What gram stain is Streptococcus pyogenes?
What shape is Streptococcus pyogenes?
Is Streptococcus pyogenes catalase positive or negative?
Is Streptococcus pyogenes anaerobe or aerobes?
How motile is Streptococcus pyogenes?
Can Streptococcus pyogenes do hemolysis?
Yes, beta hemolysis
True/False: Streptococcus pyogenes is not sensitive to bacitracin
False, Streptococcus pyogenes is bacitracin sensitive, will not grow if there is bacitracin in agar
True/False: some Streptococcus pyogenes requires carbon dioxide
True, some are capnophilic
What type of agar is used for Streptococcus pyogenes?
Is Streptococcus pyogenes fastidious or non-fastidious?
Streptococcus pyogenes group A could be found where?
- Has a human reservoir
- Normal microbiota of oropharynx
Streptococcus pyogenes has what kind of capsule?
What kind of infections are caused by Streptococcus pyogenes?
- Necrotizing fasiciitis
- Acute rheumatic fever
- Acute post-streptococcal glomeruloneph
What are some virulence factors of Streptococcus pyogenes?
- M protein
- Against C5a peptidase
- Exotoxin B
What is the function of hyaluronic acid?
It is non immunogenic because we have this too, so our immune system won’t recognize it
What is ScpC?
A cell envelope proteinase that prevents neutrophil recruitment by clipping IL-8
What is C5a peptidase?
Blocks phagocyte chemotaxis by inactivating C5a
What is M protein?
- Adhesins, binds fibronectin, keratinocytes
Which hemolysins can Streptococcus pyogenes produce?
Streptolysin S and Streptolysin O
What is streptolysin S?
- B-hemolysin that causes rapid Cl- into cells that lead to lysis
- Works in aerobic condition
What is streptolysin O?
B-hemolysin that works only in anaerobic condition, more antigenic than S
What are some extracellular spreading factors of Streptococcus pyogenes?
- DNases A-D
What are superantigens?
Pyrogenic exotoxins formed by S.pyogenes
What is exotoxin B?
A superantigen formed by S.pyogenes that degrades immune proteins
What gram stain is Clostridium perfringens?
What shape is Clostridium perfringens?
Is Clostridium perfringens anaerobic or aerobic?
Aertotolerant to anaerobic
Do Clostridium perfringens for endospores?
Yes, they are one of the two major clinical bugs that form endospores
What is characteristic of Clostridium perfringens when it is related to necrotizing infection?
What is characteristic of gas gangrene?
What is typically associated with gas gangrene?
Deep penetrating wound
Where are Clostridium perfringens found?
- Normal microbiota of GI tract
- Normal microbiota in female GU tract
Do Clostridium perfringens have a capsule?
Are Clostridium perfringens motile or nonmotile?
Do Clostridium perfringens have hemolytic abilities?
Yes, double zone hemolysis from alpha and theta toxins
How fast do Clostridium perfringens grow?
Very fast in culture
What are some virulence factors of Clostridium perfringens
- Alpha-toxin = lecithinase
What are alpha-toxins (lecithinase)?
Phospholipases that disrupt host cell membrane, causing disorganization and responsible for hemolysis and tissue destruction
What are theta-toxin?
Disrupts cholesterol and lysis of RBC and WBC
What are some spreading factors of Clostridium perfringens?
When do gas gangrene usually occur?
<24 hours after deep, penetrating/traumatic injury
What is the shape and gram stain of Brucella?
Gr negative Coccobacilli
Is Brucella aerobic or anaerobic?
Where do Brucella live in host?
Facultative intracellular – can survive inside macrophages and PMNs
How fast do Brucella grow?
What kind of agar do Brucella grow in?
Blood agar with carbon dioxide
What are the source of human Brucella infections?
Pigs, cattle, goats, dogs
What is the mode of Brucella transmission from animal to human?
- Ingestion of unpasteurized dairy products
- Direct contact
How do humans show symptoms of Brucella?
- Granulomatous response
- Undulant fever
- Nonspecific flulike symptoms
- Enlarged lymph nodes, liver, spleen
How is Brucella diagnosed?
Bone marrow culture is gold standard
What is the shape and gram stain of Pasteurella multocida?
Gr negative coccobacilli
What is the common source of human Pasteurella multocida infection?
Infected dogs or cats
What is the mode of transmission of Pasteurella multocida from animal to human?
Bite, lick, scratch
Do Pasteurella multocida have capsule?
Where could Pasteurella multocida be found in its animal source?
Normomicrobiota animal oropharynx
What are diseases in human that are due to Pasteurella multocida?
- Localized cellulitis and lymphadenitis
Systemic infection for immunocompromised patients
What could happen in Pasteurella multocida infections are left untreated?
Could lead to osteomyelitis and septic arthritis
What is the shape and gram stain of Bartonella henselae?
Gr negative Rod
What are other names for Bartonella henselae?
- Cat scratch disease
- Bacillary angiomatosis
What is the source of human Bartonella henselae infection?
What is the mode of transmission of Bartonella henselae from animal to human?
Bite, lick, scratch
Where do Bartonella henselae live in its host?
What is a physiological response induced by Bartonella henselae?
How fast do Bartonella henselae grow?
What diseases are caused by Bartonella henselae?
- Localized, chronic lymphadenopathy in children
- Possible complications including endocarditis, encephalopathy, granulomatous lesion on liver and spleen in immunocompromised patients
What is a disease caused by Bartonella henselae in HIV patients?
What are symptoms of bacillary angiomatosis?
- Multiple cutaneous or subQ vascular lesions that bleed profusely when traumatized
- Liver lesions
- Osteolytic bone lesion of the long bones
What is Bartonella quintana mode of transmission?
What is another name for Bartonella quintana?
True/False: Bartonella henselae is more common cause of bacillary angiomatosis than B.quintana
Which population are Bartonella quintana prevalent in?
What is necrotizing fasciitis?
- Community acquired deep-seated infection of SubQ tissues
- Progressive destruction of fascia and fat
- May spare skin
What microbe usually causes necrotizing fasciitis type II?
Group A Streptococcus pyogenes (GAS)
Describe pathogenesis of necrotizing fasciitis?
- Could occur any part of body, usually begin as cellulitis
- Spreads along fascial planes and causes destruction of those plus fat
- Lead to systemic symptoms
What are symptoms of necrotizing fasciitis?
- Fevers, hypotension, tachycardia
- Pain out of proportion
- Erythema, skin induration
- Bullae (blue, large blisters)
- Darken, reddish purple color skin within 24-48 hours
What could happen to patient with necrotizing fasciitis?
- Multiple organ failure
How id necrotizing fasciitis diagnosed?
- When symptoms fail to respond to broad spectrum IV abx
- Cutaneous manifestation
How is necrotizing fasciitis treated?
- immediate surgical debridement
- Hemodynamic support
What is myonecrosis?
Necrotizing infection of the muscle
What is gas gangrene?
Necrotizing infection of muscle that is caused by Clostridia instead of Streptococcus
What are symptoms of gas gangrene?
- Sever pain
- Edema, tenderness
- Crepitus at subQ tissue/muscle
- Systemic findings of toxicity
What could happen to patients with gas gangrene if left untreated within 48 hours?
Multiorgan failure, death
How is gas gangrene diagnosed?
- Confirm with gram stain, anaerobic cultures
- Double zone hemolysis on blood agar
- Lecithinase activity on egg yolk agar
What is pyomyositis?
Purulent infection of soft tissue infection that spread to the bone, usually with abscess caused by S.aureus or S.pyogenes
What is osteomyelitis
Subacute to chronic infection to the bone
What is the common cause of osteomyelitis?
What are some symptoms of osteomyelitis?
- Localized pain
What are the risk factors for osteomyelitis?
- Immunocompromised patients
- IV drug users
What are some types of osteomyelitis?
- Hematogenous (monomicrobial)
- Contiguous (polymicrobial)
How is osteomyelitis diagnosed?
- Patient unable to bear weight
- Unilateral extremity pain
- Recent trauma or puncture wound
- Chronic draining ulcer
What are some diagnostic methods for osteomyelitis?
- MRI imaging
- Gold standard – isolation of microbe from bone bx
How to treat osteomyelitis?
- Abx after bone bx
- Debridement either surgically or non-surgically
- Could consider amputation