Comparative study between methicillin-resistant coagulase positive and negative Staphylococci

Other Title(s)

دراسة مقارنة بين أنواع Staphylococci المنتجة و غير المنتجة للإنزيم المخثر للبلازما المقاومة للمثسلين

Dissertant

al-Husni, Halah Muhammad Husayn

Thesis advisor

Fulayyih, Mayy Talib

University

University of Baghdad

Faculty

College of Science

Department

Department of Biology

University Country

Iraq

Degree

Master

Degree Date

2011

English Abstract

One hundred and sixty one specimens were collected from patients and carriers (workers in the hospitals and restaurants), the specimens included nasal swab, wound swab, burn swab, abscess and pus, sputum, ear swab, breast discharge, urine and blood culture.

Only 49 (30.4%) isolates identified as Staphylococcus, the coagulase test was performed and the results showed that from total 49 isolates of Staphylococci, 37 isolates (75.5%) were coagulase-positive (COPS), while only 12 isolates (24.5%) were coagulasenegative (CONS). The distribution of Methicillin resistance among Staphylococcus spp.

was investigated by disc diffusion method and MRSA Kit.

The results indicated that from all 49 isolates, 41 isolates (83.7%) showed resistant to the Methicillin while 5 isolates (10.2%) were sensitive and only 3 isolates (6.1%) was intermediate resistance.

The highest rate of Methicillin resistance Staphylococci (63.4%) was obtained from nasal swabs (carriers). On the other hand the results showed that out of total 37 coagulasepositive isolates (COPS), 30 isolates (81%) were resistant to Methicillin and 4 isolates (10.8%) were sensitive while only 3 isolates (8.1%) were intermediate resistance to the Methicillin.

The total 12 isolates that identified as coagulasenegative (CONS), 11 isolates (91.6%) showed resistance to Methicillin while only 1 isolate (8.3%) was sensitive, and there was no intermediate resistance among CONS isolates. The results obtained from antimicrobial sensitivity test showed that both COPS and CONS isolates were resistant to many other antimicrobial agents in addition to the Methicillin (Multi-drug Resistant). Summary II The ability of Methicillin-Resistant Staphylococcus aureus (MRSA) and Methicillin-Resistant Coagulase-Negative Staphylococci (MR-CONS) isolates to produce some virulence factors were investigated and the results showed that MRSA isolates produce many enzymes and toxins that contributed in their virulence such as protease, lipase, urease, DNase and gelatinase, and also produce three types of haemolysins (alpha, beta, and delta), while MR-CONS showed the ability to produce only two enzymes (protease and urease) and three types of haemolysins.

Toxic Shock Syndrome Toxin (TSST-1) has not detected by any tested isolates. The ability to produce slime layer by MRSA and MR-CONS isolates was also investigated and the results showed that all isolates of both MRSA and MR-CONS were produced slime layer when tested by tube method but the amounts of adherent materials were different among the isolates.

However, the results by Congo red agar method showed that 60% of MRSA isolates produced strong slime layer and 40% of MRSA obtained negative result, and in the case of MR-CONS all tested isolates (100%) had the ability to produce strong slime layer by this method.

Similarly the ability of MRSA and Methicillin-Resistant Staphylococcus epidermidis (MRSE) isolates to produce biofilm by tissue culture plate (TCP) was investigated and the results indicated that both MRSA and MRSE showed highly and strong biofilm formation, and the OD value of biofilm formation ranged between 0.520 - 0.738, and the OD value obtained from MRSE isolates were higher compared to the MRSA isolates.

Additionally the OD value of biofilm formation significantly increased in addition of 1% glucose to the media. The results showed that there are a possible correlation between Methicillin susceptibility and the biofilm formation in S.

aureus isolates. Summary III The effect of Subinhibitory Antibiotics Concentration (sub-MIC) of two antibiotics (Vancomycin and Clindamycin) on the biofilm formation by MRSA and MRSE isolates were investigated and the results showed that both antibiotics at two subinhibitory concentration (one-half and two-half the MIC) were significantly inhibited the biofilm formation by both isolates when using of each antibiotic alone, but Vancomycin was most effective than Clindamycin.

Additionally the results showed that the combination of these two antibiotics at different sub-MIC were also significantly reduced or inhibited the biofilm formation by both isolates. In comparison between the using of each antibiotics alone and the using of antibiotics combination the results showed that in the case of MRSE isolate there was no significant difference between the two treatment methods, while in the MRSA isolate there was a significant difference between the two methods.

The using of each antibiotic alone (Vancomycin or Clindamycin) was most effective than the using of combination of these two antibiotics in the inhibition of biofilm formation.

Main Subjects

Biology

No. of Pages

145

Table of Contents

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Language

English

Data Type

Arab Theses

Record ID

BIM-597408