Microbiology of lower respiratory tract infection with special reference to extended spectrum beta lactamase and metallo-beta-lactamase-producing strains among the patients attending Tribhuvan University Teaching Hospital.
ABSTRACT: Background :The emergence of extended spectrum ß-lactamase (ESBL) and metallo- ß-Lactamase (MBL) producing bacterial isolates causing lower respiratory tract infection (LRTI) has resulted in fewer therapeutic options in treatment modalities. No studies regarding MBLs had been done so far...
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| Format: | Unknown |
| Language: | English |
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c2008.
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| Summary: | ABSTRACT: Background :The emergence of extended spectrum ß-lactamase (ESBL) and metallo- ß-Lactamase (MBL) producing bacterial isolates causing lower respiratory tract infection (LRTI) has resulted in fewer therapeutic options in treatment modalities. No studies regarding MBLs had been done so far in Nepal and a few researches on ESBLs were also just pilot studies. Therefore, detection of such isolates was quite crucial in our context. Objective :The study was carried out to determine the bacterial etiology of LRTI and to assess the current levels of antimicrobial resistance with special reference to ESBL and MBL producing strains. Methods:This was a prospective study conducted over a period of six months (June to November 2008) at Bacteriology laboratory of TUTH. A total of 1120 specimens representing lower respiratory tract (sputum, endotracheal secretion and bronchial washing) were received from outpatients and inpatients, with suspected LRTI, at TUTH. The specimens were collected and processed according to the standard methodology. Combination disk method and Double disk synergy test method were used for the detection of ESBL and MBL producing isolates. Results:Respiratory pathogens were recovered from 44.38% cases. Among these, gram-negative bacteria were observed in 84.05%, while gram-positive bacteria were found in 15.95% of cases. Growth was more common in endotracheal secretion (67.21%) than in sputum (43.70%) and bronchial washing (10.0%). Ninety-one percent growth was monomicrobial while the rest accounted for mixed infections. Among the organisms isolated, Hemophilus influenza 112 (21.01%) was the most predominant pathogen followed by Klebiella pneumonia 102 (18.95%), Pseudomonads 91 (17.07%), Acinetobacter calcoaceticus baumannii complelx 60 (10.85%) and Steptococcus pneumonia 46 (8.63%). Multidrug resistance (MDR) strains were found in 53.66% of the total bacterial isolates. These isolates were resistant to at least three classes of antimicrobials. Out of total 286 cases, multiresistance was found in K. pneumoniae (23.42%) seudomonads (20.48%), Acb complex (20.63%), E. coli (11.57%), S. aureus (9.10%) and others. MDR isolates were more common among inpatients. Of the total 314 isolates belonging to Enterobacteriaceae and nonfermentative bacteria, 24.20% were ESBL producers which included 42.16% of K. pneumonia. 8.79% of Pseudomonads, 41.94% of E. coli, 12.9% of Acineobacter spp. 13.33% of Citrobacter spp. and 66.67% of M. morganii. Though ESBL producers were more common among inpatients, they were also isolated from outpatients. For ESBL producers, the most effective drug was found to be carbapenem, followed by cefoperazone-sulbactam and amikacin. Among the 76 ESBL producers, only 63 were found positive by double disk synergy test while all cases were detected by combination disk method. MBL was present in 1.34% of the total 448 gram-negative isolates. MBL was detected by both DDST and CD methods in 3 isolates each of P. aeruginosa and Acinetobacter spp. from inpatients. All ESBL and MBL producers were MDR. Forty-two percent of S. aureus were resistant to methicillin. Besides, one Vancomycin resistant S. aureus (VRSA) was also found. Conclusion:A high level of antibiotic resistance was found in LRTI isolates. One-fouth of the isolates belonging to Enterobacteriaceae and non-fermentative bacteria were ESBL producing and the prevalence of MRSA was also relatively higher. Moreover, for the first time MBL was detected in this study. Thus, the results of this study indicated that the problem of antimicrobial resistance is high in LRTI. It is quite essential to have effective antimicrobial and infection control policy in the hospital and special care should be taken to prevent the dissemination of the resistant clones to the community. Further studies should be done to generalize this study and to find out different genes responsible for drug resistance. |
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| Item Description: | Thesis Report. |
| Physical Description: | xxxiii, 165p. : |