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العنوان
Detection of Antibiotic Susceptibility by Colorimetric Minimum Inhibitory Concentration in Staphylococcal Isolates/
المؤلف
Mahmoud, Basma Sherif Fahmy.
هيئة الاعداد
باحث / Basma Sherif Fahmy Mahmoud
مشرف / Manal Abd Elalim Abd Elsattar
مشرف / Omnia Abu El Makarem Shaker
مشرف / Sherin Ahmed El Masry
تاريخ النشر
2019.
عدد الصفحات
161 p. :
اللغة
الإنجليزية
الدرجة
الدكتوراه
التخصص
أمراض الدم
تاريخ الإجازة
1/1/2019
مكان الإجازة
جامعة عين شمس - كلية الطب - الباثولوجيا الإكلينيكية
الفهرس
Only 14 pages are availabe for public view

from 161

from 161

Abstract

Staphylococci are important bacteria that commonly come out as causative agents in many infections, ranging from superficial skin infections to deep-seated tissue infection and bacteremia with both hospital and community origin. Staphylococcus aureus (S. aureus) especially the antibiotic-resistant strains are associated with high morbidity and mortality in nosocomial infections. Coagulase negative staphylococci (CONS) are one of the most frequent causes of hospital-acquired infections and usually most infections are subacute or chronic and occur mainly in immunocompromised individuals or in patients with indwelling medical devices as a result of biofilm formation.
Staphylococcal infections are of particular concern because the causative agent offers resistance to a wide range of antibiotics, therefore, accurate detection of breakpoints of staphylococcal isolates is crucial in the management and treatment of both colonized and infected patients. In order to obtain reliable results, many researchers have been working on the sensitivity of susceptibility tests and comparing the different methods.
The current study was designed to compare the performance of colorimetric BMD using 3 (4, 5 dimethyl thiazole -2-yl) -2, 5 diphenyl tetrazolium bromide (MTT) and colorimetric agar dilution method with the performance of the standard BMD. This comparison is mainly regarding their antibiotic susceptibility performance among clinical isolates of Staphylococci for different groups of antimicrobial agents as penicillins, glycopeptides, aminoglycosides.
In this study, 80 staphylococcal isolates were obtained from patient specimens from different departments submitted to the Microbiology Laboratory of Ain Shams University Hospitals during the period from December 2016 to the end of April 2017. The isolates were subjected to identification according to morphology by Gram stain, cultural characters and conventional biochemical reactions. All staphylococcal isolates were tested for antibiotic susceptibility performed by Kirby Bauer disc diffusion method, standard BMD, colorimetric BMD (MTT) and colorimetric agar dilution using MTT with both the standard (104) as well as high bacterial concentration (108) and agar dilution using TTC.
Colorimetric BMD using MTT was rapid; provided results within 7 hours, was easier for interpretation through detection of color changes of the redox indicator and showed the highest agreement with standard BMD regarding all antibiotics among all isolates, except for clindamycin (DA) among S. aureus, gentamycin (CN) among CONS and tetracycline (TE) among both of them.
Disc diffusion method guaranteed reliable results compared with standard BMD except for erythromycin (E), where S. aureus showed poor agreement versus moderate agreement among CONS.
By comparing both concentrations in colorimetric agar dilution using MTT, the standard bacterial concentration (104) showed higher agreement in case of clindamycin (DA) versus, higher agreement with the higher bacterial concentration (108) in case of erythromycin (E) among both S. aureus and CONS.
Colorimetric BMD showed better agreement with the standard BMD in comparison with colorimetric agar dilution using MTT with the standard as well as the high bacterial concentration.
Colorimetric agar dilution test using TTC was imprecise and showed non-significant agreement with the standard BMD.