Tuberculosis (TB) is one of the world’s deadliest diseases:1

  • One fourth of the world’s population is infected with TB.
  • In 2016, 10.4 million people around the world became sick with TB disease.
  • There were 1.7 million TB-related deaths worldwide.
  • In 2017, a total of 9,093 new cases of tuberculosis (TB) were provisionally* reported in the United States, representing an incidence rate of 2.8 cases per 100,000 population.
  • In 2017, the provisional TB case count and incidence were the lowest in the United States since national TB surveillance began in 1953.
  • TB is a leading killer of people who are HIV infected.

For local or county specific information, please contact your State TB Control Program.

* This report is limited to National Tuberculosis Surveillance System case reports verified as of February 12, 2018. Updated data will be available in CDC’s annual TB surveillance report later this year.

1. CDC Tuberculosis (TB)

AFB Culture

The AFB lab is open and testing is performed 7 days a week. ARUP’s AFB lab can identify and perform susceptibility testing on most mycobacteria species. We use a combination of TB Accuprobe, MALDI-TOF, and 16S DNA sequencing. There are occasionally organisms that have not been previously characterized by sequencing, so there is no data in the databases we use for comparison.

Tests

  • Acid Fast Bacillus culture #0060152: AFB stain is performed and reported within 24 hours. This test does not reflex to TB PCR.
  • Acid Fast Bacillus culture with reflex to M. tuberculosis complex detection and rifampin resistance by PCR #0060738 (when the AFB stain is positive, it will reflex to PCR): AFB stain is performed and reported within 24 hours.
  • M. tuberculosis complex detection and rifampin resistance by PCR #2010775: Testing is performed daily.
  • Blood culture, Acid Fast Bacillus #0060060 & Blood culture, AFB and Fungal #0060024: This is continuously monitored by blood culture instrument.

Run Times

ARUP processes several runs per day, every day of the week, and report stains as soon as completed.

Result Reporting

Preliminary report and AFB stain results within 24 hours:

“Specimen received and in progress. Positive culture reports are called as soon as detected. Final report to follow in seven to eight weeks.”

Positive stain results are called.

AFB Identification Methods

  • Cultures are set in MGIT broth and are continuously monitored, also set on solid media.
  • Positive results are called and reported as soon as detected.
  • TB probe, MALDI-TOF and DNA sequencing are performed daily when the culture has sufficient growth.
  • We will do TB probe from growth on solid media, ESP vials, MB/BactT bottles and 7H9 broth. We do not perform TB probes directly from MGIT broths. MGITs are subbed to 7H9 and probed when growth is equal to 1.0 McFarland.
  • M. tuberculosis complex positive organisms will be identified to species by PCR.
  • Positive culture preliminary reports are updated with the progress of the identification.
  • Positive cultures are reported as a final report after the organism has grown on solid media and the organism morphology is consistent with the identification.

Susceptibility Testing

  • Susceptibility testing is performed on all isolates of M. tuberculosis complex and rapidly growing mycobacteria isolated from culture.
  • Susceptibility testing for all other organisms must  be specifically requested by the client.

Drugs Reported if Susceptibility Is Performed

M. tuberculosis complex: Isoniazid (INH), Ethambutol, Rifampin, and  Pyrazinamide (PZA). We send isolates to National Jewish for all secondary drug testing as requested by physician. INH 0.4 ug/mL resistant, Ethambutol sensitive organisms are reflexed to Ethambutol resistance detection by sequencing.

M. kansasii: Rifampin and Clarithromycin. For rifampin resistant isolates of M. kansasii: ethambutol, rifabutin, amikacin, ciprofloxacin, linezolid, moxifloxacin, and trimethoprim/sulfamethoxazole are also reported.

M. avium-intracellulare: Clarithromycin, Moxifloxacin, Linezolid, MIC only on Ciprofloxacin and Amikacin. In vitro results for Rifampin, Rifabutin, and Ethambutol are not predictive of clinical response and may be misleading; therefore results for these drugs are not reported routinely.

Rapid growers (M. abscessus, M. chelonae, M. immunogenum, M. fortuitum complex & M. mucogenicum): Amikacin, Cefoxitin, Ciprofloxacin, Clarithromycin, Doxycycline, Imipenem, Linezolid, Minocycline, Moxifloxacin & Trimethoprim/sulfamethoxazole. Tobramycin reported on M. chelonae. Tigecycline MIC is reported by request only.

Other slow growing MOTT: Rifampin, Clarithromycin, Ethambutol, Rifabutin, Amikacin, Ciprofloxacin, Linezolid, Moxifloxacin and Trimethoprim/sulfamethoxazole

AFB Susceptibility Testing

ARUP’s AFB lab can identify most mycobacteria species. We use a combination of TB Accuprobe, MALDI-TOF and 16S DNA sequencing. There are occasionally organisms that have not been previously characterized by sequencing so there is no data in the databases we use for comparison.

Organisms that we will automatically perform susceptibility testing on when MC AFBIS is ordered include:

  • M. tuberculosis complex, M. kansasii, M. avium-intracellulare, M. abscessus, M. chelonae, M. immunogenum, M. fortuitum complex & M. mucogenicum

For organisms outside the above list we want the physician to decide if susceptibility testing is appropriate. We will proceed with susceptibility testing at the physician’s request for these isolates.

  • M. tuberculosis complex: Isoniazid (INH), Ethambutol, Rifampin & Pyrazinamide (PZA). We send isolates to National Jewish for all secondary drug testing as requested by physician.
  • M. kansasii: Rifampin & Clarithromycin. For rifampin resistant isolates of M. kansasii: ethambutol, rifabutin, amikacin, ciprofloxacin, linezolid, moxifloxacin and trimethoprim/sulfamethoxazole are also reported.
  • M. avium-intracellulare: Clarithromycin, Moxifloxacin, Linezolid, MIC only on Ciprofloxacin & Amikacin. In vitro results for Rifampin, Rifabutin and Ethambutol are not predictive of clinical response and may be misleading; therefore results for these drugs are not reported routinely.
  • Rapid growers: (M. abscessus, M. chelonae, M. immunogenum, M. fortuitum complex, and M. mucogenicum): Amikacin, Cefoxitin, Ciprofloxacin, Clarithromycin, Doxycycline, Imipenem, Linezolid, Minocycline, Moxifloxacin, Tigecycline, and  Trimethoprim/sulfamethoxazole. Tobramycin reported on M. chelonae.
  • Other slow growing MOTT: Rifampin, Clarithromycin, Ethambutol, Rifabutin, Amikacin, Ciprofloxacin, Linezolid, Moxifloxacin, and Trimethoprim/sulfamethoxazole

Test Information

Test Number Test Name Recommended Use and Advantage
0060217 Antimicrobial Susceptibility, AFB/Mycobacteria Order for SUSCEPTIBILITY of clinically significant isolates of M. tuberculosis complex (MTBC), M. kansasii, M. avium-intracellulare complex, M. fortuitum complex, M. abscessus complex, M. chelonae, M. immunogenum, and any isolate from a significant source.
0060347 Antimicrobial Susceptibility, AFB/Mycobacterium tuberculosis Primary Panel Order when phenotypic drug susceptibility testing is required for M. tuberculosis treatment. For genotypic (DNA sequencing) resistance testing, refer to Mycobacterium tuberculosis Drug Resistance by Sequencing (2011713).
2011713 Mycobacterium tuberculosis Drug Resistance by Sequencing Order for rapid identification of mutations associated with drug resistance for M. tuberculosis treatment. For phenotypic drug susceptibility testing, refer to Antimicrobial Susceptibility, AFB/Mycobacterium tuberculosis Primary Panel (0060347).

References