Chapter 18 Flashcards
What part of the body do staphylococcus inhabit?
skin and mucous membranes
Responsible for staph infections
staphylococcus
Describe the morphology of staphylococcus
- Clusters of short chains (grape racemes)
- No spores or flagella
- Sometimes encapsulated
How many species does the genus staphylococcus have? Name 3.
31
*S. aureus, S. epidermis, S. capitis
Staphylococcus are not _____________ any more.
harmless commensals
Describe the colonies of S. aureus
large, round, and opaque
What is the best temp for growth of S. aureus? and the temperature range?
37 degrees Celsius
10 - 46 degrees C
Facultative anaerobe
S. aureus
S. aureus look _____ under the microscope
grape-like
The growth of S. aureus is enhanced with ____ and ____.
O2 (oxygen) and CO2 (carbon dioxide)
S. aureus are metabolically versatile meaning…
They digest proteins and lipids and ferment sugars
Name 3 things S. aureus can resist
- extremes of pH
- extremes of temp (60 degrees C in 1 hour)
- most current antibiotics and many disinfectants
Why is S. aureus a troublesome hosipital pathogen?
Because it is highly resistant to most disinfectants and can remain viable after months of air drying. Also highly resistant to most current antibiotics.
No other pathogen produces as many virulence factors as
S. aureus
Name the 6 staphylococcal enzymes
Coagulase + Hyaluronidase Staphylokinase Nuclease Lipases Penicillinase
Spreading factor that digest the intercellular ‘glue’ and binds connective tissue
Hyaluronidase
intercellular “glue”
hyaluronic acid
Enzyme that digests blood clots
Staphylokinase
Enzyme that digests DNAse
Nuclease
Enzyme that help bacteria colonize oily skin and stay in sebaceous glands
Lipases
What enzymes inactivates penicillin?
penicillinase
Which enzyme must be positive in order for the bacteria to be S. aureus
coagulase
Pathogenic strains of staphylococcus produce which enzyme?
coagulase (coagulates plasma and blood)
What does coagulase do?
Coagulase causes fibrin to be deposited around staph cells.
Fibrin stops _______ or _____________.
phagocytosis; promote adherence to tissues
Which enzyme is present in 97% of all isolates?
coagulase
Name the 5 toxins of staphylococcus?
- Hemolysins
- leukocidins
- enerotoxins
- exfoliative toxin
- toxic shock syndrome toxin
Which toxin will cause damage by lysing the cell membranes of neutrophils and macrophages?
Leukocidins
Which toxins act on the gastrointestinal tract?
enterotoxins
How does the exfoliative toxin cause damage?
Separates the epidermal layer from the dermis.
Which toxin breaks down and disrupts the cell membranes of RBC?
hemolysins
Hemolysins produce a zone of _______ in ___________.
hemolysis; blood agar
The most powerful toxin
alpha toxin
Alpha toxin produces
beta hemolysis
Alpha toxins damage the __________, ___________, __________, and ________.
leukocytes, muscles, heart, renal tissues
Which toxin is associated with tampons and the binding/absorption of Mg++?
Toxic shock syndrome toxin
Which toxin is an intimate human associate?
TSST
Where is TSST present?
in all environments including fomites
Name the circumstances that predispose a person to infection?
- poor nutrition
- poor hygiene
- immunodeficiency
- preexisting primary infections
- diabetes mellitus (people w/ no control)
- tissue injury
Which type of infections are the 3rd most common nosocomial infection in the newborn nursery and surgical wards?
staph infections
________ can readily spread an epidemic pattern within and outside the hospital.
Hospital strains
Name the four different types of localized staph infections.
- folliculitis
- furuncles
- carbuncles
- impetigo
Osteomyelitis
systemic staph infection
Every 20 mins bacteria _____ in population.
double
_____ of certain strains responsible for the most common type of food infection in the USA
Enterotoxins
Toxigenic strains are found in
custards, sauces, pastries, processed meats, ham… anything salty
Toxigenic strains are dangerous because….
toxigenic strains are not noticible in food because they do not alter the smell or taste of food.
Toxigenic strains are heat-stable and have in activation at ______ for ______.
100 degrees celsius for 30 mins
Toxigenic strains usually last how long?
one day
toxins act on _________ and stimulate ______.
gastrointestinal epithelium; nerves
Effects of toxins are…..
cramping, nausea, vomit, diarrhea
Staph responsible for a large % of nosocomial infections since the 1970s.
Coagulase -
coagulase - are _______. They infect immunocompromised people.
opportunistic
Name the types of staph that infect via instruments through the skin.
- S. epidermitis
- S. hominis
- S. capitis
Which type of staph infects exclusively young sexually active women?
S. saprophyticus
The 2nd most common cause of urinary infections in staph.
S. saprophyticus
How is staphylococcus identified?
- Catalase test. (Plasma clots if it is +)
* Sugar fermentation
All types of staph are coagulase negative except ________ which is coagulase +.
S. aureus
Which type of staph is novobiocin-resistant?
S. saprophyticus
How is S. epidermidis identified?
S. epidermidis ferments mannose
S. capitis lacks ________.
urease
Which type of staph lacks anaerobic growth?
S. hominis
Is there a vaccine for staph? why or why not?
No, because it mutates so much so immunization is not successful.
How is staph treated?
pus must be removed (pyogenic cocci)
What are the clinical concerns for staph?
- They are notorious for in their resistance to many drugs
* Difficult to control
What is the biggest concern with S. aureus?
95% of S. aureus strains have acquired genes for penicillase making them resistant to penicillin and ampicillin.
MRSA can only be controlled by ________?
vancomycin
Name 3 antibiotics that MRSA is resistant to.
Erythromycin, tetracyclins, cephalosporins
How can nosocomial staph infections be prevented in a hospital?
consistent practice of universal precautions by all hospital staff
Family of gram- cocci.
Neisseriaceae
Two pathogen types of Nesseria
- Neisseria gonorrhoeae
* Neisseria meningitidis
What is unique about the shape of Neisseriaceae
coffee bean shaped.
Nesseria are found in pairs or ________ with flat side touching.
diplococci
Neisseria gonorrehoae are also known as
gonococcus
What kind of incubator do Neisseria need?
Capnophylic incubator … produces more CO2
How would Neisseria be identified in a lab?
Neisseria are catalase + so it should make bubbles when combined with Hydrogen peroxide
*it can also be identified with cytochrome oxidase
Respiration of Neisseria?
aerobic or microaerophilic
Neisseria will survive for how long outside?
2 hours
What affects Neisseria?
light, temp, pH
Neisseria gonorrhoeae are often confused with _______________.
syphilis
Claudius Geller thought gonococcus was caused by ___________________.
excess flow of semen
Humans are the only resevoirs for
N. gonorrhoeae
Among the top 5 reported STD’s.
Neisseria gonorrhoeae
How many cases of gonorreah are reported each year
400,000.
What type of media is N. gonorrohoea grown in?
Martin - Tayer media(chocolate agar)
How is neisseria gonorrhoea identified?
gram stain (stains pink bc it’s negative) and oxidase test
special type of neisseria?
has no fimbriae
antibiotic formulated for control of gonorrohea?
spectinomycin
causes epidemic cerebrospinal meningitis
Neisseria meningitidis
How is Neisseria meningitidis transferred?
respitory secretion or droplets from carrier
Most common in US
meningococcus
