Master’s Thesis at the College of Medicine, University of Babylon, on Patients with Acute Tonsillitis
The Department of Microbiology at the College of Medicine, University of Babylon, discussed the master’s thesis of student Muhannad Shaheed Mahmood Matlab, titled “Genetic Variation of Staphylococcus aureus Isolates Recovered from Patients with Acute Tonsillitis”, supervised by Prof. Dr. Lamees Abdulrazzaq Abdulatif and Prof. Dr. Safaa Hussein Al-Turaihi.
The discussion was attended by the Associate Dean for Scientific Affairs, Assistant Professor Dr. Ashraf Mohammed Ali Hussein, along with several faculty members, academics, and postgraduate students.
During his thesis defense, the researcher explained that all samples were subjected to both aerobic and facultative anaerobic culture on different media. It was found that 70 samples (63.63%) out of the total 110 samples showed positive bacterial growth, while no bacterial growth was observed in the remaining 40 samples (36.36%).
Among the 70 positive samples cultured on Mannitol Salt Agar (a selective medium), only 15 samples (21.43%) showed positive results identified as S. aureus isolates. No growth was observed on the selective medium for the remaining 55 samples (78.57%). These isolates were then tested using the Vitek 2 compact system, and all 15 samples (100%) tested positive.
To confirm the identification of Staphylococcus aureus at the molecular level, polymerase chain reaction (PCR) targeting the Sau gene was performed. All 15 isolates showed positive results, confirming the effectiveness of molecular techniques in providing results within 24 hours, compared to traditional culture methods that take 36–48 hours.
Among the 15 confirmed cases, male patients accounted for a higher percentage (60%) of S. aureus isolates compared to females (40%). When classified by age groups, the highest rate of bacterial isolation was observed in the second group (33.3%), followed by the first and third groups (20% each), and then the fourth group (26.7%).
Overall, CRISPR Cas2 was identified in 13 isolates (86.67%), followed by CRISPR Cas10 in 8 isolates (53.33%), CRISPR Cas6 in 6 isolates (40%), and finally CRISPR Cas1 in 5 isolates (33.3%). The phylogenetic tree analysis showed that the presence of CRISPR-Cas types varied among the isolates.
By analyzing the relationship between the CRISPR/Cas types of the isolates and drug resistance, no significant difference was found in the distribution of CRISPR/Cas types between sensitive and resistant isolates. This could be attributed to variability related to factors such as antibiotic types, bacterial strains, and geographic location.
Staphylococcus aureus isolates that were positive for CRISPR-Cas showed higher resistance rates to most antibiotics compared to CRISPR-Cas-negative isolates. In general, Cas2 was predominant in antibiotic-sensitive isolates. The presence of CRISPR-Cas is linked to the absence of certain antibiotic resistance genes acquired through horizontal gene transfer.
Moreover, the High-Resolution Melting (HRM) method can be used to detect different variants of the Spa gene.