CHARACTERISTICS OF GENERA Flashcards
1
Q
Staphylococcus Characteristics:
A
- Gram-Positive
- Facultatively anaerobic
- Catalase positive
- S. aureus and S. intermedius are coagulase positive
- Oxidase negative
- Divide in all planes
- Daughter cells remain attached
- Non-spore forming
- Not conventionally motile
- Salt tolerant
- Desiccation tolerant
- Radiation and heat-tolerant
- Hyaluronidase present (S. aureus)
- Protein A binds to fc region of antibodies (S. aureus)
- S. aureus typically has DNase
- Have capsules
2
Q
Streptococci Characteristics:
A
- Gram-Positive
- Facultatively anaerobic
- Catalase negative
- Coagulase-negative
- Oxidase-negative
- 0.5 -1.2 um diameter
- Non-motile
- Divides in one plane
- Strep A doesn’t require blood agar unlike others, but growing Strep spp. on blood agar can show haemolysis patterns.
- Streptolysin O is oxygen sensitive and immunogenic, Streptolysin S is neither
- Strep A has SLO and S, GBS has SLS but not O
3
Q
Escherichia (E.coli) Characteristics:
A
- Gram negative bacillus
- Catalase positive
- Oxidase negative
- Indole positive
- Urease negative
- Motile
- Can produce exotoxins (shiga), endotoxins, or cytotoxins
- O157:H7 only produces shiga like toxin and haemolysin
- Shiga-like toxin has A and B section, B binds, once cleaved, A removes adenine from section of 28s rRNA from 60s subunit
- Facultative anaerobe
- Lactose fermenter
4
Q
Neisseria Characteristics:
A
- Gram-negative diplococci
- Non-motile
- Fastidious (commonly used agar is chocolate agar)
- N. gonorrhoea are pathogenic, N. meningitidis are opportunistic
- Obligate aerobes, but can adapt to microaerophilic environments
- Typically inhabit mucous membranes
- Production of polysaccharide capsule is major virulence factor for pathogenic species
- Oxidase positive
- Catalase positive
- Indole negative
- Lipooligosaccharide instead of lipopolysaccharide (lack O antigen)
5
Q
Pseudomonas Characteristics:
A
- Gram-negative rods
- Normally listed as an obligate aerobe, but can reduce nitrate to nitrite, nitrite to N2O and NO then N2O and NO to N2. These electron acceptors allow it to respire without oxygen.
- Motile, single polar flagellum
- Oxidase positive
- ## Can grow at 42oC
6
Q
Bacillus Characteristics:
A
- Gram-positive rods
- Usually motile (anthracis isn’t)
- Spore forming
- Aerobic or facultatively anaerobic, (anthracis and subtilis are aerobic, cereus is facultatively anaerobic).
- Bacillus subtilis produces bacitracin
7
Q
Clostridium Characteristics:
A
- Gram positive rods
- Spore forming (terminal)
- Obligate anaerobes
- Some motile (difficile/perfringens)
- Some non-motile (tetani/botulinum)
8
Q
What causes farmers lung?
A
Thermoactinomyces vulgaris.
Micropolyspora faeni
Aspergillus
9
Q
Entamoeba histolytica:
A
- Protozoan parasite
- Causes disease in 50mil people worldwide
- Can invade soft tissue sites.
10
Q
Ascaris lumbricoides:
A
- Nematode worm
- One of most common helminth infections
11
Q
Shigella Characteristics:
A
- Enterobacteriaceae
- Gram-negative bacilli
- Unlike many other enterobacteriaceae, non-motile
- Facultative anaerobe
- Non-lactose fermenter
- Known for invasion of epithelium
- Shiga toxin
- S.dysenteriae pathogenic
12
Q
Corynebacterium Characteristics:
A
- Gram-positive rods (form V shape clusters)
- Non-motile
- Obligate aerobes, or facultative anaerobes
- Short chain mycolic acids, so not acid-fast like M. tuberculosis
- Non-spore forming, unlike other G+ rods
- Catalase positive (all positive spp are potentially toxigenic)
- Negative pyrazinamidase test spp are all potentially toxigenic)
- Oxidase negative, but unlike most gram-positive bacteria, some spp. are positive.
- Coagulase negative
- C.diphtheriae, pathogenic, produces diphtheria toxin
- Diphtheria toxin has A and B fragments, B binds to heparin-binding epidermal growth factor and enters cell, once inside toxin is cleaved and A ribosylates elongation factor 2, stopping protein synthesis
- C. jeikeium is lipophilic and needs lipids to grow and survive.
13
Q
Klebsiella Characteristics:
A
- Enterobacteriaceae
-Gram-negative bacilli - Catalase positive
- Oxidase negative
- Indole negative (usually),E. coli is positive
- Facultative anaerobes
- Unlike many other Enterobacteriaceae, non-motile
- Characteristic large polysaccharide capsule
- Lactose fermenters, like E. coli
- Urease positive (E.coli isn’t)
The pathogenic species is Klebsiella pneumoniae.
14
Q
Proteus Characteristics:
A
- Enterobacteriaceae
- Gram-negative rods
- Extremely motile (characteristically)
- Catalase positive
- Oxidase negative
- Strongly urease positive (E. coli isn’t)
- Proteus vulgaris is indole positive, mirabilis is negative
- Same TSI test results as Salmonella
- Non-lactose fermenters
- Facultative anaerobe
- P.mirabilis and P.vulgaris are opportunistic
- P spp (especially P. mirabilis) can cause UTIs for example cystitis (bladder) or pyelonephritis (kidney), because P. spp strongly urease positive (urea to ammonia, raising pH and resulting in more kidney stones)
15
Q
Yersinia Characteristics:
A
- Enterobacteriaceae
- Facultative anaerobic
- Gram-negative coccobacilli
- Non-lactose fermenter
- Oxidase negative
- Catalase positive
- Urease negative (like E.coli)
- Usually indole negative
- Generally motile, but only below 37oC, thus not in the human body
- Produce exotoxins (YOPs)?
- Can resist phagocytosis (superoxide dismutase and catalase)
- Facultative anaerobe
- Y. pestis and Y. enterocolitica are pathogenic.
- Typically Zoonotic
- Can form capsules
- Virulence factors are yersinia outer proteins, injected into immune cells to interrupt cellular processes, and plasminogen activator protease, which helps break down fibrin clots.
