Tuberculosis Diagnosis: Updates and Challenges

Tuberculosis (TB) is caused by a single infectious agent, Mycobacterium tuberculosis, and a public health concern due to increased cases of drug-resistance and high mortality rates. Rapid identification of tuberculosis is necessary for its early treatment and to prevent the emergence of drug-resistant strains. For effective management of patients, rapid, cost-effective, and point-of-care (POC) diagnostic methods are required. The commonly used screening and identification methods are clinical examination, radiography, sputum smear microscopy, culture method, serological method, and tuberculin skin test. In addition, several molecular methods such as NAAT based GeneXpert, loop-mediated isothermal amplification (LAMP), line probe assay (LPA), whole genome sequencing (WGS) and other non-invasive methods of lateral flow urine lipoarabinomannan assay (LF-LAM) and eNose assays are developed. Sputum smear microscopy, Xpert MTB/RIF, and LED-Fluorescence microscopy (LED-FM) are the preferred methods to use in peripheral laboratories. The non-invasive methods of tuberculosis diagnosis are more beneficial in patients from whom collecting sputum sample is difficult particularly in children and HIV co-infected patients. Molecular methods can simultaneously identify the pathogen, M. tuberculosis, and mutations in drug-resistance genes. Even though, many advanced methods are currently available, accurate and affordable diagnostic method for tuberculosis is still challenging. Here, we review and highlight the uses and challenges of currently available conventional and advanced diagnostic methods of tuberculosis screening and diagnosis

Characteristics of microbial drug resistance and its correlates in chronic diabetic foot ulcer infections

Free to read While virulence factors and the biofilm-forming capabilities of microbes are the key regulators of the wound healing process, the host immune response may also contribute in the events following wound closure or exacerbation of non-closure. We examined samples from diabetic and non-diabetic foot ulcers/wounds for microbial association and tested the microbes for their antibiotic susceptibility and ability to produce biofilms. A total of 1074 bacterial strains were obtained with staphylococci, Pseudomonas, Citrobacter and enterococci as major colonizers in diabetic samples. Though non-diabetic samples had a similar assemblage, the frequency of occurrence of different groups of bacteria was different. Gram-negative bacteria were found to be more prevalent in the diabetic wound environment while Gram-positive bacteria were predominant in non-diabetic ulcers. A higher frequency of monomicrobial infection was observed in samples from non-diabetic individuals when compared to samples from diabetic patients. The prevalence of different groups of bacteria varied when the samples were stratified according to age and sex of the individuals. Several multidrug-resistant strains were observed among the samples tested and most of these strains produced moderate to high levels of biofilms. The weakened immune response in diabetic individuals and synergism among pathogenic micro-organisms may be the critical factors that determine the delicate balance of the wound healing process