Abstract:
Candida albicans is an opportunistic fungal pathogen. Hospital identification test
for C. a!bica1ls vary but the germ tube test, followed by the CHROMagar, and
possibly the Biolog tests are the main tests utilized for correct identification.
These techniques are subjective and none of them have a 100% identification
accuracy. Recently a molecular test based on C. albicans-specific microsatellite
DNA genotyping was introduced which eliminates all subjectivity in
identification. The present study involves collecting 125 isolates labeled as C.
albicans from 5 different Lebanese hospitals and utilizing the microsatellite
genotyping test to determine the following: First, the accuracy of hospital
identification by comparing micro satellite results to the results of the above
mentioned tests. Second the number and genotype of infectious strains present
relative to tissue and hospital location- a possible indicator of nosocomial
infection, and third a possible relationship between lack of microsatellite heterozygosity and drug resistance. Our results showed that the most accurate identification test was the germ tube test (94.8% sensitivity), followed by the
CHROMagar test (88.8% sensitivity, and where some CHROMagar negative
Candida albicans strains were observed) and lastly the Biolog (53.4% sensitivity).
The error in identification varied from 2-33% amongst hospitals with hospitals
combining the germ tube test to any other non-molecular identification test
having the best results. Furthermore the highest identification error was found in
sputum and stool. These tissues also contained isolates with similar genotypes
regardless of hospital origin suggesting that they could be a reservoir for
potentially pathogenic strains. Moreover, strains with similar genotypes were
found to occur in relatively high frequency within certain hospitals suggesting a
possible nosocomial infection rate. Finally, a relationship between lack of
heterozygosity and azole drug resistance was observed since 8 out of 9 homozygous isolates sharing a common allele with a heterozygote strain were
sensitive to at least one drug. In conclusion, Lebanese hospital should eventually
incorporate molecular data in their identification techniques as that would
decrease the number of false identifications and improve the well-being of
patients suffering from fungal infections.
