I= BETA-LACTAM ANTIBIOTIC RSISTANCE PATTERN AND ITS DEVELOPMENT IN INDIGENOUS CLINICAL ISOLATES
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Title of Thesis
BETA-LACTAM ANTIBIOTIC RSISTANCE PATTERN AND ITS DEVELOPMENT IN INDIGENOUS CLINICAL ISOLATES

Author(s)
SHAMIM MUMTAZ
Institute/University/Department Details
Department of Biological Sciences/ Quaid-i-Azam University Islamabad, Pakistan
Session
2006
Subject
Microbiology
Number of Pages
168
Keywords (Extracted from title, table of contents and abstract of thesis)
beta-lactam antibiotic rsistance pattern, antimicrobial agents, β-¬lactamases, β-lactam drugs, antibiotics, extended-spectrum β-lactamase, cephaolosporins, aztreonam

Abstract
The emergence of resistance to antimicrobial agents is a global public health problem. Although a number of factors can be identified which contribute to this problem, β-lactamases of Gram-negative bacteria are the most important mechanism of resistance against β-lactam drugs.

This study was carried out to evaluate the prevalence of the infection and the development of resistance in clinically significant bacteria against commonly used antibiotics with special reference to β-lactam agents. In addition, the study was also aimed to determine the frequency of Extended-Spectrum β-Lactamase (ESBL) production among Enteric Gram-negative rods (EGNRs) and their sensitivity pattern as well.

A total of 9712 samples, received in the Clinical Microbiology Laboratory of Fauji Foundation Hospital, Rawalpindi during April 2004 to March 2006, both from in-patients and out-patients, were processed and subjected to culture and sensitivity, followed by ESBL detection by Double Disk Diffusion Synergy Test.

The incidence of bacterial infection was 43.3%. The Gram- negative rods (GNRs) were most prevalent (57.5%) followed by Gram-positive cocci (40.1%). Staphylococcus aureus (32.6%) was most prevalent organism, followed by Escherichia coli (24.7%) and Pseudomonas aeruginosa (15.9%).

The frequency of ESBL in Gram-negative rods was 38.9%. The most common ESBL producing EGNR was E. coli (47.5%) followed by K. pneumoniae (45.0%). Highest resistance of ESBL-producing E. coli was noted against 3rd generation cephalosporins {ceftazidime (97.1%), cefotaxime (97.2%)}, followed by aztreonam (96.1%), cotrimoxazole (89.9%), piperacillin/tazobactam (2I.l%) and imipenem (1.9%). Similar pattern of resistance was noted for ESBL-producing K. pneumoniae ceftazidime (96.8%), cefotaximc (98.1%), followed by aztreonam (92.2%), ciprofloxacin (89.6%), gentamicin (89.1%), piperaciIlin/tazobactam (9.1%) and imipenem (3.1%).

The sensitivity of ESBLs-producing K. pneumoniae and E. coli was reduced not only towards 3rd generation cephalosporins but cross-resistance was noted against other antibiotics as well like co-trimoxazole, doxycycline, co-amoxiclav, norfloxacin and gentamicin. Carbapenems, β-lactam/ β-lactamase inhibitors and fosfomycin were found most effective against both ESBL-producing and ESBL non-producing Gram negative rods.

In conclusion, considerable resistance was demonstrated amongst the isolated organisms against all the commonly used antibiotics including β-lactams. So it is important to avoid the misuse of antibiotics, as well as to screen for ESBLs routinely by all the laboratories. If an isolate is found to be an ESBL-producer, it should be considered resistant to all β-Iactam drugs including third generation cephaolosporins and aztreonam. Administration of these antibiotics as an empirical therapy could be disastrous in these cases because these would not only be ineffective thus causing increased mortality but would also promote the ESBL-production. The best empirical therapy for these cases would be carbapenems, β-lactam β-lactamase inhibitor combinations and fosfomycin. On the other hand, regarding ESBL non-producer, most of the conventional cheap antibiotics would be effective to combat the infection.

Download Full Thesis
1857.84 KB
S. No. Chapter Title of the Chapters Page Size (KB)
1 0 Contents
113.31 KB
2 1 Introduction 1
95.21 KB
3 2 Review of literature 8
257.4 KB
4 3 Aims and Objectives 32
19.34 KB
5 4 Materials and Methods 33
131.75 KB
6 5 Results 44
651.72 KB
7 6 Discussion 107
429.07 KB
8 7 Conclusions 134
19.81 KB
9 8 Recommendations 135
33.55 KB
10 9 References 137
337.26 KB