Chiranjay Mukhopadhyay

Rapid immunochromatographic test for the identification and discrimination of Mycobacterium tuberculosis complex isolates from non-tuberculous mycobacteria

BACKGROUND A new rapid Immunochromatographic test (ICT) kit (SDBioline TB Ag MPT64RAPID(®)) developed by Standard Diagnostics, South Korea was evaluated for rapid differentiation of M. tuberculosis from non tuberculous mycobacteria (NTM). It detects MPT 64 antigen in M. tuberculosis isolates using mouse monoclonal MPT 64 antibody. The kit was assessed for routine identification of the Acid Fast Bacilli(AFB) isolated in our laboratory. MATERIALS AND METHODS Two hundred eight culture isolates of Mycobacteria were tested using ICT test kit for detection of MPT 64 antigen from liquid and solid culture. H37Rv strain was employed as the positive reference control. Any negative result was referred for confirmation by Gen Probe Accu Probe assay for MTB Complex (Gen-Probe, San Diego, Calif.). Speciation of NTM was performed using genotypic Mycobacterium CM assay (Hains life sciences, Germany). RESULTS Of the 208 culture positive isolates tested, 182 (87.5%) were found positive for Mycobacterium tuberculosis Complex and remaining 26 (12.5%) were considered as NTM. These results were further confirmed by Gen Probe Accu probe assay that served as the reference method for detection of MTBC. H37Rv reference strain was taken as a control for ICT test and molecular tests. The reference strain showed the presence of MPT64 antigen band in the ICT test. Similar bands were formed in all MTBC (182) isolates tested, proving 100 per cent sensitivity and no bands were detected in 48 (100%) NTM isolates tested, proving 100 per cent specificity of the ICT kit. CONCLUSION Tuberculosis is a global pandemic. Rapid identification of Mycobacteria as MTB complex or non-tuberculous Mycobacteria from culture is important for treatment of infected cases and drug susceptibility testing of the culture isolate. MPT 64 TB antgen detection using SD Bioline Immunochromatographic test is a simple and cost effective method for differentiation of Mycobacterial cultures as MTB complex from non- tuberculous Mycobacteria.

Pulmonary melioidosis in febrile neutropenia: the rare and deadly duet.

Summary We present the first two fulminant cases of pulmonary melioidosis in febrile neutropenic patients with acute and varied presentations seen in our institution and their fatal outcome. A high index of suspicion coupled with microbiological confirmation can facilitate the administration of the appropriate therapy in cases of melioidosis that differ from other bacterial infections in terms of presentation and the response to antimicrobials.

Performance evaluation of Active Melioidosis Detect-Lateral Flow Assay (AMD-LFA) for diagnosis of melioidosis in endemic settings with limited resources

Melioidosis is a fatal infection caused by the soil saprophyte Burkholderia pseudomallei. Early diagnosis and befitting medical management can significantly influence the clinical outcomes among patients with melioidosis. Witnessing an annual increment in the number of melioidosis cases, over the past few years, mainly from the developing tropical nations, the present study was undertaken to evaluate the diagnostic utility of Active Melioidosis DetectTMLateralFlow Assay (AMD-LFA), in comparison with enrichment culture and PCR. A total of 206clinical specimens obtained from 175 patients with clinical suspicion of melioidosis were considered for the evaluation. Positivity for B.pseudomallei using enrichment culture, PCR and AMD-LFA were observed among 63 (30.5%), 55 (26.6%) and 63 (30.5%) specimens respectively. The AMD-LFA failed to detect melioidosis from 9 culture-confirmed cases (6 whole blood specimens, 2 pus samples, and one synovial fluid). Further the test gave faint bands from 9 urine samples which were negative by culture and PCR. AMD-LFA demonstrated a sensitivity, specificity, of 85.71%(CI:74.61% to 93.25%) and 93.62% (CI:88.23% to 97.04%), with positive predictive value of 85.71% (CI: 75.98% to 91.92%) and negative predictive value of 93.62% (CI:88.89% to 96.42%). The test needs further evaluation in view of the faint bands from negative urine samples, for incorporating the test as a point of care assay.In view of its rapidity and ease of testing AMD-LFA might be useful in early diagnosis of melioidosis at resource constraint settings.

Improved detection of Burkholderia Pseudomallei from non-blood Clinical Specimens using Enrichment Culture and PCR: Narrowing Diagnostic gap in Resource Constrained Settings

To evaluate the diagnostic utility of enrichment culture and PCR for improved case detection rates of non‐bacteraemic form of melioidosis in limited resource settings.

Human brucellosis: an experience from a tertiary care hospital in southern India

The aim of our study was to examine and compare the clinical presentations, complications, laboratory findings, treatment and outcome of patients with acute, subacute and chronic forms of brucellosis in a tertiary care setting. This hospital-based observational study was undertaken between April 2015 and March 2017. Patients diagnosed with brucellosis, either by blood culture and/or serology, were recruited. A total of 94 cases of brucellosis of acute, subacute and chronic forms were observed in 78.7%, 15.9% and 5.3%, respectively. Blood culture grew Brucella spp. in 70.2% cases. Serological tests showed positivity in 96.8% of the patients. Using multivariate logistic regression analysis, fever and upper back pain were significant predictors for both acute and chronic forms of the disease, respectively. There is a need to increase awareness and understand the local sero-epidemiological pattern of brucellosis as it is still little known.

Finding Salmonella in unusual sites: look before you leap. A case series

Enteric fever caused by Salmonella Typhi and S. Paratyphi remains an important public health problem in lowand middle-income countries. Salmonella infection of humans can be broadly divided into five clinical groups: enteric fever; septicaemia without localisation; focal disease (with or without associated bacteraemia); gastroenteritis; and the carrier state. Extra-intestinal involvement occurs most commonly in the central nervous system, followed by the cardiovascular, hepatobiliary, pulmonary systems and rarely involving the genitourinary and skeletal systems. The clinical significance of these extra-intestinal manifestations of Salmonella is not often appreciated. A high degree of clinical suspicion must be included in the differential diagnosis of deep seated infections. Fluoroquinolones are recommended by the World Health Organization (WHO) as empirical therapy for multidrug-resistant (MDR) typhoidal Salmonella. Globally, a reduced susceptibility to ciprofloxacin with previously documented resistance to nalidixic acid is emerging, leading to poor clinical outcome and treatment failure.

Anaerobic bacteria in clinical specimens – Frequent, but a neglected lot: A five year experience at a tertiary care hospital

INTRODUCTION Anaerobic bacteria which constitute a significant proportion of the normal microbiota also cause variety of infections involving various anatomic sites. Considering the tedious culture techniques with longer turnaround time, anaerobic cultures are usually neglected by clinicians and microbiologists. AIM To study the frequency of isolation of different anaerobic bacteria from various clinical specimens. MATERIALS AND METHODS A retrospective study to analyse the frequency of isolation of different anaerobic bacteria, was conducted over a period of five years from 2011 to 2015 including various clinical specimens submitted to anaerobic division of Microbiology laboratory. Anaerobic bacteria were isolated and identified following standard bacteriological techniques. RESULTS Pathogenic anaerobes (n=336) were isolated from 278 (12.48%) of overall 2227 specimens processed with an average yield of 1.2 isolates. Anaerobes were isolated as polymicrobial flora with or without aerobic bacterial pathogens in 159 (57.2%) patients. Anaerobic Gram-negative bacilli (140, 41.7%) were the predominant isolates. B. fragilis group (67, 19.9%) were the most commonly isolated anaerobic pathogens. Anaerobes were predominantly isolated from deep seated abscess (23.9%). CONCLUSION Pathogenic anaerobes were isolated from various infection sites. Unless culture and susceptibility tests are performed as a routine, true magnitude of antimicrobial resistance among anaerobic pathogens will not be known. Knowledge of the distribution of these organisms may assist in the selection of appropriate empirical therapy for anaerobic infections.

An Unusual Occurrence of Methicillin Resistant Staphylococcal Endocarditis with Vancomycin Creep Phenomenon – A Therapeutic Challenge

Infective endocarditis by Methicillin Resistant Staphylococcus aureus (MRSA) bacteraemia is a common association and carries a high mortality. However, rising Minimum Inhibitory Concentrations (MICs) for vancomycin amongst MRSA strains is an emerging threat which carries poor prognosis and higher mortality. Here, we report a case of 41-year-old young non-addict gentleman presenting with fever of 3 days duration following recovery from an acute kidney injury necessitating haemodialysis. Systemic examination revealed signs of mitral regurgitation and left sided cerebellar signs. Laboratory investigations revealed anaemia, MRSA bacteraemia and transthoracic echocardiogram showed a mitral valve vegetation. He was diagnosed with MRSA mitral valve endocarditis with acute left cerebellar infarct. He was initially treated with intravenous vancomycin based on MIC at the dose of one gram every twelfth hourly. As the MRSA strain was shown to demonstrate a vancomycin creep phenomemon along with worsening clinical condition of the patient, treatment was changed to intravenous daptomycin at dose of 9mg/kg as per blood culture and sensitivity pattern which was administered for 6 weeks. Following initiation of daptomycin patient became afebrile and vegetations reduced in size and finally disappeared.