staph Flashcards
Micrococci belongs to the family of
Micrococcaceae
Gram (+) or Gram (-)
Micrococci
Gram (+) cocci
in clusters ; in tetrads
Belongs to the family Staphylococcaceae
staphylococci
this means grapelike clusters
staphylococcus
Gr (+) cocci (0.5 - 1.5 um) in clusters, in pairs, singly
staphylococcus
Staphylococcus
all are catalase (+) except
S. aureus subsp anaerobius and S. saccharolyticus
Staphylococcus
all are modified oxidase (-) except
S. sciuri, S. lentus, S. vitulus
majority of motile bacterias are
bacilli
all are non-motile and non-sporeformers
staphylococcus
gaseous requirement
aerobic or facultative
except S. aureus and S. saccharolyticus
halophilic and nitrate reducers
staphylococcus
colonial morphology
- pinhead
- raised
- creamy
- lemon yellow or golden yellow colonies
colonial morphology
S. albus
white
colonial morphology
S. aureus
golden yellow
due to the pigment of staphyloxanthin
colonial morphology
S. citreus
lemon yellow colonies
more seen in loeffler’s serum slant
this is an initial test that’s performed to differentiate the Staphylococcus spp.
coagulase test
coagulase producing saphylococcus
- S. aureus
- S. intermedius
- S. pseudointermedius
- S. hyicus
- S. delphini
- S. lutrae
- S. agnetis
2 groups of coagulase negative staphylococci (CONS)
- Novobiocin Susceptible
- Novobiocin Resistant
Novobiocin Susceptible
has zone of inhibition
- S. epidermis
- S. haemolyticus
Novobiocin Resistant
has NO zone of inhibition
- S. saprophyticus
- S. xylosus
primary reservoir of staphylococcus
human nares
particulary S. aureus
clinically significant staphylococcus
- S. aureus
- S. epidermis
- S. lugdunensis
- S. saprophyticus
first 2 is coag. (+), last 2 is coag. (-)
less common but implicated as opportunistic pathogens
- S. warneri
- S. capitis
- S. hominis
- S. schleiferi
- S. haemolyticus
staphyloccocus
most clinically significant
S. aureus
causes a wide variety of diseases such as
- pimples
- sty
- cellulitis
- folliculitis
- toxic shock syndrome
- scalded skin syndrome
- food poisoning
- impetigo
- furuncles and carbuncles
also causes nosocomial and opportunistic
pathologic determinants
- protein A: antiphagocytic
- capsular polysaccharide
- peptidoglycan and teichoic acids
- endotoxin like activity
- activates complement, interleukin 1
- chemotactic factor for PMN
protein a is a cell wall component of S. aureus
Heat stable toxins
Enterotoxins
virulence factors
- hemolysins (alpha, beta, gamma and delta)
- panton valentine factor leukocidin
- beta-lactamase
- PBP2
- Hyaluronidase
- Lipases
- Staphylocoagulase
- TSST-1 - superantigens
- Enterotoxins
- Exfoliative Toxin
- Protein A: antiphagocytic
- Capsular Polysaccharide
- Peptidoglycan and Teichoic Acids
- Nucleases
Enterotoxins
A, B, D
staphylococcus food poisoning
Enterotoxins
B
Staphylococcus pseudomembranous enterocolitis
Enterotoxins
B, C, G, I
Toxic Shock Syndrome
Enterotoxins
F
Toxic Shock Syndrome toxin 1 (TSST - 1) / Pyrogenic Exotoxin
causes almost all cases of menstruating TSS
TSST - 1
also known as Epidermolytic Toxin
Exfoliative Toxin
Epidermolytic Toxin is implicated in
- Ritter-Lyell Disease
- Scalded Skin Syndrome
- Dermatitis Exfoliativa
Epidermolytic Toxin is also implicated in
Bullous Impetigo
extracellular toxins that affect RBCs and WBCs
Cytolytic Toxins
Hemolysins
- Alpha
- Beta/hot cold lysin (type of sphingomyelinase)
- Delta-toxic to RBCs and other mammalian cells
Gamma (associated with PVL)
what are the 2 cytolytic toxins
- hemolysins
- leukocidin
Ezymes
- DNAse, lipase, hyaluronidase, staphylokinase
- detroys tissue and responsible for spread of infection - staphylocoagulase
- cell free r bound ; localization of abscess
- virulence marker
other factors not related to pathogenecity
- penicillinase
- catalase
- thermonuclease
- gelatinase
What are the skin wound infections: suppurative
- Folliculitis
- Furuncles (boils)
- catbuncles
- bullous impetigo
- acne
Exfoliative dermatitis that occurs among newborns and previously healthy young children; also seen among adults with chronic renal failure
SSS: Scalded Skin Syndrome
Toxic Shock Syndrome
Signs and Symptoms
- sudden onset of fever
- chills
- vomiting
- diarrhea
- muscle pain
- rashes
- can progress to hypotension and shock
2 categories of Toxic Shock Syndrome
- menstruating associated
- non menstruating associated
involves the ingestion of a preformed enterotoxin from food that is improperly stored
staphylococcal food poisoning: gastrointestinal disturbances
incubation period of staphylococcal food poisoning
2-8 hrs
most common enterotoxin causing food poisoning
Enterotoxin A
50% of CONS isolates
S. epidermidis
usually a normal inhabitant of the skin
S. epidermidis
- most common cause of prosthetic valve endocarditis
- infection are nosocomial
- causes “stitch abscess”
S. epidermidis
2nd most common cause of UTI after E. coli
S. saprophyticus
associated with pyelonephritis and cystitis in young women and in older men using catheters
S. saprophyticus
colony counts may be < 100,000 CFU / ml but is still significant to be considered as a cause of UTI
S. saprophyticus
a cause of nosocomial infections such as endocarditis, septicemia, meningitis and skin and soft tissue infections
S. lugdunensis
positive for clumping factor (slide coagulase)
S. lugdunensis
- causes an aggressive type of endocarditis
- high mortality rate
S. lugdunensis
samples for staphylococcus
aspirates are preferred; if swabs are submitted, it must be at least 2
what are the culture media for isolation and ID
- BAP
- CAP
- Broth: Thioglycollate, BHI, Blood-Broth
- Selective Media such as Columbia Colistin Nalidixic Agar, PEA
- Selective and Differential Media such as: MSA, CHROMagar staph aureus
Colonial Characteristics of BAP
- Round
- Smooth
- White or Yellow pigmented
- Creamy colonies
Colonial Characteristics of CAP
S. aureus
- pinhead colonies (greenish discoloration)
Colonial Characteristics of S. epidermidis
- small-medium sized
- gray colonies
- yellow pigmented colonies
Colonial Characteristics of S. lugdunensis
medium sized colonies; Beta-hemolytic
beta-hemolysis can be seen in what colony
S. aureus colonies
non-mannitol fermentor can be seen in
S. epidermidis
mannitol fermentor can be seen in
S. aureus
