ABSTRACT

Tuberculosis treatment remains a challenge due to the need to consider, when approaching it, the context of individual and collective health. In addition, social and economic issues have been shown to be variables that need to be considered when it comes to treatment effectiveness. We conducted a critical review of the national and international literature on the treatment of tuberculosis in recent years with the aims of presenting health care workers with recommendations based on the situation in Brazil and better informing decision-making regarding tuberculosis patients so as to minimize morbidity and interrupt disease transmission.

Keywords: Tuberculosis/drug therapy; Tuberculosis/prevention & control; Tuberculosis/surgery; Tuberculosis/classification.

RESUMO

O tratamento da tuberculose permanece um desafio em função da necessidade de que, em sua abordagem, seja considerado o contexto da saúde do indivíduo e da saúde coletiva. Adicionalmente, as questões sociais e econômicas têm-se mostrado como variáveis a ser consideradas na efetividade do tratamento. Ao revisarmos de forma crítica a literatura científica nacional e internacional sobre o tratamento da tuberculose nos últimos anos, tivemos como objetivos apresentar aos profissionais da área de saúde as recomendações baseadas na realidade brasileira e fornecer os subsídios necessários para a melhor tomada de decisão frente ao paciente com tuberculose, de modo a minimizar a morbidade e interromper a transmissão da doença Em função disso, o TDO é recomendado.

Palavras-chave: Tuberculose/tratamento farmacológico; Tuberculose/prevenção & controle; Tuberculose/cirurgia; Tuberculose/classificação.

INTRODUCTION

Tuberculosis treatment is aimed at curing and rapidly reducing disease transmission. For this to occur, the drugs used should be able to reduce the bacillary population rapidly (interrupting transmission); prevent selection of naturally resistant strains (avoiding the emergence of drug resistance during therapy); and sterilize the lesion (preventing disease relapse).(1)

Although antituberculosis regimens have an efficacy of up to 95%, treatment effectiveness (patients who are cured at the end of treatment under routine conditions) varies greatly with location, with the national average being around 70% (50-90%). One of the causes of low effectiveness is nonadherence, which can occur at three levels(2,3):
 treatment default (patients stop using all medications) or
 incorrect medication use (patients use some of the prescribed medications) and/or
 irregular medication use (patients take the medications some days of the week but not every day of the week)
 Treatment adherence problems are responsible both for treatment failure and for selection of resistant organisms and disease relapse. In order to improve adherence to tuberculosis treatment and restructure health care facilities, the World Health Organization (WHO) has, since the early 1990s, recommended the adoption of the directly observed treatment, short course (DOTS) strategy. The DOTS strategy includes five elements(4,5):

1. Political commitment and financial support to maintain tuberculosis control activities
2. Identification of tuberculosis cases on the basis of sputum smear microscopy among patients with respiratory symptoms
3. A standardized antituberculosis drug regimen administered as directly observed treatment (DOT) for at least the first 2 months of treatment
4. Guarantee of a regular supply of antituberculosis drugs
5 A system for reporting and assessment of treatment results for each patient and for the tuberculosis control program as a whole

Although supervised medication-taking through DOT allows frequent contact between patients and the health care system and favors treatment adherence, systematic reviews have failed to demonstrate greater effectiveness of DOT compared with self-administered treatment.(6-8) This probably occurs because treatment effectiveness is in fact related to several factors (Chart 1) and not only to medication-taking, which is a variable related to patient care.
 




Nevertheless, DOT remains the standard practice of most tuberculosis control programs in the USA and Europe, since it appears to be significantly associated with sputum smear conversion (from positive to negative) during treatment. As a result, DOT is recommended in both Europe and the USA for all forms of tuberculosis. In 1998, the Programa Nacional de Controle da Tuberculose (PNCT, Brazilian National Tuberculosis Control Program) implemented DOT in Brazil, and, since 2000, measures of decentralization have been taken, including integration of tuberculosis control into primary health care and the proposal to provide DOT at 100% of the health care clinics in the priority cities and for at least 80% of patients with active tuberculosis in those cities; however, this has not occurred. It should be borne in mind that most of the countries that use DOT offer intermittent (non-daily) treatment, as is the case in Brazil.(1,2,9,10)

There are situations in which self-administered treatment cannot be used, however, and, in such cases, all efforts should be made toward DOT. Such cases include patients with drug-resistant tuberculosis or at high risk of developing drug resistance (individuals without a fixed home; drinkers; users of illicit drugs; individuals who cannot take medications on their own because of mental, emotional, or physical impairment; children and adolescents; individuals deprived of their liberty; and individuals with a history of nonadherence to treatment).(11,12)

TUBERCULOSIS AND THE BRAZILIAN NATIONAL HEALTH CARE SYSTEM

Reporting of tuberculosis is mandatory in Brazil. The report form should record patient identification data, place of origin of the case, clinical form of the disease, and comorbidities. In addition, tuberculosis case type should be indicated on the form (field 32: type of admission). Below are the definitions of the types of admission for tuberculosis cases used in the Brazilian Case Registry Database. A new case is defined as one in which the individual has never received antituberculosis treatment or received it for up to 30 days. A retreatment case or a case of readmission after default is defined as one in which the individual was treated for more than 30 days and requires additional treatment because of relapse after cure or return after default. A relapse case is defined in the PNCT manual (2011) as one in which the individual with active tuberculosis has been previously treated and cured, regardless of the time elapsed since the previous treatment. In tuberculosis relapse cases, it is mandatory to request sputum culture and drug susceptibility testing for Mycobacterium tuberculosis, and the possibility of resistance to antituberculosis drugs should be ruled out. Until culture and drug susceptibility testing results are available, treatment with the basic regimen should be initiated. This working definition does not include relapse due to lack of sterilization of a lesion of exogenous reinfection, a piece of information that might be relevant in the assessment of the efficacy and effectiveness of both the treatment and the tuberculosis control program. Studies conducted in Africa, Europe, and the USA suggest that most relapse cases occurring two years after cure are due to reinfection and not to relapse. In fact, a certain diagnosis of relapse of tuberculosis would be made regardless of length of discharge as cured and would be based on the identification of the same M. tuberculosis cluster by a molecular biology technique (fingerprinting). However, in Brazil, fingerprinting is available only in research laboratories and in some private laboratories. Field 32 (type of admission) also includes the following options: "transfer"; "post-death"; and "unknown." The term "transfer" is used to refer to the admission of patients coming from another city, and this type of admission can produce changes in tuberculosis indicators, since these data are excluded from the calculation of the rates of diagnosis and treatment outcomes, such as treatment default. The same applies to the terms "unknown" and "post-death". Therefore, in Brazil, there is uncertainty regarding the representativeness of the tuberculosis indicators presented by the PNCT.

Antituberculosis drugs are provided free of charge, this being guaranteed by the PNCT, and they are not commercially available. These drugs are widely available in the public health care system, but they are dispensed to patients only upon presentation of a completed report form. The responsibility of completing the report form lies with the health care worker who makes the diagnosis of tuberculosis and prescribes the medication.(1,10,13,14)

TUBERCULOSIS TREATMENT

Tuberculosis treatment in adults

In the 1940s, the Brazilian National Campaign against Tuberculosis was started, and, during that period, two antituberculosis drugs were used: streptomycin and para-aminosalicylic acid. In the 1950s, Brazil chose to use a twice-weekly regimen with isoniazid and streptomycin. In the 1960s, given bacterial resistance and the increase in mortality from tuberculosis, treatment regimens began to be standardized, and the use of isoniazid (H), streptomycin (S), and pyrazinamide (Z) for 18 months (HSZ regimen) was implemented. (15,16) In the mid 1970s, short-term antituberculosis chemotherapy, with rifampin (R), isoniazid (H), and pyrazinamide (Z) for 6 months (RHZ regimen), was developed. Brazil was the first country in the world to implement the 6-month regimen in the public health care system, with all drugs being administered p.o. and being distributed free of charge. In the 1980s, combination capsules of RH were implemented already aiming to prevent acquired bacterial resistance. In 2009, Brazil introduced the use of fixed-dose combination (FDC) tablets and added ethambutol (E) to the RHZ regimen, as defined by the PNCT, on the basis of the preliminary results of the Second National Survey on Antituberculosis Drug Resistance, which showed an increase in primary resistance to isoniazid (from 4.4% to 6.0%). In addition, besides the change in presentation to FDC, the doses of isoniazid and pyrazinamide in the tablets were reduced in the treatment change (from 400 mg to 300 mg and from 2,000 mg to 1,600 mg, respectively), without bioavailability or bioequivalence studies being carried out. The basic regimen currently used in Brazil for the treatment of adults with tuberculosis and without clinical suspicion of drug resistance is presented in Chart 2. It consists of a 2-month intensive phase with the FDC RHZE regimen, followed by a 4-month maintenance phase with the FDC RH regimen, and it is used for all forms of the disease in patients over 10 years of age. The exception is patients with meningitis due to tuberculosis, who, in the maintenance phase, are treated for 7 months and with the combination of an oral corticosteroid (prednisone, at a dose of 1-2 mg/kg/day for 4 weeks) or an i.v. corticosteroid (dexamethasone, at a dose of 0.3-0.4 mg/kg/day for 4-8 weeks).(10,15,16) The medications are available in FDC tablets. Each tablet contains 150 mg of rifampin, 75 mg of isoniazid, 400 mg of pyrazinamide, and 275 mg of ethambutol.

As defined in the PNCT handbook on tuberculosis,(10) the second phase of treatment can be extended for 7 months, after consultation with a referral center, in the following cases:
Patients with HIV/AIDS
Patients whose direct smears show few organisms at 5 or 6 months of treatment, alone, as long as there is clinical and radiological improvement-treatment can be extended for an additional 3 months, at which period cases should be redefined or closed
Patients with negative direct smears and an unsatisfactory clinical and radiological course
Patients with cavitary forms who remain smear-positive at the end of the second month of treatment-in such cases, culture and drug susceptibility testing are mandatory
Patients with monoresistance to rifampin or isoniazid, identified in the maintenance phase of treatment-a careful assessment of the clinical, bacteriological, and radiological course, as well as of adherence and previous tuberculosis treatment, should be performed at or under the guidance of a tertiary referral center
 




According to the literature, individuals at the highest risk of relapse of tuberculosis (due to lack of sterilization of the lesion) include those whose weight is less than 10% of the ideal weight and whose weight gain is less than or equal to 5% in the intensive phase of treatment; smokers; and patients with insulin-dependent diabetes, HIV infection, or another immunosuppressive condition. For such individuals, extension of the maintenance phase of treatment should be considered. In addition, in patients who had cavitation (total diameter ≥ 2 cm) on the initial chest X-ray and are culture positive for M. tuberculosis at the end of the first 8 weeks of treatment (completion of the intensive phase of treatment), the maintenance phase of treatment can be extended for an additional 3 months because of the increased risk of relapse. Unfortunately, only 15-20% of the cases of pulmonary tuberculosis in Brazil undergo sputum culture and drug susceptibility testing.(1,17-23)

In cases in which it is impossible to use the basic regimen because of intolerance to two or more drugs, the use of a regimen for multidrug-resistant tuberculosis (MDR-TB) is indicated (Chart 3). In instances of treatment failure (as defined by the PNCT: individuals who remain sputum smear-positive at the end of treatment; individuals who are ++ or +++ smear positive and remain so until the fourth month of treatment; and those with initial smear-positivity followed by smear-negativity and then smear-positivity again for 2 consecutive months, from the fourth month of treatment onward), the use of the basic regimen should be extended until culture and drug susceptibility testing results are available. The possibility of nontuberculous mycobacterial infection should be considered, as should medication dosage error, irregular medication use, and inadequate drug absorption. The bioavailability of the drugs used in the treatment of tuberculosis (except rifapentine) is increased when they are taken on an empty stomach (the bioavailability of rifapentine increases by up to 86% with high-fat meals). If the medications need to be taken with foods or liquids, glucose-rich or lactose-rich foods should be avoided, since glucose and lactose reduce the absorption of isoniazid. Few drug interactions can cause substantial changes in the concentrations of medications for tuberculosis treatment; however, medications for tuberculosis treatment often cause clinically relevant changes in the concentrations of other drugs.(1,10,24,25)
 

 


 




Tuberculosis treatment in children

In Brazil, patients under 10 years of age are treated with three medications: rifampin (10 mg/kg), isoniazid (10 mg/kg), and pyrazinamide (35 mg/kg). This decision is based on the lower risk of resistance to isoniazid in patients with a low bacterial load, as is more common in children with tuberculosis, and on the risk of ethambutol-related visual impairment, the diagnosis of which can be difficult in children.(24,26,27)

On the basis of systematic reviews of the literature, the American Academy of Pediatrics(27) recommends the four-drug treatment, with the addition of ethambutol, in the intensive phase of treatment, along with monitoring of visual acuity and of the ability to discriminate between red and green colors. In cases of children whose visual acuity cannot be monitored, the risk-benefit ratio of the use of ethambutol should be considered, observing that ethambutol can be routinely used to treat active tuberculosis in infants and children unless there is some other contraindication. (27) The WHO recommends that HIV-negative children with pulmonary tuberculosis who live in areas with a low prevalence of HIV infection and a low prevalence of resistance to isoniazid can be treated with three drugs (RHZ regimen) in the induction phase, without the addition of ethambutol. In cases of children who live in areas with a high prevalence of HIV infection and/or a high prevalence of resistance to isoniazid, ethambutol should be added to the regimen in the induction phase.(27,28)

Tuberculosis treatment: approaches in cases of treatment interruption

Occasionally, patients interrupt drug therapy during treatment. Chart 4 presents the management of such cases in each of six circumstances.(1)

Tuberculosis treatment outcomes

Reporting of treatment completion (outcome) is obligatory in the same way as reporting of tuberculosis cases for treatment initiation. Below are the definitions of treatment outcome. Cure is defined as a negative sputum smear or culture in the last month of treatment and at least once previously, in cases of tuberculosis confirmed bacteriologically at the start of treatment. Failure is defined as a positive sputum smear or culture at 5 months or later during treatment. Default is defined as tuberculosis treatment interruption of ≥ 30 days after the predicted date of return (self-administered treatment) or of 30 days after the last drug intake (DOT; for management of treatment interruptions, see Chart 4). A death from tuberculosis is defined as a death caused by tuberculosis and occurring during treatment. A death from another cause is defined as a death from a cause other than tuberculosis and occurring during treatment.(10,29)
 


DRUG-RESISTANT TUBERCULOSIS
Cases of drug-resistant tuberculosis are classified according to the susceptibility of M. tuberculosis to first- and second-line drugs used in the pharmacological treatment of this disease. Below are the definitions of the main terms used in communication about cases of drug-resistant tuberculosis. Monodrug-resistant tuberculosis is defined as tuberculosis caused by organisms resistant to one first-line antituberculosis drug. Polydrug-resistant TB is defined as tuberculosis caused by organisms resistant to more than one first-line antituberculosis drug (except isoniazid and rifampin, resistance to both of which is characterized as multidrug resistance). MDR-TB is defined as tuberculosis caused by organisms resistant to both isoniazid and rifampin. Extensively drug-resistant tuberculosis is defined as tuberculosis caused by organisms resistant to rifampin, isoniazid, a fluoroquinolone, and at least one of three injectable second-line drugs (amikacin, kanamycin, or capreomycin). Rifampin-resistant tuberculosis is defined as tuberculosis caused by organisms identified as having resistance to rifampin by rapid molecular testing for tuberculosis drug resistance (with it being possible that there are other resistances still unknown, since a large proportion of cases identified as having resistance to rifampin also have resistance to isoniazid).(29,30)
In addition to the classification of tuberculosis based on the susceptibility of organisms to drugs, mycobacterial resistance can be classified as primary or acquired. Primary resistance occurs in tuberculosis caused by a bacillary population that is primarily resistant to an antituberculosis drug. In such cases, the individuals have never used an antituberculosis drug and are infected with an already resistant strain, presumably transmitted by a case of acquired resistance. Acquired resistance is that which occurs in a bacillary population that is initially susceptible to antituberculosis drugs and subsequently acquires resistance to some of them. Since the frequency of spontaneous mutations is low and since the use of an appropriate combination of drugs in the pharmacological treatment of tuberculosis makes the occurrence of clinically significant resistance unlikely, this type of resistance is presumably the result of irregular or inadequate treatment.(1)

Drug-resistant tuberculosis treatment

Drug-resistant tuberculosis treatment depends on the type of resistance identified. The approaches in cases of monoresistance and polyresistance are described in Chart 5.
 



The presence of multidrug resistance (resistance to RH or to RH and another first-line drug) is an indication for the use of the MDR-TB treatment regimen. The MDR-TB treatment regimen (Chart 3) has been changed by including capreomycin (as the injectable drug of choice because it results in fewer side effects and less cross-resistance with other injectable drugs); by replacing ethambutol with ethionamide when drug susceptibility testing shows resistance to ethambutol; and by using levofloxacin (in accordance with the recommendations of the WHO). Note that pyrazinamide should always be used in the intensive phase of treatment, even when drug susceptibility testing shows resistance, since there are limitations to interpreting such results (do not use pyrazinamide only in cases of hepatotoxicity or severe adverse effects).(30)

In cases of rifampin-resistant tuberculosis as determined by a rapid molecular test for tuberculosis drug resistance, initiate treatment with the recommended regimen (Chart 4) and wait until drug susceptibility testing results are available. If drug susceptibility testing shows susceptibility to all drugs, assess the risk of resistance on a case-by-case basis. In low-risk patients, start the basic regimen, which should be administered for 6 months, regardless of duration of MDR-TB regimen use. In high-risk patients (for example, retreatment cases, contacts of MRD-TB patients, or alcohol and drug users), maintain the MDR-TB regimen.

In patients who have already used capreomycin, use amikacin as an alternative in those who do not have resistance to streptomycin as determined by drug susceptibility testing and who have not used amikacin; amikacin can be considered for use in patients with a history of previous treatment. Assess each case individually on the basis of medications used and drug susceptibility testing results.(30)

Treatment of extensively drug-resistant tuberculosis (Chart 3) should be carried out at a tertiary health care facility, specializing in the treatment of drug-resistant tuberculosis. Individualized regimens and salvage drugs are used.(24)

Adverse reactions to tuberculosis treatment

The most frequent adverse reactions to the RHZE regimen are a change in urine color (it occurs universally), gastric intolerance (in 40% of patients), skin changes (in 20%), jaundice (in 15%), and joint pain (in 4%). The major associated factors are age (from the fourth decade of life onward), alcohol dependence (daily alcohol intake > 80 g), malnutrition (loss of more than 15% of body weight), history of liver disease, and HIV coinfection. Chart 6 presents the suggested approaches to major adverse reactions; it is important to note that, when an adverse reaction results from a hypersensitivity reaction (thrombocytopenia, hemolytic anemia, or renal failure), the suspected drug should not be restarted after discontinuation, since the adverse reaction upon reintroduction is even more intense and severe.(10,24,31,32)
 



In two observational studies conducted in Brazil,(32,33) the frequency of adverse reactions to the use of the RHZE regimen was found to be 47.5% and 83.4%, respectively, which is higher than that historically seen in the medical literature; however, there were no severe reactions or the need for treatment discontinuation. The most common adverse reactions were joint pain and gastric reactions, followed by skin reactions.(32,33)

TUBERCULOSIS AND LIVER DISEASE

The risk of hepatitis induced by drugs used in tuberculosis treatment is increased in patients with liver disease, especially in those with advanced liver disease, those undergoing liver transplantation, and those with hepatitis C, and therefore it is necessary to monitor transaminases-alanine aminotransferase (ALT) and aspartate aminotransferase (AST)-and bilirubin every 1-4 weeks in the first 2-3 months.(1) In patients with chronic, stable liver disease who are asymptomatic, do not have cirrhosis, and have ALT levels ≤ 3 times the upper limit of normal (ULN), the basic regimen can be used unchanged; in those with ALT levels > 3 times the ULN, the RHE regimen should be used for 2 months in the intensive phase and RH should be used for 7 months in the maintenance phase.(34,35) In symptomatic chronic liver disease with ALT levels > 3 times the ULN, the following regimens can be used: HRES for 2 months followed by HE for 6 months; HRE for 2 months followed by HE for 6 months; HSE for 2 months followed by HE for 10 months; or SE + ofloxacin (O) for 3 months followed by EO for 9 months. In patients with cirrhosis, the regimen with the least hepatotoxic potential is used: RE + a fluoroquinolone or ofloxacin or cycloserine, for 12-18 months. In cases of acute hepatitis, an attempt should be made to defer tuberculosis treatment initiation until hepatitis resolves. If this is not possible, prescribe the SE regimen for 3 months followed by RH for 6 months or the SEO regimen for 3 months followed by RH for 6 months (in extensive tuberculosis) and ofloxacin (400 mg/day) once daily in the morning, regardless of body weight.(1,10,11,24,27,34-40)

A transient increase in ALT/AST may occur during the first weeks of treatment, being of no clinical significance. Treatment should be discontinued only if there is anorexia, malaise, and vomiting and the ALT level is > 3 times the ULN or when the ALT level is > 3 times the ULN, even in the absence of symptoms, if jaundice is present. In cases of hepatotoxicity induced by tuberculosis treatment and ALT > 5 times the ULN, even in the absence of symptoms, treatment should also be discontinued.(1,10,24)

After discontinuation of tuberculosis treatment, investigate alcohol abuse and use of other hepatotoxic medications. Every patient with a history of alcoholism and being treated for tuberculosis should receive pyridoxine (50 mg/day) to prevent peripheral neuritis. In severe cases, until the cause of the abnormality is identified, or in cases in which transaminase and/or bilirubin levels do not return to normal after 4 weeks off treatment, use the SEO regimen for 3 months followed by EO for 9 months, with or without the addition of isoniazid. Given the efficacy of isoniazid and, especially, of rifampin, their use should always be attempted, even in the presence of preexisting liver injury.(1,10,24)

In cases of hepatotoxicity caused by tuberculosis treatment, the medication can be restarted when the ALT level is < 2 times the ULN. Reintroduction should occur gradually, with one drug at a time. First rifampin, with or without ethambutol; after 3-7 days, reassess the ALT level: if there is no increase, restart the use of isoniazid 1 week after the introduction of rifampin and restart the use of pyrazinamide 1 week after the introduction of isoniazid. If ALT levels increase or if symptoms recur, discontinue the last medication added. In patients experiencing prolonged or severe hepatotoxicity (ALT > 10 times the ULN), do not use pyrazinamide; use the RHE regimen for 2 months followed by RH for 7 months.(1,10,24)

TUBERCULOSIS AND DIABETES

In insulin-dependent patients, it is suggested that the RHZE regimen be extended for 9 months. In non-insulin-dependent patients, the regimen remains unchanged, with attention being given to the prophylactic use of pyridoxine and the possible need for the use of insulin during tuberculosis treatment.(1,10,21,24)

TUBERCULOSIS AND IMMUNOSUPPRESSION

In cases of tuberculosis/HIV coinfection, initiation of antiretroviral therapy (ART) should be based on the degree of immunosuppression; in cases of patients whose CD4 counts are below 50 cells/mm3, ART should be initiated 2 weeks after initiation of antituberculosis treatment, and, in other cases, ART should be initiated only after the eighth week of treatment. When tuberculosis is diagnosed in patients already receiving ART, it may be necessary to change ART to allow the addition of rifampin to therapy, and, in such cases, efavirenz is the antiretroviral of choice. Replacing rifampin with rifabutin is recommended when it is necessary to combine a protease inhibitor with ritonavir in the ART regimen. The recommended dose of rifabutin is 150 mg/day in such cases. The most frequent adverse reactions to rifabutin are exanthema (in 4%), gastrointestinal intolerance (in 3%), and neutropenia (in 2%).(1,23)

Immune reconstitution inflammatory syndrome is not an indication for discontinuation of any treatment. Its management includes the use of medications for treating symptoms and corticosteroids in cases that are more severe.

Transplant recipients should be treated at referral centers, with the RHZE regimen for 2 months followed by RH for 4 months, and treatment can be extended for up to 9 months. Attention should be given to possible drug interactions with corticosteroids, cyclosporine, and azathioprine.(1,23,35)

TUBERCULOSIS AND PREGNANCY

During pregnancy, the RHZE regimen can be administered at the usual doses, and concurrent use of pyridoxine (50 mg/day) is recommended because of the risk of newborns having convulsive seizures. Although the medications in the RHZE regimen cross the placental barrier, they do not appear to be teratogens. Regarding breastfeeding, although the medications are present in breast milk in small amounts, there is no risk of toxicity to newborns nor is there any prophylactic effect.(10,24,40)

TUBERCULOSIS AND RENAL FAILURE

Tuberculosis patients with renal failure have poorer outcomes than do those with normal renal function and should be assessed more often. Rifampin and isoniazid are metabolized in the liver and do not require dose adjustment. Pyrazinamide is also metabolized in the liver, but its metabolite may accumulate in patients with renal failure, as may ethambutol, since its metabolism occurs mainly (80%) in the kidneys; therefore, for these two medications, the recommended use is 3 times a week.(41,42)

Another recommendation is that the medications be administered after a hemodialysis session, since, although the hemodialysis session cannot eliminate rifampin, it efficiently removes pyrazinamide metabolites and partially removes isoniazid and ethambutol. The influence of peritoneal dialysis on the concentrations of antituberculosis drugs is unknown, and the recommendations for hemodialysis patients should not be applied to peritoneal dialysis patients; however, attention should be given to possible toxicity.(1)

The safest regimen in renal failure is RHZ for 2 months followed by RH for 4 months (creatinine clearance between 30-50 mL/min). The treatment is changed in renal failure patients with creatinine clearance < 30 mL/min or undergoing dialysis (administer after dialysis). In such patients, use isoniazid at a dose of 300 mg/day or 900 mg 3 times a week; rifampin at a dose of 600 mg/day or 600 mg per administration 3 times a week; pyrazinamide at a dose of 25-35 mg/kg per administration 3 times a week (do not administer daily); ethambutol at a dose of 20-25 mg/kg per administration 3 times a week (do not administer daily); levofloxacin at a dose of 750-1,000 mg/kg per administration 3 times a week (do not administer daily); moxifloxacin at a dose of 400 mg daily; ethionamide at a dose of 250-500 mg/kg per administration daily; streptomycin at a dose of 15 mg/kg per administration 2-3 times a week (do not administer daily); and amikacin at dose of 15 mg/kg per administration 2-3 times a week (do not administer daily).(1)

SURGICAL TREATMENT OF TUBERCULOSIS

Although tuberculosis is treated by using medications, occasionally, it may even be treated surgically in specific cases, especially in cases of drug resistance and in some pulmonary tuberculosis complications. Surgical lung biopsy has application in the differential diagnosis of pulmonary tuberculosis and lung cancer. The indications for surgical treatment include mainly endobronchial tuberculosis, as well as severe adverse reactions, severe hemoptysis, empyema, pneumothorax, and bronchopleural fistula. In tuberculosis sequelae, surgical interventions may be required in cases of symptomatic pulmonary residue, fungus ball, and hemoptysis.(24)

LATENT TUBERCULOSIS INFECTION (LTBI)

LTBI is defined as the presence of a specific immune response to M. tuberculosis in the absence of clinical signs of disease. The number of viable organisms in such cases is unknown, but it is believed to be low. The lifetime risk of reactivation tuberculosis in individuals with documented LTBI is 5-10%, and most develop the disease in the first 5 years after the initial infection. However, this risk depends on several factors, the most important of which is the immune status of the individual. In Brazil, the estimated number of individuals infected with M. tuberculosis is 50 million, which represents a challenge for tuberculosis control in the country. One of the tuberculosis control strategies is the reduction of this large reservoir of individuals infected with M. tuberculosis who are at risk of progression to active disease.(3,43-45)

Assessment of patients on anti-TNF-α therapy and immunosuppressive therapy

TNF-α plays a central role in granuloma formation, and, since anti-TNF-α agents began to be used, the reported incidence rate of tuberculosis has increased, many of such cases being cases of extrapulmonary tuberculosis and usually occurring during the first six infusions. Therefore, every patient who is a candidate for TNF-α blocker therapy should be assessed for LTBI (epidemiology, chest imaging, and specific immunity to M. tuberculosis). Tuberculin skin testing (TST) and IFN-γ release assays are adversely affected by several immunosuppressive drugs commonly used by this group of patients, and uncertainty persists as to the screening test of choice. Until better evidence is available, both seem feasible for the diagnosis. TST results ≥ 5 mm(10) or positive IFN-γ release assays indicate the need for LTBI treatment, which should be instituted for at least 30 days before the initiation of anti-TNF-α therapy. When it is not possible to carry out TST, take epidemiological risk and imaging tests into special account and assess each case individually in terms of risk/benefit. Chest CT can bring additional information because it is more sensitive than chest X-ray in detecting lesions suggestive of LTBI.(20,46-51)

Corticosteroid therapy with doses equivalent to 15 mg/day of prednisone for more than 1 month is an indication for LTBI treatment if TST results are ≥ 5 mm in individuals under 65 years of age. In individuals aged 65 years or older, the increased risk of hepatotoxicity would be a limitation for this indication. In dialysis patients, the risk of reactivation tuberculosis is at least 10 times higher than in the general population. A TST result ≥ 10 mm appears to identify patients at increased risk of developing the disease and is an indication for LTBI treatment. It is estimated that 25-30% of patients with silicosis will develop tuberculosis. LTBI treatment is recommended if TST results are ≥ 10 mm.(10,52,53)

LTBI treatment

LTBI is treated with isoniazid at a dose of 5-10 mg/kg of body weight up to a maximum of 300 mg/day for 6 months or with isoniazid (900 mg) plus rifapentine (900 mg) once a week for 3 months, and LTBI cases should be reported using a specific form. The risk of hepatitis with either regimen is very low, and monitoring of hepatic aminotransferase levels during LTBI treatment is recommended only in individuals with liver disease or with risk factors for liver disease. In individuals who do not tolerate isoniazid, an alternative treatment is the use of rifampin for 4 months.(10,43,54)

There is as yet no clear evidence to guide the choice of drugs for LTBI treatment in contacts of index cases that are known to be drug-resistant. Logic indicates that contacts of MDR-TB cases should be treated with drugs to which the organisms are susceptible. The decision regarding optimal treatment should be made at the referral center where the index case is followed. The WHO suggests that contacts should be carefully monitored for the development of active tuberculosis for 2 years instead of being treated for LTBI.(10,44)

A recent study demonstrated that 3-month administration, once a week, of a combination of isoniazid and rifapentine for LTBI treatment is safe and has efficacy similar to that of monotherapy with isoniazid in children aged 2-17 years. However, the small number of children under 5 years of age and of children infected with HIV limits the generalization of the study results in these important risk groups.(55,56)

NEW TREATMENTS FOR DRUG-SUSCEPTIBLE TUBERCULOSIS AND DRUG-RESISTANT TUBERCULOSIS

New drugs and new combinations of already known drugs have been tested in tuberculosis treatment with the aims of reducing treatment duration and increasing treatment effectiveness in cases of drug-susceptible tuberculosis and in cases of MDR-TB. After five decades without new drugs for tuberculosis treatment, bedaquiline (TMC-207) and delamanid (OPC-67683) have been approved by the US Food and Drug Administration for use in clinical practice. These two drugs are basically indicated for MDR-TB. Since 2009, clinical studies have demonstrated that the use of fluoroquinolones, especially moxifloxacin, in combination with other antituberculosis drugs, RHZ and rifapentine, significantly increases the rate of M. tuberculosis culture conversion in the eighth week of treatment, suggesting the possibility of treatment shortening. In a systematic review of clinical trials of fluoroquinolones versus ethambutol, which was published in 2016, the results showed that it was possible to reduce treatment to 4 months, while maintaining the same effectiveness in patients with noncavitary pulmonary tuberculosis and a positive culture; however, the results in clinical practice remain controversial.(57-59)

New scientific evidence

A recent joint publication by the Infectious Diseases Society of America, the Centers for Disease Control and Prevention, and the American Thoracic Society(2) presented tuberculosis treatment recommendations based on scientific evidence obtained by using the Grading of Recommendations, Assessment, Development and Evaluations (GRADE; Chart 7) approach,(60) all of which have been endorsed by the European Respiratory Society.(1) GRADE is a systematic approach that assesses quality of evidence and strength of scientific recommendations. The GRADE approach has been developed by the GRADE working group and is seen as the most effective method of assessing quality of evidence and clinical recommendations.
 

 




In comparing the PNCT recommendations with the new scientific evidence, we can see that some points can be assessed with a view to future revised PNCT recommendations, such as adopting supervised intermittent treatment in the second phase of treatment and not using corticosteroids in tuberculous pericarditis.(1)
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