Exogenous Reinfection with MultidrugResistant Mycobacterium tuberculosis in Patients with Advanced H

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Exogenous Reinfection with Multidrug-Resistant
Mycobacterium tuberculosis in Patients with
Advanced HIV Infection

• Celeste Nadal

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Purpose

• Determine the epidemiological connections between
  cases of
• multidrug-resistant tuberculosis (MDRT)
• Prevention of future MDRT outbreaks

Rationale
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Outline

• Background
• Mycobacterium tuberculosis
• Tuberculosis disease
• HIV and Tuberculosis
• Methods
• Results
• Conclusions

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Mycobacterium tuberculosis

• Characteristics
• Obligate aerobe
• Rod shaped
• Acid fast
• Mycolic acid cell wall

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Tuberculosis Disease (TB)

• Sites of infection
• Mode of infection
• Airborne

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Pulmonary TB

• Internal symptoms
• Development of tubercles
• Consumption
• Sputum
• External symptoms
• Minor cough
• Mild fever
• Fatigue
• Weight loss
• Coughing up blood
• Chest pain

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TB and HIV

• Increased susceptibility in immunosuppressed
  individuals
• Infection in HIV positive individuals
• 113 times more likely
• 7 to 10 risk PER YEAR

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Multidrug-Resistant Tuberculosis Infection

• Primary drug resistance
• Infection with multidrug-resistant TB
• Acquired drug resistance
• Development of resistance during therapy
• Possibly due to inadequate treatment

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Research Protocol

• Trace M. tuberculosis transmission
• Isolation and culture of bacterial sample
• Evaluation of medical records
• Follow-up studies
• Radiometric broth method
• Restriction-fragment-length polymorphisms
  analysis

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Radiometric Broth Method

• Determine susceptibility to
• Isoniazid (0.1-0.2 mg/ml)
• Rifampin (2 mg/ml)
• Streptomycin (6.0 mg/ml)
• Ethambutol (7.5 mg/ml)
• Pyrazinamide (100 mg/ml)- testing began later in
  study
• Tests for critical concentration
• The level of a drug which distinguishes the
  strain from a strain that has never been in
  contact with the drug
• 1 colony growth in presence of antibiotic

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Restriction-Fragment-Length- Polymorphisms
(RFLPs) Analysis

• Form of DNA fingerprinting
• Extract genomic DNA
• Restriction enzyme digestion
• PvuII
• Southern blot
• Gel electrophoresis
• Transfer to nylon membrane
• Hybridized with labeled probes

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RFLP Patterns of Patients with Persistently
Drug-Susceptible Isolates
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RFLP Patterns of Patients with Increasingly
Drug-Resistant Isolates
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RFLP Patterns Indicating Exogenous Reinfection
with New Multidrug-Resistant Strain in HIV
Patients
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Clinical Course of Four Patients with AIDS and
Multidrug-Resistant Tuberculosis

• Triangles
• Out-patient visits
• Circle
• Negative TB culures
• Boxes
• Positive TB cultures
• PCP
• Pneumonia

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Conclusion

• RFLP Analysis
• Confirmed acquired drug resistance
• Demonstrated Third mechanism of developing
  Multidrug-resistant tuberculosis infection
• Exogenous reinfection
• Follow-up
• Lack of acquired immunity to MTB in HIV pos
  patients are more likely to become reinfected
  with MDR-TB

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Prevention

• Routine skin testing for tuberculosis
• Prompt and consistent treatment
• Decrease open tuberculosis units