LEC-6 Bacterial Pyogenic Infections Flashcards
_________ results as an accumulation of dead phagocytes.
Pus
_________ infections are referred to as pus-forming infections and are usually associated with toxin production, such as leukocidins.
Pyogenic
A(n) ___________ is a pyogenic infection of the skin and/or subcutaneous tissues.
Pyoderma
As a pyogenic infection proceeds deeper into the layers of skin, what is the primary concern?
As deeper layers of skin are involved in the infection, the bloodstream becomes compromised. This causes systemic signs and fever to appear. There is a concomitant increase in the need for systemic antibiotics if this occurs.
Describe what is shown in the picture.
Vesicle is shown
- Small (<1.0cm), serum-filled blister in or just beneath the epidermis.
- It is often of viral in orgin, but not necessarily infectious
- A “honey colored crust” develops post-rupture
Describe what is shown in the picture.
Purpura is shown
- Rash of purple caused by the leakage of blood into surrounding tissues
Describe what is shown in the picture.
Bullae is shown
- A large (>1.0cm) type of vesicle that may result in pupura
- Can result in purpura
What type of bacterior most commonly cause skin infections?
Gram-positive bacteria
The bacterial genuses ____________ and ____________ are the primary cause of nearly all skin and soft tissue infections.
Staphylococcus and Streptococcus
Staphylococcus ___________ is the most toxogenic form of this genus.
Staphylococcus aureus
Streptococcus ____________ is the most toxogenic form of this genus.
Streptococcus pyogenes
- Pyogenes as in pyogenic
Grape-like clusters are characteristic of, but not exclusive to, (staphylococcus/streptococcus).
Staphylococcus
Bacterial spores are characteristic of (coccus/bacillus/spirillum) types of bacteria.
Bacillus (rod-shaped)
Staphylococci (do/do not) form spores.
Do not.
- Spores are characteristic of rod-shaped bacteria (bacilli)
(T/F) Staphyloccocus are heat-resistant, antiseptic-resistant, and resistant to drying, but they cannot form spores.
True.
______________ is a bacterial enzyme that brings about the coagulation of blood or plasma and is produced by disease-causing forms of staphylococcus.
Coagulase
Staphyloccocus aureus is coagulase (positive/negative).
Positive
Coagulase (positive/negative) strains of bacteria are the primary pathogenic strains.
Positive
What is the difference in shape between staphylococcus and streptococcus?
- Grape-like cluster of staphylococcus
- Chain formation of streptococcus
(α/β/γ) hemolysis involves no hemolysis at all.
γ hemolysis
(α/β/γ) hemolysis involves incomplete (green-appearing) hemolysis. This is characteristic of Streptococcus viridans (throat bacteria).
α hemolysis
(α/β/γ) hemolysis involves complete hemolysis, characteristic of Streptococcus pyogenes.
β hemolysis
____________ is a bacterial enzyme that catalyzes the reduction of hydrogen peroxide.
Catalase
Staphylococcus strains test catalase (negative/positive).
Positive
Streptococcus strains tests catalase (negative/positive).
Negative
What is folliculitis?
- A bacterial infection localized to a hair follicle.
- It is almost always confined strictly to the epidermis and is also usually caused by S. aureus.
- These infections rarely, if ever, require systemic antibiotics.
What is a furuncles (boils)?
- A deep folliculitis where the lesion extends in to the dermis.
- This is also most commonly caused by S. aureus.
- These infections rarely, if ever, require systemic antibiotics.
- For small lesions, apply moist heat to promote drainage.
- For large lesions, incision and drainage is recommended.
What is a Carbuncle?
- Forms when multiple furuncles (boils) join together.
- These infections rarely require systemic antibiotics, but always require incision and drainage.
Effective antimicrobial therapy of a pyogenic infection always requires ____________ irregardless of acquired resistance.
Drainage
Impetigo and erysipelas are characteristic of the (epidermis/dermis/fascia/muscle).
Epidermis
Fasciitis is characteristic of the (epidermis/dermis/fascia/muscle).
Fascia
Erysipelas and cellulitis are characteristic of the (epidermis/dermis/fascia/muscle).
Dermis
Myositis is characteristic of the (epidermis/dermis/fascia/muscle).
Muscle
What is Impetigo?
- A superficial pyoderma with discrete borders.
- Results as an infection by either Staph. aureus or Step. pyogenes and is commonly seen in children.
- It is characterized by thick, honey-colored crust and is uncommon for systemic involvement.
What is the accepted topical treatment of impetigo?
- Mupirocin (Bactroban)
- Fusidic acid (Fucidin)
- If extensive, combine with oral antibiotic
Both protein synthesis inhibitors
(Fusidic acid/Mupirocin) is a protein synthesis inhibitor that is available for topical and systemic use, but is not currently available in the U.S.
Fusidic acid
What is Staphylococcal Scalded Skin Syndrome (SSSS)?
- AKA Ritter’s Disease
- Caused by S. aureus and results in mass exfoliation of patient’s skin, resmbling a burned area
- Results in toxemia: But cannot isolate S. aureus from lesions
- Physicians must do nasopharyngeal culture to identify responsible bacteria
(T/F) Infections by Staph. aureus causing SSSS require localized topical antibiotics.
False. Infections by Staph. aureus causing SSSS require systemic antibiotics.
Culture of what region of the body is most useful in obtaining bacterial identification in a patient suffering from Ritter’s disease?
The nasopharyngeal region. The rest of the lesions will be sterile.
What is Bullous Impetigo?
- A localized form of SSSS that features bullae.
- Staph. aureus is able to be isolated from the lesions.
(T/F) Bullous impetigo requires systemic antibiotics
True.
Describe Toxic Shock Syndrome.
- Caused from a superantigen.
- Results in massive induction of immunological cytokine release leading to:
- Fever, diarrhea, vomiting
- Sunburn-like petechial rach, the desquamation of the hands and feet
- Strawberry tongue.
Toxic Shock Syndrome may progress into what other ailments if not treated and controlled?
- Disseminated intravascular coagulation (DIC)
- Rapid drop in blood pressure
- Acute respiratory distress syndrome (ARDS)
- Multiple organ system failure (MOSF)
What is Erysipelas?
- A superficial form of cellulitis
- Distinguished by a raised, clearly demarcated border.
- Systemic signs are common but do not appear in all cases.
- It is most common on the face and legs and spreads rapidly within hours.
- Its most common causes are, in order of likelihood:
- Strep. pyogenes
- Staph. aureus
What is Cellulitis?
- An infection of the deeper, subcutaneous tissues that is less demarcated and spreads more slowly than erysipelas.
- Its most common causes are, in order of likelihood:
- Strep. pyogenes
- Staph. aureus
What is Fasciitis?
- An infection that occurs in deep subcutaneous tissue and spreads along the fascial planes.
- This type of infection is a true infectious disease emergency and most often presents with pain that is out of proportion to appearance of the condition.
- Infections of this type require surgical intervention.
- Its most common causes are, in order of likelihood:
- Strep. pyogenes
- Staph. aureus
Complete the following table.
Image
What is Myositis?
- One of the deepest infections involving spread through muscle planes.
- It may be caused by 1. Strep. pyogenes or 2. Staph. aureus, but is classically associated with 3. Clostridium perfringens.
- May result in gas gangrene or suppurative myositis with accumulation of pus in the muscle planes and always requires surgical intervention.
Hot tub folliculitis is caused by __________________.
Pseudomonas aeruginosa
An infection following a puncture through one’s tennis shoe would most likely be caused by ________________.
Pseudomonas aeruginosa
Hematogenous osteomyelitis infections are most common in (adults/children) and are caused by problems within the circulatory architecture that allows for bacterial invasion into the bone.
Children
Osteomyelitis that occurs secondary to a contiguous focus of infection is most common in (adults/children) and usually affects the __________ of the axial skeleton and the __________ of the appendicular skeleton.
- Adults
- Spine and long bones
Patients with _____________ may develop osteomyelitis secondary to vascular insufficiencies or foot injuries.
Diabetes
(Acute/Chronic) osteomyelitis infections almost always require surgical debridement.
Chronic
What bacterial infection could also be considered in diabetics and drug addicts?
Pseudomonas aeruginosa
- Doesn’t replase S. aureus as primary cause
Sickle cell patients are particularly susceptible to an infection by ___________.
Salmonella
Prosthetic joints and hardware increase the risk of infection by ____________.
Staph. epidermidis
Patients suffering from vertebral osteomyelitis have an increased risk of infection from _______________
Mycobacterium tuberculosis
Inflammation of the joints due to bacterial infection is known as ____________.
Septic arthritis
The most common cause of septic arthritis infection is _____________.
Staph. aureus
What are the most likely bacterial suspects for infection at each layer of the skin, muscle, and bone?
Image
The most common etiological bacterial agent involved in osteomyelitis is ______________.
Staph. aureus
