Clostridium, Actinomyces, Nocardia, Aeromonas/Plesiomonas Flashcards Preview

Bacteriology Lectures > Clostridium, Actinomyces, Nocardia, Aeromonas/Plesiomonas > Flashcards

Flashcards in Clostridium, Actinomyces, Nocardia, Aeromonas/Plesiomonas Deck (42):
1

Clostridium organism and appearance

Gram positive rods

rounded ends, in pairs or short chains

*spores often wider than the cell

2

Clostridium metabolism

Can be found in ____

Strict anaerobe

Found in soil

3

C. botulinum clinical presentation

bilateral cranial nerve palsies

descending flaccid paralysis

dysphagia/diplopia/ptosis

4

Sources of C. botulinum

Home canned foods

Alaskan native food

Entry via wounds, needles (IV drugs)

5

Major source of "floppy baby syndrome" (C. botulinum)

Ray honey - up to 70% of cases

6

Serotypes of C. botulinum

7 serotypes, A through G

A, B, E in humans

7

C. botulinum pathogenic factor

AB neurotoxin

B binds to NMJ

A cleaves synaptobrevin --> blocks fusion --> blocks Ach release

8

Control/Tx of C. botulinum

Antitoxin injection (A-G) as soon as you suspect botulism in the differential

 

*No ABX!

9

C. tetani clinical presentation

Spasms (Jaw then back)

Death occurs when spasms interfere with breathing

10

C. tetani sources

  • soilanimal feces  (introduced by fomites penetrating the skin)
  • Neonatal = from umbilical infections
  • IV drug use

11

C. tetani pathogenic factor

AB neurotoxin = Tetanospasmin (plasma encoded)

  • asorbed at NMJ, retrograde transport to cell body of motor neuron
  • binds irreversibly
  • reuptaken by presynaptic membrane of inhibitory neurons
  • cleaves synaptobrevin --> prevents GABA release

12

C. tetani control (vaccine, treatments, antibiotics)

  • VAX with tetanus toxoid -- boosters every 10 years
  • Antitoxin (Tetanus Immune Globulin) = only works if given early
  • Early tracheostomy, avoid stimulation
  • Muscle relaxants
  • ABX = Mzole (preferred over Penicillin)

13

C. perfringens strains 

5 strains based on toxin profile

14

C. perfringens clinical presentation

1-3 days until it starts from a wound

--> Tissue necrosis, toxemia, shock, death

*Can also present as food poisoning (1-2 days) if ingested ("enteritis necroticans")

15

How is C. perfringens acquired

Tramautic injury coupled with anaerobic conditions (i.e. ischemia)

**other organisms that are present will help facilitate anaerobic environment

16

C. perfringens pathogenic factors (5)

  • Alpha-toxin (lecithinase = phospholipase)
  • Hyaluronidase + Collagenase
  • Beta-toxin (food poisoning = e. necroticans)
  • Enterotoxin (in some strains) 

17

C. perfringens pathogenic process

Gas fermentations --> tissue distension --> compress vessels and stops bloodflow --> necrosis

 

*Necrotic tissue induces toxemia

18

C. perfringens control (treatment, antibiotics,)

Surgical debridement or amputation

ABX (to stop multiplying) = Mzole, penicillin, clindamycin

19

C. diff major disease

pseudomembranous colitis

20

C. diff usually beigins when? 

How is it acquired?

Main cause of symptoms?

  • 4-10 days after broad-spec ABX - Beta Lactams and Clindamycin are big offenders
  • Infects via nosocomial route, associated with PPI use
  • Main cause = disruption of native gut flora 

21

C. diff disease progression

  • Early Sx = watery diarrhea
  • leukocytes and cells form exudate = pseudomembrane
  • May involve part or entire length of colon

22

______ leads to asymptomatic carriage of C. diff

Ingestion of spores without dysbiosis (fancy word for native bacterial disruption)

23

is C. diff normal flora?

Yes, seems to be inportant for Treg cell development in colon

24

C. diff acquired by what route? Where does this normally happen?

Nosocomial

In health care settig (94% of cases)

25

C. diff pathogenesis

Toxin A = Enterotoxin --> fluid accumulation

*Toxin B* = Cytotoxin --> Kills gut epithelial cells

 

 

26

______ antibodies are useful in C. diff diagnosis

Anti-ToxinB

 

(anti-cytotoxin)

27

C. diff control (treatments, antibiotics, vaccine

Stop ABX if possible

  • Probiotic, fluid replacement, FECAL TRANSPLANT

 

  • ABX = Vancomycin + Mzole
    • Fidaxomycin (RNApol inhibitor) = for recurrent infection
  • Vax = toxoid against toxins A and B

28

Actinomyces israelii organism and appearance

Metabolism?

Gram positive branching, fragmenting filaments

Faculatative anaerobes (like higher CO2)

Grow Slowly --> molar tooth colonies

 

29

Actinomycosis clinical presentation

  • Lumpy Jaw (pyogenic abcess)
  • occurs at cervicofacial, thoracic, abdominal, skin (feet)

**Sulfur granules = Actinomyces surrounded by PMN's

30

Actinomyces normal flora?

Infection epidemiology?

Yes

Infection is usually just in IC patients and is non-communicable

31

Actinomyces acquisition?

Tooth extraction, bad hygeine, aspiration (lungs), perforated gut/ruptured appendix

 

*Food infection is found from soil bacteria

32

Actinomyces  control (Tx, ABX) and prophylaxis

Drainage of abcess

PenG for a few weeks (I.M.) and then oral for 6-12 months

**Tetracycline, erythromycin, clindamycin can be used with a penicillin allergy

 

Prophylactic Pen = with recurring infection or before oral surgery

33

Nocardia asteroides organism

Nocardia metabolism

actinomycete morphology

(= Gram positive branching, fragmenting filaments)

 

Partially acid fast (produces shorter mycolic acids)

Aerobic (lives in surface soil)

34

Nocardiosis presentation

Lobar PNA, usually in alcoholics or IC patients

  • abcess in lung lobe --> can spread to CNS (Meningitis or Abcess)

 

35

Nocardiosis can also occur...

on the foot from soil-based infections

36

Nocardia lung infection from _____.

Disseminates to _____ and ______

From Aspiration

Dissemination to CNS and Kidneys

37

Nocardia control

Bactrim

 

(also carbapenems + amikacin)

38

Aeromonas and Plesiomonas organism and origin

Gram negative rod, facultative anaerobe, motile

*Common fish pathogens

Aeromonas = Freshwater

Plesiomonas = Saltwater

39

Aeromonas and Plesiomonas...most common presentation?

Gastroenteritis

Watery (cholera-like) or Bloody (dysenteric) diarrhea

 

**Also cellulitis and myonecrosis

40

Aeromonas and Plesiomonas often acquired from...

fish-hook injury, SCUBA activity (??)

41

Aeromonas and Plesiomonas pathogenic factors

  • Typical Gram negative stuff (LPS, PG tox)
  • Pili for attachment
  • ACT Toxin = "aerolysin-cytotoxin-enterotoxin"

---> lyses cells + upregulates cAMP

42

Aeromonas and Plesiomonas control and Tx?

Avoid undercooked fish

IC patients and wound cellulitis =  Bactrim or Tetracycline

 

(Diarrhea is self limiting)