infections. Candidemias are a major cause of morbidity and mortality. Having an understanding of Candida epidemiology and antifungal susceptibility patterns in each center is crucial in guiding the management of candidemia. In this study, the species distribution and antifungal susceptibility of Candida spp. isolated from blood culture at the University of Health Sciences, Bursa Yuksek Ihtisas Training & Research Hospital were examined and the first data on the epidemiology of candidemia in our center were presented. Methods A total of 236 Candida strains isolated from blood cultures in our hospital over a four-year period were analyzed and their antifungal susceptibilities were studied retrospectively. Strains were identified at the species complex (SC) level by the germ tube test, morphology in cornmeal-tween 80 medium, and the automated VITEK 2 Compact (bioMérieux, Marcy-l'Étoile, France) system. Antifungal susceptibility tests were performed on VITEK 2 Compact (bioMérieux, Marcy-l'Étoile, France) system. The susceptibilities of the strains to fluconazole, voriconazole, micafungin, and amphotericin B were determined according to Clinical and Laboratory Standards Institute (CLSI) guidelines and epidemiologic cut-off values. Results Of the Candida (C.) strains, 131 were C. albicans (55.5%), 40 were C. parapsilosis SC (16.9%), 21 were C. tropicalis (8.9%), 19 were C. glabrata SC (8.1%), eight were C. lusitaniae (3.4%), seven were C. kefyr (3.0%), six were C. krusei (2.6%), two were C. guilliermondii (0.8%) and two were C. dubliniensis (0.8%). Amphotericin B resistance was not detected in Candida strains. Micafungin susceptibility was 98.3%, and four C. parapsilosis SC strains (10%) were intermediate (I) to micafungin. Fluconazole susceptibility was 87.2%. Apart from C. krusei strains which intrinsically resistant to fluconazole, three C. parapsilosis (7.5%), one C. glabrata SC (5.3%) strain were resistant (R) to fluconazole, and one C. lusitaniae (12.5%) strain was wild-type (WT). Voriconazole susceptibility of Candida strains was 98.6%. Two C. parapsilosis SC strains were I to voriconazole, while one strain was R. Conclusion In this study, the first epidemiological data of candidemia agents in our hospital were presented. It was determined that rare and naturally resistant species did not cause any problem in our center yet. C. parapsilosis SC strains showed decreased susceptibility to fluconazole, whereas Candida strains were highly susceptible to the four antifungals tested. Close monitoring of these data will help guide the treatment of candidemia.

Comparison of Clinical Laboratory Standards Institute (CLSI) Microdilution Method and VITEK 2 Automated Antifungal Susceptibility System for the Determination of Antifungal Susceptibility of Candida Species

Introduction

Changes in the epidemiology of Candida infections, increasing resistance, and advances in treatment have increased the need to perform antifungal susceptibility testing in clinical laboratories. Standardized reference, the microbroth dilution method, and various commercial antifungal susceptibility test systems are used to determine antifungal susceptibility. This study aims to determine and compare the antifungal susceptibility of various Candida species isolated from blood cultures in our laboratory with the CLSI M27 microdilution reference method and VITEK 2 automated system (bioMérieux, Marcy-l'Étoile, France).

Methods

The antifungal susceptibility of a total of 140 Candida strains to fluconazole, voriconazole, and amphotericin B, and a total of 92 strains to anidulafungin was tested with the CLSI M27 method and the VITEK 2 automated system. For fluconazole, voriconazole, and amphotericin B, essential and categorical agreement percentages were calculated between the two methods. Because there is no anidulafungin in the VITEK 2 system, anidulafungin results obtained with CLSI were compared with micafungin only in terms of categorical agreement. In the category comparison, CLSI clinical breakpoints were used; the epidemiological cut-off values were used when they were not available. Very major error, major error, and minor error rates were calculated.

Results

In general, the minimum inhibitory concentration (MIC) values obtained with VITEK 2 for azole group drugs were found to be one-fold higher than the CLSI MICs read at the 24th hour. While the essential agreement between the two methods was >90% for amphotericin B and voriconazole, it remained at 85% for fluconazole. Overall, the best categorical agreement was obtained with amphotericin B (99.3%), and the least categorical agreement was obtained with voriconazole (85.7%). A very major error was seen with amphotericin B (0.7%) and fluconazole (0.7%) in one C. parapsilosis strain each. No resistance was detected with VITEK 2 in one C. glabrata strain found to be resistant to fluconazole by the reference method. Major and minor error rates were higher for azole drugs than amphotericin B and anidulafungin/micafungin.

Conclusion

The VITEK 2 system is a fast and highly applicable system, and with these features, it is advantageous for routine laboratories. In this study, although the error rate was not very high, one fluconazole-resistant C. parapsilosis and C. glabrata strain could not be detected with VITEK 2. The increase in data on the antifungal performance of the VITEK 2 system, which is available in many routine laboratories due to its ability to be used for bacteria identification and sensitivity, will contribute to the usability of the system for this purpose. In this study, data that will support the literature information in terms of the antifungal performance of the VITEK 2 system are presented.

Do initial hematologic indices predict the severity of COVID-19 patients?

Background/aim

In this study, we aimed to evaluate the initial hematological findings analyzed on admission in confirmed COVID-19 patients who were transferred to the intensive care unit (ICU), to predict possible hematological indices.

Materials and methods

Initial neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR), monocyte to lymphocyte ratio (MLR), red cell distribution width to platelet ratio (RPR), mean platelet volume to platelet ratio, and lymphocyte multiplied by platelet count (LYM × PLT), of 695 patients with laboratory-confirmed COVID-19 were investigated and comparisons were made between the mild/moderate and severe groups.

Results

The proportion of COVID-19 cases admitted to the ICU was 3.9%. The median age of patients admitted to the ICU was significantly higher than those who were not; [68.5 (interquartile range (IQR); 21.5] years vs. 41.0 (IQR; 15.7) years; P < 0.001.Severe cases had higher NLR (6.6 vs. 2.4; P < 0.001), and MLR (0.40 vs. 0.28; P = 0.004) and lower PLR (180.0 vs. 129.0; P < 0.001) compared to that of mild or moderate patients. Among all of the parameters, the ROC curve of NLR gave us the best ability to distinguish serious patients at an early stage (AUC = 0. 819, 95% confidence interval 0.729–0.910; P < 0.001).

Conclusion

These data showed that age, initial NLR, PLR, and LYM × PLT were associated with the severity of COVID-19 disease and patients’ need for the ICU. Therefore, initial hemogram parameters may be essential to predict the prognosis of COVID-19 patients.

[Comparison of Clinical Laboratory Standards Institute (CLSI) and European Committee on Antimicrobial Susceptibility Testing (EUCAST) broth microdilution methods for determining the susceptibilities of Candida isolates]

Candida species are among the top 10 pathogens causing bloodstream infections associated with high morbidity, mortality. In spite of the development of new antifungal drugs, epidemiological studies have shown that resistance to antifungal drugs among Candida isolates is becoming a serious problem. The aim of this study was to compare the antifungal broth microdilution methods of the Clinical and Laboratory Standards Institute (CLSI) and European Committee on Antimicrobial Susceptibility Testing (EUCAST) for amphotericin B, fluconazole, itraconazole, voriconazole, posaconazole and anidulafungin susceptibility of Candida blood isolates. The study consisted of 74 Candida albicans, 67 Candida parapsilosis, 30 Candida glabrata, and 18 Candida tropicalis isolates. The minimum inhibitory concentrations were determined after 24 and 48 hour of incubation with CLSI method and only 24 hour of incubation with EUCAST method except anidulofungin. The MIC values obtained by both methods were considered to be compatible within ± 2 dilution limits. The categorical agreement between methods for each antifungal agent was assessed using clinical break points and epidemiological cut-off values. The agreement (± 2 dilution) between the methods was found to be species, drug, and incubation time dependent. After 24 hour incubation, good agreement category (> 90%) was detected between amphotericin B, itraconazole, posaconazole and anidulofungin, but was lower category (< 85%) was determined with fluconazole and voriconazole especially for relatively slow growing C.glabrata and C.parapsilosis isolates. Excellent categorical agreement (100%) was observed for amfoterisin B/C.parapsilosis, C.glabrata, C.tropicalis and anidulofungin/C.albicans, C.glabrata, C.tropicalis but least category was determined for posaconazole and C.albicans (71.6% at 24 hour; 73% at 48 hour). In vitro resistance of therapeutically used fluconazole and anidulafungin determined by both methods was rare among C.albicans (1.3%, 2.7% respectively), C.glabrata (0%, 3.3% respectively) and C.tropicalis (0%, 5.6% respectively) isolates but, an increase of non-susceptible isolates were observed among C.parapsilosis (11.9% at 24 hour of incubation; 17.9% at 48 hour of incubation) for fluconazole. There was also a cross resistance between fluconazole and voriconazole for three C.parapsilosis isolates and one multidrug resistant (fluconazole, itraconazole, posaconazole and anidulofungin) C.albicans isolate (fluconazole, itraconazole, posaconazole and anidulofungin). As a result in this study, it was determined thatboth methods were similar and can be used according to preference of laboratories. The CLSI antifungal susceptibility test results can be assessed at the end of 24 hour incubation, but sometimes it is important that the evaluation should be performed as a result of 48 hour incubation in slow growing species such as C.glabrata.

First determination of azole resistance in Aspergillus fumigatus strains carrying the TR34/L98H mutations in Turkey

Aspergillus fumigatus is the most important etiological agent of invasive aspergillosis. Recently, an increasing number of azole-resistant A. fumigatus isolates have been described in various countries. The prevalence of azole resistance was investigated in this study using our culture collection of A. fumigatus isolates collected between 1999 and 2012 from clinical specimens. Seven hundred and forty-six A. fumigatus isolates, collected from 419 patients, were investigated. First, all isolates were screened for resistance to itraconazole by subculturing on Sabouraud dextrose agar that contained 4 mg/L itraconazole. For isolates that grew on the itraconazole containing agar, the in vitro activities of amphotericin B, itraconazole, voriconazole and posaconazole were determined using the Clinical and Laboratory Standards Institute (CLSI) M38-A reference method. After PCR amplification, the full sequence of the cyp51A gene and its promoter region was determined for all in vitro azole-resistant isolates. Itraconazole resistance was found in 10.2% of the A. fumigatus isolates. From 2000 onwards, patients were observed annually with an itraconazole-resistant isolate. According to in vitro susceptibility tests, amphotericin B exhibited good activity against all isolates whereas the azoles were resistant. Sequence analysis of the promoter region and CYP51A gene indicated the presence of TR34/L98H in 86.8% (n = 66) of isolates. This initial analysis of the resistance mechanism of A. fumigatus from Turkey revealed a common TR34/L98H mutation in the cyp51A gene.

[Development of a real-time polymerase chain reaction method for the identification of Candida species]

Candida species are one of the major causes of nosocomial infections and are the fourth most common agent involved in bloodstream infections. The impact of non-albicans Candida species is increasing, however C.albicans is still the most common species. Since the antifungal susceptibility pattern among Candida spp. may be different, rapid diagnosis and identification of non-albicans Candida spp. are important for the determination of antifungal agents that will be used for treatment. The aim of the study was to describe a real-time polymerase chain reaction (Rt-PCR) assay that rapidly detects, identifies and quantitates Candida species from blood culture samples. A total of 50 consecutive positive blood culture bottles (BACTEC, Beckton Dickinson, USA) identified at our laboratory between June-November 2013, were included in the study. Reference strains of Candida spp. (C.albicans ATCC 10231, C.glabrata ATCC 90030, C.tropicalis ATCC 1021, C.krusei ATCC 6258, C.parapsilosis ATCC 22019 and C. dubliniensis CD36) grown on Sabouraud dextrose agar were used for quality control. BACTEC bottles that were positive for Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus were also studied to search the cross-reactivity. A commercial kit (Zymo Research, USA) was used for DNA extraction. Real-time PCR was performed on LightCycler 480 (Roche, Germany) with primers and probes specific for 18S rRNA of Candida species. Twenty microlitres of the reaction mix contained 2 μl of extracted DNA, 2 μl of LightCycler Fast Start DNA Master Probe (Roche Diagnostics, Germany), 2 μl of MgCl(2) (5 mmol), 2 μl of 10x PCR buffer (Roche Diagnostics, Germany), 0.5 μl of each primer (0.01 nmol/μl) and 1 μl of each probe (0.1 μmol/μl) (TibMolBiol, Germany). Amplification was performed using the following conditions; 95°C for 10 mins and 50 cycles of denaturation at 95°C for 10 secs, annealing at 62°C for 10 secs and polymerisation at 72°C for 20 secs. A melting curve was created by cooling the producs at 50°C for 30 secs and then heating to 80°C at a rate of 0.1°C/sec measuring of the fluorescence simultaneously. For the quantitation of fungal DNA according to the standard curve, serial dilutions of C.albicans ATCC 10231 DNA from 3 x 10(5) to 3 x 10(2) ng/μl were used. All of the strains were also identified by conventional methods and sequence analysis in order to compare the results obtained by Rt-PCR. In our study, all patient and standard samples could be amplified, identified and quantitated by this developed Rt-PCR method. A total of 50 strains, of them 26 were C.parapsilosis, 15 were C.glabrata, 6 were C.albicans, and 3 were C.tropicalis have been detected and identified among patient samples. The results were completely concordant with the sequencing and conventional methods, so the sensitivity and specificity of this method were estimated as 100 percent. In conclusion, it was novel Rt-PCR developed and evaluated in this study is considered as a rapid, accurate, reproducible, sensitive and specific method for the detection, identification and quantitation of commonly observed Candida spp. strains.

Investigation of vancomycin resistant Enterococcus faecium outbreak in neonatal intensive care unit

Enterococci are one of the major agents of community-acquired and nosocomial infections. In this study we aimed to analyze the clonal relation of the vancomycin-resistant Enterococci outbreak seen at the Neonate Intensive Care Unit (NICU) of Uludag University Hospital. Vancomycin resistance gene was investigated in the Enterococcus faecium strains and pulsed field gel electrophoresis (PFGE) was used to investigate the genetic relation between outbreak strains. Enterococci grown in all patient samples were identified as Enterococcus faecium by BD Phoenix 100 (Becton Dickinson, USA). We found vanA resistance gene in all of the swab samples by Xpert VanA/B test on Cepheid (Cepheid, USA). PFGE band patterns revealed two different strains, of which the majority of them (22/24) had the same clonal origin. The common clonal origin was also isolated from rectal probes. Perianal swab culture positivity was evaluated as colonization but culture growth in two blood cultures, two urine cultures and one wound culture was evaluated as infection and treated with linezolid. All of the patients survived the outbreak. Besides the infection control precautions determining the genetic relation between outbreak strains which can be done in the microbiology laboratory is necessary to control an outbreak. PFGE is a reliable method in the microbiologic analysis of outbreaks. Molecular microbiologic analysis of outbreak strains will contribute to prove the epidemiologic and evolution of outbreaks.

Fatal disseminated infection with Fusarium petroliphilum

Members of the Fusarium solani species complex (FSSC) are causing the majority of the fusariosis in humans. Disseminated fusariosis has a high mortality and is predominantly observed in patients with leukemia. Here, we present the case of a fatal infection by a Fusarium strain with a degenerated phenotype, in a patient with acute lymphatic leukemia. Multiple nasal and skin biopsies as well as blood cultures yielded fungal growth, while in direct and histopathological examination of biopsy material septate hyphae were visible. Initial colonies were white with slimy masses with microconidia reminiscent of Fusarium/Acremonium, but with conidiospore production directly on the hyphae. Multi-locus sequence typing discerned a pionnotal-morphologically degenerated-colony of the recently recognized F. petroliphilum as etiological agent. The culture returned to a typical F. solani species complex morphology only after several weeks of growth in culture. Antifungal susceptibility tests indicate amphotericin B as best drug for this FSSC member rather than any of the azoles or echinocandins.

Investigation of methicillin resistant Staphylococcus aureus in neonatal intensive care unit

Methicillin resistant Staphylococcus aureus (MRSA) strains lead to severe infections in immunosupressive patients, geriatric population and premature infants. 27 MRSA strains isolated in the Neonatal Intensive Care Unit was considered as an outbreak and it was aimed to investigate the genetic and epidemiologic relation of the MRSA outbreak. MecA gene was investigated in the S. aureus strains and pulsed field gel electrophoresis (PFGE) was used to investigate the genetic relation between outbreak strains. MecA gene was showed in all isolates. PFGE revealed that there were two different strains and most of the isolates (25/27) were owing to same clone. One of the samples were found closely related with the common strain and the other sample was found genetically unrelated. To terminate the outbreak; liquid baby food was gained to the baby food kitchen, no more new patient was imported to the neonatal unit and none of the patients were exported from neonatal unit to other clinics during outbreak, education about infection control precautions was given to all the staff and nursing bottle dishwasher was obtained. To manage and terminate the outbreak, besides the infection control precautions, tests to determine the genetic relation between outbreak strains which are done in the microbiology laboratory are needed. Molecular analysis of outbreak strains will contribute to prove the epidemiologic and evolution of outbreaks.