agar and Tuberculosis

There is considerable demand for quicker and more affordable yet accurate diagnostic tools for tuberculosis (TB). The microscopic observation drug susceptibility (MODS) assay and the thin-layer agar (TLA) assay are inexpensive, rapid microcolony-based culture methods.. A systematic review and meta-analysis was performed to assess the accuracy and other test characteristics of MODS and TLA compared to a reference standard of traditional solid or liquid culture. Pooled estimates of sensitivity and specificity and their 95% confidence intervals were estimated with an exact binomial likelihood random effects meta-analysis.. A total of 21 eligible studies were identified, 12 that evaluated MODS, seven that evaluated TLA and two that evaluated both. The overall pooled sensitivity and specificity of MODS were respectively 92% (95%CI 87-97) and 96% (90-100), and for TLA they were respectively 87% (95%CI 79-94) and 98% (95%CI 94-100), although there was considerable heterogeneity of results. When the studies were restricted to those assessing accuracy of MODS in sputum samples only, the sensitivity was 96% (95%CI 94-98) and the specificity 96% (95%CI 89-100). The mean intervals from reception of specimens to results were 9.2 days with MODS and 11.5 days with TLA; contamination rates averaged 6.6% with MODS and 12.3% with TLA; materials and supplies costs averaged US$1.48 for MODS and US$2.42 for TLA.. MODS and TLA appear to be accurate and rapid yet inexpensive diagnostic tools for active TB. However, this review did not find sufficient evidence on the feasibility and costs of implementation of these tests, nor on the impact of these tests on patient outcomes.

Topics: Agar; Antitubercular Agents; Cost-Benefit Analysis; Evidence-Based Medicine; Health Care Costs; Humans; Microbial Sensitivity Tests; Microscopy; Mycobacterium tuberculosis; Predictive Value of Tests; Reproducibility of Results; Sensitivity and Specificity; Tuberculosis

Antimicrobial susceptibility testing is the mainstay of tuberculosis drug development programs. In this chapter, we describe methods for determination of the minimum inhibitory concentration of compounds against Mycobacterium tuberculosis growing in liquid media as a function of carbon source, detergent, and environmental stress imposed by acidic pH as well as reactive nitrogen intermediates. Methods for determining the effect of bovine serum albumin in the growth medium on antimicrobial susceptibility are also described. Finally, we provide a method for antimicrobial susceptibility testing on agar medium.

Topics: Agar; Antitubercular Agents; Carbon; Culture Media; Humans; Hydrogen-Ion Concentration; Microbial Sensitivity Tests; Mycobacterium tuberculosis; Serum Albumin, Bovine; Stress, Physiological; Tuberculosis

Topics: Agar; Antitubercular Agents; Culture Media; Ethambutol; Humans; Isoniazid; Microbial Sensitivity Tests; Mycobacterium tuberculosis; Rifampin; Streptomycin; Tuberculosis

We evaluated the use of the molecular bacterial load (MBL) assay, for measuring viable Mycobacterium tuberculosis in sputum, in comparison with solid agar and liquid culture. The MBL assay provides early information on the rate of decline in bacterial load and has technical advantages over culture in either form.

Topics: Agar; Antitubercular Agents; Bacterial Load; Culture Media; Humans; Microbial Sensitivity Tests; Microbial Viability; Molecular Diagnostic Techniques; Mycobacterium tuberculosis; Sputum; Tuberculosis

Sputum smear microscopy for the diagnosis of tuberculosis (TB) is cheap and simple but its sensitivity is low. Culture on Löwenstein-Jensen (LJ) is more sensitive but it takes a long time to yield results. Thin-Layer Agar (TLA) culture was suggested as an equally sensitive and faster alternative. We evaluated the performance of TLA for diagnosing TB in Jogjakarta, Indonesia. People with suspected TB presenting from July 2010 to July 2011 to two chest clinics of the National TB Control Programme network of Jogjakarta were eligible for inclusion. A sputum sample was sent to the Gadjah Mada University microbiology laboratory for concentration, smearing, Ziehl-Neelsen staining and culture on LJ and TLA. Sensitivity of cultures was evaluated against a composite reference standard (any positive culture). Time to detection of Mycobacteria was recorded. Out of 1414 samples, 164 (12%) were smear positive, 99 (7%) were scanty and 1151 (81%) were negative. On TLA and LJ respectively, 168 (12%) and 149 (11%) samples were positive, 72 (5%) and 32 (2%) were contaminated (κ = 0.64; 95% CI 0.59-0.69, p <0.01). Using the reference standard, 196 (14%) TB cases were identified. The sensitivity of TLA was 0.86 (95% CI 0.80-0.90), significantly higher (p 0.03) than for LJ (0.76; 95% CI 0.69-0.81). The median time to detection in days was significantly shorter (p <0.01) for TLA (12; 95% CI 11-13) than for LJ (44; 95% CI 43-45). TLA is a rapid and sensitive method for the diagnosis of TB. Implementation studies to evaluate the cost-effectiveness and impact of its introduction into programmatic settings are urgently needed.

Topics: Adult; Agar; Aged; Aged, 80 and over; Culture Media; Female; Humans; Indonesia; Male; Middle Aged; Mycobacterium; Prospective Studies; Sensitivity and Specificity; Time Factors; Tuberculosis; Young Adult

This study was aimed to evaluate the performance of blood agar for the growth of mycobacteria from clinical specimens sent to Mycobacteriology Laboratory of Samsun Chest Diseases Hospital. One hundred fifty six clinical specimens including 123 sputum, 28 bronchoalveolar lavage (BAL) and 5 pleural fluid specimens were inoculated in Löwenstein-Jensen (LJ), BACTEC MGIT 960 system (Becton Dickinson, USA) and blood agar following decontamination process. The specimens were also simultaneously examined for the presence of acid-fast bacilli (AFB). Thirty five mycobacteria strains (33 Mycobacterium tuberculosis and 2 atypical mycobacteria) grew in blood agar, 38 (36 M.tuberculosis and 2 atypical mycobacteria) in LJ media and 46 (44 M.tuberculosis and 2 atypical mycobacteria) in BACTEC MGIT 960 system. Among 29 AFB negative specimens, 20 revealed growth in both blood agar and LJ medium and 27 in MGIT system. AFB positive 20 samples yielded growth in 15 samples in blood agar, 18 in LJ medium and 19 in MGIT system. Among the total of 156 samples, contamination was observed in 15 (9.6%) samples in blood agar, 16 (10.2%) in LJ medium and 18 (11.5%) in MGIT system. Growth time was 5-35 days (mean 18 ± 7.4), 11-35 days (mean 19 ± 5.9) and 5-15 days (mean 10 ± 2.4) for blood agar, LJ medium and BACTEC MGIT 960 system, respectively. The three samples which revealed contamination in BACTEC MGIT 960 system, grew successfully in both blood agar and LJ medium without contamination. In one sample, growth was observed only in LJ medium but neither in blood agar nor BACTEC MGIT 960 system. However, in another sample, growth was observed only in blood agar while no growth was detected in LJ or BACTEC MGIT 960 system. Six samples yielded mycobacteria only in BACTEC MGIT 960 system. These results indicated that simultaneous use of one liquid and one solid medium to grow mycobacteria from the clinical samples seemed to be complementary. Blood agar was a promising choice since it was found to be as effective as LJ medium for the growth of mycobacteria, however, this issue needs to be further evaluated in a multicentre study with a larger specimen collection.

Topics: Agar; Blood; Bronchoalveolar Lavage Fluid; Culture Media; Humans; Mycobacterium Infections, Nontuberculous; Mycobacterium tuberculosis; Nontuberculous Mycobacteria; Pleural Effusion; Sputum; Tuberculosis

We report the efficiency and cost-effectiveness of p-nitrobenzoic acid (PNB) testing in Middlebrook 7H10 agar medium for the identification of Mycobacterium tuberculosis complex (MTC). PNB-7H10 was compared with PNB-MGIT and BACTEC-NAP using 200 clinical mycobacterial isolates. PNB-7H10 showed 100% agreement with PNB-MGIT and BACTEC-NAP tests, and reduced the cost of PNB-MGIT test by 80%. PNB-7H10 agar is therefore an effective alternative to the costly PNB-MGIT and BACTEC-NAP tests, especially in resource-poor settings.

Topics: Agar; Bacteriological Techniques; Cost-Benefit Analysis; Mycobacterium tuberculosis; Nitrobenzoates; Tuberculosis

We investigated the performance of blood and chocolate agar as alternatives to Middlebrook 7H11 agar for testing the susceptibility of Mycobacterium tuberculosis to first-and second-line drugs by the Etest method. A total of 39 strains of M. tuberculosis including 22 multidrug-resistant M. tuberculosis strains and 17 susceptible strains were tested. In conclusion, our results showed that chocolate agar gave insufficient growth, needing up to 21 days of incubation, while results on blood agar were comparable to those on Middlebrook 7H11 agar and can be further explored as an alternative for Etest-based susceptibility testing of M. tuberculosis.

Topics: Agar; Antitubercular Agents; Culture Media; Humans; Microbial Sensitivity Tests; Mycobacterium tuberculosis; Tuberculosis

A rapid and accurate antimycobacterial susceptibility test is essential for effective treatment of tuberculosis. The aim of this study was to evaluate a modified method applying 2,3-diphenyl-5-thienyl-(2)-tetrazolium chloride (STC) to the Clinical and Laboratory Standards Institute (CLSI) guideline for susceptibility testing of Mycobacterium tuberculosis. A total of 132 clinical isolates of M. tuberculosis, forty-eight isolates showing resistance to one or more of the first-line antituberculosis drugs, and eighty-four fully susceptible isolates were collected from hospitals of a nationwide distribution from June to September 2004. The modified procedure was conducted basically according to the agar-proportion method described in the CLSI Guideline both with STC 50 mug/mL. The amount of growth in each well was recorded and graded at 2nd and 3rd weeks after inoculation. After 3 weeks of incubation, the diagnostic sensitivity and specificity for the detection of drug-resistant strains of STC-containing agar proportion methods were 100%, except ethambutol-low level resistance, of which the diagnostic sensitivity was 93.4%. After two weeks of incubation in STC-containing agar proportion methods, one hundred of the 107 strain-drug combinations have shown drug resistance, indicating the sensitivity of 93.5%. Especially, all 41 isoniazid-resistant strains and 19 of 21 rifampin-resistant strains (90.5%) could be detected after two weeks of incubation. A modification of the agar proportion method using STC resulted in a reliable and more easily interpretable data, and detected most of resistant strains a week earlier than conventional method.

Topics: Agar; Antitubercular Agents; Colorimetry; Drug Resistance, Bacterial; Humans; Microbial Sensitivity Tests; Mycobacterium tuberculosis; Tetrazolium Salts; Tuberculosis

Tuberculosis represents a public health problem worldwide, mainly in developing countries where 95% of the cases occur. New technologies that support rapid diagnosis are not available in these settings because of high cost. New, rapid, and less expensive techniques are necessary before diagnosis can be improved in these areas. The present work compared the performance of a rapid and costly culture media, thin layer agar (CD7H11), with the traditional Lowenstein-Jensen (LJ) culture method. For this comparison, 1,809 clinical specimens were processed for diagnosis of mycobacterial infections. Clinical samples were processed according to standard procedures and cultured concomitantly in LJ and CD7H11. The times required to obtain an isolate were compared for culture media. Sensitivity (S), specificity (Sp), predictive values (PPV, NPV) and agreement (kappa coefficient) were calculated for CD7H11, with LJ serving as the gold standard. CD7H11 showed S to be 73.5% (C.I.95%: 69.6-80.4), Sp to be 99.2% (C.I.95%: 98.8-99.6), PPV 90.4% (C.I.95%: 85.3-95.6) and NPV 97.6% (C.I.95%: 96.8-98.3). Agreement had a kappa coefficient of 0.52. The mean time for CD7H11 was 11 days (SD+/-4.9) compared with 26.5 (SD+/-8.6) days for LJ. Similar results were obtained in a comparison of respiratory and multibacillary clinical samples. In extrapulmonary samples and those with lowered bacillus count, CD7H11 demonstrated a lower sensitivity. The concomitant use of both culture media enhanced sensitivity of detection. CD7H11 proved a simple and rapid technique for culturing mycobacteria and can be combined with traditional methods for improving laboratory capability for diagnosis of tuberculosis.

Topics: Agar; Bacteriological Techniques; Culture Media; Humans; Sensitivity and Specificity; Time Factors; Tuberculosis

Incidental blood agar-based recovery of Mycobacterium tuberculosis led us to further investigate this routine medium for primary isolation and culture of M. tuberculosis. Fifteen respiratory tract and eight lymph node Ziehl-Neelsen-positive specimens were inoculated in parallel into tubes containing egg-based medium and 5% sheep blood agar. Colonies appeared sooner on this medium than on the egg-based medium, but this difference was not significant (P = 0.11, analysis of variance [ANOVA] test). Further experiments compared the growth of 38 respiratory and lymph node M. tuberculosis isolates when subcultured on the two media. After 6 days of incubation, 21 of 38 isolates had grown on blood agar, and the mean number of colonies was significantly greater on blood agar than on the egg-based medium (P < 0 0.001, ANOVA test). These results demonstrate that M. tuberculosis grows easily on blood agar within 1to 2 weeks, indicating that this basic medium is suitable for laboratory diagnosis of tuberculosis in addition to other media. Laboratories that routinely use prolonged incubations of blood plates, for example, for the recovery of Bartonella species, should consider the potential safety implications of encountering this highly infectious pathogen.

Topics: Agar; Bacteriological Techniques; Blood; Colony Count, Microbial; Culture Media; Humans; Lymph Nodes; Mycobacterium tuberculosis; Respiratory System; Tuberculosis

Reproducibility of ethambutol (EMB) susceptibility test results for Mycobacterium tuberculosis has always been difficult for a variety of reasons, including the narrow range between the critical breakpoint for EMB resistance and the MIC for susceptible strains, borderline results obtained with the BACTEC 460TB method, the presence of microcolonies determined using the agar proportion (AP) method, and a lack of agreement between these two testing methods. To assess the frequency of these problems, M. tuberculosis drug susceptibility data were collected in a multicenter study involving four laboratories. Resistant, borderline, and susceptible isolates were shared among the laboratories to measure interlaboratory test agreement. Half of isolates determined by BACTEC 460TB to be resistant were determined to be susceptible by the AP method. Isolates determined to be resistant to EMB by both BACTEC 460TB and AP methods were almost always resistant to isoniazid. Results from isolates tested by the BACTEC 460TB method with an EMB concentration of 3.75 micro g/ml in addition to the standard 2.5 micro g/ml did not show improved agreement by the AP method. While these results do not indicate that the AP method is more accurate than the BACTEC 460TB method, laboratories should not report EMB monoresistance based on BACTEC 460TB results alone. Monoresistance to EMB should only be reported following confirmation by the AP method. Microcolonies could not be confirmed as resistant by the BACTEC 460TB method or by repeat testing with the AP method and do not appear to be indicative of resistance.

Topics: Agar; Antitubercular Agents; Culture Media; Drug Resistance, Bacterial; Ethambutol; Humans; Microbial Sensitivity Tests; Mycobacterium tuberculosis; Radiometry; Reproducibility of Results; Tuberculosis

Primary BACTEC 12B cultures with serpentine cords observed in Kinyoun-stained smears were tested with a probe for Mycobacterium tuberculosis complex, while cultures without cords were tested with a probe for M. avium complex. The sensitivity, specificity, and positive and negative predictive values of cording for the presumptive identification of M. tuberculosis were 95, 95, 90, and 98%, respectively. With experience, the selection of a probe for testing of primary BACTEC 12B cultures on the basis of cord formation and history of tuberculosis can provide a rapid and reliable approach to the laboratory diagnosis of tuberculosis.

Topics: Agar; Bacteriological Techniques; Culture Media; Diagnostic Errors; DNA Probes; Evaluation Studies as Topic; Humans; Molecular Probe Techniques; Mycobacterium; Mycobacterium avium Complex; Mycobacterium Infections; Mycobacterium tuberculosis; Sensitivity and Specificity; Tuberculosis

Using the serum-soft agar technic of Staphylococcus epidermidis typing, an epidemiologic study of pollution with S. epidermidis in the tuberculosis and pediatric wards of a hospital was conducted. Specimen samples were taken from 334 locations, including beds, bedspreads, pillows, doors and window knobs, chairs, tables, and incubators of premature infants. These were cultured on Staphylococcus 110 medium and the strains identified as S. epidermidis were obtained. Of the strains from both patients' rooms and the nurses' station in the tuberculosis ward a considerable number were of serotype 53, suggesting an interrelationship of this organism and these locations. In the rooms of newborns and premature infants in the pediatric ward, 55.5% of the strains of S. epidermidis isolated were of the serotype 53/408, indicating a high degree of pollution of these environments with these serotype strains.

Topics: Agar; Animals; Child, Preschool; Equipment Contamination; Humans; Infant, Newborn; Serotyping; Serum; Staphylococcal Infections; Staphylococcus epidermidis; Tuberculosis

Topics: Agar; Animals; Antigens, Bacterial; Birds; Cattle; Chemical Precipitation; Culture Media; Humans; Mycobacterium bovis; Mycobacterium tuberculosis; Tuberculosis; Tuberculosis, Avian; Tuberculosis, Bovine

The value of various serological tests in the diagnosis of paracoccidioidomycosis was studied. Quantitative agar-gel immunodiffusion and indirect immunofluorescent tests were performed, and the results were compared with those of complement fixation and qualitative agar-gel procedures. The quantitative immunodiffusion procedure was found to serve as the simplest and safest quantitative test that could be performed for evaluation purposes, whereas the indirect fluorescent-antibody test gave nonspecific reactions and, as such, proved unsuitable.

Topics: Agar; Animals; Antigens; Blastomycosis; Coccidioidomycosis; Complement Fixation Tests; Cross Reactions; Diagnosis, Differential; Evaluation Studies as Topic; Fluorescent Antibody Technique; Fungi; Histoplasmosis; Humans; Immune Sera; Immunodiffusion; Methods; Paracoccidioides; Rabbits; Serologic Tests; Tuberculosis

Topics: Agar; Antibodies; Antigens, Bacterial; Gels; Humans; Mycobacterium tuberculosis; Precipitin Tests; Tuberculosis

Topics: Agar; Bacteriological Techniques; Mycobacterium tuberculosis; Nicotinic Acids; Temperature; Tuberculosis

Topics: Agar; Antibodies; Antigens; Chromatography; Chromatography, Gel; Humans; Immunodiffusion; Precipitin Tests; Serologic Tests; Tuberculosis

Topics: Agar; Carbohydrate Metabolism; Culture Media; Ethionamide; Mycobacterium tuberculosis; Oxidation-Reduction; Pharmacology; Rabbits; Research; Tuberculosis

Topics: Agar; Animals; Antibodies; Bacillus; Blood; Cattle; Clinical Laboratory Techniques; Complement Fixation Tests; Hemagglutination Inhibition Tests; Immunodiffusion; Mycobacterium bovis; Precipitin Tests; Rabbits; Tuberculin; Tuberculin Test; Tuberculosis; Tuberculosis, Bovine

Topics: Agar; Immunoelectrophoresis; Lipids; Lipoproteins; Neoplasms; Precipitin Tests; Tuberculosis

Topics: Agar; Humans; Precipitin Tests; Tuberculosis

Topics: Agar; Animals; Bacillus; Bacteriological Techniques; Cattle; Cresols; Culture Media; Diagnosis, Differential; Humans; Lacticaseibacillus casei; Mycobacterium bovis; Mycobacterium tuberculosis; Niacin; Nicotinic Acids; Tuberculosis; Tuberculosis, Bovine

Topics: Agar; Animals; gamma-Globulins; Immunization; Mycobacterium; Precipitin Tests; Precipitins; Rabbits; Tuberculosis

Topics: Agar; Antibodies; Emotions; Humans; Immune System Phenomena; Tuberculosis

Topics: Agar; Empyema; Empyema, Pleural; Humans; Immune System Phenomena; Mycobacterium tuberculosis; Tuberculosis

Topics: Agar; Animals; Antibodies; Antigens; Incidence; Rabbits; Sensitivity and Specificity; Tuberculosis

Topics: Agar; Antibodies; Antigens; Oxidation-Reduction; Tuberculosis

Topics: Agar; Coloring Agents; Culture Media; Mycobacterium tuberculosis; Neutral Red; Tuberculosis

Topics: Agar; Diffusion; Precipitins; Tuberculosis

Topics: Agar; Charcoal; Culture Media; Disease Susceptibility; Mycobacterium tuberculosis; Pharmacology; Tuberculosis

Topics: Agar; Blood Banks; Culture Media; Gastrointestinal Contents; Humans; Mycobacterium tuberculosis; Sputum; Tuberculosis

Topics: Agar; Microscopy; Mycobacterium; Mycobacterium tuberculosis; Physiological Phenomena; Tuberculosis

Topics: Agar; Culture Techniques; Humans; Mycobacterium tuberculosis; Streptomycin; Tuberculosis