03 - gram positive bacilli - Microbes 37 - 41 Flashcards
a. Gram-positive bacillus, aerobic, non-sporeforming (NSF)
b. Grows at refrigerator temperature
c. Source: soil, forage, animal feces
Listeria monocytogenes
Etiologic agent of:
(1) Food poisoning (esp. cold cuts, unpasteurized cheeses); tolerates & grows in cold temperatures (e.g. refrigerated foods)
(2) Intracellular pathogen
(3) Causes fever, muscle aches, GI symptoms
(4) Miscarriage, stillbirth, neonatal infection
(5) Encephalomeningitis
Gram + bacillus
Listeria monocytogenes
Gram-positive bacillus, aerobic, non-sporeforming (NSF), pleomorphic
b. Etiologic agent of : Diphtheria:
(1) Pseudomembrane formation in the throat; Necrotic surface epithelium enmeshed in fibrous exudate
(2) Diphtheria toxin affects myocardium and other tissues;
Rarely occurs in US
Corynebacterium diphtheriae
a. Gram-positive bacillus, spore-forming, aerobic
b. Natural soil/environmental bacterium
c. Causes ~5% of foodborne illness, especially improperly cooked rice or dried
beans (i.e. spore survival)
d. Spores germinate and produce toxins
e. Diarrhea – 6-24 hr after consumption; duration 20-26 hr
f. Emetic (primarily from rice) – 1-6 hr after consumption; duration 8-10 h
Bacillus cereus
a. Gram-positive bacillus, spore-forming, aerobic
b. Grows rapidly on blood agar (without hemolysis)
c. Etiologic agent of Anthrax
Bacillus anthracis
(a) Easily aerosolized – spores become and stay airborne easily
(b) Highly infectious – 8000-10,000 spores (avg) required to establish infection
(c) Incubation period 1-6 days
(d) Host defense – phagocytic cells carry spores to lymph nodes
(e) Initially – flu-like; fever, malaise, mild chest discomfort
(f) Chest X-ray – widened mediastinum
(g) Spores germinate into bacteria –>
toxin (Edema Toxin and Lethal Toxin) -> disease
(h) High mortality rate
Pulmonary anthrax (60-100% mortality) – & Woolsorter’s disease and biological warfare & biological terrorism
(a) Spores enter through cut, abrasion
(b) Papule -> blister-like vesicle -> necrotic lesion with black eschar (black scab)
(c) Can lead to systemic infection
(d) 20-25% mortality in untreated cases
(e) Responds well to early antibiotic treatment
(Bacillus anthracis)
Cutaneous anthrax, 95% (20% mort.)
Bacillus anthracis causes
Pulmonary anthrax
Cutaneous anthrax
a. Gram-positive bacilli, spore forming
b. Anaerobe
c. Several species cause deep wound abscesses, especially when contaminated with exogenous material
Clostridium species
Name the genii of the Clostridium species
Clostridium perfringens
Clostridium difficile
Clostridium botulinum
Clostridium tetani
(1) Etiologic agent of:
(a) Food poisoning due to enterotoxin and infection (spores on undercooked meat
germinate and secrete enterotoxins)
(b) Tissue invasion and possible necrosis due to exotoxins (cytotoxins) and “invasive” enzymes (also known as “Gas gangrene”)
Clostridium perfringens
if you hear gangrene think of these two microbes:
Streptococcus pyogenes, group A (causing necrotizing fascitis) Grame positive coccus in chains
Clostridium perfringens gram positive bacilli, spore forming
Antibiotic Associated Diarrhea due to overgrowth of the normal gut flora following antibiotic treatment.
Pseudomembranous Colitis is a severe form that includes the formation of a “pseudomembrane” of inflammatory cells, fibrin, and necrotic cells.
Clostridium difficile
Clostridium difficile
antibiotic associated diarrhea
Virulence factors: enterotoxin (Clostridium difficile toxin A) and cytotoxin (Clostridium difficile toxin B) which cause diarrhea and inflammation. There is increasing resistance to multiple antibiotics (e.g. fluoroquinolones).
(3) Transmitted person-to-person via fecal to oral route; spores germinate after passing through the acid of the stomach. Spores survive routine surface cleaning
Clostridium difficile
Epidemiology:
(a) In 2011, there were about 500K infections and 29K deaths in the US.
- —Infection occurs in 4 to 8 per 1000 persons admitted to hospital
(b) Especially problematic in hospitals and nursing homes, and increasingly problematic outside of medical settings.
(c) C. diff acquisition is estimated to occur in 13% of patients with hospital stays up
to two weeks and 50% with stays longer than 4 weeks.
Clostridium difficile
hospital acquired commonly (nosocomial) and gram positive bacillus
Clostridium difficile
Fecal transplant therapy reestablishes normal healthy colon flora with good
success after which microbe?
Clostridium difficile
Virulence Factor: Bacteria produce neurotoxin (8 types identified, A-H) that is heatlabile at 100C
(a) Toxin types A, B, E cause food poisoning due to ingestion of preformed heatlabile toxin. Type E is especially associated with fish products. (Special request needed, toxin test, not bacteriology).
(b) Lethal dose of 2 ng by injection or 13 ng by inhalation – deemed to be one of the
most toxic substances
Clostridium botulinum
botulism
Clostridium botulinum
(2) Foodborne botulism
(a) Signs and symptoms usually begin 18 36 hours after ingestion
(b) Double vision, blurred vision, drooping eyelids, slurred speech, weakened facial and throat muscles, nausea, vomiting
(3) Wound botulism – most common in people who inject drugs
(4) Infant botulism – ingested via unpasteurized honey and certain other foods
(5) Biological Threat Agent
(6) Beneficial effects: very diluted toxin used to treat spasmodic dysphasia (larynx muscle problems), paralysis of facial and other muscles, other muscle-related problems, and cosmetic (facial wrinkles)
Clostridium botulinum
(1) Causes tetanus
(2) Due to neurotoxin
(3) Lockjaw – continuous muscle contraction
Clostridium botulinum
tetanus
Clostridium botulinum
(3) Causes fever, muscle aches, GI symptoms
(4) Miscarriage, stillbirth, neonatal infection
(5) Encephalomeningitis
Gram + bacillus
Listeria monocytogenes
d. Spores germinate and produce toxins
e. Diarrhea – 6-24 hr after consumption; duration 20-26 hr
f. Emetic (primarily from rice) – 1-6 hr after consumption; duration 8-10 h
Bacillus cereus
Bacillus cereus
a. Gram morphology etc?
b. Natural _______ bacterium
c. Causes ~5% of foodborne illness, especially improperly cooked ____ or _____ (i.e. spore survival)
d. _____ germinate and produce ____
e. Diarrhea – _____ hr after consumption; duration 20-26 hr
f. Emetic (primarily from ____) – 1-6 hr after consumption; duration 8-10 h
gram positive bacilli, aerobic, spore forming
soil/environmental
rice or dried beans
Spores germinate and produce toxins
6-24
rice
Corynebacterium diphtheriae
Gram-___ ___, aerobic, non-sporeforming (NSF), ____
b. Etiologic agent of : ______
(1) _______ formation in the throat; Necrotic surface epithelium enmeshed in _____ ______
(2) Diphtheria toxin affects ______ and other tissues;
Rarely occurs in US
Gram-positive bacillus, aerobic, non-sporeforming (NSF), pleomorphic
b. Etiologic agent of : Diphtheria:
(1) Pseudomembrane formation in the throat; Necrotic surface epithelium enmeshed in fibrous exudate
(2) Diphtheria toxin affects myocardium and other tissues;
Rarely occurs in US
