Candidemia Cases Caused by Candida parapsilosis Complex Species: Epidemiology and Antifungal Susceptibility of Strains

BACKGROUND

Candida parapsilosis is a common non-albicans Candida species isolated from blood cultures. The increase in fluconazole-resistant C. parapsilosis complex isolates is worrying, especially in strains with Y132F changes in the ERG11 gene since this ultimately leads to outbreaks. This study aimed to investigate the distribution and antifungal susceptibility of C. parapsilosis complex species isolated from bloodstream, clinical characteristics of patients, prevalence of risk factors, and to determine ERG11 gene region mutations in strains that were not susceptible to fluconazole.

METHODS

Between 2014 and 2018, 96 patients with C. parapsilosis candidemia were evaluated. Thermo Scientific SensititerTM YeastOneTM YO10 was used for antifungal susceptibility testing. The ERG11 gene region sequence analysis was performed for fluconazole non-susceptible isolates.

RESULTS

All the strains were defined as C. parapsilosis sensu stricto. The rate of fluconazole resistance was 6.3%, and that of susceptibility to fluconazole at an increased dose was 2.1%. Two isolates showed Y132F or G458S ERG11 changes associated with azole resistance, with the most common change being identified as R398I, which was shown not to encode azole resistance. No resistance to echinocandins and amphotericin B was observed. The use of broad-spectrum antibiotics (83.3%) was the most common risk factor.

CONCLUSIONS

This study highlights the importance of susceptibility testing when making a decision to use fluconazole in the treatment of C. parapsilosis candidemia. The presence of resistance associated with ERG11 Y132F changes indicated that azole resistance should be closely monitored. Increasing awareness of fluconazole-resistant C. parapsilosis candidemia will help identify strategies to overcome these infections.

Evaluation of the BD Phoenix CPO Detect Test for the detection of carbapenemase-producing Enterobacterales

Aims: This study aimed to evaluate the performance of the BD Phoenix CPO Detect Test (BD Diagnostic Systems) for the detection and classification of carbapenemase-mediated carbapenem resistance. Methods: A total of 447 Enterobacterales strains were included in the study. All strains were tested with the BD Phoenix CPO Detect Test and the modified carbapenem inactivation method. Results: Carbapenemase production was detected in 157 of 159 carbapenemase producers, including 95.7% of class B and 99.2% of class D isolates using the BD Phoenix CPO Detect Test. BD Phoenix CPO Detect has a sensitivity of 98.7% and a specificity of 95.5% in detecting carbapenemase production. Conclusion: The classification of OXA-48 and class B carbapenemases, the most common carbapenemases circulating in Turkey, was highly accurate.

In vitro Activity of Cefiderocol and Ceftazidime-Avibactam, Against Carbapenemase-Producing Enterobacterales

BACKGROUND

Carbapenemase production is an issue of significant clinical and public health concern, because of the shortage of effective antimicrobial agents available for treatment. Here, we present antimicrobial susceptibility data of ceftazidime-avibactam, cefiderocol, and other clinically relevant antibiotics for carbapenemase-producing Enterobacterales bloodstream isolates, in accordance with European Committee on Antimicrobial Susceptibility Testing (EUCAST) guidelines.

METHODS

A total of 133 carbapenemase producing Enterobacterales bloodstream isolates from May 2010 to September 2018 were included in the study. Species were identified using matrix-assisted laser-desorption ionization time-of-flight mass spectrometry (Bruker Daltonics, Germany). The presence of the blaKPC, blaNDM, blaOXA-48, blaVIM, and blaIMP carbapenemase genes were investigated by BD Max CRE assay (Becton Dickinson, USA) and in-house PCR. Antimicrobial susceptibility testing was performed by the BD Phoenix automated system (Becton Dickinson, USA), except cefiderocol and colistin. Cefiderocol and colistin susceptibility was determined by disk diffusion and broth microdilution method, respectively.

RESULTS

Except for cefiderocol and ceftazidime-avibactam, the percentage of susceptible isolates did not exceed 90% for any of the antibiotics tested. Although none of the isolates were resistant to cefiderocol, the ceftazidime-avibactam resistance rate was 9.8%. All of the ceftazidime-avibactam resistant strains were NDM (New Delhi metallo-beta-lactamases) producers. Among the other clinically relevant antibiotics tested, only amikacin, colistin, tigecycline, and fosfomycin susceptibility rates exceeded 50%. Of the 133 isolates 22.6% were resistant to colistin which is the preferred antibiotic with a second active agent for infections caused by metallo-beta-lactamase producing Enterobacterales in Turkey.

CONCLUSIONS

In our study, resistance to ceftazidime-avibactam was detected only in metallo-beta-lactamase producing Enterobacterales isolates, while cefiderocol was found to be effective against all strains. It is important to monitor regional antimicrobial susceptibility data, as the emergence of antimicrobial resistant phenotypes is directly linked to the use of any given antimicrobial agent.

Demodex Species Frequency and Risk Factors in Patients With Rheumatoid Arthritis

Objectives

This study aims to investigate the presence of Demodex species in rheumatoid arthritis (RA) patients, to identify the risk factors for developing Demodex infestation, and to determine the effect of immunosuppressant drugs on Demodex mite infestations.

Patients and methods

The study included 93 RA patients (16 males, 77 females; mean age 53.3±11.3 years; range, 27 to 83 years) and 76 healthy controls (19 males, 57 females; mean age 50.3±13.9 years; range, 19 to 86 years). Specimens were collected from face skin by using standardized sur- face skin biopsy. Demodex infestation was considered for ≥5 living parasites/cm2 of skin while Demodex mite presence was defined as any Demodex larvae, adults, or eggs found in the specimen.

Results

The frequencies of Demodex mite presence were 44% for the RA patients and 15.7% for the healthy controls (p<0.001). The rates of Demodex infestation were similar between the two groups (18.3% versus 7.9%, p=0.054). There were no statistically significant differences between the groups regarding skin type, skin care, epilation, body washing, use of a moisturizer, personal towel use, the number of residents at home, or whether there were pets at home or in proximity. Itching in eyes was higher in RA patients, but the frequency of other skin symptoms was not differ- ent from healthy controls. Logistic regression analysis indicated that the diagnosis of RA was an independent risk factor for Demodex mite presence in this study population. Disease activity and duration, use of corticosteroids, conventional disease-modifying anti-rheumatic drugs (DMARDs) and biological DMARDs were not effective factors on Demodex mite presence in RA patients.

Conclusion

Although Demodex mite presence was 3.5-fold higher in RA patients, the rate of Demodex infestation was similar to that of healthy controls.

The Evaluation of the Performance of C. Diff Quik Chek Complete and Toxin A + B (Clostridium difficile) DUO Diagnostic Tests Compared with Toxigenic Culture in the Diagnosis of Clostridium difficile Infection

BACKGROUND

Clostridium difficile is an important cause of nosocomial diarrhea and the best standard laboratory method for the diagnosis of C. difficile infection is controversial. In this study, we aimed to investigate the performance of Toxin A + B (Clostridium difficile) DUO kit which detects C. difficile toxin A and B by the immunochromatographic method and C. Diff Quik Chek Complete (QCC) rapid membrane immunoassay kit which determines the presence of glutamate dehydrogenase (GDH) and C. difficile toxin A and B in stool samples, compared with toxigenic culture in the diagnosis of C. difficile infection.

METHODS

One hundred ninety-three stool samples from patients suspected of having C. difficile infection were included in the study. The performances of two commercial tests were compared with toxigenic culture which was accepted as the reference method.

RESULTS

The sensitivity and specificity of the GDH component of QCC were 94.4% and 97.7%, the sensitivity and specificity of the toxin component were 92.3% and 100%, respectively. The sensitivity and specificity of Toxin A + B (Clostridium difficile) DUO test were found as 53.8% and 87.8%, respectively.

CONCLUSIONS

C. Diff Quik Chek Complete test, which is a rapid test with high sensitivity and specificity, can be used alone for the diagnosis of C. difficile infection while Toxin A + B (Clostridium difficile) DUO test cannot be used for the same purpose due to the low sensitivity and specificity of the test.

The molecular patterns of resistance to anti-tuberculosis drugs: an analysis from Istanbul, Turkey

Resistances to anti-tuberculosis (TB) drugs are related to the mutations in the genome of the Mycobacterium tuberculosis complex (MTBC). To expose the genomic mutations that cause anti-TB drug resistance. The GenoType MTBDRplus and MTBDRsl assays were used to detect genetic mutations. In this study of 1329 MTBC isolates, the sensitivities and specificities of genotypic methods for the detection of isoniazid (INH), rifampicin (RIF), ethambutol (EMB), and multi-drug resistance were 0.77, 0.84, 0.65, 0.89 and 0.99, 0.98, 0.67, 0.94, respectively. MUT3 mutations (S531L) of the rpoB gene for RIF resistance and MUT1 mutations (S315T1 and C15T) of the katG and inhA genes for INH resistance were dominant. The most frequently observed mutations that created resistance to fluoroquinolones (FLQ) were MUT3C (D94G) of the gyrA gene. The predominant mutations of EMB resistance were MUT1B (M306V) of the embB gene. Aminoglycosides/cyclic peptides (AG/CP) resistance was rare. The molecular mechanisms of anti-TB drugs resistance in MTBC strains found in Istanbul are similar to those in the literature.

Evaluation of an Automated Yeasts Identification System for Identification of Yeast Isolates

BACKGROUND

Invasive candidiasis is the most important health-care-associated fungal infection worldwide. In the last two decades, the cause of the increase of fungal infections is immunosuppression or serious underlying diseases. Additionally, Rhodotorula species, Blastoschizomyces capitatus, and Trichosporon species are emerging as important human pathogens in immunocompromised patients with hematological malignancy.

METHODS

Between January 2012 and January 2018, a total of 603 fungal organisms were isolated from blood culture samples and included in the study. All of the isolates were identified by using standard mycological methods, MALDI TOF MS system, and the Phoenix system. Sequence analysis was performed on yeasts that could not be definitively identified by using SMM and incompatible according to the results with Phoenix and MALDI-TOF MS analysis.

RESULTS

603 fungal isolates including 594 Candida spp. and 9 other yeasts like species were analyzed. C. albicans was the most frequently isolated species. The results of identification by conventional methods and MALDI TOF MS were compared to the results of the Phoenix system. The observed concordance was 99.2%. The compatibility with other systems of the Phoenix system was 100%, 100%, 97.3%, 100%, and 96.9% for C. albicans, C. parapsilosis, C. tropicalis, C. glabrata, and C. krusei, respectively.

CONCLUSIONS

The BD Phoenix system was found to be a simple, reliable, and effective method to identify the main species of the genus Candida in our study.

Evaluation of the BD Phoenix system for detection of methicilin resistance in Staphylococcus aureus isolates in comparison to BD GeneOhm MRSA assay

BACKGROUND

In order to identify methicillin-resistant Staphylococcus aureus isolates quickly, automated and semiautomated systems, commercial media, and identification kits are widely used. The Phoenix system (BD, Sparks, MD, USA) has been available since 2004 in our laboratory. This study evaluated the reliability of the Phoenix system for the detection of methicillin resistance in Staphylococcus aureus isolates in comparison to BD GeneOhm MRSA assay (Becton Dickinson Diagnostics GeneOhm, CA, USA).

METHODS

A total of 206 clinically significant Staphylococcus aureus isolates, submitted to the clinical microbiology laboratory between March 2011 and May 2013, were included in the study. Phoenix panels were studied for identification and susceptibility testing according to manufacturers' instructions. The detection of MRSA was performed using the BD GeneOhm MRSA assay (Becton Dickinson Diagnostics GeneOhm, CA, USA). The assay is a qualitative real-time PCR method.

RESULTS

The Phoenix system results and mecA gene pozitivity were concordant for 134 methicillin-resistant and 71 methicillin-susceptible strains. One discordant isolate, identified as mecA negative by the PCR method, was methicillin-resistant Staphylococcus aureus positive by the Phoenix system (oxacilline MIC = 2 microg/mL; cefoxitin MIC = 8 microg/mL). In this study, Phoenix automated system's sensitivity, specificity, negative predictive value, and positive predictive value are found as 100%, 100%, 100%, and 100%, respectively.

CONCLUSIONS

As a result of our study, use of the Phoenix automated identification method for the detection of methicillin-resistant Staphylococcus aureus isolates is a practical and reliable approach for daily clinical laboratory procedures.

Analysis of human herpes virus 6 infections with a quantitative, standardized, commercial kit in pediatric stem cell transplant recipients after transplantation

BACKGROUND AND OBJECTIVES

The aim of the study was to assess the incidence and clinical relevance of active Human Herpes Virus 6 (HHV6) infections in pediatric patients after allogeneic stem cell transplantation.

DESIGN AND SETTINGS

Retrospective analysis of samples prospectively collected at Akdeniz University Medical Faculty Hospital, Antalya, Turkey, between May 2006 and July 2007 from 15 pediatric patients with allogeneic hematopoietic stem cell transplantation (HSCT).

SUBJECTS AND METHODS

A commercial quantitative real-time polymerase chain reaction kit was used to analyze plasma samples collected from 15 pediatric allogeneic HSCT recipients.

RESULTS

HHV6 DNA was found positive in 8 (53%) patients. HHV6 DNA levels above 1000 copies/mL were found only in 2 patients and they were also consecutively positive for HHV6 DNA. Age at transplantation, use of ATG, and receiving grafts other than HLA identical siblings increased the risk, with a statistically significant difference, of having HHV6 reactivation with levels exceeding 1000 copies/mL (P values, respectively, P=.03, .001, .025). Active HHV6 infections with HHV6 viremia levels higher than 1000 copies/mL were associated with subsequent delayed platelet engraftment (P=.001), acute graft versus host disease (P=.001), skin rash, and fever of unknown origin.

CONCLUSION

More than half of pediatric allogeneic HSCT patients develop active HHV6 infection, and especially in patients with high viremic loads, the infection can result in serious clinical situations. A clinically significant cutoff value for viremia seems to be necessary to predict serious clinical complications.