Drug Resistant Tuberculosis Michael Lauzardo, MD MSc Director, Southeastern National Tuberculosis Center Chief, Division of Infectious Diseases and Global Medicine University of Florida

Section 1 Epidemiology of Drug Resistant Tuberculosis

Epidemiology of MDR-TB Globally • There were an estimated 390,000 to 510,000 cases of MDR TB globally in 2014 • Twenty-seven countries account for 86% of these cases • Four highest: • • • •

China 100,000 India 100,000 Russia 40,000 South Africa 15,000

• Almost all countries with the capability to diagnose XDR-TB have had at least one case of XDR-TB

MDR TB in the United States-2014 • Overall, the percentage of MDR TB cases decreased slightly from 1.4% (96 cases) in 2013 to 1.3% (91 cases) in 2014.** • Of the total number of reported MDR TB cases, the proportion occurring among foreign-born persons increased from 31% (149 of 484) in 1993 to 88% (80 of 91) in 2014. • The percentage of MDR TB cases among persons without a previous history of TB (1.0%) and the percentage of MDR TB cases among persons with a previous history of TB (3.4%) were lower in 2012 than in 2011.

Question List three reasons why Multi-drug resistant tuberculosis in the United States is low? What are some barriers that prevent us from lowering it even further?

Section 2 Pathogenesis and Transmission of Drug Resistant Tuberculosis

Multi-Drug Resistant (MDR) TB • Defined as resistance to isoniazid and rifampin • Created by poorly managed TB programs • Non-adherence to therapy • Poor quality drugs or supply

• Leads to bad outcomes • • • • •

Longer treatment (go from 6-24 months) Toxic regimens Cost increases 10-100 fold High death rates Disastrous outcomes in HIV settings

Mutations and TB Drug Resistance

Nature Genetics 45,1183– 1189(2013)

Spontaneous mutations develop as bacilli proliferate to >108

Drug Mutation Rate Rifampin 10-8 Isoniazid 10-6 Pyrazinamide 10-6 20

Multidrug therapy: Drug-resistant mutants No bacteria resistant to all 3 drugs in large bacterial population INH

RIF PZA

INH Monotherapy: INHresistant bacteria proliferate 21

Spontaneous mutations develop as bacilli proliferate to >108 INH resistant bacteria multiply to large numbers

INH RIF INH INH mono-resist. mutants killed, RIF-resist. mutants proliferate  MDR TB 22

Question Are drug resistant strains as transmissible as drug-susceptible strains?

Are drug resistant strains as transmissible as drugsusceptible strains? • A case-control study by Snider et al. demonstrating that contacts of patients with drug-resistant and drugsusceptible incident cases of TB had an equal prevalence of positive tuberculin skin test results suggests that infectivity was not diminished by drug resistance. • In contrast, animal studies have shown that isoniazidresistant strains caused significantly less disease in guinea pigs than drug-susceptible strains. Snider et al Am Rev Respir Dis 1985; 132:125 32, Middlebrook Am Rev Tuberc 1954; 69:471 2, Riley Am Rev Respir Dis 1962; 85:511 25.

Question Are drug resistant strains likely to progress to active disease once infection is established?

Are drug resistant strains likely to progress to active disease once infection is established? • In the context of an effective TB program in San Francisco, Burgos et al found that strains that were resistant to isoniazid either alone or in combination with other drugs were less likely to result in secondary cases than were drugsusceptible strains. • In this setting, isoniazid-resistant and MDR TB cases were not likely to produce new, incident drug-resistant TB cases. • This presumed reduced pathogenicity may be related to mutations in the katG gene.

Are drug resistant strains likely to progress to active disease once infection is established? • It will depend on various factors: • Pathogen related • Undefined virulence factors • Variability in virulence between genotypes • Size of the infecting inoculum

• Host related • Presence of immunosuppression • Ethnic susceptibility to various strains

Genetic Diversity and MDRTB • Epistasis occurs when phenotypic effect of a mutation changes depending on other mutations. • Can either increase or decrease the “fitness cost” of mutations and can lead to increased prevalence of certain strains. • Beijing strain

Borrell and Gagneux, CMI 2011

Section 3 Diagnosis of Drug Resistant Tuberculosis

Diagnosis of Active TB Disease

Key: THINK TB

Diagnosis of Drug Resistance Clinical Characteristics • Previous treatment for TB disease (*recent? Selfadministered?) • History of exposure to an individual with MDR-TB • Recent emigration from a geographic region with a high prevalence of resistance to tuberculosis therapy (former USSR, China, Korea, Honduras, Peru) • Progressive clinical and/or radiographic findings while on TB therapy

Diagnosis of Drug Resistance Clinical Characteristics • Lack of sputum culture conversion to negative after 2 months of therapy for TB • Travel to a region with high rates of drug resistant TB • Residence or work in an institution or setting in which drug-resistant TB is documented • HIV

Diagnosis of Drug Resistance Limits of Clinical History and Epidemiology

• Retrospective, case control study to identify risk factors for MDR-TB and analyze impact of testing for rifampin resistance by rpoB gene mutation identification • Of 42 confirmed MDR-TB cases that were evaluated almost half (43%) of patients did not have any of the conventionally recognized risk factors for MDR

O’Riordan P. et al PLoS September 2008

Agar Proportion Method • Plate bacteria on media containing • No drugs • Critical concentrations of a drug

• Incubate for 3 weeks • Count colonies Isolate is resistant if the number of colonies on drugcontaining media is >1% of the colonies on drug-free media 35

Critical Concentration The lowest concentration of a drug that

•Inhibits growth of all susceptible strains AND

•Allows growth of all resistant strains

36

Critical Concentration Ethambutol

37 S.J.

Kim. 2005. Eur Respir J 25:564.

Group Activity The patient is a 35 year old engineer from India who developed symptoms compatible with TB 18 months after arriving in the US. He was diagnosed with TB started on four drug therapy and responded well initially but his susceptibility report came back showing MDR. His physician put him on an MDR regimen and sent for confirmatory results at a different lab. Review the results below and come up with five reasons why the results are what they are. Drug Tested

Lab 1

Lab 2

Lab 3

INH

R

R

S

Rifampin

R

S

S

PZA

S

S

N/A

Ethambutol

S

S

S

Strep

R

R

R

Reasons for Discordant DST Results • Bacterial population (isolate vs. subculture) • Differential growth kinetics • Different inoculation methods (size, clumps) • Different methods or media • Cross-contamination • Transcription, labeling errors • Problem strains and drugs • MIC ≈ critical concentration

39

Diagnosis of Drug Resistance • Conventional methods: (indirect/proportion method?) • Molecular Beacon Testing: • Real-time PCR test • Performed directly on AFB+ smears or on growth on solid media or MGIT tube • INH resistance: katG, inhA (85%) • RIF resistance: rpoB core region (>95%)

Diagnosis of Drug Resistance •

Line Probe Assays • commercially available in Europe – not cleared yet by FDA • Hain: detects presence of TB complex and gene mutations associated with Rifampin resistance (rpoB ) and INH resistance (kat G and inhA ) • In smear positive specimens: • Rifampin resitance: Sensitivity (98.9%) Specificity (99%) • INH resistance: Sensitivity (94%) Specificity (99%) • Turnaround times: 1-2 days

Molecular Detection of Resistance

Sensitivity and Specificity of MTB/RIF test for Detection of Rif and MDR as compared to Phenotypic Drug-Susceptibility Testing

Boemhme et al, NEJM 2010

•

Missed Rifampin Resistance with Liquid Media Phenotypic drug susceptibility testing (DST) methods for TB are assumed to

be the gold standard for identifying rifampin (RMP) resistance. • However, previous results indicated that low-level, yet probably clinically relevant, RMP resistance linked to specific rpoB mutations is easily missed by some growth-based methods. • OBJECTIVE: To compare the level of resistance detected on LöwensteinJensen (LJ) medium with resistance detected by the Bactec MGIT 960 automated DST (MGIT-DST) system for various rpoB mutants. • RESULTS:

• Full agreement between LJ and MGIT-DST was observed for mutations located at codons 513 (Lys or Pro) and 531 (Leu, Trp), which were always resistant by both methods. • For mutations 511Pro, 516Tyr, 533Pro, 572Phe, and several 526 mutations, LJ and MGIT results were highly discordant, with MGIT-DST failing to give a result or declaring the strains susceptible. •

J Clin Microbiol. 2013 Aug;51(8):2641-5.

Missed Rifampin Resistance with Liquid Media • CONCLUSIONS: • Phenotypic RMP resistance testing of M. tuberculosis is not a binary phenomenon for some rpoB mutations and that the widely used automated MGIT 960 system is prone to miss some RMP resistance-conferring mutations, while careful DST on LJ missed hardly any. • Given the association of these mutations with poor clinical outcome, our findings suggest that the gold standard for rifampin resistance should be reconsidered, in order to address the present confusion caused by discrepancies between phenotypic and genotypic results. • The impacts of these mutations will depend on the frequency of their occurrence, which may vary from one setting to another.

Section 4 Treatment of Drug Resistant Tuberculosis

Bonus Questions What is the infectious process that led to the x-ray appearance below? What is the patient’s sister’s favorite color? Hint: Answers must be in French

General Principles of Chemotherapy for TB Disease • Existence of mutant bacilli with innate resistance to antibiotic action

General Principles of Chemotherapy for TB Disease • Existence of mutant bacilli with innate resistance to antibiotic action • Slow or intermittent growth of mycobacterium which permits the persistence of viable organisms despite prolonged antibiotic treatment, because only actively replicating organisms are killed by antibiotics

Treatment of active TB disease FIRST TWO MONTHS

FOUR MONTHS POST CONVERSION

INH

300 MG/D PO

300 MG/D

RIF

600 MG/D PO

600 MG/D

PZA

15-30 MG/KG/D PO

EMB

15-25 MG/KG/D PO

STM

1 GM/D IM

“DOT Therapy Works!” • 95% of patients with TB will be cured by DOT • Decreases morbidity and mortality and cost (~ $1500/pt) • Decreases spread of disease • Average patient with TB infects 30 other individuals • Decreases resistance • MDR costs ~ $250,000 to cure with only ~ 80% success

• 5% of patients with active TB will be unable to complete therapy; requiring legal interventions and facilities to cure them • In S.F. one non-compliant patient with MDR-TB was responsible for 40 other cases

Causes of Inadequate Response to Therapy • Non-adherence ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! – DOT – Involuntary detention

• Increased drug resistance/incorrect sensitivities • Malabsorption/increased metabolism • Inability of drugs to penetrate effected tissues

Case Question A 48 year old man from Mexico who has lived in the United States for more than 20 years was evaluated by his primary care physician because of a cough of six weeks duration. The work up included the chest x-ray below. He was started on four drugs and after six weeks susceptibility tests came back showing low level INH resistance. What treatment regimen would you continue and why? How long would you treat?

Isoniazid Mono-resistant Disease • Among patients with INH mono-resistant TB, outcomes were improved with longer duration of RIF and PZA, use of daily treatment (not intermittent treatment) and with greater numbers of effective drugs. • Studies in the United States have reported relapse rates of 2 to 5% using 3- to 4-drug regimens administered for 6 or more months. • However, a large proportion (26-59%) of patients had treatment discontinued or the duration of treatment extended because of drug-related adverse reactions, usually associated with PZA. • Treatment outcomes do not differ based on whether the isolate has low- or high-level INH resistance in vitro

Rifampin Mono-Resistant TB • Include Isoniazid, ethambutol, fluorquinolone, supplemented with PZA for the first two months. • Consider using an injectable for the first two months in patients with extensive disease. • Duration of therapy is 12-18 months • In a BRMC trial, daily and thrice weekly therapy with isoniazid, PZA, and streptomycin given for 9 months was effective. • Not sure if ethambutol will be interchangeable with streptomycin in this regimen

Group Case Activity The patient is a 19 year old student from Peru who was seen in the Emergency Department because of worsening cough, weight loss, and now hemoptysis. He is immediately isolated, sputum specimens are obtained for AFB and he is started empirically on RIPE therapy. He initially responds well but after six weeks his susceptibilities come back and he is found to be resistant to isoniazid and rifampin. He has no other medical problems. His initial films are below.

10-13-2007

Group Case Activity With your small group develop an action plan about next steps that addresses the following:

1. Treatment regimen 2. Baseline Laboratory monitoring and other studies before starting new drugs 3. Further testing if any on the isolate 4. Contact Investigation

Guiding Principles for Treating MDR-TB • A single new drug should never be added to a failing regimen. • When initiating or revising therapy, always attempt to employ at least three previously unused drugs to which there is in vitro susceptibility. One of these should be an injectable agent. • Do not limit the regimen to three agents if other previously unused drugs that are likely to be active are available. • Patients should receive either hospital-based or domiciliary DOT. The implications of treatment failure and further acquired resistance are such that these cases should receive highest priority for DOT. • Intermittent therapy should not be used in treating tuberculosis caused by drug-resistant organisms, except perhaps for injectable agents after an initial period (usually 2--3 months) of daily therapy.

Guiding Principles for Treating MDRTB • The use of drugs to which there is demonstrated in vitro resistance is not encouraged because there is little or no efficacy of these drugs assuming the test results are accurate. • It should be noted that the use of INH was associated with better survival rates in patients with the strain-W variety of MDR M. tuberculosis that was susceptible to higher concentrations of INH. • Resistance to RIF is associated in nearly all instances with cross-resistance to rifabutin and rifapentine.

Case Question A 53 year old woman from Ukraine with a history of macular degeneration is diagnosed with pulmonary and renal tuberculosis and she is started on appropriate four drug therapy. After three weeks of therapy she develops a severe rash as seen in the photo below. After sequential re-introduction it is determined that the cause is rifampin and . Which of the following in fact she developed questionable angioedema options is the best option? 1.Treat with Benadryl or Atarax and continue treatment 2. Treat with INH, PZA, and EMB for 9 months 3. Treat with INH and PZA for 18 months 4. Admit to a hospital and desensitize to rifampin 5. Treat with four drugs but use rifabutin instead of rifampin

Guiding Principles for Treating MDR-TB • There is no cross-resistance between SM and the other injectable agents: amikacin, kanamycin, and capreomycin (although resistance to all may occur as independent events); however, cross-resistance between amikacin and kanamycin is universal. • Simultaneous use of two injectable agents is not recommended due to the absence of proof of efficacy and potential amplification of drug toxicity. • However, resistance to PZA is uncommon in the absence of resistance to other first-line drugs.

Second-line Drugs for Drug Resistant TB • • • • • • • • • •

Isoniazid Rifamycins Pyrazinamide Ethambutol Aminoglycosides Capreomycin Quinolones Thioamides Cycloserine PAS

• Need lab testing and or epi information on prevalent resistant strains • 4-6 drugs for 2 years • Less effective •