Granulomatous infections: tuberculosis, leprosy, actinomycosis, nocardiosis Prof. dr hab. n. med. Beata M. Sobieszczańska Wrocław Medical University Dept. of Microbiology Granulomatous inflammation Chronic inflammatory reaction – protective response to chronic infection or foreign material preventing dissemination and restricting inflammation Tuberculous M. tuberculosis M. africanum Typical M. bovis Noncultivable M. leprae Mycobacterium Skin ulcers M. ulcerans, M. balnei Atypical (MOTT) slow growers Saprophytic M. kansasii M. phlei, M. smegmatis M. scrofulaceum M. avium-intracellulare (MAI) Rapid growers: M. fortuitum, M. chelonei General characteristics: ► slender curved-rods ► nonmotile ► non-spore forming obligate aerobes ► fastidious (enriched special culture media) ► slow generation time (18-24 h) ► facultative intracellular pathogens Acid fast = retains carbolfuchsin dye when decolorized with acid-alcohol Acid fast bacteria: Mycobacterium, Nocardia High concentration of lipids in the mycobacterial cell wall is associated with: • Cell wall impermeability • Antibiotic resistance • Resistance to killing by acids & alkalis • Resistance to osmotic lysis via complement deposition • Resistance to lethal oxidation • Survival inside of macrophages • Slow growth (lipids determine hydrophobic cell surface that causes mycobacteria to clump & inhibits nutrients access) – infection is an insidious, chronic process taking several weeks or months to become apparent Microscopy – acid fast Ziehl-Neelsen = acid fast staining Auramine staining - more sensitive than an acid fast stain requires fluorescence microscopy Virulence factors The ability to survive within macrophages (superoxide dismutase, catalase, mycolic acids) Cord factor (wax C) = responsible for the growth as serpentine cords / present only in M. tuberculosis toxic to mammalian cells & inhibits PMNs migration Mycobacteria do not produce toxins !!! Infects humans & wide Mycobacterium host range of animals africanum (cattle, nonhuman Humans primates, cats, goats, Airborne transmission dogs, pigs etc.) - East & West Africa worldwide • Ingestion of Mycobacterium tuberculosis MTB contaminated milk from infected cows Humans are the only reservoir for the bacterium Mycobacterium Optimal conditions for bovis transmission include: overcrowding poor public hygiene Droplet nuclei • IFNƔ activates macrophages making them capable of destroying MBT • The cell mediated immune response (delayed hypersensitivity) control the infection Primary tuberculosis • Caseous necrotic tissue • Most patients with primary tuberculosis are asymptomatic & the granulomas resolve Caseation – a form of necrosis characteristic of tuberculosis in which diseased tissue form a firm, dry mass like cheese in appearance Primary infection • The patient will heal & a scar will appear in the infected loci • The bacteria at this time goes into a dormant state, as long as the person's immune system remains active & functions normally there is no disease symptoms • When a person's immune system is depressed a primary progressive tuberculosis will develop Primary Tuberculosis Primary tuberculosis: – Self limiting disease – no symptoms, recovery or mycobacteria remain in a dormant state Primary progressive TB in 5% of infected – Miliary TB & TB meningitis – Common in malnourished children – 10% of adults (immunosuppressed individuals) Milliary lesions which are small granulomas, resemble, millet spread throughout the lung fields Patients are highly contagious Milliary tuberculosis Secondary tuberculosis • Reactivation (endogenous in 99% of cases) or reinfection (rare) • Tubercules liquefy & MBT starts to multiply extracellulary • Walls of nearby bronchi become necrotic & rupture = cavity formation and MBTspreading Cavitary Secondary TB Extensive cavitation of multiple granulomas of lung are typical for secondary tuberculosis Tuberculous spodylitis- Potts disease PRIMARY & POST-PRIMARY TB • Primary overt TB (5% infected) - single lesion or milliary TB (no immunity yet – still developing) • Post-primary/secondary TB - endogenous reactivation accompanied by a single (cavitary) lesion (strong cellular immunity) Hematogenous spread = miliary tuberculosis = secondary lesions at almost any anatomical location; may occur in a primary or secondary tuberculosis Reactivation is associated with deterioration of the cell-mediated immune response Tuberculosis may affect any tissue, any organ, any system Most common disseminated disease: kidneys, bones, spleen, meninges Exposure to TB Hypersensitivity Primary infection Immunosupression age under 5 y.o. 5% 95% Primary progressiveTB Latent TB 5% 90% Reactivation No disease Pulmonary Extra-pulmonary Dissemination Diagnosis • Tuberculin skin test with PPD (purified protein derivate) intradermal injection • Measurement of skin lesion after 48-72 hours (delayed hypersensitivity) • <5 mm induration (bump) = negative • >5 mm induration = TB infection in people who are in a high-risk group (HIV infection) • ca. 10 mm induration = TB infection in people who are in a moderate-risk group • >15 mm induration = TB infection in people who are in low-risk group Diagnosis Interferon gamma – release assay (IGRA) BCG (Bacilli Calmet-Gengou) vaccine contains viable, attenuated M. bovis Does not prevent tuberculosis !!!! The vaccine prevents only from dissemination of the disease (prevents hematogenous spread of tuberculosis) Multidrug resistant TB (MDR): strain resistant to two of the most powerful first-line drugs Extensively resistant TB (XDR): strain resistant to some of the most powerful drugs MOTT M. kansasii - lung disease M. scrofulaceum – cervical lymphadenitis in children M. avium-intracellulare (MAI) - disseminated disease in immunocompromissed M. mariunum - cutaneous disease Buruli ulcer - M. ulcerans • Contiguous disseminated • Clinical: small or large oedematous indurated plaque that may ulcerate late • Reservoir: uncertain (environment) • Treatment: rifampicin, streptomycin • Photographs show disseminated edematous BU that has been widely excised MOTT summary Exist saprophytically in the soil or water Infection initiate inhalation or introduction into skin abrasions Crucial difference between M. tuberculosis & 'atypical' mycobacteria: lack of transmission from patients to patients Resistant to drugs used in the treatment of tuberculosis, but sensitive to antibiotics: macrolides, tetracyclines, quinolones Antibiotic regimen may require 5 or 6 drugs Mycobacterium leprae • Leprosy (Hansen disease) • Non-cultivated (mouse sole, armadillo) • Acid-fast (Ziehl-Neelsen staining) • Aerobic; grow at 30oC • Grow intracellulary in skin histiocytes, endothelial cells, nerves - Schwann cells) • Endemic: Asia, Pacific region, Americas, North Africa, China • Transmission: direct contact, air-borne route Actinomyces israelii • GP, anaerobic • Colonize upper respiratory tract, gastrointestinal tract, female genital tract • Low virulence potential –– natural barriers disruption (trauma, surgery, infection) Actinomyces infections: ENDOGENOUS (polymicrobic, endodontic, odontogenic) Three types of actinomycosis • Cervicofacial • Thoracic/pulmonary • Abdominopelvic / genital Rarely: • Cerebral Actinomycosis Sulfur granule characteristic granules consisting of bacterial colony (dense rosettes of filamentous bacteria) Nocardia asteroides • Strict aerobes • Branched filaments • Virulence factors: mycolic acids (cord factor) = replicate inside macrophages, catalase, superoxide dismutase • Ubiquitous in soil rich with organic matter • Worldwide distributed, but most common in tropical/subtropical Transmission: • Inhalation (person-to-person) • Direct introduction into tissues Nocardia asteroides • Inhalation=pulmonary / bronchopulmonary nocardiosis (bronchitis, pneumonia, lung abscesses) • Traumatic introduction = cutaneous nocardiosis - Mycetoma (Madura foot) - Lymphocutaneous infections - Chronic ulcerative lesions - Subcutaneous abscesses - Cellulitis Secondary infections: meningitis, brain abscesses Mycetoma .