- Gram positive rod
- Slight hemolysis
- Acid but no gas from CHO fermentation...facultative psychrophile (facultative intracellular parasite)
- Weird tumbling motility
Food sources of listeria
unpasteurized milk, cheese, processed meats
or long term storage of meats and cheese in the refrigerator
- Adult presentation of listeria
- Perinatal listeria from infected _____ during ____
- What are the types?
Diarrhea & dysentery
*Followed by meningitis or bacteremia (occasionally myocarditis) in IC patients
From infected placenta during Third trimester
- Early onset = stillbirth & granulomas
- Late onset = Type 4b
Listeria pathogenic factors (5)
Siderophores (bind iron)
- Intracellular growth
Internalin = binds cadherin receptor (uptake into cell)
Listeriolysin O = activated by low pH of phagolysosome
ActA = causes actin polymerization (moves to new cell)
Listeria preferred antibiotic
(or amp + aminoglycoside)
*erythromycin can also be used
Pseudomonas aeruginosa organism
gram negative rod (single polar flagellum)
- respiratory metabolism but can use NO3- as electron acceptor. Can use many Carbon sources
- Fruity aroma, blue-green fluorescent pigment
Major pseudomonas pathogenic factor?
How does this occur?
via homoserine lactones and Quorum-sensing signal
(Pseudomonas Quinolone Signal = PQS)
Pseudomonas are almost always _______ infections
Who are susceptible to skin biofilm pseudomonas infections?
burn patients and diabetics
Cystic fibrosis presentation for pseudomonas
lung biofilms with high amts of persister cells
Pseudomonas causes what other localized infections? (5)
- otitis externa
- eye infections (#1 lasik complication...you'll get green eyes!)
- UTI (catheters)
Ecthyma gangrenosum in diabetics
- Folliculitis (from contaminated water)
What do ecthyma gangrenosum lesions look like?
erythematous, non-pyrogenic ulcerations
Does Pseudomonas cause bacteremia?
Especially in Leukemia & burn patients, and diabetics
Is pseudomonas resident flora?
Yes, on moist areas of skin
NON-invasive in people with normal immunity
**CF patients have it as normal URT flora!
Pathogenic factors of pseudomonas (6)
Hypermutable strains in biofilm
Biofilm + Alginate capsule
LPS (typical of G-)
Type 3 Secretion System
Toxins = exotoxins A and S, Elastase, Pyocyanin/Polychelin
Function of toxins A and S from pseudomonas
A = ADP ribosylates EF-2 (diptheria toxin analog)
S = ADP ribosylates H-ras p21; signals apoptosis
Pyocyanin and Pyochelin create ________
3 Control measures for pseudomonas
- sterile environment (blue light?)
- topical ABX
- Prevention of biofilm (DNAase)
ABX for pseudomonas
Severe infection Tx?
Cipro is most frequently used (but resistance is problem)
Cipro + aztreonam
Severe = Gentamycin + ticarcillin or carbenicillin
**Meropenem + levofloxacin can prevent
Why shouldn't we treat pseudomonas with quinolones?
Activates biofilm formation
Acinetobacter baumanii - ventilator associated
burkholderia cepacia - catheter associated
Infections are almost always _____
Prefer to live at ______. How is this made possible?
Low redox potential (less O2) - which is generated by facultative organisms like E. coli
None of the anaerobes has ______. Thus...
...no ETC or respiration
Six common anaerobes
- Bacteroides fragilis
- Prevotella melaninogenica
- Porphyromonas gingivalis
- Propionibacterium acnes
Bacteroides: organism and location
Gram negative rod that hangs out in colon
- Antiphagocytic capsule
- Can produce some SuperOxide Dismutase and CAT (so a little O2 resistant)
- Extracellular enzymes- Neuraminidase and Heparinase
Prevotella organism, virulence factor, and infection location
Oral gram negative coccobacillus
Brain and Lung abcesses
Porphyromonas gingivalis organism, locations
Gram negative rod (oral)
implicated in gingivitis, oral abcesses, and infections of warm moist areas
Fusobacterium organism and location
gram neg fusiform
oral and colonic
Peptostreptococcus organism and location
Gram positive coccus
Propionibacterium acnes organism and location
Gram positive pleomorphic
Epidermal (acne, possibly brain abcesses)
What antibiotic is particularly good at treating anaerobes?
What causes the abcesses in anaerobe infections?
production of tissue-destroying enzymes
General control of anaerobes
Drainage (also allows O2)
PenG (NOT for bacteroides or prevotella... use Metronidazole and clindamycin)
Ceph3 for brain abcess
2nd line drugs = Ceph2, Ceph3, and carbapenems