Rapid drug-susceptibility testing of Mycobacterium tuberculosis clinical isolates to first-line antitubercular drugs by nitrate reductase assay: A comparison with proportion method

AbstractObjective/backgroundEarly initiation of therapy in patients with tuberculosis is imperative for its control. Conventional methods of susceptibility testing such as the proportion method (PM) require visual detection and counting of colonies that takes up to 6weeks. Rapid and simple phenotypic methods that have been endorsed by the World Health Organization can serve as alternatives.MethodsIn this study, we evaluated the colorimetric nitrate reductase assay, which utilizes the detection of nitrate reduction as an indicator of growth much earlier compared with PM (within 7–14days). The susceptibility of 75 clinical isolates of Mycobacterium tuberculosis to four first-line antitubercular drugs was tested by nitrate reductase assay and compared with the standard PM. In this assay, inoculation was done on both drug-free and drug-containing Löwenstein–Jensen medium containing sodium nitrate. After incubation for 7–14days, reduction to nitrite was taken as an indicator of growth, which was detected by color change on addition of Griess reagent.ResultsAgreement between nitrate reductase assay and PM was 100% for rifampicin, 97.30% for isoniazid, 93.30% for streptomycin, and 98.60% for ethambutol. Cost/isolate with this assay was found to be approximately two times lesser than that of PM. All results were obtained in 7–14days by nitrate reductase assay, which was significantly rapid compared with 42days taken for obtaining results by PM.ConclusionNitrate reductase assay can be used as a rapid and inexpensive method for drug-susceptibility testing of M. tuberculosis for first-line antitubercular drugs without compromising accuracy of standard methods

A prospective study on metallo-beta-lactamase producing pseudomonas aeruginosa in hospitalized patients in a tertiary care hospital in Kashmir, India.

Objectives: 1) To determine the prevalence of metallo-β-lactamase producing Pseudomonas aeruginosa in SKIMS; 2) To study the risk factors associated with MBL producing Pseudomonas aeruginosa; 3) To study sensitivity pattern of MBL producing Pseudomonas aeruginosa isolates. Study Design: Prospective hospital based study. Material & Methods: 283 isolates of Pseudomonas aeruginosa were obtained from various samples from patients in SKIMS over a period of one and a half year from 1 January 2007 to 30th June 2008. Antimicrobial susceptibility testing was done by Kirby-Bauer disk diffusion method. Pseudomonas aeruginosa isolates resistant to imipenem were then subjected to combined-disk test, MIC reduction and E-test for detection of metallo-β-lactamases. Results: Out of 283 Pseudomonas aeruginosa strains isolated during the study period, 38 (13.42%) were resistant to imipenem and 33 (11.66%) were found to be MBL producers by different methods. Highest number 8 (24.2%) of MBL positive isolates were from ICU and the predominant source was urine. Prolonged hospitalization, ICU stay, antineoplastic chemotherapy and indwelling urinary catheterization showed a statistically significant association with MBL production. MBL producers were 100% resistant to gentamicin, tobramycin, ofloxacin, cefoperazone, carbenicillin, ceftazidime plus clavulanic acid and meropenem. All MBL producers were sensitive to polymyxin B. Conclusions: MBL producing P. Aeruginosa is a problem in our hospital with a prevalence of 11.66%. Prolonged hospitalization, ICU stay, antineoplastic chemotherapy and indwelling catheters were the risk factors. MBL producers were resistant to most of the antibiotics tested

MHD flow of Jeffrey liquid due to a nonlinear radially stretched sheet in presence of Newtonian heating

This communication describes the magnetohydrodynamic (MHD) flow of Jeffrey liquid persuaded by a nonlinear radially stretched sheet. Heat transfer is characterized by Newtonian heating and Joule heating effects. The transformed nonlinear governing ordinary differential equations are solved employing homotopic approach. The obtained results of the velocity and temperature are analyzed graphically for various pertinent parameters. Skin friction coefficient and Nusselt number are tabulated and addressed for the various embedded parameters. Furthermore the temperature decays for increasing nonlinear parameter of axisymmetric stretching surface. The nonlinear parameter has reverse effect for temperature and skin friction coefficient. Keywords: MHD, Jeffrey fluid, Nonlinear stretching sheet, Newtonian heatin

Incidence and surgical outcome of pulmonary aspergilloma

Background: Pulmonary aspergillosis is a spectrum of mycotic diseases caused by Aspergillus species, usually Aspergillus fumigatus. Pulmonary aspergilloma is the most common form. This form is non-invasive and involves the colonization of pre- existing cavities. Objectives: (1) To assess the incidence of Aspergillus infection in various lung cavities admitted to Department of CVTS; (2) To assess the surgical outcome of pulmonary aspergilloma. Material & Methods: A retrospective analysis (from January 2000 to April 2006) of patient records and prospective (from May 2006 to October 2008) study of patients of pulmonary aspergilloma operated in the Department was done. Results: 52 patients (males, 61%) were operated for pulmonary aspergilloma during the study period; constituting one percent of all admissions to the Department of CVTS. The mean age of patients was 39.3±11.2 years. Episodic hemoptysis was the commonest mode of presentation (96%). The duration of hemoptysis ranged from one month to 48 months. Tuberculosis was the most common underlying lung pathology (80.7%), followed by bronchiectasis (11.5%) and lung abscess (5.7%). In one of our patients, concomitant ruptured lung hydatid cyst was present. 90% of the patients had aspergilloma present in upper lobes. Lobectomy was the most common procedure performed (82%), followed by bilobectomy (6%), segmentectomy (6%) and pneumonectomy (6%). Postoperative mortality was 2% only. Postoperative non-fatal complications included incomplete re-expansion (15.5%), prolonged air leak (11.5%), bleeding (5.7%), wound infection (2%) and empyema (2%). The median survival was 36 months (95% C. I., 26-46) with a mean follow-up of 33±18.6 months. There was no recurrence of hemoptysis or pulmonary aspergilloma in any patient. Conclusions: Surgical resection is the most effective treatment for pulmonary aspergilloma. Preoperative preparation of the patient, meticulous surgical technique and post operative chest physiotherapy reduces the rate of complications. Complications may still occur and are largely related to the underlying lung pathology; however, the long term outcome is good

Molecular identification of Candida species isolated from cases of neonatal candidemia using polymerase chain reaction-restriction fragment length polymorphism in a tertiary care hospital

Context: Candida spp. is an emerging cause of bloodstream infections worldwide. Delay in speciation of Candida isolates by conventional methods and resistance to antifungal drugs in various Candida species are responsible for the increase in morbidity and mortality due to candidemia. Hence, the rapid identification of Candida isolates is very important for the proper management of patients with candidemia. Aims: The aim was to re-evaluate the identification of various Candida spp. by polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) and to evaluate the accuracy, speed, and cost of phenotypic methodology versus PCR-RFLP. Settings and Design: Hospital-based cross-sectional study. Materials and Methods: Ninety consecutive clinical isolates of seven Candida species, isolated from blood of neonates and identified by routine phenotypic methods, were re-evaluated using universal primers internal transcribed spacer 1 (ITS1) and ITS4 for PCR amplification and Msp I restriction enzyme for RFLP. Statistical Analysis Used: Kappa test for agreement. Results: The results of PCR-RFLP were 100% in agreement with those obtained using conventional phenotypic methods. Identification could be achieved within 3 work days by both the methods. Our routine methods proved to be cost effective than PCR-RFLP. Conclusions: We can continue with our routine phenotypic methods and PCR-RFLP can be used for periodic quality control or when conventional methods fail to identify a species

Early Detection of Antibiotic Resistance in Positive Blood Cultures: A Study from a Tertiary Care Center in India

Background and objectives: Conventional culture and sensitivity methods take around 48 hours to generate antibiotic sensitivity results after a blood culture is flagged as positive by automated systems. However, it is imperative to initiate early targeted antibiotic therapy for effective management of sepsis and to reduce morbidity, mortality, and cost of treatment. This study aimed to evaluate the direct sensitivity test (DST) as a potential tool to obtain quicker antibiotic susceptibility results from positive BacT/ALERT blood culture vials and the VITEK-2 system (the reference method). Methods: Blood culture bottles flagged as positive by BacT/ALERT were Gram-stained. Cultures with polymicrobial growth were excluded from the study. The isolates were then simultaneously cultured and processed for the DST using the disk diffusion method. Agreements or errors were interpreted according to the Clinical and Laboratory Standards Institute’s guidelines. Results: Among 76 Gram-positive isolates, we observed 99.2% essential agreement between the DST and AST. The rate of minor and major errors was 4.04% and 1.18%, respectively. Among 75 Gram-negative isolates, we observed 98.99% essential agreement between the DST and AST. The rate of minor and major errors was 4% and 2%, respectively. No very major error was seen in either Gram-negative or -positive isolates. Conclusions: The DST results are available earlier than the AST results, which can ultimately help in the early initiation of targeted antibiotic therapy