L5: STAPH, STREP, ENTERO Flashcards
Staphylococcus, Genera from the Family _____
Micrococcaceae
Greek word “Staphyle” means
bunch of grapes,
Greek word “Kokkos” = means
berry
Staphylococcus are ____ anaerobes (capable of growth both aerobically and anaerobically)
Facultative anaerobes
Gram Positive cocci, arranged in CLUSTERS or tetrads
Staphylococcus
first to see staphylococci in pus specimen
Robert Koch
first to cultivate in liquid medium
Louis Pasteur
named the bacteria as ‘staphylococcus’
Sir Alexander Ongston
3 important human Staphylocci species
- Staphylococcus aureus
- Staphylococcus epidermidis
- Staphylococcus saprophyticus
Based on pigment formation on Nutrient Agar- golden yellow pigment
S. aureus
Based on pigment formation on Nutrient Agar. white pigment
S. epidermidis
Based on pigment formation on Nutrient Agar. bright yellow pigment
S. saprophyticus
Pathogenic staph
S. aureus
Less Pathogenic staph
S. epidermidis, S. saprophyticus
what test has a POSITIVE REACTION = bubble formation after drops of H2O2
Catalase test
Staph that is positive on Coagulase test
S. aureus
Staph that is negative on Coagulase test
S. epidermidis, S. saprophyticus
S. aureus possesses ____ enzyme which causes blood clot formation
COAGULASE enzyme
Based on Novobiocin Susceptibility Test. S. epidermidis
SENSITIVE
Based on Novobiocin Susceptibility Test. 2. S. saprophyticus -
RESISTANT
Gr (+) cocci in clusters
Staphylococcus aureus
Staphylococcus aureus. Generally in ____ um diameter
0.5 -1.5um
Staphylococcus aureus. Natural Habitat:
Skin, Upper Respiratory Tract
S. aureus. Opt. Temp for growth
37C
S. aureus. Opt. pH for growth
7.5
S. aureus. Color on Nutrient agar
Golden yellow and opaque colonies
S. aureus. Color on Blood agar
golden yellow colonies surrounded by a clear zone of hemolysis
S. aureus. Color on MacConkey agar
smaller colonies with pink color due to lactose fermentation
S. aureus. Color on Mannitol salt agar
yellow colonies
useful selective medium for recovering S. aureus from faecal specimens when investigating food poisoning
Mannitol salt agar
S. aureus. Virulence factors. Cell wall associated structures
Peptidoglycan
Capsule
protein A
Clumping factor (bound coagulase)
S. aureus. Virulence factors. Extracellular toxins
Haemolysin
Leukocidin
Enterotoxin
TSST
Exfoliatin toxin
S. aureus. Virulence factors. Coagulase
Staphylokinase
DNAase
Phosphatase
lipase
Phospholipase
hyaluronidase
serokinase
protease
ability to cause
damage to its host
Virulence
Toxins are ____ which can
stimulate the immune system causing massive cytokine release
SUPERANTIGENS
massive cytokine release causes
SEPSIS
MOT of S. aureus
Person with lesion
Airborne droplets
Asymptomatic carrier
Cross-infection
Clinical Diseases in S. aureus
- Impetigo
- Folliculitis
- Furuncles (boils) and carbuncles
- Osteomyelitis
- Staphylococcal Scalded Skin Syndrome (Ritters disease)
- Toxic Shock Syndrome (TSS)
- Food Poisoning
localized skin infection characterized by pus-filled vesicles (when ruptured, they form yellowish marks) on a reddened or erythematous base; seen mostly in children on their face and limbs
Impetigo
inflammation of the hair follicles
Folliculitis
large pus-filled skin nodules, can progress to deeper layers of the skin and spread into the blood and other body areas
Furuncles (boils) and carbuncles
- inflammation of the bones via bloodstream or through the injury
- Clinical features: Pain, Swelling, Deformity,
Osteomyelitis
caused by the EXFOLIATIN TOXIN which target the desmoglein 1 complex in
the zona granulosa of the epidermis, resulting in skin exfoliation
Staphylococcal Scalded Skin Syndrome (Ritters disease)
- cause by TSS toxin
- acute-onset illness characterized by fever, hypotension, sunburn
-like rash, and end-organ damage (life threatening)
Toxic Shock Syndrome (TSS)
associated with the use of Tampons
Toxic Shock Syndrome (TSS)
-caused by consuming foods with ENTEROTOXIN
- Poultry and uncooked meat products such as ham or corned
beef
- Symptoms: Nausea, Vomiting, Diarrhea, Abdominal pain and
cramping
Food Poisoning
Treatment S. aureus
Antibiotic therapy
Wound drainage
Device removal
Removal of dead tissue
Treatment S. aureus. Antibiotic Therapy
- Cephalosporins, Penicillins,
- Clindamycin
- Cloxacillin, Nafcillin,
- Vancomycin
group of gram-positive bacteria that are genetically distinct from other strains of
Staphylococcus aureus
Methicillin Resistant S. aureus (MRSA)
Developed a multiple drug resistance to beta-lactam antibiotics ( Methicillins)
Methicillin Resistant S. aureus (MRSA)
common in hospitals, prisons, and nursing homes, where people with open wounds, invasive devices such as catheters, and weakened immune systems are at
greater risk of healthcare-associated infection
Methicillin Resistant S. aureus (MRSA)
Methicillin Resistant S. aureus (MRSA). Treatment antibiotics
Vancomycin
Normal flora of the skin. Not usually pathogenic however patients with compromised immune systems are
at risk of developing infection
Staphylococcus epidermidis
Most infections are hospital acquired. Common cause of bacterial endocarditis in patients with valvular prostheses
Staphylococcus epidermidis
Staphylococcus epidermidis. Major Virulence Factor –
formation of BIOFILMS on plastic devices
Primarily responsible for FOOT ODOR
Staphylococcus epidermidis
Staphylococcus epidermidis
ID:
- Microscopy
- Culture
- Biochemical Tests: Catalase (+), Coagulase (-)
Staphylococcus epidermidis. Treatment
Vancomycin
Normal flora of the female genital tract and perineum
2nd Common cause of Acute UTI in women in reproductive years
Staphylococcus saprophyticus
Staphylococcus saprophyticus.
Source of specimen: ___ 🡪 Microscopy, Culture
Urine
Staphylococcus saprophyticus. Treatment:
Quinolones
Gram POSITIVE cocci in CHAINS
Streptococcus
Streptococcus. From the family
SPTREPTOCOCCACEAE
FASTIDIOUS bacteria which require enriched media (Blood Agar)
Streptococcus
Sensitive to DRYING, HEAT, DISINFECTANTS
Streptococcus
Based on Hemolytic reaction on Blood. _____ toxin
STREPTOLYSIN toxin
Based on Hemolytic reaction on Blood – STREPTOLYSIN toxin. (_____ Classification)
Browns Classification
base on the precipitins of CHO like antigens on the Cell wall (Polysaccharide and TECHOIC Acid in their cell wall)
Lancefield Group of Classification
Hemolytic reaction types
- Beta Hemolysis
- Alpha Hemolysis
- Gamma Hemolysis
- complete hemolysis/clearing on the zone of hemolysis
- appear as lightened yellow or transparent
Beta Hemolysis
Beta Hemolysis. Strep.
S. pyogenes, S. agalactiae
– incomplete hemolysis
- appear as greenish dark
Alpha Hemolysis
Alpha Hemolysis. Strep.
S. pneumonia, Viridans strep
no hemolysis occur. ex. Enterococcus
Gamma Hemolysis
base on precipitin reactions on CHO like antigens on a specific cell wall polysaccharide; ID by Rebecca Lancefield in 1933
Lancefield Group
Strep. Classification. Group A
S. pyogenes
Strep. Classification. Group B
S. agalactiae
Strep. Classification. Group C –
S. dysagalactiae
Strep. Classification. Group D –
Enterococcus: E. faecialis, E. facium
Non enterococcus: S. bovis
Biochemical reactions type
- Optochin Susceptibility
- Bile solubility
- Capsule
- Bacitracin Susceptibility
- CAMP Positive
- Enterococcus
- Fermentation of Inulin
Optochin Susceptibility – Sensitive:
S. pneumoniae
Optochin Susceptibility – Resistant:
Viridans
Bile solubility – Soluble:
S. Pneumoniae
Bile solubility – Insoluble:
Viridans
Capsule
(+) quellung reaction/Neufeld Reaction
S. pneumoniae
Capsule. (-) Reaction:
Viridans
Bacitracin Susceptibility – Sensitive:
Group A (S. pyogenes)
CAMP Positive –
S. agalactiae
Fermentation of Inulin – Fermenter:
S. pneumonia
Fermentation of Inulin. - Non fermenter :
Viridans
Important Streptococcal species to
Human
A. Streptococcus pyogenes
B. Streptococcus agalactiae
C. Streptococcus pneumoniae
D. Viridans Streptococci
- Inhabits throat, Nasopharynx, skin
- Best growth achieved at pH 7.4-7.6 and temp of 37C
Streptococcus pyogenes
Streptococcus pyogenes. Important Virulent Factors
- Enzymes
- Toxins
- M CHONs
Most common cause of bacterial pharyngitis
Streptococcus pyogenes
Streptococcus pyogenes. Individuals at high risk:
- 2-3 y.o with poor personal hygiene 🡪 pyoderma
- 5-15 y.o. with recurrent pharyngitis 🡪 RF
- Pts with soft tissue infection 🡪streptococcal toxic
shock syndrome - Pts with previous pharyngitis 🡪 RHD, GN
Streptococcus pyogenes. Clinical Diseases
- Pharyngitis
- Scarlet fever
- Pyoderma
- Impetigo
- Erysipelas
- Cellulitis
- Necrotizing fasciitis
- Streptococcal toxic shock syndrome
- Rheumatic fever
- Acute Glomerulonephritis
- reddened pharynx (involving tonsils) with exudates
- generally present; cervical lymphadenopathy
- can be prominent
Pharyngitis
- complication of strep pharyngitis;
- causes “strawberry tongue”
Scarlet fever
localized skin infection with vesicles progressing to pustules; no evidence of systemic disease
Pyoderma
localized skin infection characterized by pus-filled vesicles (when
ruptured, they form yellowish marks) on a reddened or erythematous
base; seen mostly in children on their face and limbs
Impetigo
localized skin infection with pain, inflammation, lymph node
enlargement, and systemic symptoms (involve SQ but it is more
demarcated)
Erysipelas
(similar to erysipelas but it has more irregular borders and
doesn’t have demarcation) skin infection involving the SQ tissues
Cellulitis
deep skin infection involving destruction of muscle and
fat layers; flesh- eating bacteria
Necrotizing fasciitis
multiorgan systemic infection resembling staphylococcal toxic shock syndrome but most patients are bacteremic and with evidence of fasciitis
Streptococcal toxic shock syndrome
non-suppurative complication of strep pharyngitis characterized by inflammatory changes of the heart (pancarditis),
joints (arthralgia, arthritis), blood vessels, and SQ tissues
Rheumatic fever
non-suppurative complication of strep
pharyngitis or soft tissue infections characterized by acute
inflammation of the renal glomeruli with edema (sequalae
of destruction of renal parenchyma), HTN, hematuria, proteinuria
Acute Glomerulonephritis
Streptococcus pyogenes. Specimen samples frequently from
skin, throat, urine, blood, sputum
