Analysis of CDR1 and MDR1 Gene Expression and ERG11 Substitutions in Clinical Candida tropicalis Isolates from Alexandria, Egypt.

INTRODUCTION: Candida tropicalis is a common non-albicans Candida (NAC) species that causes numerous fungal infections. Increasing antifungal resistance to azoles in NAC is becoming a major health problem worldwide; however, in Egypt, almost no data is available regarding fluconazole resistance mechanisms in C. tropicalis. The current study aims to investigate two possible important molecular mechanisms involved in fluconazole resistance in C. tropicalis isolates. MATERIALS: Fifty-four clinical C. tropicalis isolates were included. Identification and antifungal susceptibility profiles of the isolates were carried out using the VITEK 2 compact system. The molecular investigation of fluconazole resistance included the expression of the CDR1 and MDR1 genes by quantitative real-time RT-PCR as well as the sequence analysis of the ERG11 gene. RESULTS: Antifungal susceptibility testing identified 30 fluconazole-non-susceptible isolates. Statistically, CDR1 gene expression in fluconazole-non-susceptible isolates was significantly higher than that in fluconazole-susceptible isolates, with MDR1 gene expression levels that were similar in both non-susceptible and susceptible isolates. Sequence analysis of the ERG11 gene of 26 fluconazole-resistant isolates identified two missense mutations: A395T (Y132F) and G1390A (G464S). CONCLUSIONS: This study has highlighted the role of overexpression of the CDR1 gene and ERG11 gene mutations in fluconazole non-susceptibility. Further studies in Egypt are required to investigate other possible molecular mechanisms involved in azole resistance.

Virulence Factors and Antifungal Susceptibility Profile of C. tropicalis Isolated from Various Clinical Specimens in Alexandria, Egypt.

BACKGROUND: The incidence of candidiasis caused by non-albicans Candida (NAC) species is increasing. Candida tropicalis has emerged as one of the most important NAC species. This study aims to examine the antifungal susceptibility profile and some virulence factors of C. tropicalis isolated from various clinical specimens. METHODS: A total of 71 C. tropicalis isolates from various clinical specimens (69.01%, 18.31%, 9.86%, and 2.82% of isolates were collected from urine, respiratory samples, blood, and skin and soft tissue infections, respectively) from ICU patients in Alexandria, Egypt. The isolates were identified at species level by CHROMagar Candida and VITEK 2 compact system. Furthermore, the antifungal susceptibility was determined using the VITEK 2 system AST-YS07 card containing different antifungals. Hemolysin, phospholipase, and proteinase activity and biofilm formation were also tested as virulence factors. RESULTS: Only 30 isolates (42.25%) were non-susceptible (MIC ≥ 4 µg/mL) to fluconazole, of which 28 isolates showed non-susceptibility (MIC ≥ 0.25 µg/mL) to voriconazole. All isolates showed both hemolysin and proteinase activities, while only 9 isolates (12.68%) showed phospholipase production and 70 isolates (98.59%) demonstrated biofilm formation. Strong biofilm production was observed among the blood culture isolates (85.71%), followed by the respiratory and urinary isolates (61.54% and 46.94%, respectively). CONCLUSIONS: This study sought to provide useful data on the antifungal susceptibility of C. tropicalis isolates from ICU patients suffering from invasive infections with an increased trend towards elevated MICs levels of both fluconazole and voriconazole. Due to the high incidence of systemic candidiasis and antifungal resistance, C. tropicalis is emerging as a serious root of infections. Therefore, early and accurate identification of Candida species along with susceptibility testing is of utmost importance.

Occult hepatitis B virus infection among chronic hemodialysis patients in Alexandria, Egypt.

The prevalence of end-stage renal disease has increased dramatically in developing countries. Hepatitis B virus (HBV) infection is a global health problem that represents a significant co-morbidity event that has led to outbreaks of hepatitis B. There are inadequate data concerning occult HBV infection among Egyptian chronic hemodialysis patients. This study aimed to detect occult HBV infection among chronic hemodialysis patients in Alexandria, Egypt. A cross-sectional study was performed on 100 patients with end-stage renal disease that received maintenance hemodialysis and had tested negative for HBV surface antigen. Blood samples were collected before the initiation of hemodialysis. Sera were tested for hepatitis C virus (HCV) and hepatitis B core (HBc) antibodies using ELISA, and HBV DNA was detected by SYBR Green real-time PCR using specific primers for the s and c genes and by nested PCR using pol gene-specific primers. The serum activity of alanine and aspartate aminotransferase (ALT and AST) were also measured. Anti-HCV and anti-HBc antibodies were detected in 34% and 48% of patients, respectively, and 70.6% of anti-HCV positive patients were also positive for anti-HBc antibodies. This association was statistically significant (p=0.001). HBV DNA was detected in 32% of the hemodialysis patients. A significant association was determined between the presence of HBV DNA and anti-HCV positivity (p=0.021). Aminotransferases were elevated in 21% of the studied patients, more often in patients with positive anti-HCV profiles than in patients negative for anti-HCV (p<0.05). In conclusion, the serological markers of HBV infection should be verified with molecular tests to investigate possible occult infections, especially among anti-HBc-positive hemodialysis patients, to improve our understanding of their clinical, laboratory, and epidemiological characteristics.