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Published on: December 28, 2017
Molecular Identification and Echinocandin Susceptibility of Candida parapsilosis Complex Bloodstream Isolates in
Grazia Lovero1, Elisa Borghi2, Stella Balbino1
1Department of Biomedical Science and Human Oncology, Hygiene Section, Università degli Studi of Bari "Aldo Moro", Bari, Italy.
Abstract:
The Candida parapsilosis group encompasses three species: C. parapsilosis, C. orthopsilosis, and C. metapsilosis. Here, we describe the incidence and echinocandin susceptibility profile of bloodstream isolates of these three species collected from patients admitted to an Italian university hospital from 2007 to 2014. Molecular identification of cryptic species of the C. parapsilosis complex was performed using polymerase chain reaction amplification of the gene encoding secondary alcohol dehydrogenase, followed by digestion with the restriction enzyme BanI. Minimum inhibitory concentrations were determined using the broth microdilution method according to European Committee for Antimicrobial Susceptibility Testing (EUCAST EDef 7.2) and Clinical Laboratory Standards Institute (CLSI M27-A3) guidelines, and the results were compared with those obtained using the E-test and Sensititre methods. Of the 163 C. parapsilosis complex isolates, 136 (83.4%) were identified as C. parapsilosis, and 27 (16.6%) as C. orthopsilosis. The species-specific incidences were 2.9/10,000 admissions for C. parapsilosis and 0.6/10,000 admissions for C. orthopsilosis. No resistance to echinocandins was detected with any of the methods. The percent essential agreement (EA) between the EUCAST and E-test/Sensititre methods for anidulafungin, caspofungin, and micafungin susceptibility was, respectively, as follows: C. parapsilosis, 95.6/97.8, 98.5/88.2, and 93.4/96.3; C. orthopsilosis, 92.6/92.6, 96.3/77.8, and 63.0/66.7. The EA between the CLSI and E-test/Sensititre methods was, respectively, as follows: C. parapsilosis, 99.3/100, 98.5/89.0, and 96.3/98.5; C. orthopsilosis, 96.3/92.6, 100/81.5, and 92.6/88.9. Only minor discrepancies, ranging from 16.9% (C. parapsilosis) to 11.1% (C. orthopsilosis), were observed between the CLSI and E-test/Sensititre methods. In conclusion, this epidemiologic study shows a typical C. parapsilosis complex species distribution, no echinocandin resistance, and it reinforces the relevance of using commercially available microbiological methods to assess antifungal susceptibility. These data improve our knowledge of the national distribution of species of the psilosis group, as there are very few studies of these species in Italy.
Insights
This study found no echinocandin resistance in Candida parapsilosis complex bloodstream infections in Italy. It confirmed typical species distribution and validated commercial methods for antifungal susceptibility testing.
Area of Science:
- Medical Mycology
- Infectious Diseases
- Clinical Microbiology
Background:
- The Candida parapsilosis group includes C. parapsilosis, C. orthopsilosis, and C. metapsilosis.
- Understanding the epidemiology and antifungal susceptibility of these species is crucial for patient management.
Purpose of the Study:
- To determine the incidence and echinocandin susceptibility profiles of Candida parapsilosis complex bloodstream isolates in an Italian university hospital.
- To compare the performance of different methods for antifungal susceptibility testing.
Main Methods:
- Molecular identification of Candida species using PCR and restriction enzyme digestion.
- Determination of minimum inhibitory concentrations (MICs) using broth microdilution (EUCAST and CLSI guidelines).
- Comparison of MIC results with E-test and Sensititre methods.
Main Results:
- Candida parapsilosis (83.4%) and Candida orthopsilosis (16.6%) were identified; C. metapsilosis was not found.
- No echinocandin resistance was detected in any of the isolates.
- High essential agreement was observed between EUCAST/CLSI and commercial methods for most antifungal drugs, with minor discrepancies.
Conclusions:
- The study observed a typical species distribution for the C. parapsilosis complex in Italy.
- Echinocandin resistance was absent in the studied isolates.
- Commercially available microbiological methods are reliable for assessing antifungal susceptibility in this species complex.
