Mid 13 Anaerobes

Front 1

Characteristics of anaerobic infections:
1) Infection source?
2) What leads to infection development?
3) Infection due to single organism?
4) Gross effect commonly seen
5) Exotoxin formation?

Back 1

1) Part of normal flora in GI, oropharyngeal, or UT
2) Trauma or change in host's tissues
3) Polymicrobial, often aerobic with anaerobe
4)Abcesses common
5) For clostridial diseases

Front 2

Oxygen cut off values:
a) Strict anaerobes
b) Moderate anaerobes
c) Facultative
d) Microaerophilic

Back 2

a) <0.5% O2
b) 2-8%
c) can grow in both aerobic and anaerobic conditions
d) grow poorly in air

Front 3

What do anaerobes lack that prevents their survival in aerobic conditions?

Back 3

Cytochromes and enzymes (superoxide dismutase, catalase, and peroxidase) necessary to neutralize toxic products formed by the metabolism of O2.

Front 4

What are common causes of flora modification that favor anaerobes?

Back 4

Antibiotic use, antacids, GI motility drugs, surgery, and cancers

Front 5

What are exogenous sources of anaerobic exogenous infections?

Back 5

Spore forming organisms in water, sewage, and soil

Front 6

Virulence Factors related to attachment and adhesion

Back 6

Polysaccharide capsule --> attachment to peritoneal surfaces

Pili (fimbriae) adherence to epithelial cells

Front 7

Virulence Factor related to invasion

Back 7

Most anaerobes don't have virulence factors for this and depend on changes in the host tissue (from surgery or cancer). Anaerobes usually found adjacent to primary infections. Some have ability to produce small amounts of catalase and superoxide dismutase which can be considered an invasive virulence factor

Front 8

Virulence Factors: establishment of infection and avoidance of host defense mechanisms (polysaccharide capsule, spores, reduced microenvironment)

Back 8

Polysacharride capsule: antiphagocytic
Spore formation: spores are resistant to heat desiccation and disinfectants --> survival in adverse env. and can return to vegetative state in favorable env.
Reduced microenvironment via polymicrobial mixture with some facultative bacteria (E.coli)

Front 9

Bacteroides fragilis possesses which virulence factor and what does it do?

Back 9

Polysaccharide capsule both inhibits phagocytosis and induces abscess formation in absence of living bacteria. Also produces EC enzymes contributing to abscess formation.

Front 10

Clostridium perfringins toxins

Back 10

alpha toxin --> myonecrosis via lecithinase which lyses erythrocytes, platelets, and EC --> vascular permeability increase with hemolysis, bleeding and tissue destruction
beta toxin --> necrotizing activity
0 toxin --> cytolytic
Enterotoxin -->Binds brush border of GI and disrupts transport and permeability, can survive for yrs.

Front 11

Clostridium tetani toxins

Back 11

Tetranospasm --> muscle spasm b/c degrades protein necessary for docking and release of NT responsible for inhibition
Tetranlysin -->unknown fxn

Front 12

Clostridium botulinum toxin

Back 12

Botulinum --> Prevents release of Ach, binding is irreversible so recovery depends on regeneration of new nerve endings

Front 13

Clostridium dificile toxin

Back 13

ABCD
Toxin A --> Enterotoxin, chemotaxis of PMN's, cytokine production, hypersecretion of fluid, and hemorrhagic necrosis
Toxin B --> Cytotoxin, loss of cytoskeleton via induction of actin polymerization

Front 14

Peptosterptococcus
1) organism type
2) source
3) associated disease

Back 14

1)Gram + cocci
2)Mouth and intestine
3)Oropharyngeal infections, brain abscess

Slides say chronic bone and joint infxns as well as female genital tract and intrabdominal infections

Front 15

Veillonella
1) organism type
2) source
3) associated disease

Back 15

1) Gram - Cocci
2) Normal oral flora
3) Rare opportunist - isolated from infected human bites

Front 16

Propionobacterium
1) organism type
2) source
3) associated disease

Back 16

1) Gram + bacilli
2) skin
2) Acne, rare opportunist with prosthetic devices

Front 17

Actinomyces
1) organism type
2) source
3) associated disease

Back 17

1) Gram + bacilli
2) Upper respiratory tract, intestine
3) Actinomycosis - endogenous, low virulence. Ex-cervicofacial, poor hygiene or procedure, chronic granulomatous lesion with sinus tract

Front 18

Lactobacillus
1) organism type
2) source
3) associated disease

Back 18

1) Gram + bacillus
2) Mouth, intestine, genitourinary
3) Rare bacteremia, endocarditis

Front 19

General Characteristics of Clostridium

Back 19

1) Gram + bacilli
2) From intestine, and env (soil)
3) spore forming which can survive for years
4) exotoxin forming

Front 20

Intra-abdominal infextion biphasic clinical presentation

1) Phase 1
2) Phase 2

Back 20

1) Phase one is characterized by generalized peritonitis with fever, rigid abdomen, nausea, diffuse abdominal pain, vomiting, and some signs of shock
2) Phase 2 --> abscess formation

Front 21

Anaerobe most common to intra-abdominal infections?
Why? What factors contribute to infxn and abcess formation?

Back 21

Bacteroides fragilis - has polysacharide coat --> abcess plus EC enzymes collagenase, fibrinolysin, etc.

Front 22

Clostridium dificile colitis
1) sxs.
2) txt

Back 22

1) most common cause of diarrhea with antimicrobial use. Begins 5-10 days after txt initiation. Watery or bloody and can also have cramping, leukocytosis, and fever. "Pseudomembrane" = colonic membrane becomes studded with inflammatory plaques
2) Cessation of previous treatment, choice of new antimicrobial, relapse is common due to spores not killed by antibiotics

Front 23

C difficile NAP-1

Back 23

New strain of C. dificile that generated far more toxin and poorer response to metronidazole treatment.

Front 24

Clostridium myonecrosis (Gas gangrene)
1) Where does it develop?
2) Sxs
3) X-Ray appearance
4) Txt

Back 24

1) Traumatic wound with muscle damage
2) 1-4 days - intense pain, pressure, and heaviness
Progresses to necrosis and shock
3) looks airy due to necrotic tissue with gas from mitotic bacteria
4) Labs confirmatory, prognosis pore but surgical debridement and penicillin

Front 25

C. tetani
1) Source?
2) Common means of transmition?
3) sxs
4) txt

Back 25

1) Contaminated soil and gi of animals
2) Spores in wounds contaminated with soil or foreign bodies. Often seen in nonsterile removal of umbilical cord.
3) Lock-jaw, sardonic smile, drooling, sweating, irritability, back spasms
4) Diagnosed based on sxs, txt = surgical debridement and metronidazole, Ig for human tetanus, and vaccination with tetanus toxoid

Front 26

Clostridium botulism
Infant:
1) cause
2) common exposure source
3) sxs

Back 26

1) C. botulinum in infant GI, can't survive in adult GI
2) Honey
3) Nonspecific, flaccid paralysis, respiratory arrest

Front 27

Food bourne clostridium botulism
1) Cause
2) Souce
3) sxs
4) txt

Back 27

1) Ingestion of toxin
2) Canned foods, or food not cooked at high enough temperature
3) Initial: blurred vision, dry mouth, constipation, abdominal pain. Later bilateral descending weakness and respiratory paralysis
4) mechanical ventilation, metronidazole, botulinum antitoxin