Vigorous debate followed the presentations, with great interest in Dr. Shen's algorithm, based on the growing evidence supporting the use of PCT as a tool to differentiate between causative CAP pathogens. Dr. Shen reported that a low PCT (< 0.35 ng/mL) is indicative of viral disease and the rise in PCT correlates with disease severity. While not routinely used at present, Prof. Kao said that he uses PCT in severe infections that have not responded to antibiotics.
Prof. Tsao was concerned at the algorithm's recommendation to use penicillin in patients with a positive pneumococcal urinary antigen test as many areas report high levels of penicillin resistance, and he believed that broad-spectrum, well-tolerated fluoroquinolones would be preferable.
Differences in regional resistance rates were discussed, with queries over the high rate of fluoroquinolone-resistant K. pneumoniae in China. The general view was that this reflected inappropriate fluoroquinolone regimens, and non-standardized generic drugs. Prof. Yew commented that this is also a possible reason for higher fluoroquinolone-resistant MDR-TB rates in China, where poor quality fluoroquinolones might have been used indiscriminately.
In regard to routine testing of TB in CAP patients, the faculty preferred testing to be targeted at patients with risk factors. Prof. Yew routinely recommends testing the sputum of CAP patients presenting with significant immunosuppression and diabetes, in particular. Dr. Lee agreed that while he would not perform routine sputum studies in young patients with a short history of RTI, he would perform a sputum analysis for AFB in patients with risk factors.
Prof. Tsao raised the issue of whether only fluoroquinolones or all antimicrobials delay the diagnosis of TB. Dr. Lee responded that results from a recent large study (Int J Tuberc Lung Dis 2011; 15(8): 1062-8) indicate that all antimicrobials delay the diagnosis of TB, not just fluoroquinolones. He stressed the need for a high level of suspicion of TB, and for the patient to have a chest X-ray followed by sputum examination. The need for improved initial chest X-ray analysis was raised, since many chest X-rays show signs of TB when assessed retrospectively.
In the Panel Discussion, Dr. Norio Doi, MD, PhD, Chief of New Anti-TB Drugs and Chemotherapy Project, Japan Anti-Tuberculosis Association, Tokyo, Japan, reported current incidence rates and trends in TB in Japan. There are approximately 23,000 new TB cases per year, with 1,400 deaths and less than 100 cases of MDR-TB. The rate of TB and HIV co-infection is very low, 20 cases or less. He drew attention to the large elderly population, with more than 80% of all new Japanese TB cases diagnosed in patients aged 60 to 90 years. The treatment results were very positive, with more than 80% of new MDR-TB patients cured following long-term chemotherapy.
Dr. Doi reported that the rate of levofloxacin-resistant M. tuberculosis is 3.2%, which Prof. Kao thought may be due to the high use of fluoroquinolones in Japan, while Prof. Yew commented that it may also reflect the high proportion of elderly population, with TB transmission occurring in nursing home facilities. Significant differences in the incidence of MDR-TB throughout Asia were of concern, with more than 16% of new TB cases in Thailand being MDR.
At the end of the Discussion, the faculty agreed on five take-home messages that, if followed, would improve the outcome of patients presenting with CAP and TB.
Improving outcome in CAP patients with possible TB
- TB must always be considered in patients presenting with CAP.
- An appropriate diagnostic work-up, including laboratory and radiographic evaluation, must be performed in patients suspected of having TB.
- IDSA and ATS guidelines for CAP should be followed, including ordering chest X-rays before starting empiric antimicrobial therapy.
- When clinical and/or chest X-ray findings suggest TB, sputum analysis for AFB should be performed.
- Physicians must remember that previous treatment with any antibiotic is associated with a delay in diagnosing TB.