Introduction: Klebsiella pneumoniae carbapenemase (KPC) belongs to the Group-A βlactamases that incorporate serine at their active site and hydrolyze various penicillins, cephalosporins, and carbapenems. Metallo-beta-lactamases (MBLs) are group-B enzymes that contain one or two essential zinc ions in the active sites and hydrolyze almost all clinically available β-lactam antibiotics. Klebsiella pneumoniae remains the pathogen with the most antimicrobial resistance to KPC and MBLs. Methods: This research investigated the blaKPC, and MBL genes, namely, blaIMP, blaVIM, and blaNDM-1 and their phenotypic resistance to K. pneumoniae isolated from urinary tract infections (UTI) in Bangladesh. Isolated UTI K. pneumoniae were identified by API-20E and 16s rDNA gene analysis. Their phenotypic antimicrobial resistance was examined by the Kirby-Bauer disc diffusion method, followed by minimal inhibitory concentration (MIC) determination. blaKPC, blaIMP, blaNDM-1, and blaVIM genes were evaluated by polymerase chain reactions (PCR) and confirmed by sequencing. Results: Fifty-eight K. pneumoniae were identified from 142 acute UTI cases. Their phenotypic resistance to amoxycillin-clavulanic acid, cephalexin, cefuroxime, ceftriaxone, and imipenem were 98.3%, 100%, 96.5%, 91.4%, 75.1%, respectively. Over half (31/58) of the isolates contained either blaKPC or one of the MBL genes. Individual prevalence of blaKPC, blaIMP, blaNDM-1, and blaVIM were 15.5% (9), 10.3% (6), 22.4% (13), and 19% (11), respectively. Of these, eight isolates (25.8%, 8/31) were found to have two genes in four different combinations. The coexistence of the ESBL genes generated more resistance than each one individually. Some isolates appeared phenotypically susceptible to imipenem in the presence of blaKPC, blaIMP, blaVIM, and blaNDM-1 genes, singly or in combination. Conclusion: The discrepancy of genotype and phenotype resistance has significant consequences for clinical bacteriology, precision in diagnosis, the prudent selection of antimicrobials, and rational prescribing. Heterogeneous phenotypes of antimicrobial susceptibility testing should be taken seriously to avoid inappropriate diagnostic and therapeutic decisions.
Colistin is considered a last-resort reserved drug for the treatment of critical human infections by Gram-negative bacteria. Phenotypic colistin-resistance is strongly associated with plasmid-mediated mobile colistin resistance (mcr) genes. The mcr-bearing Enterobacteriaceae have been detected in many countries from environments, animals, and humans. This study investigated phenotypic colistin-resistance and the distribution of mcr-1, mcr-2, mcr-3, mcr-4, and mcr-5 genes in chicken-gut bacteria in Bangladesh. Bacteria were isolated from poultry- and native-chicken droppings, and their susceptibilities to colistin were determined by agar dilution and E-test minimal inhibitory concentration (MIC) measurements. Multiplex polymerase chain reactions detected mcr-1 to mcr-5 genes. Overall, 61.7% (92/149) of the isolates showed colistin resistance by agar dilution assessment (MIC > 2.0 μg/mL). The phenotypic resistance was observed considerably higher in poultry-chicken isolates (64.6%, 64/99) than in native-chicken isolates (56%, 28/50; p = 0.373). All the resistant isolates showed MIC levels between > 2 and > 128 μg/mL. The mcr-genes (mcr-1and mcr-2 combined) were detected more in poultry gut bacteria (36.4%) than native-chicken isolates (20%, p = 0.06). Despite bacteria sources, mcr-genes appeared to be significantly associated with phenotypic colistin-resistance phenomena (p < 0.001). Prior colistin usage led to a substantial increase in the proportion of bacteria with mcr-genes and phenotypic resistance (p < 0.001).
Background:The indiscriminate uses of antimicrobials in either human or animal husbandry generate selection pressure to develop resistance in diverse microbial populations. Colistin is a polymyxin group antibiotic used for the treatment of critical human infections by multidrug-resistant (MDR) Gram-negative bacteria (GNB) and veterinary healthcare. In recent years, colistin usage has been expanded considerably in Argo, fishery, and food animal farming in Bangladesh. This study investigated phenotypic colistin-resistance and the prevalence of colistin-resistance mcr-1 gene in bacterial isolates from droppings of poultry chickens and household native chickens.Methods and materials: A cross-sectional study was conducted and colistin usage history to chickens was collected by a structured questionnaire. Bacteria were isolated from chicken droppings by inoculating on different selective culture media. The purified bacterial colonies were identified by conventional biochemical procedures followed by a rapid biochemical-test kit (API 20E, BioMérieux, Durham, NC). A part of bacterial identification was validated further by genotyping using 16S rDNA analyses. The colistin susceptibility of the isolates were determined by disk-diffusion and minimal inhibitory concentration (MIC) measurement. mcr-1 gene was detected by polymerase chain reactions (PCR) and confirmed by sequence blasting.Results: Overall 39.6% (59/159) isolates showed colistinresistant by disk-diffusion assessment. The resistance prevalence was significantly higher in poultry-chicken isolates (48.5%, 48/99) than in native-chicken isolates (22%, 11/50; p = 002). All the resistant isolates showed MIC level, between >8 g/mL to >256 g/mL. Likely, the mcr-1 gene was detected more in poultry gut bacteria (34%) than in native-chicken isolates (14%, p = 0.02). mcr-1 appeared significantly associated with phenotypic colistinresistance phenomena (p < 0.001). Previous colistin usage yielded a substantially higher proportion of mcr-1 in bacteria (p = 0.06).Conclusion: mcr-1 gene circulates in bacteria isolated from both poultry chicken and native chicken. Higher acquisition of mcr-1 in bacteria was associated with colistin-usage for chickens. The increased mcr-1 prevalence may increase the risk of critical human disease transmission. Specifically, mcr-1 can enter humans via zoonotic infections from poultry-human interface, which poses a big threat to public health.
Urinary tract infection (UTI) is a global problem. Most UTI research focuses on gram-negative etiology. Enterobacteriaceae was found to be the most prevalent UTI infection constituting more than 80% of all the reported cases. The major gram-positive bacteria in UTI cases are Staphylococcus saprophyticus, Enterococcus faecalis, Streptococcus agalactiae. Gram-positive pathogens were reported in multiple countries in both uncomplicated and complicated UTI. Antibiotic therapy of gram-positive bacteria is completely different than that of gram-negative UTI pathogens. However, symptoms associated with UTI caused by gram-positive and gram-negative are very similar. Without proper diagnosis, there is a high possibility of getting the wrong diagnosis and subsequent antibiotic therapy. Very limited studies are available focusing etiology and their antibiotic susceptibilities in Bangladesh perspective. We aimed to seek in this gap-filling research area. This study has detected 8.2% of gram-positive bacteria in UTI patients. The prevalence shows the harmony with the earlier published reports. Male and female were found to be infected equally by gram-positive UTI pathogens. Most of the earlier publication shows that female is more vulnerable to gram-negative UTI bacteria. Unlikely, our findings look males are equally vulnerable by gram-positive in comparison to females. Further studies with more sample sizes can warrant the preliminary findings. Antibiogram analyses showed amikacin and gentamicin as the most effective antibiotics against our tested isolates. In contrast, nitrofurantoin was found the most ineffective drug in this study. Findings of the study could help in prescribing antibiotics from this evidence-based study.
Pleural effusion is a common clinical problem with different possible causes. It can be due to local, systemic, infectious or non-infectious causes. Aetiological diagnosis is important for proper treatment. To evaluate the aetiological diagnosis of pleural effusion of hospitalized adult patients this cross-sectional, descriptive study conducted from April to September 2012 at Bangabandhu Sheikh Mujib Medical University (BSMMU). A total of 100 cases were selected by purposive sampling. Data were collected using a structured questionnaire. Complete history was taken either from patient or accompanying attendants. Clinical examination was done and relevant investigations report were collected. Data were analyzed using statistical package for the social sciences (SPSS). The mean age of the patient was 41.2 SD± 7.4 years with a male to female ratio of 3:1. Over half (52%) of the patients were poor, 34% were middle class and 14% were rich. Over two-third (67%) of the patients were smoker and the remaining 33% were non smoker. Out of 100 patients with pleural effusion, 52 had tuberculosis and 16 patients had malignancy. Among the malignant cases 14 were found to have bronchial carcinoma and 2, had lymphoma. The remaining 32 patient had other causes of pleural effusion which included nephrotic syndrome 14, congestive cardiac failure 5, cirrhosis of liver 4, rheumatoid arthritis 3, amoebic liver abscess 2, and undiagnosed 4. Tuberculosis is the predominant cause of pleural effusion in our country and the second leading cause is malignancy. Bangladesh Med J. 2018 May; 47 (2): 29-34
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