Streptococcus/Staphylococcus Flashcards
1
Q
Streptococcus
A
- Gram positive
- Catalase negative: cannot breakdown hydrogen peroxide - often cultured on BAP.
- Round bacteria that tends to link to other bacteria in chain-link structures.
- Many different types of strep. The best is to grow it on BAP and let it differentiate itself by hemolytic activity. (alpha, beta, gamma)
2
Q
Alpha-Hemolysis
A
- Partial decomposition of hemoglobin RBC. Presents itself as a greenish/brown color around the bacterial colony.
- Characteristic of Streptococcus Pneumonia
3
Q
Beta-Hemolysis
A
- Bacteria completely breaks down RBC. There is a zone of clearing surrounding the bacteria.
- Characteristics of Streptococcus Pyogenes and some strands of Staphylococcus Aureus
4
Q
Gamma-Hemolysis
A
- The lack/absence of hemolytic activity. The cells appear white/tan on BAP.
- Characteristic of Enterococcus Faecalis
5
Q
Lancefield Groupings
A
- Antigenic groups of streptococcus
- All groups are catalase and coagulate negative. The distinction lies in the carbohydrate composition of bacterial antigens in the cell wall
- Based on similarities, each group is designated by a single letter: (group a, b, c, etc)
6
Q
Streptococcal Pharyngitis
A
- Caused by Streptococcus Pyogenes (group a)
- Aka known as strep throat
- Characteristics: Fever, enlargement of lymph nodes in the neck and reddening within the throats lining.
- Can cause complications in the ear, lung, or sinus cavities.
- If untreated, it can cause rheumatic fever.
7
Q
Steptococcus Pyogenes
A
- Lancefield Group A
- The causal agent behind 90% of human streptococcal infections
- Results in Streptococcus Pharyngitis (strep throat), Rheumatic Fever and Scarlet Fever.
8
Q
Rheumatic Fever
A
- Causal agent is Streptococcus Pyogenes
- Occurs in 3% of untreated cases of streptococcal pharyngitis. Leads to a 2-3 week infection.
Characteristics:
- Most serious: Bacteria targets the heart valves due to the similarities of antigens present within the heart tissue and the bacteria. (antibodies attack wrong cells)
- Inflammation of the joints
- Involuntary jerking movements
- Development of pea-sized nodules in the skin
- Reddened areas with raised edges across the skin.
- Treatment: Penicillin
9
Q
Streptococcal Septicemia
A
- Aka “blood poisoning” but can also infect other surrounding tissues.
- Caused by streptococcus lancefield group B.
- The immune response to the infectious foreign agent can equally be equally damaging to the body.
- Septicemia (sepsis) is a life-threatening infection that worsens quickly due to its systematic nature. It can arise from infections in the lungs, abdomen, or UT. May precede or accompany meningitis or endocarditis.
- Characteristics: Fever, chills, rapid breathing, and an increased HR. Can progress to shock with fever or hypothermia and a decrease in BP.
- Streptococcal Septicemia can also be caused by E. Coli, Pseudomonas, and Klebsiella.
- Treatment: Antibiotics, IV fluids, and oxygen.
10
Q
Staphylococcus
A
- Gram positive, round bacteria.
- Forms grape-like structures with other bacteria.
- Coagulase and Catalase negative.
- Facultative anaerobes (can survive without air)
- It is a commensal bacterium, meaning it neither harms nor benefits its host that is getting its nutrients from unless in certain conditions (like immunocompromised).
11
Q
Folliculitis
A
- Caused by staphylococcus aureus
- Impacts the hair follicles, forming lesions called pustules.
- Boils and carbuncles (larger pus-filled lesions) can grow sky where on the skin.
12
Q
Scalded Skin Syndrome
A
- Caused by Staphylococcus Aureus
- Most often seen in infants and kids
- Causes pustules (lesions) to rupture creating a scalded appearance.
Treatment: staph infections can be treated with penicillin/erythromycin antibiotics
13
Q
Impetigo
A
- Caused by Staphylococcus Aureus
- A contagious childhood skin disease that presents as fluid-filled sores near the mouth and nose.
- If sores are ruptured, the fluid can spread to other parts of the body spreading the sores. Can be uncomfortable and itchy.
Treatment: Penicillin
14
Q
Conjunctivitis
A
- Aka “pink eye”.
- An infection of the thin layer of tissue on the eye and the inside of the eyelid, causing a redness/itchiness of the eye.
- Can be caused by both viral/bacterial infections. Both staphylococcus and streptococcus can yield similar results.
- Viral infections presents with common cold symptoms and upper respiratory infection, sore throat, cough, etc.
- Best Precaution: wash your hands!
15
Q
Ophthalmia Neonatorum
A
- Severe form of conjunctivitis that is present in newborns. It occurs if the newborn is exposed to chlamydia or gonorrhea bacteria in the birth canal.
- If not treated quickly, permanent eye damage can occur.
- Preventing: Am antibiotic ointment contains neomycin is applied to the eyes to prevent infection/eye damage.
