Basic Principles and Concepts of M. TB and Resistance

1. Biological Characteristics and Condition of M. Tuberculosis Growth 2. Definitions and Basic Concepts in Resistances 3. Likelihood Generating MDR under NTP conditions

1. Biological Characteristics and Condition of M. Tuberculosis Growth

1. Causal Agent 1. Causal Agent 2. Reservoir. Source of infection 2. Reservoir. Source of infection 3. Mechanism of Transmission 3. Mechanism of Transmission 4. Susceptible Host 4. Susceptible Host

1. Causal Agent 1. Causal Agent

Causal Agent - Mycobacterium tuberculosis complex - Mycobacterium tuberculosis complex - M. tuberculosis - M. tuberculosis - M. bovis - M. bovis - M. africanum - M. africanum - M. microti - M. microti - M. caneti - M. caneti - M. pinnipedii - M. pinnipedii - M. caprae - M. caprae Difficult to Fight

Causal Agent - Mycobacterium tuberculosis complex - Mycobacterium tuberculosis complex - Resistant to: - Resistant to: Cold, Cold, Freezing Freezing and and Desiccation Desiccation

Causal Agent - Mycobacterium tuberculosis complex - Mycobacterium tuberculosis complex. - Very sensitive to Heat, Sunlight and U.V. radiation - Very sensitive to Heat, Sunlight and U.V. radiation

Causal Agent Causal Agent - Mycobacterium tuberculosis complex - Mycobacterium tuberculosis complex - Strictly aerobic (depends on Oxygen and pH)

Causal Agent - Mycobacterium tuberculosis complex - Mycobacterium tuberculosis complex - Polyvalent - Polyvalent behaviour behaviour depending depending on medium. on medium.

In a tuberculosis patient, there are different bacillary populations formed of bacilli in different situations ■ In a tuberculosis patient, there are different bacillary populations formed of bacilli in different situations - Location - pH - Replication rate, susceptibility to drugs, … Bacillary populations

1. Rapidly multiplying bacilli - Optimum medium: Extracellular. PH 6.5-7, maximum oxygenation (cavern wall) - Large number of bacilli → High probability of spontaneous natural mutations Many Millions Natural Resistant Mutants Failure

Relapses 2. Slow multiplication Bacilli - Intramacrophagic location. Acid pH. Population<10 5 No Naturally Resistant Mutants Bacillary populations

3. Intermittently growing bacilli - Unfavourable conditions. Solid caseum. Extracellular - Population <10 5- Relapse capacity No Naturally Resistant Mutants Relapses

Bacillary populations 1. Rapidly multiplying bacilliINH 1. Rapidly multiplying bacilli → INH - Optimum medium: Extracellular. PH 6.5-7, maximum oxygenation (cavern wall) - Large number of bacilli → High probability of spontaneous mutations 2. Slowly multiplying bacilliPZ 2. Slowly multiplying bacilli → PZ - Intramacrophagic location. Acid pH. Population< Intermittently growing bacilliRIF 3. Intermittently growing bacilli → RIF - Unfavourable conditions. Solid caseum. Extracellular - Population <10 5. Relapse capacity 4. Bacilli in latent state: 4. Bacilli in latent state: Not susceptible to drugs - Reactivations and relapses

- Slow and Little Alarmant Clinical Presentation - Excessive Delay to Consult the HC - Very Late Diagnosis Long time to be contagious when the Cases are Diagnosed Long time to be contagious when the Cases are Diagnosed - M. tuberculosis delay h. to be divided (60 < Estafiloc.) - M. tuberculosis delay h. to be divided (60 < Estafiloc.) M tuberculosis. Very Slow Division Capacity

Causal Agent - M. tuberculosis complex - M. tuberculosis complex - Differentiate from - Differentiate from Environmental M. (Atypical) (Atypical)

1. Biological Characteristics and Condition of M. Tuberculosis Growth 1. Causal Agent 1. Causal Agent 2. Reservoir. Source of infection 2. Reservoir. Source of infection 3. Mechanism of Transmission 3. Mechanism of Transmission 4. Susceptible Host 4. Susceptible Host Caminero JA. Tuberculosis Guide for Specialist Physicians. The Union 2004

2. Reservoir. Source of Infection

- MAN: - MAN: * Infected, healthy * Infected, healthy World Population: Millions M. TB Infection: Millions ¡¡ Possible Reservoir MDR-TB: 50 Millions !!

2. Reservoir. Source of Infection - MAN: - MAN: * Active disease * Active disease TB Cases: 16 million MDR-TB Cases:

2. Reservoir. Source of Infection - MAN: - MAN: * Infected, healthy * Infected, healthy * Active disease * Active disease - Animals: - Animals: * Bovine cattle (M. bovis) * Bovine cattle (M. bovis) * Others: Monkeys, Dogs, Cats, etc * Others: Monkeys, Dogs, Cats, etc

2. Reservoir. Source of Infection - MAN: - MAN: * Infected, healthy * Infected, healthy * Active disease * Active disease - Animals: - Animals: * Bovine cattle (M. bovis) * Bovine cattle (M. bovis) * Others: Monkeys, Dogs, Cats, etc * Others: Monkeys, Dogs, Cats, etc - Not Reservoir: Kitchen and cleaning utensils, etc

1. Biological Characteristics and Condition of M. Tuberculosis Growth 1. Causal Agent 1. Causal Agent 2. Reservoir. Source of infection 2. Reservoir. Source of infection 3. Mechanism of Transmission 3. Mechanism of Transmission 4. Susceptible Host 4. Susceptible Host

Mechanism of Transmission - Fundamentally AEROGEN - Fundamentally AEROGEN - Very Uncommon: - Very Uncommon: - Cutaneous-Mucosal - Cutaneous-Mucosal - Urogenital - Urogenital - Inoculation - Inoculation - Tran placental, etc - Tran placental, etc

TB Transmission. Contagious aerosol (droplets < 5 micras) The TB MDR/XDR-TB have the same capacity to generate Aerosols

Patients with TUBERCULOSIS must cover their Mouth when Coughing Surgical Masks only work if used by the Patient

Greatest TB Transmitters 1.- Persons with bad Coughs 2.- Sputum Sm+ Patients 3.- Untreated patients 4.- Patients who have just commenced treatment 5.- Cases with poor response to treatment

1. Biological Characteristics and Condition of M. Tuberculosis Growth 1. Causal Agent 1. Causal Agent 2. Reservoir. Source of infection 2. Reservoir. Source of infection 3. Mechanism of Transmission 3. Mechanism of Transmission 4. Susceptible Host 4. Susceptible Host

Epidemiological Sequence of TB Host Susceptible to Disease - Age Distribution - Age Distribution

TB Risk Groups Relative Risk of developing TB (compared with control population, regardless of PPD) - HIV/AIDS150 -Silicosis30 -Diabetes2 – 4.1 -Chronic renal failure / Haemodial.10 – Gastrectomy2-5 -Jejunoileal by-pass Kidney transplant37 -Heart “ Head or neck carcinoma 16 ATS/CDC. Am J Respir Crit Care Med 2000; 161 (part 2)

Basic Principles and Concepts of M. TB and Resistance 1. Biological Characteristics and Condition of M. Tuberculosis Growth 2. Definitions and Basic Concepts in Resistances 3. Likelihood Generating MDR under NTP conditions

2. Definitions and Basic Concepts in Resistances

M. tuberculosis Resistance Basic Concepts and Definitions Natural resistance Resistance in previously treated patients Resistance in previously untreated patients Poly-resistance Multidrug-resistance (MDR) Extensive-resistance (XDR) Failure Relapse and Poor Adherence

All these concepts are related to the growth and multiplication characteristics of M. tuberculosis Basic Concepts in TB Resistance

Basic Concepts in TB Resistances NATURAL Resistance

M. Tuberculosis Resistances 1. The ORIGIN

M. Tuberculosis Resistance Natural Resistance (1) - When all live species, - for the purpose of perpetuating the species reach a certain number of divisions, they undergo genomic mutations at random, which gives rise to organisms with certain altered functions. - This always occurs in the successive divisions of each species. It is therefore a dynamic function 15 million 12 hours

M. Tuberculosis Resistance Natural Resistance (2) Therefore, when the live species attain a number above 10,000 or 1 million, many of the organisms that make up the species present genetic mutations. Fortunately, the majority of these mutations do not have an obvious phenotypic expression. Sometimes it is necessary to subject the species to selective pressure for it to express the selected mutation

M. Tuberculosis Resistance Natural Resistance (3) Ever since M. tuberculosis has attacked man, way back in time, it has always presented multiple genomic mutations in its continuous divisions. Some of these mutations affect the genes in which anti- tuberculosis drugs work This means that these antibiotics cannot work against M. tuberculosis, and therefore phenotypically they show resistance to them.

M. tuberculosis Resistance Natural Resistant Mutants according to Bacillary Population INH1 x Bacilli RIF1 x Bacilli SM 1 x Bacilli EMB1 x Bacilli PZ1 x Bacilli ? Quinolones 1 x Bacilli ? Others 1 x Bacilli ?

M. tuberculosis Resistance Bacillary Population in different TB Lesions TB Sm Bacilli Cavitary Bacilli Infiltrated Bacilli Nodules Bacilli Adenopathies Bacilli Renal TB Bacilli Extrapul. TB Bacilli

M. Tuberculosis Resistance Selection of Resistant Mutants If Smear positive TB is treated with just ONE drug (H), for each million bacilli, it will kill 999,999, but it will select the resistant mutant (1) that exists. If this TB has a minimum of 1,000 million (10 9 ), in 2-8 weeks it will have selected the 1,000 mutant bacilli (10 -6 Bacilli) that are resistant in this population

M. Tuberculosis Resistance Selection of Resistant Mutants These 1,000 bacilli are insufficient to cause clinical symptoms or to be smear +. The problem is that these 1,000 will soon be 10 9

Appearance of resistance to INH administrated in Monotherapy Resistant Mutants Sensitive Bacilli Months after Start of Treatment No. of viable bacilli Mitchison DA. En: Heaf F, et al. Churchill, London, 1968

M. tuberculosis Resistance Resistant Mutants according to Bacillary Population As each drug has a different target to attack the bacilli, the genomic mutation that causes the resistance is different for each one of them. This is why the probability of finding a bacillus with 2 genetic mutations, that express resistance to 2 drugs, is equal to the exponential sum of their respective mutation rates: for INH+RIF for INH+RIF+EMB

M. Tuberculosis Cellular Wall & target point of Drugs

Selection of Resistant Mutants to M. tuberculosis Anti-TB Drugs select the resistant mutants They do not cause the mutation

Bacteriological Fundaments of TB Treatment 1. Drug combinations The combination of drugs prevents the appearance of resistance, because it avoids the selection of naturally resistant mutants

Basic Concepts in TB Resistance Resistance in Previously Treated Patients ACQUIRED Resistance

M. Tuberculosis Resistance ACQUIRED OR SECONDARY Resistance A patient with selection of resistant mutants from poor treatment will present a resistant TB  ACQUIRED RESISTANCE, also named “in previously treated patients”A patient with selection of resistant mutants from poor treatment will present a resistant TB  ACQUIRED RESISTANCE, also named “in previously treated patients” Therefore, acquired R. is always an expression of poor treatment:Therefore, acquired R. is always an expression of poor treatment: –Direct Monotherapy –Indirect Monotherapy (adding just one drug to an inefficient association) Behind an MDR TB patient, there is usually a long and unfortunate list of therapeutic errors (successive indirect monotherapies)Behind an MDR TB patient, there is usually a long and unfortunate list of therapeutic errors (successive indirect monotherapies)

Selection of Natural Resistance, Acquired and Initial Resistance SUSCEPTIBLE to Drugs RESISTANT Latent Contagious Latent Contagious Develop into DR TB transmission acquire DR-TB acquire (M)DR-TB transmission Develop into TB

Basic Concepts in TB Resistance Resistance in Preivously Untreated Patients Primary or INITIAL Res.

M. Tuberculosis Resistance PRIMARY or INITIAL Resistance If a person is infected by a patient with selected resistant mutants (Acquired R.), he/she may suffer TB with the same resistance pattern  PRIMARY RESISTANCE Primary resistance is that which presents in TB patients who have never received treatment (< 1 month)

M. Tuberculosis Resistance PRIMARY or INITIAL Resistance Initial R. is the same concept as primary R., but it is a practical term, and includes all patients who state they have Never been treated (some do not remember, others lie) Resistance in “previously untreated patients”

Basic Concepts in TB Resistance Poly-Resistance to Anti-TB Drugs to Anti-TB Drugs

Resistance to 2 or more drugs, independent of the drug. The worst situation is resistance to H+R, very difficult to cure M.D.R.For this reason, these patients receive an special name ---> M.D.R. M. tuberculosis Resistance Poly-Resistance

Basic Concepts in TB Resistance M.D.R.

M. Tuberculosis Resistance Multidrug-resistance (MDR) Defined as resistance at a minimum to “INH+RIF” It is extremely dangerous, as this TB is very difficult to cure MDR may be: –Primary or Initial –Acquired Will it determine the future of TB?

Basic Concepts in TB Resistance X.D.R.

Extensively-Drug-Resistant TB (XDR) - MDR. - Resistance, at least, to 3 of the 6 D.S.L. Groups: -Quinolones -Aminoglycosides: Kn, Ak -Polypeptids: Cm -Thioamides (Eth-Pth) -PAS -Cicloserine / terizidone WHO, October 10, MDR. - Resistance, at least, to: -Quinolones - One or More of the Injectable: - Aminogliyosides: Kn, Ak - Polypeptids: Cm

In TB, resistance is always the expression of poor individual or general management of patients The most Basic Concept in TB Resistance

Basic Concepts in TB Resistance Pharmacological Failure

- This is when a patient does not achieve a negative sputum smear at the end of the 4th- 5th month, or after achieving a negative one, it then becomes positive.

Pharmacological Failure -It is caused by continually growing bacilli. - Theoretically, It is accompanied by resistance to drugs used (not always in the field) - Drug Susceptibility Test (DST) should be performed

Basic Concepts in TB Resistance Bacteriological Relapse

-This is when a patient has concluded treatment and has been cured and then presents TB symptoms with positive bacteriology again.

Relapses 2. Slow multiplication Bacilli - Intramacrophagic location. Acid pH. Population<10 5 No Naturally Resistant Mutants Bacillary populations

3. Intermittently growing bacilli - Unfavourable conditions. Solid caseum. Extracellular - Population <10 5- Relapse capacity No Naturally Resistant Mutants Relapses

Bacteriological Relapse - It may be early (< 24 months) or late - Theoretically, it keep the same initial pattern of resistance (not always in the field). - DST should be performed.

Treatment After Default -A patient is defined if he/she returns to treatment bacteriologically positive after stopping taking treatment for more than 1-2 months. - Default in taking medication may be: - Total: Like a relapse Probably sensitive to drugs taken - Partial: Like a failure Probably resistant to the drugs taken

The High Risk of the Bad Adherence to Select Resistances in TB

streptomycin Isoniazid Ethambutol Rifampicin Mitchison DA, et al. Postgr Med J 1971;47: Post-Antibiotic Effects with M. tuberculosis Lag Periods before Commencement of Growth after Exposure in 7H10 Medium Lag after 24 hr exposure to drug (days) Sequential Monotherapy INH

streptomycin Isoniazid Ethambutol Rifampicin Mitchison DA, et al. Postgr Med J 1971;47: Post-Antibiotic Effects with M. tuberculosis Lag Periods before Commencement of Growth after Exposure in 7H10 Medium Lag after 24 hr exposure to drug (days) Sequential Monotherapy INH

Mitchison DA. In J Tuberc Lung Dis 1998;2:10-15 Bacteriopausal Effects During Regrowth Regrowth Killing phase Mutants resistant to A Mutants resistant to B Regrowth starting Lag due to drug A Lag due to drug B Number of viable bacilli

TB Re-treatment and Selection of Resistance - Theoretically: - Relapses and total defaulters have the same initial pattern of drug susceptibility - Failures and partial defaulters could amplify resistance - However, in the Field: - Relapses and total defaulters have an increased risk of resistance - A substantial proportion of failures are susceptible

Can the Relapses and Defaulters increase the Initial Pattern of Resistance? YES, because in the Field are influencing a lot of circumstances YES, because in the Field are influencing a lot of circumstances

The possible change in the Pattern of Resistances of the Relapses in the last years - However, currently, when the initial resistance to H is high in many settings, a lot of these failures are coming from the initial H resistant cases  selecting R resistance in the continuation phase years ago, when most of the TB cases in the community were susceptible to the anti-TB drugs, usually the relapses came from the dormant bacillus do not killed by the drugs.

Why the Relapses and Defaulters can increase the Initial Pattern of Resistance? - Definition of Cured Cases based in Sm  Some patients could be Sm-, but Culture +  In NTP they are classified as Cured but are Failures - Many times the Relapse is coming for the Initial resistance to a H  at the end of the continuation phase the Resistance to R has been selected - A lot of times after a Relapse there is a patient with maintained Bad Adherence  Danger to select Res.

Can a Failure be Susceptible ? YES, above all the Failures to Category I YES, above all the Failures to Category I

- In the field, Not all patients who fail a Cat. I regimen has MDR-TB, and the percentage may depend on a number of factors, above all: - Including whether rifampicin was used in the continuation phase - Whether DOT was used throughout treatment - Some other Circumstances Failures to Category I and MDR

Why a Failure can be Susceptible ? 5 Possibilities in the Field 5 Possibilities in the Field

Why an Operational Failure can be Susceptible? 5 POSSIBILITIES 1.Very Delayed Negativization (Later than 4º m.) 2. Bad Adherence (Supervision) to the Treatment 3. Nontuberculous Mycobacteria 4. Bacillary Escapes 5. Died Bacillus

However, this possibility that a Failure was Susceptible decrease very much in the Failures to Category II?

3. Likelihood Generating MDR under NTP conditions. Inadequate Strategies

Known Factors contributing to the MDR-TB 1.No DOTS 2.Bad Adherence / Supervision 3.No Standard Treatments 4.Frequent drug stock-outs 5.Anti-TB Drugs of Poor Quality 6.Important Private Sector 7.No Hospital Infection Control 8.High Virulent Strains M. TB 9.HIV in some settings Is it Possible to Generate MDR and XDR in NTP Conditions ?

The Risk to Amplify Resistances with Non Adequate Strategies The possibility to generate MDR in NTP conditions

2 HRZE / 4 HR Pansusceptible Initial Res. H Initial MDR The possibility to generate MDR in NTP conditions

2 HRZE / 4 HR Pansusceptible Strict DOT Strict DOT Bad Maintained Bad MaintainedAdherence CURE CURE Danger ! Danger ! Intermittent Tr. The possibility to generate MDR and XDR in NTP conditions

streptomycin Isoniazid Ethambutol Rifampicin Mitchison DA, et al. Postgr Med J 1971;47: Post-Antibiotic Effects with M. tuberculosis Lag Periods before Commencement of Growth after Exposure in 7H10 Medium Lag after 24 hr exposure to drug (days) Sequential Monotherapy INH

Mitchison DA. In J Tuberc Lung Dis 1998;2:10-15 Bacteriopausal Effects During Regrowth Regrowth Killing phase Mutants resistant to A Mutants resistant to B Regrowth starting Lag due to drug A Lag due to drug B Number of viable bacilli

2 HRZE / 4 H R Initial Res. H Initial Res. H Sm (-) 2ºMonth Sm (+) 2º M. Sm (+) 2º M. % CURE Extend 1ª Phase Extend 1ª Phase Go to 2ª Phase Go to 2ª Phase ¡ High Risk MDR-TB !, but Susceptible ZE ¡ High Risk MDR-TB !, but Susceptible ZE The possibility to generate MDR in NTP conditions

2 HRZE/ 4 HR FAILURE FAILURE 2. Initial Resistance to H (+%) The Risk to Amplify Resistance in the Failures to Cat. I receiving Category II Regime (2) 2 HRZE/4 H R MDR, but suscpt. Z+E 2HRZES/1HRZE/5H R E Risk to Amplify Resistance E (Avoidable if DST before 3rd Month)

Initial MDR Initial MDR 2 HRZE / 4 H R CURE (20-50%) CURE (20-50%) MDR-TB, Amplifying Resist. to Z+E MDR-TB, Amplifying Resist. to Z+E The possibility to generate MDR in NTP conditions

2 HRZE/4 HR FAILURE FAILURE 3. Initial M.D.R. (-%) The Risk to Amplify Resistance in the Failures to Cat. I receiving Category II Regime (3) 2 HRZE/4 H R HR+E+Z Resistance to HR+E+Z 2HRZES/1HRZE/5H R E Risk to Amplify Resistance to S

1.) Produce MDR, when: - Bad Maintained Adherence - Drugs Not Associated In the same Tablet - To Pass to 2ª Phase with Sm+, - Above all, if there is Initial Resistance to H 2.) Amplify Res. to ZE in Initial MDR and Sm+ - The Regimen Category I could: The possibility to generate MDR in NTP conditions

- Recommendations: 1. To Assure, at the maximum, the Adherence 2. To Prolong 1 month 1 st phase if Sm+ at 2º Month. 3. To Give all the Drugs associated in the same Tablet. 4. To evaluate DST at the start of treatment in Cases and Risk Populations Risk Populations The possibility to generate MDR and XDR in NTP conditions 1.) Produce MDR, when: - Bad Maintained Adherence - Drugs Not Associated In the same Tablet - To Pass to 2ª Phase with Sm+, - Above all, if there is Initial Resistance to H 2.) Amplify Res. to ZE in Initial MDR and Sm+ - The Regimen Category I could:

1.) Amplify Resistance to EMB in cases with Initial Res. to H  MDR with Cat.I Res. to H  MDR with Cat.I 2.) Amplify Resistance to SM in cases with Initial MDR  Amplification ZE with Cat. I MDR  Amplification ZE with Cat. I - The Regimen Category II could: BUT THE CATEGORY II DO NOT GENERATE M.D.R.  BUT THE CATEGORY II DO NOT GENERATE M.D.R.   The MDR come from the Category I The possibility to generate MDR in NTP conditions

- Recommendations: 1. Culture + DST to all the Sm+ at the end of the 2-3 month  MDR 2. To Evaluate Rate of MDR-TB in Failures Cat. I 3. To Evaluate Rate of MDR-TB in Relapses and Defaulters Cat. I Defaulters Cat. I The possibility to generate MDR in NTP conditions 1.) Amplify Resistance to EMB in cases with Initial Res. to H  MDR with Cat.I 2.) Amplify Resistance to SM in cases Initial MDR  Amplification ZE with Cat. I - The Regimen Category II could: BUT THE CATEGORY II DO NOT GENERATE M.D.R.  The MDR come from the Category I BUT THE CATEGORY II DO NOT GENERATE M.D.R.  The MDR come from the Category I

Under Special Conditions, the NTP have the Risk to Amplify Resistances with Not Adequate Strategies NTP should Address all the Strategies to Minimize this Risk

M. tuberculosis Resistance In TB, resistance is always the expression of poor individual or general management of patients