Antimicrobial resistance poses a threat in the treatment of infectious diseases in Bangladesh as well as in the world. Multidrug-resistant (MDR) Enterobacteriaceae, the most common cause of one such infectious disease, urinary tract infection (UTI), has contributed to the escalating problem of selecting empiric antibiotics against UTIs. The aim of this study was to investigate the presence of the efflux pump in MDR Escherichia coli isolates from UTI in the North-East region of Bangladesh, to isolate and characterize the AcrAB-TolC efflux pump genes of these locally isolated strains and to do mutation analysis of the efflux pump repressor AcrR gene to understand the AcrAB-TolC efflux pump mechanism. In the presence of omeprazole, an efflux pump inhibitor, every MDR E. coli isolate showed increased susceptibility to at least 1 of the 7 antibiotics investigated, indicating that efflux pump might be involved in their antibiotic resistance. Omeprazole decreased the minimum inhibitory concentration of every antibiotics being investigated by 2- to 8-fold. DNA and the deduced amino acid sequences of the polymerase chain reaction (PCR) products analyzed by bioinformatics tools revealed that the chromosomal AcrAB-TolC and AcrR genes were present in all MDR and antibiotic-susceptible E. coli isolates. However, the deduced amino acid sequences of the amplification refractory mutation system (ARMS) PCR product of the AcrR gene revealed that the substitution of arginine to cysteine at position 45 of AcrR was observed only in the MDR E. coli whose antibiotic susceptibility increased in the presence of omeprazole. Data reported herein support the notion that the increased antibiotic susceptibility of the MDR E. coli isolates in the presence of omeprazole might be due to efflux pump(s) inhibition and the AcrAB-TolC efflux pump might be a contributor to antibiotic resistance when the mutation of arginine to cysteine occurs at position 45 of AcrR.
Background: Escherichia coli causes urinary tract infection (UTI), one of the most frequent bacterial infections in humans, shows resistance to various commonly prescribed antibiotics. This is termed as multi drug resistance, which is increasing among E. coli. The multi-drug resistant E. coli isolates harbor multiple plasmids that might be responsible for antibiotic resistance. The resistance can be transferred among bacteria through horizontal transfer of the genetic materials. Objectives: We undertook this study 1) to find a link between antibiotic resistance and plasmid of E. coli from UTI patients of Sylhet region of Bangladesh 2) to analyze the spread of the plasmid mediated antibiotic resistant gene between E. coli isolates. Methods: Conjugation experiment was carried out in Luria Broth with E. coli DH5α as recipient. For transformation, competent cells were prepared using E. coli DH5α. Plasmid isolation was done by mini alkaline lysis method and plasmid was extracted from agarose gel and transferred to the competent cell. Results: After conjugation, the donor E. coli isolate that showed resistance to amoxicillin (AMX), ciprofloxacin (CIP) and ceftriaxone (CTR) tranferred its AMX and CIP resistance to the recipient E. coli DH5α, that was previously sensitive to all antibiotics. After transformation, the recipient E. coli DH5α became resistant to CIP and AMX, while the donor showed resistance to gentamycin (CN), ceftriaxone (CTR), amoxicillin (AMX), ciprofloxacin (CIP), cefixime CFM, and cotrimoxazole (COT). Plasmid extracted from the transformant revealed that, three genes (3 kb, 5 kb and 20 kb) have been transferred from the donor to recipient. Conclusion: Plasmids responsible for amoxicillin and ciprofloxacin were transferred.
The effects of pH, buffer constituents, duration of storage, presence of air, heavy metal ions, extracting solvents and various additives and cofactors on the aerial oxidation of some aliphatic primary and secondary hydroxylamines were investigated. Copper ions were particularly effective catalysts of the oxidation reaction. Conditions to minimize this transformation are described.
Various f a c t o r s t h a t cause t h e r u s t i n g o f t a b l e t punches anddies by a hydrochloride s a l t were evaluated. r i c h i n n i c k e l content was found t o have t h e b e s t r e s i s t a n c e t o r u s t i n g by t h e hydrochloride s a l t . humidity, temperature and c o n t a c t time w i t h t h i s hydrochloride s a l t were a l s o found t o be responsible f o r r u s t i n g o f t o o l i n g Tooling m a t e r i a l Other f a c t o r s such as materi a1 . The hydrogen c h l o r i d e l i b e r a t e d from t h e s a l t was found t o A c o r r e l a t i o n between the be t h e cause of r u s t i n g o f t o o l i n g . s t a b i i i t y o f hydrochloride s a l t as determined by thermogravim e t r i c a n a l y s i s and i t s e f f e c t on r u s t i n g o f t o o l i n g m a t e r i a l was demonstrated. Optimization o f t o o l i n g composition d u r i n g p r e f o r m u l a t i o n i s recommended.
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