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Latent tuberculosis infection (LTBI) is characterised by the presence of immune responses to previously acquired Mycobacterium tuberculosis infection without clinical evidence of active tuberculosis (TB). Here we report evidence-based guidelines from the World Health Organization for a public health approach to the management of LTBI in high risk individuals in countries with high or middle upper income and TB incidence of, Guidelines on LTBI for low TB incidence countries – essential element of the @WHO #EndTB strategy and TB elimination http://ow.ly/RW8xn

External quality assessment (EQA) for the Xpert MTB/RIF assay is part of the quality system required for clinical and laboratory practice. Five newly developed EQA panels that use different matrices, including a lyophilized sample (Vircell, Granada, Spain), a dried tube specimen (CDC), liquid (Maine Molecular Quality Control, Inc. [MMQCI], Scarborough, ME), artificial sputum (Global Laboratory Initiative [GLI]), and a dried culture spot (National Health Laboratory Services [NHLS]), were evaluated at 11 GeneXpert testing sites in South Africa. The panels comprised Mycobacterium tuberculosis complex (MTBC)-negative, MTBC-positive (including rifampin [RIF] susceptible and RIF resistant), and nontuberculosis mycobacterial material that was inactivated and safe for transportation. Twelve qualitative and quantitative variables were scored as acceptable (1) or unacceptable (0); the overall panel performance score for the Vircell, CDC, GLI, and NHLS panels was 9 of 12, while the MMQCI panel scored 6 of 12 (owing to the need for cold chain maintenance). All panels showed good compatibility with Xpert MTB/RIF testing, and none showed PCR inhibition. The use of a liquid or dry matrix did not appear to be a distinguishing criterion, as both matrices had reduced scores on insufficient volumes, a need for extra consumables, and the ability to transfer to the Xpert MTB/RIF cartridge. EQA is an important component of the quality system required for diagnostic testing programs, but it must be complemented by routine monitoring of performance indicators and instrument verification. This study aims to introduce EQA concepts for Xpert MTB/RIF testing and evaluates five potential EQA panels.

If tuberculosis (TB) is to be eliminated as a global health problem in the foreseeable future, improved detection of patients, earlier diagnosis and timely identification of rifampicin resistance will be critical. New diagnostics released in recent years have improved this perspective but they require investments in laboratory infrastructure, biosafety and staff specialisation beyond the means of many resource-constrained settings where most patients live. Xpert MTB/RIF, a new assay employing automated nucleic acid amplification to detect Mycobacterium tuberculosis, as well as mutations that confer rifampicin resistance, holds the promise to largely overcome these operational challenges. In this article we position Xpert MTB/RIF in today's TB diagnostic landscape and describe its additional potential as an adjunct to surveillance and surveys, taking into account considerations of pricing and ethics. In what could serve as a model for the future formulation of new policy on diagnostics, we trace the unique process by which the World Health Organization consulted international expertise and systematically assessed published evidence and freshly emerging experience from the field ahead of its endorsement of the Xpert MTB/RIF technology in 2010, summarise subsequent research findings and guidance on who to test and how, and provide perspectives on scaling up the new technology.

In 2006, the Australian Mycobacterium Reference Laboratory Network identified 905 bacteriologically confirmed cases of disease caused by members of the Mycobacterium tuberculosis complex. The annual reporting rate was 4.4 cases per 100,000 population. Of the 905 isolates, 903 were Mycobacterium tuberculosis and two were Mycobacterium bovis. Fourteen children aged under 10 years (male n = 5, female n = 9) had bacteriologically confirmed tuberculosis. A total of 100 (11.1%) isolates of M. tuberculosis were resistant to at least one first-line anti-tuberculosis agent. Resistance to at least H and R (defined as multi-drug resistant--MDR) was detected in 22 (2.4%) M. tuberculosis isolates. Of the 22 MDR-TB isolates, 17 were from the respiratory tract (sputum n = 11 bronchoscopy n = 5, nasogastric aspirate n = 1), three from lymph node, one from a sacral mass, and one sterile site fluid. Smear-positive specimens from the MDR-TB cases were found in sputum (n = 6), lymph node (n = 2), and one each of bronchoscopy and nasogastric aspirate specimens. The country of birth was known for all 100 cases with a drug-resistant isolate; 10 of whom were born in Australia. The 90 overseas-born cases with drug-resistant disease were from 27 countries. Two Australian-born cases had MDR-TB; one had worked extensively in the Philippines; the other was a contact of a known MDR-TB case. No cases of extensively drug-resistant TB (XDR-TB) were identified in 2006. However, an on-going review of laboratory data identified one case of XDR-TB in 2004.

Several protocols for isolation of mycobacteria from water exist, but there is no established standard method. This study compared methods of processing potable water samples for the isolation of Mycobacterium avium and Mycobacterium intracellulare using spiked sterilized water and tap water decontaminated using 0.005% cetylpyridinium chloride (CPC). Samples were concentrated by centrifugation or filtration and inoculated onto Middlebrook 7H10 and 7H11 plates and Lowenstein-Jensen slants and into mycobacterial growth indicator tubes with or without polymyxin, azlocillin, nalidixic acid, trimethoprim, and amphotericin B. The solid media were incubated at 32°C, at 35°C, and at 35°C with CO 2 and read weekly. The results suggest that filtration of water for the isolation of mycobacteria is a more sensitive method for concentration than centrifugation. The addition of sodium thiosulfate may not be necessary and may reduce the yield. Middlebrook M7H10 and 7H11 were equally sensitive culture media. CPC decontamination, while effective for reducing growth of contaminants, also significantly reduces mycobacterial numbers. There was no difference at 3 weeks between the different incubation temperatures.

The Australian Mycobacterium Reference Laboratory Network (AMRLN) collects and analyses laboratory data on new cases of disease caused by the Mycobacterium tuberculosis complex. In 2005, a total of 810 cases were identified by bacteriology; an annual reporting rate of 4.0 cases per 100,000 population. Isolates were identified as M. tuberculosis (n = 806), Mycobacterium africanum (n = 2) and Mycobacterium bovis (n = 2). Fifteen children aged under 10 years had bacteriologically-confirmed tuberculosis. Results of in vitro drug susceptibility testing were available for all 810 isolates for isoniazid (H), rifampicin (R), ethambutol (E), and pyrazinamide (Z). A total of 74 (9.1%) isolates of M. tuberculosis were resistant to at least one of these anti-tuberculosis agents. Resistance to at least H and R (defined as multi-drug resistance, MDR) was detected in 12 (1.5%) isolates; nine were from the respiratory tract (sputum n = 8, bronchoscopy n = 1). Of the 74 M. tuberculosis isolates resistant to at least one of the standard drugs, 67 (90.5%) were from new cases, 6 from previously treated cases, and no information was available on the remaining case. Eight were Australian-born, 65 were overseas-born, and the country of birth of one was unknown. Of the 65 overseas-born persons with drug resistant disease, 41 (63.1%) were from 4 countries; Vietnam (n = 16), Papua New Guinea (n = 10), the Philippines (n = 9), and India (n = 6). A retrospective review of AMRLN data on isolates collected between 2000 and 2005 found that none of 70 MDR-TB isolates met the new definition for extensively drug resistant TB (XDR-TB, i.e. MDR-TB with additional resistance to quinolones and second-line injectable agents).

The Australian Mycobacterium Reference Laboratory Network collected and analysed laboratory data on new cases of disease caused by Mycobacterium tuberculosis complex in the year 2004. A total of 787 cases were identified by bacteriology, representing an annual reporting rate of 3.9 cases per 100,000 population. Almost all isolates were identified as M. tuberculosis (n = 785), the remaining isolates being one each of Mycobacterium africanum and Mycobacterium canettii. Seven children under 10 years of age (female n = 5, male n = 2) had bacteriologically confirmed tuberculosis (gastric aspirate n = 4, lymph node n = 1, pleural n = 1, thigh wound n = 1). Results of in vitro drug susceptibility testing were available for all 787 isolates for isoniazid (H), rifampicin (R), ethambutol (E), and pyrazinamide (Z). A total of 71 (9.0%) isolates of M. tuberculosis were resistant to at least one of these anti-tuberculosis agents. Resistance to at least both H and R (defined as multidrug resistance) was detected in 12 (1.5%) isolates; 10 were from the respiratory tract (sputum n = 7, bronchoscopy n = 3). The country of birth was known for 68/71 (95.8%) cases with a drug resistant strain; eight were Australian, 60 were overseas born, and three were unknown. Of the 60 migrants with drug resistant disease, 37 (61.7%) were from three countries; Viet Nam (n = 20), China (n = 9) and India (n = 8).

The Australian Mycobacterium Reference Laboratory Network collected and analysed laboratory data on new cases of disease caused by Mycobacterium tuberculosis complex in the year 2003. A total of 784 cases were identified by bacteriology, representing an annual reporting rate of 3.9 cases of laboratory confirmed tuberculosis per 100,000 population. The most commonly encountered culture-positive specimens were sputum (n = 351), lymph node (n = 176) and from bronchoscopy (n = 97). Smears containing acid fast bacilli were present in sputum (53.0%), bronchoscopy (32.0%) and lymph node (23.3%). Five children (female n = 3, male n = 2) under 10 years of age had bacteriologically confirmed tuberculosis. Eighty isolates of M. tuberculosis and one of Mycobacterium africanum (10.3%) were resistant to at least one of the standard anti-tuberculosis agents. Mono-resistance to isoniazid, ethambutol, rifampicin, and pyrazinamide was detected in 45, three, two, and one isolates respectively. Multidrug-resistance (MDRTB) defined as resistance to both isoniazid and rifampcin was observed in seven (0.9%) isolates. Of the seven MDRTB isolates, six were from the respiratory tract and four were from smear positive specimens. Of the 81 patients with drug resistant isolates, 78 (96.3%) were classified as having initial resistance; two had acquired resistance and no information was available for one isolate; five were Australian-born; and 76 (93.8%) had migrated from a total of 30 countries.

The Australian Mycobacterium Reference Laboratory Network collected and analysed laboratory data on new cases of disease caused by Mycobacterium tuberculosis complex in the year 2002. A total of 712 cases were identified by bacteriology, representing an annual reporting rate of 3.6 cases of laboratory-confirmed tuberculosis per 100,000 population. The most commonly encountered culture-positive specimens were sputum (n=325), lymph node (n=142) and bronchoscopy (n=100). Smears containing acid fast bacilli were present in sputum (53.2%), bronchoscopy (37.9%) and lymph node (21.2%). Eight children (male n=3, female n=5) under 10 years of age had bacteriologically-confirmed tuberculosis. A total of 55 isolates (7.7%) of M. tuberculosis were resistant to at least one of the standard anti-tuberculosis agents. Resistance to at least isoniazid and/or rifampicin was noted for 53 isolates (7.4%), with multidrug-resistance (MDRTB) observed in 12 (1.9%) isolates. Of the 12 MDRTB isolates, eight were from the respiratory tract and five were from smear positive specimens. Of the patients with drug resistant M. tuberculosis isolates, 51/55 (92.7%) were classified as having initial resistance, none had acquired resistance during treatment in Australia. The country of birth was known for 54 of 55 such patients; four were Australian-born, and 50 (90.9%) had migrated from a total of 17 countries. Nucleic acid amplification testing (NAAT) was performed on 139 (19.5%) of the 712 culture-positive specimens. Of smear positive respiratory specimens, 74/80 (92.5%) were NAAT positive. For smear negative respiratory specimens, 12/17 (70.6%) reported a NAAT positive result. Importantly, false-negative NAAT results were obtained from 1/16 and 5/64 of smear positive bronchoscopy and sputum specimens respectively.

The Australian Mycobacterium Reference Laboratory Network collected and analysed laboratory data on new cases of disease caused by Mycobacterium tuberculosis complex in the year 2001. A total of 771 cases were identified, representing an annual reporting rate of 4.0 cases of laboratory-confirmed tuberculosis per 100,000 population. The predominant specimen type was sputum, (n=369) and a further 111 were collected at bronchoscopy. Smears were positive for 214 of 369 (58.0%) sputum and 42 of 111 (37.8%) bronchoscopy specimens respectively. Seven children (male n=5, female n=2) under 10 years of age had bacteriologically confirmed tuberculosis. A total of 69 isolates (8.9%), comprising 67 M. tuberculosis, one M. africanum, and one M. bovis, were resistant to at least one of the anti-tuberculosis agents. Excluding the M. bovis isolate, 61 of 64 (93.5%) were classified as having initial resistance, three had acquired resistance, and no data were available on the presence or absence of previous treatment for four patients. Resistance to at least isoniazid and/or rifampicin was noted for 67 isolates (8.7%), with resistance to both isoniazid and rifampicin (i.e. defined as multidrug-resistant disease) observed in 12 (1.6%) isolates. All of the multidrug-resistant isolates were M. tuberculosis, 10 were from the respiratory tract. The country of birth was known for 63 of 68 (92.6%) patients with a drug-resistant strain of M. tuberculosis or M. africanum; five were Australian-born and 58 (92.1%) had migrated from a total of 22 countries. One hundred and seven respiratory specimens had a nucleic acid amplification testing performed; 89 of 90 (98.9%) smear positives were nucleic acid amplification testing positive, whilst only 13 of 17 (76.5%) smear negative specimens were nucleic acid amplification testing positive. The 2001 laboratory data reveals a stable incidence rate and level of drug resistance in isolates from Australian patients with tuberculosis.

The Australian Mycobacterium Reference Laboratory Network collected and analysed laboratory data on new diagnoses of disease caused by Mycobacterium tuberculosis complex in the year 2000. A total of 765 cases were identified, representing an annual reporting rate of 4.0 cases of laboratory-confirmed tuberculosis (TB) per 100,000 population. Pulmonary disease was diagnosed in 64.9 per cent of cases with a male:female ratio of 1.5:1. Smears were positive for 209/365 (57.3%) of sputum isolates and 39/117 (33.3%) bronchoscopy isolates. Sputum from males was more likely to be smear-positive (63.3%) than from females (47.5%). Isolates from lymph node accounted for 136 (17.7%) of all cases; only 28.7 per cent were smear-positive. Eighty-four (11.0%) isolates, comprising 82 M. tuberculosis and 2 M. bovis strains, demonstrated in vitro resistance to at least one of the standard anti-TB medications. Resistance to at least isoniazid and rifampicin (defined as multidrug-resistant TB) was observed for only 8 (1.0%) strains, a rate similar to previous years. Almost all (96.3%) of patients with drug resistant strains were classified as having initial resistance. The country of birth was known for 76 (92.7%) of 82 patients with a drug resistant strain of M. tuberculosis; 6 were Australian-born and 70 (92.1%) had migrated from a total of 17 countries. Of these 70 migrants with drug-resistant disease, 68.6 per cent had migrated from one of the following countries: Vietnam (n=15), China (n=11), Philippines (n=11), India (n=6), and Indonesia (n=5).

Non-tuberculous mycobacteria (NTM) have become increasingly important over the last 20 years. These mycobacteria are classified as ?rapid growers? (growth in 7 days or less) or slow growers (growth of isolated colonies in more than 7 days). The rapidly growing mycobacteria (RGM) are the group of mycobacteria which are being recognised in cultures performed in routine diagnostic microbiology laboratories. The increase in notification rate of RGM is partially due to a heightened alertness for mycobacteria by clinicians and laboratory scientists and technicians. However, diagnostic delays remain relatively common, with mycobacteria being considered only following failed treatment with empiric therapy.

Tuberculosis remains a low prevalence disease in Australia, with approximately 800 new bacteriologically confirmed cases detected each year. In Australia, this low incidence rate corresponds to less than five cases per 100,000 population. The highest incidence occurs in migrants from high prevalence countries followed by indigenous Australian-born people. Among non-indigenous Australians, tuberculosis most often occurs among elderly males, largely due to re-activation of latent tuberculosis.