Improved rapid identification of mycobacteria by combining solid-phase extraction with high-performance liquid chromatography analysis of BACTEC cultures

Recent technological advancements in tuberculosis diagnostics - A review

Early diagnosis and on-time effective treatment are indispensable for Tuberculosis (TB) control - a life threatening infectious communicable disease. The conventional techniques for diagnosing TB normally take two to three weeks. This delay in diagnosis and further increase in detection complexity due to the emerging risks of XDR-TB (Extensively drug Resistant-TB) and MDR-TB (Multidrug Resistant-TB) are evoking interest of researchers in the field of developing rapid TB detection techniques such as biosensing and other point-of-care (POC) techniques. Biosensing technologies along with the collaboration with nanotechnology have enormous potential to boost the MTB detection and for overall management in clinical diagnosis. A diverse range of portable, sensitive and rapid biosensors based on different signal transducer principles and with different biomarkers detection capabilities have been developed for TB detection in the early stages. Further, a lot of progress has been achieved over the years in developing various point-of-care diagnostic tools including non-molecular methods and molecular techniques. The objective of this study is to present a succinct review of the available TB detection techniques that are either in use or under development. The focus of this review is on the current developments occurred in nano-biosensing technologies. A synopsis of ameliorations in different non-molecular diagnostic tools and progress in the field of molecular techniques along with the role of emerging Lab-on-Chip technology for diagnosing and mitigating the TB consequences have also been presented.

Mycobacterium paraseoulense sp. nov., a slowly growing, scotochromogenic species related genetically to Mycobacterium seoulense

A previously unidentified, slowly growing, scotochromogenic Mycobacterium species, represented by strain 31118(T), was discovered during hsp65 sequence-based reidentification of Korean clinical isolates that had been previously identified as Mycobacterium scrofulaceum by conventional biochemical tests. Although the 16S rRNA gene sequence of strain 31118(T) was identical to that of the recently described Mycobacterium seoulense, phylogenetic analyses based on three independent alternative targets (rpoB, hsp65 and the 16S-23S internal transcribed spacer) showed that it was closely related to M. seoulense but was a distinct phylogenetic entity. Furthermore, the phenetic characteristics of this strain were more similar to those of M. scrofulaceum than to those of M. seoulense. Taken together, these results support the conclusion that this strain represents a novel mycobacterium species, for which the name Mycobacterium paraseoulense sp. nov. is proposed. The type strain is 31118(T) (=DSM 45000(T) =KCTC 19145(T)).

Mycobacterium seoulense sp. nov., a slowly growing scotochromogenic species

A previously undescribed, slowly growing, scotochromogenic mycobacterium was isolated from a patient with symptomatic pulmonary infection during hsp65 sequence-based identification of Korean clinical isolates. Phenetic characteristics of this strain were generally similar to those of Mycobacterium nebraskense and Mycobacterium scrofulaceum. However, some phenetic characteristics differentiated it from these two species. Its 16S rRNA gene sequences were unique and phylogenetic analysis based on 16S rRNA gene sequences placed the organism in the slowly growing Mycobacterium group close to M. nebraskense and M. scrofulaceum. Its unique mycolic acid profiles and the results of phylogenetic analysis based on two independent alternative chronometer molecules, hsp65 and rpoB, confirmed the taxonomic status of this strain as representing a novel species. These data support the conclusion that this strain represents a novel mycobacterial species, for which the name Mycobacterium seoulense sp. nov. is proposed. The type strain is strain 03-19(T) (=DSM 44998(T)=KCTC 19146(T)).

Mycolic acid analysis by high-performance liquid chromatography for identification of Mycobacterium species

Mycobacterium tuberculosis is the etiologic agent of tuberculosis and can be accurately detected by laboratories using commercial genetic tests. Nontuberculosis mycobacteria (NTM) causing other mycobacterioses can be difficult to identify. The identification processes are confounded by an increasing diversity of newly characterized NTM species. The ubiquitous nature of NTM, combined with their potential to be opportunistic pathogens in immunocompromised as well as nonimmunodeficient patients, further complicates the problem of their identification. Since clinical case management varies depending on the etiologic agent, laboratories must identify the species in a timely manner. However, only a few identification methods can detect the species diversity within the Mycobacterium genus. Over the last decade, high-performance liquid chromatography analysis of the mycolic acids has become an accepted method for identification of mycobacteria. In this review, we assess its development and usefulness as an identification technique for Mycobacterium species.

Severe gastrointestinal hemorrhage due to Mycobacterium avium complex in a patient receiving immunosuppressive therapy

Intense immunosuppressive therapy is used frequently for treatment of systemic vasculitides, collagenoses, rapidly progressive glomerulonephritis, and after organ transplantation. Numerous serious treatment-related side effects include localized or disseminated opportunistic infections, and require careful monitoring of immunosuppressed patients. Gastrointestinal infections with Mycobacterium avium complex (MAC) or other nontuberculous mycobacteria have been previously identified in HIV seropositive patients only. We now report the first case of an HIV seronegative patient who received immunosuppressive therapy for rapidly progressive glomerulonephritis. The patient presented with severe lower gastrointestinal bleeding and was diagnosed to have ulcerative colitis due to infection with MAC. The patient recovered promptly after administration of antimycobacterial therapy. MAC infection should be included in the differential diagnosis of gastrointestinal bleeding in all immunodeficient patients. The significance of repeated colonoscopy to obtain multiple biopsy specimens with histological examination for foam cells and specific staining for acid-fast organisms is emphasized.

Aseptic meningitis: a seasonal concern

Outbreaks of aseptic meningitis-like illnesses have occurred in high school football players for reasons that may include the close contact among players and the overlap of football season with the peak enterovirus season. The main symptoms are fever, headache, and neck or back stiffness; physical findings may include signs of meningeal irritation. Evaluation of the cerebrospinal fluid can confirm the diagnosis. Treatment of viral meningitis is generally supportive, and patients usually do well, while other forms of aseptic meningitis may require drug treatment or removal of inciting medications. Not sharing water bottles may help reduce risk.