Raja Ray

Comparative evaluation of loop-mediated isothermal amplification and conventional methods to diagnose extrapulmonary tuberculosis

Background: Extra-pulmonary tuberculosis is difficult to diagnose by conventional methods, because they are less sensitive and more time consuming. Loop-mediated Isothermal Amplification (LAMP) is a novel gene amplification method that has been developed to diagnose Mycobacterium tuberculosis complex in pulmonary and paucibacillary extrapulmonary specimens even in resource poor settings. Aims and Objectives: To evaluate the sensitivity and specificity of LAMP to detect Mycobacterium tuberculosis complex in paucibacillary extra-pulmonary specimens and to compare the results with other conventional methods in extrapulmonary specimens. Materials and Methods: 45 specimens from suspected extrapulmonary tuberculosis patients were collected and tested by LAMP method after DNA extraction. Simultaneously, these specimens were tested by smear microscopy, solid and liquid culture methods. Culture positivity, either in solid or liquid culture, was considered as a confirmed case of extrapulmonary tuberculosis. Results: Sensitivity of LAMP was 95.6% whereas for liquid culture, solid culture and smear microscopy were 69.6%, 65.2% and 17.4% respectively. Specificity for LAMP was 95.4% and for other 3 conventional methods were 100%. Positive predictive values, negative predictive values and likelihood ratios were also evaluated. Turn-around time (TAT) for LAMP was 8 hours only whereas for liquid culture was 2-4 weeks, and for solid culture it was 4-8 weeks. Conclusion: LAMP was a simple, rapid and cost-effective procedure with good sensitivity and specificity. It was found to be better than conventional methods to diagnose extrapulmonary tuberculosis.

Rethink on recommended concentrations of disinfectants in the light of biofilm, based on in vitro study

Background: Some medical devices are reused after treatment with disinfectants at manufacturer′s recommended concentrations (RCs), based on experimental evaluation studies of their bactericidal, sporicidal, and mycobactericidal concentrations. However, this may not be sufficient to eliminate all colonized highly drug-resistant biofilms on medical devices, resulting possibility in iatrogenic infections by recolonization of highly resistant persisters. The objective of this study is to evaluate the antibacterial efficacy of different concentrations of novel and conventional disinfectants on in vitro grown biofilm of multidrug-resistant nosocomial bacterial isolates and a reference strain. Materials and Methods: Multidrug-resistant and strong biofilm producers Pseudomonas aeruginosa (n = 4) and Escherichia coli (n = 5) nosocomial isolates and one reference strain, P. aeruginosa PAO-1, were selected after testing their biofilm status by modified Christensen′s method and Stepanovic′s interpretative criteria. The activity of three different groups of new disinfectants, Novacide, Virkon, Silvicide and two conventional disinfectants, phenol and glutaraldehyde, were assessed on their in vitro grown biofilms as percentage of total surviving bacteria within biofilm matrix after challenge at different concentrations in terms of multiples of RC and different contact time. Results: Modified RCs for Virkon, phenol, and Silvicide, as pointed out by in vitro study, were 4, 8, and 10 times higher than the one suggested by the manufacturer. Novacide was least effective, whereas glutaraldehyde at its available concentration was also not effective in removal of biofilm bioburden. Conclusions: RC was not sufficient to eliminate the in vitro biofilms tested in this study. Further studies using medical devices materials should be performed for clarification. However, this study points out possible relevant limitations of currently used hospital disinfectants and concentrations against biofilms. Additional measures to prevent reinfections related to their use of medical devices are mandatory, and this study suggests that optimization of disinfectants concentrations may be highly relevant.

HIV in Intensive Care Unit: Concerns and Constraints of Intensivists

The increasing prevalence of HIV (human immunodeficiency virus) infection in recent times has led to increasing exposure, and the possibility of nosocomial transmission of HIV. The present day scenario highlights the need for intensivists to enforce strict adherence to infection control protocol at site when working in ICU. Thus strict adherence to Standard precautions when handling body fluids especially hand washing, proper management of accidental needle-stick injury and scientific disposal of biomedical waste along with current PEP guidelines are of paramount importance. In the HAART era, though hospitalisation of HIV infected patients has significantly decreased, but the rate of ICU admissions is still high. HIV patients may be admitted to ICU for many reasons, of which acute respiratory failure as a result of opportunistic infections accounts for approximately 25-50%. Today, HIV patients are being admitted to the ICU for medical and surgical causes unrelated to their HIV infection, such as malignancies, pacemaker implant, liver and renal diseases, minimal invasive surgeries like laparoscopic ones, orthopaedic surgeries for fractures and implants, brain surgery for road traffic accident injury are only a few. The number of persons living with HIV/AIDS (PLWHA) has increased and critical care specialists may be more likely to admit more HIV patients to the ICU and pursue aggressive life-support measures. But for resource constrained countries, where population and ICU bed ratio are abysmally low, decisions for admission in ICU by critical care specialists are often made in the absence of explicit policies and guidelines. Global and national commitments are required, providing proper HIV treatment and prophylaxis without discrimination and maintaining accountability and code of ethics.