03 - gram positive bacilli - Microbes 37 - 41

Question 1

a. Gram-positive bacillus, aerobic, non-sporeforming (NSF)
b. Grows at refrigerator temperature
c. Source: soil, forage, animal feces

Answer 1

Listeria monocytogenes

Question 2

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

Answer 2

Listeria monocytogenes

Question 3

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

Answer 3

Corynebacterium diphtheriae

Question 4

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

Answer 4

Bacillus cereus

Question 5

a. Gram-positive bacillus, spore-forming, aerobic
b. Grows rapidly on blood agar (without hemolysis)
c. Etiologic agent of Anthrax

Answer 5

Bacillus anthracis

Question 6

(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

Answer 6

Pulmonary anthrax (60-100% mortality) – & Woolsorter’s disease and biological warfare & biological
terrorism

Question 7

(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)

Answer 7

Cutaneous anthrax, 95% (20% mort.)

Question 8

Bacillus anthracis causes

Answer 8

Pulmonary anthrax

Cutaneous anthrax

Question 9

a. Gram-positive bacilli, spore forming
b. Anaerobe
c. Several species cause deep wound abscesses, especially when contaminated with exogenous material

Answer 9

Clostridium species

Question 10

Name the genii of the Clostridium species

Answer 10

Clostridium perfringens

Clostridium difficile

Clostridium botulinum

Clostridium tetani

Question 11

(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”)

Answer 11

Clostridium perfringens

Question 12

if you hear gangrene think of these two microbes:

Answer 12

Streptococcus pyogenes, group A (causing necrotizing fascitis) Grame positive coccus in chains

Clostridium perfringens gram positive bacilli, spore forming

Question 13

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.

Answer 13

Clostridium difficile

Question 14

Clostridium difficile

Answer 14

antibiotic associated diarrhea

Question 15

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

Answer 15

Clostridium difficile

Question 16

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.

Answer 16

Clostridium difficile

Question 17

hospital acquired commonly (nosocomial) and gram positive bacillus

Answer 17

Clostridium difficile

Question 18

Fecal transplant therapy reestablishes normal healthy colon flora with good
success after which microbe?

Answer 18

Clostridium difficile

Question 19

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

Answer 19

Clostridium botulinum

Question 20

botulism

Answer 20

Clostridium botulinum

Question 21

(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)

Answer 21

Clostridium botulinum

Question 22

(1) Causes tetanus
(2) Due to neurotoxin
(3) Lockjaw – continuous muscle contraction

Answer 22

Clostridium botulinum

Question 23

tetanus

Answer 23

Clostridium botulinum

Question 24

(3) Causes fever, muscle aches, GI symptoms
(4) Miscarriage, stillbirth, neonatal infection
(5) Encephalomeningitis

Gram + bacillus

Answer 24

Listeria monocytogenes

Question 25

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

Answer 25

Bacillus cereus

Question 26

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

Answer 26

gram positive bacilli, aerobic, spore forming

soil/environmental

rice or dried beans

Spores germinate and produce toxins

6-24

rice

Question 27

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

Answer 27

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