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1.
J Med Microbiol ; 68(10): 1431-1437, 2019 Oct.
Article in English | MEDLINE | ID: mdl-31385779

ABSTRACT

Purpose. Rapid and accurate detection of carbapenem resistance is a critical requirement for the selection of appropriate therapy and initiation of infection control measures. Although several tests are available, their use is limited by one or more factors. Phenotypic tests are lengthy, have variable sensitivity and specificity and do not generally identify the carbapenemase. Molecular assays overcome many of these issues but cost can be a barrier to adoption, particularly in low-resource settings. To address the need for affordable, molecular tools, we have assessed the performance characteristics of loop-mediated isothermal amplification (LAMP)-based assays for the major carbapenemase genes, blaNDM, blaKPC, blaOXA-48, blaOXA-23 blaVIM and blaIMP.Methodology. The assays were validated using 1849 Gram-negative Indian clinical isolates obtained from seven hospitals and diagnostic centres.Results. The assays had diagnostic sensitivities of 98.14 %, 98.92 %, 100 %, 98.48 %, and diagnostic specificities of 98.94 %, 99.61 %, 97.42 %, 99.38 % for blaNDM, blaOXA-48, blaOXA-23 and blaVIM, respectively. Due to a low number of isolates positive for blaKPC and blaIMP, the performance characteristics of assays for these two genes could not be suitably evaluated.Conclusion. The performance characteristics suggest suitability for diagnostic and surveillance purposes.


Subject(s)
Bacterial Proteins/genetics , Gram-Negative Bacteria/enzymology , Gram-Negative Bacteria/isolation & purification , Gram-Negative Bacterial Infections/microbiology , Nucleic Acid Amplification Techniques/methods , beta-Lactamases/genetics , Bacterial Proteins/metabolism , Gram-Negative Bacteria/classification , Gram-Negative Bacteria/genetics , Gram-Negative Bacterial Infections/diagnosis , Humans , beta-Lactamases/metabolism
2.
J Infect Dev Ctries ; 8(7): 831-7, 2014 Jul 14.
Article in English | MEDLINE | ID: mdl-25022292

ABSTRACT

INTRODUCTION: The present study is a retrospective analysis of a total of 36 cases of bacteriologically proven extra-intestinal salmonellosis, managed at Nizam's Institute of Medical Sciences, between 1987 and 2012 (25 years). The extra-intestinal sites involved were the skin, cerebrum, spleen, ovary, synovium, and the skeletal muscle. METHODOLOGY: The extra-intestinal specimens were first processed using standard methods. Colonies suspected as Salmonella were identified by standard laboratory methods, initially by manual biochemical reactions and later by the API system (bioMerieux, Marcy l'Etoile- France) and the Vitek-2 system (bioMerieux). All the Salmonella isolates were sent to Central Research Institute, Kasauli, for serotyping. RESULTS: The predominant serotype isolated was Salmonella Typhi (S. Typhi) in 27 (75%) patients, followed by Salmonella Senftenberg (S. Senftenberg) in 5 (14%), Salmonella Paratyphi A (S. Paratyphi A) in 3 (8%), and Salmonella Typhimurium (S. Typhimurium) in 1 (3%). There was an increasing resistance to ampicillin, chloramphenicol, cephalosporins (third generation), and quinolones over the 25 years. CONCLUSIONS: The diagnosis of extra-intestinal salmonellosis requires a high degree of clinical suspicion and should be included in the differential diagnosis in patients with deep-seated abscesses.


Subject(s)
Drug Resistance, Bacterial , Intestinal Diseases/microbiology , Salmonella Infections/etiology , Salmonella enterica/pathogenicity , Abscess/microbiology , Ampicillin/pharmacology , Ampicillin/therapeutic use , Chloramphenicol/therapeutic use , Humans , India , Retrospective Studies , Salmonella Infections/drug therapy , Salmonella Infections/microbiology , Salmonella enterica/drug effects , Salmonella enterica/isolation & purification , Tertiary Care Centers
3.
J Clin Diagn Res ; 8(12): DC23-6, 2014 Dec.
Article in English | MEDLINE | ID: mdl-25653949

ABSTRACT

BACKGROUND: Carbapenem resistant pathogens cause infections associated with significant morbidity and mortality. OBJECTIVE: This study evaluates the use of Multiplex PCR for rapid detection of carbapenemase genes among carbapenem resistant Gram negative bacteria in comparison with the existing phenotypic methods like modified Hodge test (MHT), combined disc test (CDT) and automated methods. MATERIAL AND METHODS: A total of 100 Carbapenem resistant clinical isolates, [Escherichia coli (25), Klebsiella pneumoniae (35) P. aeruginosa (18) and Acinetobacter baumannii (22)] were screened for the presence of carbapenemases (bla NDM-1, bla VIM , blaIMP and blaKPC genes) by phenotype methods such as the modified Hodge test (MHT) and combined disc test (CDT) and the molecular methods such as Multiplex PCR. RESULTS: Seventy of the 100 isolates were MHT positive while, 65 isolates were positive by CDT. All the CDT positive isolates with EDTA and APB were Metallo betalactamase (MBL) and K. pneumoniae carbapenemase (KPC) producers respectively. bla NDM-1 was present as a lone gene in 44 isolates. In 14 isolates bla NDM-1 gene was present with blaKPC gene, and in one isolate bla NDM-1 gene was present with blaVIM , gene. Only one E. coli isolate had a lone blaKPC gene. We didn't find bla IMP gene in any of the isolates. Neither of the genes could be detected in 35 isolates. CONCLUSION: Accurate detection of the genes related with carbapenemase production by Molecular methods like Multiplex PCR overcome the limitations of the phenotypic methods and Automated systems.

4.
J Med Microbiol ; 62(Pt 10): 1540-1544, 2013 Oct.
Article in English | MEDLINE | ID: mdl-23800599

ABSTRACT

Carbapenem-resistant pathogens cause infections associated with significant morbidity and mortality. This study evaluates the use of the loop-mediated isothermal amplification (LAMP) assay for rapid and cost-effective detection of bla(NDM-1) and bla(KPC) genes among carbapenem-resistant Gram-negative bacteria in comparison with conventional PCR and existing phenotypic methods. A total of 60 carbapenem-resistant clinical isolates [Escherichia coli (15), Klebsiella pneumoniae (22), Acinetobacter baumannii (23)] were screened for the presence of carbapenemases (bla(KPC) and bla(NDM-1)) using phenotypic methods such as the modified Hodge test (MHT) and combined disc test (CDT) and molecular methods such as conventional PCR and LAMP assay. In all, 47/60 isolates (78.3%) were MHT positive while 48 isolates were positive by CDT [46.6% positive with EDTA, 30% with 3' aminophenylboronic acid (APB) plus EDTA and 1.6% with APB alone]. Isolates showing CDT positivity with EDTA or APB contained bla(NDM-1) and bla(KPC) genes, respectively. bla(NDM-1) was present as a lone gene in 28 isolates (46.7%) and present together with the bla(KPC) gene in 19 isolates (31.7%). Only one E. coli isolate had a lone bla(KPC) gene. The LAMP assay detected either or both bla(NDM-1) and bla(KPC) genes in four isolates that were missed by conventional PCR. Neither gene could be detected in 12 (20%) isolates. The LAMP assay has greater sensitivity, specificity and rapidity compared to the phenotypic methods and PCR for the detection of bla(NDM-1) and bla(KPC). With a turnaround time of only 2-3 h, the LAMP assay can be considered a point-of-care assay.


Subject(s)
Bacteriological Techniques/methods , Enterobacteriaceae Infections/microbiology , Enterobacteriaceae/genetics , Molecular Diagnostic Techniques/methods , Nucleic Acid Amplification Techniques/methods , beta-Lactam Resistance , beta-Lactamases/genetics , Anti-Bacterial Agents/pharmacology , Carbapenems/pharmacology , Enterobacteriaceae/drug effects , Enterobacteriaceae/isolation & purification , Humans , Sensitivity and Specificity
5.
Indian Heart J ; 65(1): 72-7, 2013.
Article in English | MEDLINE | ID: mdl-23438616

ABSTRACT

Endocarditis due to brucellosis is considered a rare occurrence involving native, congenital and prosthetic valves. The diagnosis needs high degree of suspicion in culture negative endocarditis especially in those with history of exposure to farm animals. A positive culture in a susceptible patient confirms the diagnosis with 91% sensitivity. An early diagnosis and prompt treatment with appropriate antibiotics can restore the valve structural integrity with minimal damage. Here we present a series of five cases of culture proven Brucella endocarditis (four native valves, one prosthetic valve) and this report discusses the diagnostic and management issues involved.


Subject(s)
Brucellosis/diagnostic imaging , Endocarditis, Bacterial/diagnostic imaging , Endocarditis, Bacterial/microbiology , Adult , Animals , Brucellosis/therapy , Diagnosis, Differential , Endocarditis, Bacterial/therapy , Fatal Outcome , Humans , Male , Ultrasonography
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