رسائل ماجيستير
English
2011
Molecular Study of Sortase Enzymes and Characterization of Some Virulence Factors in Streptococcus pyogenes
رفاه فخري مزاحم الجبوري, محمد صبري عبد الرزاق
كلية الطب-جامعة بابل · العراق
This study included 90 throat swabs collected from patients suffering from acute pharyngitis who attended AL-Hilla General Teaching Hospital (ENT unit) during the period from October 2010 to January 2011. The age of the patients ranged from 3 to 33 years. Only 6 (6.6%) isolates of Streptococcus pyogenes (GAS) were obtained.
GAS isolates were found completely sensitive (100%) to Ceftriaxone, Imipenem, Meropenem, and Azithromycin, and were moderately resistant to Erythromycin (83.3%) and Cefixime (66.6%), whereas some isolates showed resistance to a lesser degree to Ampiclox, Amoxicillin, Clarithromycin, and Cefepime (16.6%).
Specific primers for PCR techniques were used for the detection of sortase enzymes (A, B, and C). Sortase A was found in all GAS strains and was designated as a housekeeping enzyme. Sortase B was also detected, and it was found that only two isolates were positive, indicating the presence of the sortase B enzyme, while the Srt C gene, which encodes sortase C enzyme, was present in only two isolates of Streptococcus pyogenes. However, only two isolates were found to have all three enzymes, whereas the others contained only the housekeeping one.
Hyaluronidase activity was investigated; it was found that 50% (3) of GAS isolates gave a positive result via the formation of a halo around the colony, which is an indicator of hyaluronidase activity. Four isolates of GAS could form agglutination in the presence of fibrinogen, whereas two were negative for this test.
Adherence factors of GAS were investigated; only four isolates revealed agglutination in the presence of mannose (mannose-resistant hemagglutination, MRHA). Two isolates failed to form agglutination in the presence of mannose (mannose-sensitive hemagglutination, MSHA).
Besides, it was observed that only four isolates had the ability to show fibrinolytic activity through the production of streptokinase enzyme, while two isolates failed to lyse fibrin, although some studies had indicated that streptokinase is a housekeeping enzyme that could be produced by all GAS isolates.
Also, the present study showed that streptokinase activity became apparent after 3 hours of incubation, the clot began to decrease after 10–16 hours, and disappeared completely after 24 hours of incubation.