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Geographical distribution of Cryptococcus neoformans in Iran, pathogenic factors, and antifungal susceptibility
Sara Hamzehee1, Marzieh Halvaeizadeh1, Maral Gharaghani2
1Department of Medical Mycology, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.
Background:
Approximately 70 species of Cryptococcus have been identified, some of which are human and animal pathogens, while others are environmental saprophytes. Cryptococcus neoformans is one of the most important pathogenic species, and pigeon droppings serve as the most important ecological niche. This study aimed to investigate the frequency of C. neoformans in pigeon droppings from various Iranian provinces, as well as assess the pathogenic factors and antifungal susceptibility of the isolates.
Methods:
428 pigeon droppings samples were collected from 10 Iranian provinces and cultured on Niger seed agar. DNAs were extracted, and CNLAC1 (Outer and Inner) and STR1 primers were used for the detection of species and varieties of C. neoformans, respectively. Virulence factors were also identified using specific culture media under appropriate conditions. Antifungal susceptibility testing was conducted against 8 antifungals using CLSI guidelines.
Results:
Out of the 428 examined samples, 37 (8.6%) were positive for C. neoformans. All isolates exhibited capsule production and dark brown pigmentation as key pathogenic factors. Urease and catalase activities were present in all isolates. Based on the established ECVs guidelines, all isolates displayed wild-type phenotypes against voriconazole and 5-flucytosine. While 100% isolates were non-wild type against amphotericin B.
Conclusions:
The frequency of C. neoformans was 8.6% in Iranian cities, with a high (31.5%) frequency in Kermanshah and a low (3.1%) frequency in Fars province. All isolates showed sensitivity to voriconazole and 5-flucytosine. Additionally, pathogenic factors were present in all strains to varying degrees.
Insights
Cryptococcus neoformans was found in 8.6% of pigeon droppings across Iran. All identified strains showed key pathogenic factors and sensitivity to voriconazole and 5-flucytosine, indicating potential treatment options.
Area of Science:
- Mycology
- Environmental Microbiology
- Medical Mycology
Background:
- Cryptococcus neoformans is a significant fungal pathogen found in pigeon droppings.
- Understanding its prevalence and characteristics is crucial for public health.
Purpose of the Study:
- To determine the frequency of C. neoformans in pigeon droppings in Iran.
- To evaluate the virulence factors and antifungal susceptibility of isolated strains.
Main Methods:
- Collected 428 pigeon dropping samples from 10 Iranian provinces.
- Used molecular methods (CNLAC1 and STR1 primers) for C. neoformans detection.
- Assessed virulence factors and performed antifungal susceptibility testing against 8 antifungals.
Main Results:
- Identified C. neoformans in 8.6% of samples (37/428).
- All isolates demonstrated capsule production, pigmentation, urease, and catalase activity.
- Exhibited wild-type phenotypes for voriconazole and 5-flucytosine, but non-wild-type for amphotericin B.
Conclusions:
- C. neoformans prevalence in Iranian pigeon droppings is 8.6%, with variations across provinces.
- All isolates possessed pathogenic factors and were sensitive to voriconazole and 5-flucytosine.
- Findings highlight the importance of environmental surveillance for Cryptococcus neoformans.
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