Atypical Mycobacteria Flashcards
General features of atypical mycobacteria?
– Common in soil, water, dust, food stuffs
– Frequent contaminants of clinical specimen
– May colonize body surfaces for prolonged times without causing disease
– Differentiation between contamination, colonization, and disease is difficult
What are the atypicals in Photochromogenes (Runyon Group I)
• M. kansasii • M. marinum • M. simia
Atypical mycobacteria in Scotochromogens (Runyon Group II)?
• M. scrofulaceum • M. szulgai • M. gordonae • M. flavescens
atypical mycobacteria in Nonchromogens (Runyon Group III)?
• M. avium-intracellulare • M. xenopi • M. ulcerans • M. gastri • M. terrae • M. triviale
Atypical mycobacteria that are Rapid Growers (Runyon Group IV)?
• M. fortuitum • M. chelonae • M. smegmatis
Guidelines to implication in disease for atypicals?
- Patients illness consistent with a non-atypical mycobacterial syndrome
- Other causes of disorder (fungal, TB) excluded
- Species of mycobacterium crucial
- Site of origin positive culture crucial – Sterile sites always significant
- Quantity of growth of the culture important
- Repeated isolation of the organism from body secretion
General features of M.Kansasii?
M. Kansasii – General
– Water is a natural reservoir
– Southwest, Midwest
– Men > Women –5 th decade
– High risk • Pneumoconiosis • COPD • Immunodeficient
Clinical disease of M. Kansasii?
–Pulmonary infection • Mild chronic symptoms • Physical exam minimal • Chest x-ray (may be similar to TB) • Sputums – Repeatedly positive without other cause – May coexist with TB
– Lymphadenitis
– Syndrome resembling sporotrichosis
– Cellulitis
– Osteomyelitis
– Hypersensitivity syndrome (E. nodosum)
– Dissemination • Immunocompromised • Pancytopenic
Therapy for M.Kansasii?
• Therapy – INH, RMP, EMB
Epidimiology and risk factors for Mycobacterium avium complex?
– Isolated sources • Soil, natural, municipal water, food, host dust, domestic, wild animals • Inhalation of aerosols • No person-to-person spread
– Risk Factors • Chronic lung disease • Gastrectomy • T-cell deficiency (<100) • Lung disease seen in “normal people”
Symptoms of MAC in AIDS patients?
– Gastrointestinal • Nausea, vomiting, diarrhea, abdominal pain, colitis, ileal and duodenal involvement
– Hematologic • Anemia, neutropenia
– Systemic • Fever, chills, night sweats, wasting syndrome, liver involvement (alkaline phosphatase)
– Pulmonary • Unusual site
Symptoms of MAC in non-AIDS patients?
Diagnosis of MAC?
– Sputums • Normal colonization • Pathogen if underlying cavities, infiltrates
– Blood Cultures
– Lymph nodes, bone marrow, liver biopsies
– Methods • AFB smear • Cultures • DNA probe • PCR
Therapy for MAC?
– Very resistant
– Requires multiple drugs
– Disseminated disease • Clarithromycin or Azithromycin • Ethambutol • Rifabutin
– Prophylaxis • Clarithromycin • Azithromycin
M.Marinum Location? infection?
– Trauma to skin • Swimming pools, aquariums, natural bodies of water • Fish spines, nips of crustaceans
– Local Infection • Papule ulcer • Sporotrichoid type spread
Therapy for M.Marinum?
Therapy • Rif, EMP • Tetracyclines • Trimethoprim - sulfamethoxazole
M. Scrofulaceum location? clinical findings?
– Frequently contaminates specimens, reagents, standing water
– Colonize respiratory secretions of well indiviulas
– Clinical • Lymphadenitis, submandibular area • Children age 1-3 years • Enlarge slowly over weeks • May rupture with draining sinus
What is the differnential and therapy for M. Scrofulaceum?
– Differential • M. Tuberculosis • PPD (-)
– Therapy • Surgical removal
Rapid growing mycobacterium, are which ones? human infections how? require how much time to grow?
- Requires 2 to 30 days for growth
- Isolated from tap water, municipal water, moist areas in hospitals, contaminated biologicals, aquariums, domestic animals
- Human infections acquired – Trauma, infection, surgery
- Species – M. Chelonei – M. Abscessus – M. Fortuitum
Clinical syndromes of the rapid growing mycobacterium?
– Infections of skin and soft tissue
– Cardiac surgery, augmentation mammoplasty, peritoneal dialysis, arthroplasty
– Bronchopulmonary infections • May colonize respiratory secretions without disease
– Other diseases • Lymphadenitis, keratitis, osteomyelitis, meningitis – Disseminated Disease • Majority immunodeficient
What are the rave species and what do they cause clinically?
- M. Szulgai – Pulmonary disease similar to M. tuberculosis
- M. Xenopi – Pulmonary disease – Human tonsils (colonizer)
- M. Malmoense – Pulmonary disease – Lymphadenitis – Disseminate
- Post-Surgical Infections – Augmentation mammoplasty – Median sternotomy – Prosthetic joint – Percutaneous catheter – Pacemaker insertion – Lipoma excision – Facial plastic surgery – Cervical laminectomy – Saphenous vein removal – Knee repair
- Primary Cutaneous Infections – With or without osteomyelitis
- Pulmonary Infections
- Disseminated Disease
- Miscellaneous – Keratitis and corneal ulceration – Prosthetic valve endocarditis – Cervical lymphadenitis – Meningitis – Hepatitis – Synovitis – Epidural abscess
How do you treat the rapid growing mycobacterium?
– M. Chelonae • Clarithromycin-sensitive • Amikacin, doxycycline, imipenem variable
– M. Fortuitum • Amikacin, Cefoxitin, Ciprofloxacin, Ofloxacin, Sulfonamide
– M. Abscessus • Amikacin, Cefoxitin
What do the rave species M.Haemophilum and M.Ulcerans cause?
- M. Haemophilum – Skin and subcutaneous lesions (immunocompromised)
- M. Ulcerans – Chronic, painless cutaneous (Buruli) ulcers – Extensor surfaces of extremities
Explain the general features of Mycobacterium Leprae?
– Acid fast, slightly curved bacillus
– Metachromatic granule near pole or center
– Contains mycolic acids (as other mycobacteria)
– Large amounts specific phenolic glycolipid
– Loss of acid fastness by pyridine extraction
– Characteristic slow growth curve in footpads of mice
– Ability to oxidize dihydrooxyphenylalanine (DOPA)
– Tendency to infect peripheral nerves of humans
Epidemiology of Mycobacterium Leprae?
– Skin not major mode of spread
– Nasal discharge high amount of organisms (1x108/ml)
– Respiratory tract
– Breast milk
– Biting insects may transmit
– Lepromatous • 20% incidence in India • 30-50% incidence in Japan, China, Korea
– Tuberculoid • Up to 90% in Africa
Explain the pathology of both the tuberculoid and Lepromatous forms of Mycobacterium Leprae?
– Tuberculoid • Histology similar to sarcoid granulomas • Nerve bundles that are grossly swollen and infiltrated with mononuclear cells • Acid-fast bacilli few to absent • Able to manifest delayed-type hypersensitivity to skin tests
– Lepromatous • Predominant cell is macrophage • Langhan type giant cells, lymphocytes are few • Granulomas not developed • Numerous acid fast bacilli • Profoundly anergic
Clinical spectrum of M.Leprae?
– Full tuberculoid • Large erythematous plaques with sharply demarcated raised outer edges • Area is anesthetic • May have damaged few peripheral nerves
– Borderline tuberculoid – Borderline Borderline • Skin manifestations more numerous • Raised satellite lesions present • Anesthesia less marked
– Full lepromatous • Extensive bilateral, symmetrical erythematous macules, papules or nodules • Advanced skin thickening of face, nose, ears (classic leonine facies) • Destruction nasal-maxillary structures • Nerve involvement patchy less severe
