03 - Microbes 20 - 27 Gram Negative Bacilli cont Flashcards
a. Gram-negative bacillus, pleomorphic, stains poorly
b. Etiologic agent of Legionellosis; usually pneumonia that occurs in outbreaks instead of single cases – in the top 5 causes of pneumonia
c. Virulence: intracellular parasites (i.e. macrophages); resists killing by superoxide & hydroxyl radicals; inhibits phagosome-lysosome activity; flagella promote invasion; secretes various proteins
d. Immuno-diagnostic tests for antigen in urine or other body fluid. Culture using special culture media
Legionella pneumophila
resists phagocytosis with superoxide and hydroxyl free radicals
Legionella pneumophila
Etiologic agent of Legionellosis; usually pneumonia that occurs in outbreaks instead of single cases – in the top 5 causes of pneumonia
Legionella pneumophila
a. Gram-negative bacilli
b. Medical significance – nosocomial infections (~10%), especially in severely compromised or debilitated patients.
(1) Infrequent agent of superficial wound and urinary tract infections
(2) Mucoid strains repeatedly colonize the respiratory tract of cystic fibrosis patients
c. Virulence factors: protein inhibitors, exotoxins, capsule (cystic fibrosis strains)
d. Treatment – Resistant to most antibiotics – Often requires combination therapy [using aminoglycosides and broad spectrum penicillins]
Pseudomonas aeruginosa
a. Gram-negative bacillus, grows on MacConkey
b. Source – soil & water (prolonged survival on environmental surfaces)
c. Opportunistic pathogen – post-traumatic wound abscess and septicemia
(1) Natural & nosocomial
(2) VietNam; Afghanistan & Iraq
(3) Increased resistant to antibiotics: 35% susceptible to imipenem only; 4% resistant to all drugs tested
d. Lab – quick ID and antimicrobial susceptibility test (AST)
Acinetobacter baumannii
Vietnam Afghanistan & Iraq and a gram-negative bacillus
Acinetobacter baumannii
a. Small Gram-negative coccobacillus, very slow growing (2 weeks to 2 months)
b. Etiologic agent of Brucellosis (zoonotic disease)
(1) Bangs disease – spontaneous abortion in bovine, sheep, goats
(2) Undulant Fever in humans – acute systemic febrile illness with sweating; initial flu-like symptoms with migratory arthralgia and myalgia (joint & muscle pain), possible neurological symptoms, may lead to bone or joint disease; may be persistent or recurrent (months/years).
c. Biological threat agent
Brucella melitensis & B. abortus
d. Virulence Factors
(1) Intracellual replication
(2) Survives and replicates in phagocytes
e. Transmitted by unpasteurized dairy products (esp. goats) or contact with animal blood or body fluids or tissues (e.g. placenta).
(1) Human to human transmission very rare
(2) Disease onset 3 days to several weeks after exposure.
Brucella melitensis & B. abortus
Small Gram-negative coccobacillus, very slow growing (2 weeks to 2 months)
unpasteurized dairy products (esp. goats) or contact with animal blood or body fluids or tissues (e.g. placenta).
Brucella melitensis & B. abortus
Human to human transmission very rare it’s mainly a zoonotic disease
Brucellosis via Brucella melitensis & B. abortus
Undulant Fever (ups and downs) in humans – acute systemic febrile illness with sweating; initial flu-like symptoms with migratory arthralgia and myalgia (joint & muscle pain), possible neurological symptoms, may lead to bone or joint disease; may be persistent or recurrent (months/years).
Brucella melitensis & B. abortus
a. Very small Gram-negative bacillus; grows poorly in standard culture media (2-3 days in enriched media)
b. Biological Select Agent
c. Disease: Tularemia
d. Transmitted by contact with infected tissues, blood, body fluids from ticks, deer flies, rabbits, cats, rodents, dried bodily fluids in blowing dust, etc.
Francisella tularensis
Disease: Tularemia
(1) Clinical
(a) Ulcerations (2-3 days after exposure) - leads to glandular, nodular, lymph node involvement
(b) Typhoidal (septicemia, systemic)
(c) Pneumonic – similar to typical pneumonia; frequently develops following other forms of tularemia
(2) Virulence Factors:
(a) Intracellular pathogen; survives prolonged periods in macrophages
(b) Antiphagocytic capsule; also protects from complement activity
(c) Requires very strong immune response (esp. CMI) to control replication
Francisella tularensis
a. Gram-negative bacillus (cocco-bacillus) (GNB, GNCB )
b. Etiologic agent of Pertussis
c. Virulence due to Pertussis Toxin, thick capsule, and exudate
d. Lab diagnosis - special request needed – requires special media and identification techniques
Bordetella pertussis
(1) Whooping Cough – Full-symptom illness
(2) Bronchitis – moderate / mild
(3) Re-emerging pathogen - possibly due to reduced immunization rate or inadequate quality of vaccine (i.e. whole-cell may be better than fractionated and may need booster)
Bordetella pertussis
