Misidentification of Candida parapsilosis as C famata in a clinical case of vertebral osteomyelitis

Prevalence and drug susceptibility of clinical Candida species in nasopharyngeal cancer patients in Vietnam

In the nature, Candida species are normal inhabitants and can be observed in a wide variety of vertebrates. In humans, especially for cancer patients who fall prey to opportunistic pathogens, this group of susceptible multi-drug resistant and biofilm-forming yeasts, are among the commonest ones. In this study, Candida species in 76 oral lesion samples from Vietnamese nasopharyngeal-cancer patients were isolated, morphologically identified using CHROMagar™, germ tube formation, and chlamydospore formation tests, and molecularly confirmed by PCR-RFLP. The drug susceptibility of these isolates was then tested, and the gene ERG11 was DNA sequenced to investigate the mechanism of resistance. The results showed that Candida albicans remained the most prevalent species (63.16% of the cases), followed by Candida glabrata, Candida tropicalis, and Candida krusei. The rates of resistance of non-albicans Candida for tested drugs were 85.71%, 53.57%, and 57.14% to fluconazole, clotrimazole, and miconazole, respectively. Although the drug-resistance rate of Candida albicans was lower than that of non-albicans Candida, it was higher than expected, suggesting an emerging drug-resistance phenomenon. Furthermore, ERG11 DNA sequencing revealed different mutations (especially K128T), implying the presence of multiple resistance mechanisms. Altogether, the results indicate an alarming drug-resistance situation in Candida species in Vietnamese cancer patients and emphasize the importance of species identification and their drug susceptibility prior to treatment.

Vertebral Candidiasis, the State of the Art: A Systematic Literature Review

OBJECTIVE

In recent years, Candida spondylodiscitis has represented an increasingly emerging disease in clinical practice. This condition requires long-term antibiotic therapy and sometimes surgical treatments. The main purpose of this study is to investigate the epidemiology, clinical and radiological aspects, treatment protocols, and outcomes of Candida-mediated vertebral osteomyelitis.

METHODS

A systematic review of the English literature was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.The research was conducted on Medline, Cochrane library, PubMed, and Scopus using as search terms "vertebral"; "spinal"; "infection"; "spondylodiscitis"; "discitis"; "osteomyelitis"; "Candida"; and "Candidosis." A case of vertebral candidiasis that was surgically managed was also reported.

RESULTS

In total, 88 articles were included in our systematic review. Including the reported case, our analysis covered 113 cases of vertebral candidiasis. Candida albicans was isolated in 64 cases (56.1%), Candida tropicalis in 21 (18.4%), Candida glabrata in 14 (12.3%), and Candida parapsilosis in five (4.4%). The mean duration of the follow-up was 395 days. Finally, 87 (82%) patients completely recovered, ten (9.4%) died, and nine (8.5%) reported sequelae.

CONCLUSION

This systematic review summarized the state of the art on vertebral candidiasis, describing data on its clinical features, diagnostic criteria and current limitations, and treatment alternatives and their outcomes.

Osteoarticular Mycoses

Osteoarticular mycoses are chronic debilitating infections that require extended courses of antifungal therapy and may warrant expert surgical intervention. As there has been no comprehensive review of these diseases, the International Consortium for Osteoarticular Mycoses prepared a definitive treatise for this important class of infections. Among the etiologies of osteoarticular mycoses are Candida spp., Aspergillus spp., Mucorales, dematiaceous fungi, non-Aspergillus hyaline molds, and endemic mycoses, including those caused by Histoplasma capsulatum, Blastomyces dermatitidis, and Coccidioides species. This review analyzes the history, epidemiology, pathogenesis, clinical manifestations, diagnostic approaches, inflammatory biomarkers, diagnostic imaging modalities, treatments, and outcomes of osteomyelitis and septic arthritis caused by these organisms. Candida osteomyelitis and Candida arthritis are associated with greater events of hematogenous dissemination than those of most other osteoarticular mycoses. Traumatic inoculation is more commonly associated with osteoarticular mycoses caused by Aspergillus and non-Aspergillus molds. Synovial fluid cultures are highly sensitive in the detection of Candida and Aspergillus arthritis. Relapsed infection, particularly in Candida arthritis, may develop in relation to an inadequate duration of therapy. Overall mortality reflects survival from disseminated infection and underlying host factors.

High diversity of yeast species and strains responsible for vulvovaginal candidiasis in South-East Gabon

OBJECTIVES

Candida albicans generally remains the principal pathogenic yeast responsible for vulvovaginal candidiasis (VVC), although with variable prevalence. In this study, we evaluated the evolution of the prevalence of the non-Candida albicans Candida (NCAC) species and investigated the genotypic diversity and the population genetic structure of the circulating C. albicans strains associated with VVC in the vicinity of Franceville (Gabon).

METHODS

A total of 110 independent isolates were identified using both MALDI-TOF MS and conventional techniques. The population genetic structure of the C. albicans strains was determined by multiple locus variable-number tandem repeat analysis using 4 microsatellite markers.

RESULTS

The mean and median age of the patients was 31 years. Seven patients had a mixed infection. C. albicans accounted for 62 % (n=68) of the total isolates. NCAC were dominated by C. glabrata, followed by P. kudriavzevii, C. parapsilosis, C. tropicalis, M. guilliermondii, and C. nivariensis. The cluster analysis revealed a high diversity, with a total of 50 different genotypes. The most represented genotype was shared by only four strains, while the vast majority (39 strains) had a unique MLVA pattern. Geographic clusters were not detected.

CONCLUSION

The study provides information on species distribution and possible changing epidemiology while reporting for the first time C. nivariensis in VVC in Africa. This study is also the first to investigate the genotypic diversity of the circulating C. albicans strains associated with VVC in Central Africa. Such analyses would help understand the molecular epidemiology of C. albicans.

Candida parapsilosis osteomyelitis following dog bite: a case report and review of the literature

Candida osteomyelitis is uncommon, especially after dog bites. We describe a case of a 63-year-old man without significant comorbidities presenting progressing swelling of the distal interphalangeal joint (DIJ) of right index finger following a dog bite. Despite empiric antibiotic therapy and local medications, there were no clinical signs of improvement. Clinical examination revealed fistula with purulent drainage on the volar region. Even though laboratory data showed inflammatory markers on range, magnetic resonance imaging (MRI) demonstrated signs of osteomyelitis. The patient was taken to exploration and debridement of the bite wound. Culture of the bone biopsy showed growth of Candida parapsilosis. Therefore, the patient was diagnosed with isolated fungal osteomyelitis and was initiated on fluconazole therapy. The treatment was effective and all symptoms were resolved in 8 weeks after the surgery. There were no signs of recurrence after 20 months of follow-up. The patient had no cosmetic abnormalities or sequelae. Concurrently with the description of the case report a review of the literature was provided. According to the authors, there are three main etiopathogenesis for this infection. The first pathogenic mechanism is direct inoculation into the deep tissues through the dog bite. The second hypothesis is direct translocation of the pathogen from the skin to the deep tissue and to the bone. The last mode of transmission is hematogenous dissemination. Fungal osteomyelitis are really rare conditions, especially after dog bites, but nevertheless it should be considered as a possible diagnosis when there is no response to antibiotics.

Species Distribution of Candidemia and Their Susceptibility in a Single Japanese University Hospital: Prior Micafungin Use Affects the Appearance of Candida parapsilosis and Elevation of Micafungin MICs in Non-parapsilosis Candida Species

Introduction: Micafungin is a recommended echinocandin antifungal agent for candidemia treatment and prophylaxis. However, overuse of echinocandin antifungals may cause resistance. There is currently no information available regarding the low susceptibility associated with using micafungin. This study investigated the effect of micafungin use on changes in the detected Candida species and low susceptibility. Methods: We conducted a retrospective survey and included records of Candida spp. detected in blood cultures from January 2010 to December 2018 in our hospital. Survey items included clinical outcomes at 30 days after positive cultures, patient characteristics, and drug prescription status. Patient background information included gender, previous hospitalization, stay in the intensive care unit, comorbidities, and history of surgery (within 90 days before candidemia onset) and drug exposure. Species detected and their minimum inhibitory concentrations (MICs) and amount of antifungal prescriptions by department were investigated. Risk factors for detecting C. parapsilosis and for low susceptibility to micafungin were evaluated using multivariate analysis. Results: A total of 153 Candida clinical blood isolates were collected and C. albicans was the most prevalent species, followed by C. parapsilosis and C. glabrata. In the analysis by department, antifungal use and non-albicans Candida species were most frequently detected in the hematology department. Multivariate analysis showed that prior micafungin use increased the risk of C. parapsilosis (odds ratio (OR) 4.22; 95% confidence interval (CI) 1.39–12.79; p = 0.011). MIC₉₀ of micafungin on C. glabrata and C. parapsilosis was 1.0 μg/mL. Prior micafungin use was clarified as a risk factor resulting in MIC > 0.06 μg/mL for micafungin in non-parapsilosis Candida species (OR 13.2; 95% CI 3.23–54.2; p < 0.01). Conclusion: Prior micafungin use increased the risk of C. parapsilosis and the MIC > 0.06 μg/mL of micafungin in non-parapsilosis Candida species. Since there are only a few antifungal options, further antifungal stewardship considering azole antifungal agents use is required.

Misidentification of a Rare Species, Cryptococcus laurentii, by Commonly Used Commercial Biochemical Methods and Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry Systems: Challenges for Clinical Mycology Laboratories

Forty-two putative Cryptococcus laurentii isolates identified by the Vitek 2 system were collected in China. The gold standard, internal transcribed spacer (ITS) sequencing, confirmed that only two isolates were genuine C. laurentii. Bruker Biotyper matrix-assisted laser desorption ionization-time of flight mass spectrometry was able to identify the C. laurentii isolates with an expanded custom database.

Misidentification of Candida guilliermondii as C. famata among strains isolated from blood cultures by the VITEK 2 system

Introduction. The aim of this study was to differentiate between Candida famata and Candida guilliermondii correctly by using matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) and gene sequencing. Methods. Twenty-eight Candida strains from blood cultures that had been identified as C. famata (N = 25), C. famata/C. guilliermondii (N = 2), and C. guilliermondii (N = 1) by the VITEK 2 system using the YST ID card were included. We identified these strains by MALDI-TOF MS and gene sequencing using the 28S rRNA and ITS genes and compared the results with those obtained by the VITEK 2 system. Results. All 28 isolates were finally identified as C. guilliermondii. Sequencing analysis of the 28S rRNA gene showed 99.80%–100% similarity with C. guilliermondii for all 28 strains. The ITS gene sequencing of the strains showed 98.34%–100% homology with C. guilliermondii. By MALDI-TOF, we could correctly identify 21 (75%) of 28 C. guilliermondii isolates. Conclusion. We should suspect misidentification when C. famata is reported by the VITEK 2 system, and we always should keep in mind the possibility of misidentification of any organism when an uncommon species is reported.

Reliability of automated biochemical identification of Burkholderia pseudomallei is regionally dependent

Misidentifications of Burkholderia pseudomallei as Burkholderia cepacia by Vitek 2 have occurred. Multidimensional scaling ordination of biochemical profiles of 217 Malaysian and Australian B. pseudomallei isolates found clustering of misidentified B. pseudomallei isolates from Malaysian Borneo. Specificity of B. pseudomallei identification in Vitek 2 and potentially other automated identification systems is regionally dependent.

Candida osteomyelitis: analysis of 207 pediatric and adult cases (1970-2011)

BACKGROUND

The epidemiology, pathogenesis, clinical manifestations, management, and outcome of Candida osteomyelitis are not well understood.

METHODS

Cases of Candida osteomyelitis from 1970 through 2011 were reviewed. Underlying conditions, microbiology, mechanisms of infection, clinical manifestations, antifungal therapy, and outcome were studied in 207 evaluable cases.

RESULTS

Median age was 30 years (range, ≤ 1 month to 88 years) with a >2:1 male:female ratio. Most patients (90%) were not neutropenic. Localizing pain, tenderness, and/or edema were present in 90% of patients. Mechanisms of bone infection followed a pattern of hematogenous dissemination (67%), direct inoculation (25%), and contiguous infection (9%). Coinciding with hematogenous infection, most patients had ≥2 infected bones. When analyzed by age, the most common distribution of infected sites for adults was vertebra (odds ratio [OR], 0.09; 95% confidence interval [CI], .04-.25), rib, and sternum; for pediatric patients (≤18 years) the pattern was femur (OR, 20.6; 95% CI, 8.4-48.1), humerus, then vertebra/ribs. Non-albicans Candida species caused 35% of cases. Bacteria were recovered concomitantly from 12% of cases, underscoring the need for biopsy and/or culture. Candida septic arthritis occurred concomitantly in 21%. Combined surgery and antifungal therapy were used in 48% of cases. The overall complete response rate of Candida osteomyelitis of 32% reflects the difficulty in treating this infection. Relapsed infection, possibly related to inadequate duration of therapy, occurred among 32% who ultimately achieved complete response.

CONCLUSIONS

Candida osteomyelitis is being reported with increasing frequency. Localizing symptoms are usually present. Vertebrae are the most common sites in adults vs femora in children. Timely diagnosis of Candida osteomyelitis with extended courses of 6-12 months of antifungal therapy, and surgical intervention, when indicated, may improve outcome.

Molecular identification of Pichia guilliermondii, Debaryomyces hansenii and Candida palmioleophila

Traditional phenotypic methods and commercial kits based on carbohydrate assimilation patterns are unable to consistently distinguish among isolates of Pichia guilliermondii, Debaryomyces hansenii and Candida palmioleophila. As result, these species are often misidentified. In this work, we established a reliable method for the identification/differentiation of these species. Our assay was validated by DNA sequencing of the polymorphic region used in a real-time PCR assay driven by species-specific probes targeted to the fungal ITS 1 region. This assay provides a new tool for pathogen identification and for epidemiological, drug resistance and virulence studies of these organisms.

Comparative evaluation of three commercial identification systems using common and rare bloodstream yeast isolates

The commercial yeast identification systems API ID32C, Auxacolor, and Vitek were evaluated using 251 molecularly identified bloodstream isolates and 2 reference strains, representing a total of 35 species (6 common and 29 rare). Correct identification rates were higher for common species (Auxacolor, 95%; API ID32C, 94%; Vitek, 92%) than for rare species (Auxacolor, 43%; API ID32C, 56%; Vitek, 64%). All systems performed equally among the former, and Vitek performed best among the latter.