Viral and bacterial Infections of the tonsils and / or pharynx 2 Flashcards
Skin infections, Complications of Strep, and diagnosis
How do skin infections typically occur?
They occur through breaks in skin
Cuts, bites, wounds, burns
* Can be minor/hardly visible
List 3 skin infections in their order of severity
Mild to severe and life-threatening
* Impetigo
* Cellulitis
* Necrotising fasciitis
What is bacteremia?
Spread of bacteria into blood, causing serious infections in other parts of the body.
Describe impetigo
It is superficial, with clear yellow crusts. It is very contagious
What is cellulitis?
It is a common bacterial skin infection that causes redness, swelling, and pain in the infected area of the skin.
What would happen if cellulitis would be left untreated?
If untreated, it can spread and cause serious health problems.
How is cellulitis prevented?
Good wound care and hygiene are important for preventing cellulitis.
What is necrotising fasciitis?
It is an infection of fascia causing necrosis.
It is a rare bacterial infection that spreads quickly in the body and can cause death.
‘flesh eating infection/bacteria’
How does necrotising fasciitis present clinically?
Often skin looks normal on outside but underneath tissues are necrotic.
Person is usually in severe pain and very sick
How is necrotising fasciitis treated?
Needs rapid antibiotics and prompt surgery to remove dead tissue
What are the suppurative complications of S. pyogenes infections?
Suppurative = Pus forming
* Abscesses (collection of pus)
* Swelling of local draining lymph nodes (adenitis)
Can also get spread from throat
* Locally to respiratory tract – middle ear, sinuses, lungs
* Via bloodstream to other parts of the body
In a case of tonsilitis, what would be an example of a suppurative complication
quinsy or peritonsillar abscess forms between tonsil and the throat wall
To what other areas can an infection of the throat spread?
-Locally to respiratory tract – middle ear, sinuses, lungs
* Via bloodstream to other parts of the body
Name 2 immune-mediated complications of S. pyogenes infection
Rheumatic fever
Acute glomerulonephritis
What does rheumatic fever affect?
Affects heart and heart valves sometimes causing permanent damage
How does rheumatic fever occur?
Somehow immune reaction to S.pyogenes cross reacts with heart tissue
* Follows pharyngeal infection with certain ‘rheumatogenic’ M type strains of S. pyogenes
T/F: rheumatic fever happens after streptococcal skin infections
F
Doesn’t happen after streptococcal skin infections. It happens after pharyngeal infection
How is recurrent episodes of rheumatic fever prevented?
use long term penicillin
prophylaxis to prevent recurrent strep throat infections.
What is acute glomerulonephritis?
Acute inflammation of glomeruli in kidney causing (usually) temporary decrease in renal function
What causes acute glomerulonephritis?
Due to different ‘nephritogenic’ M type strains
* After throat or skin infections
T/F: immune-mediated complications occur after a few days following initial infection with streptococcus pyogenes
F.
immune mediated complications are delayed, usually weeks after original streptococcal
infection which has usually disappeared, even without antibiotic treatment
Name two diseases caused by pyrogenic exotoxins that are released by S. pyogenes.
Scarlet fever
Streptococcal toxic shock syndrome
Explain streptococcal toxic shock syndrome.
Streptococcus produces a toxin that acts as a ‘super-antigen’ stimulating a massive inflammatory reaction.
Leads to shock and multi-organ failure.
Streptococcal toxic shock syndrome is sometimes associated with which infection?
Necrotising fasciitis
Clinical presentation of streptococcal toxic shock syndrome
Low Bp
Multiple organ failure, and even death
How is Streptococcal toxic shock syndrome prevented?
Good wound care
Hand hygiene
Cough etiquette
Who are streptococcal infections diagnosed? Name three tests
-Culture of swab from tonsils or skin lesion
-Antigen test
-Serology
What are the downsides of culture of swab from tonsils or skin lesion? (3)
- Microscopy less valuable for throat because lots of other types of streptococci are mouth commensals
- Susceptibility testing less important because almost always susceptible to penicillin
- Problem is time to test result: at least 24 hrs
How does Antigen test work? Also state 1 pro and 1 con of this test?
- Detects Lancefield Group A antigen directly.
*Pro: Rapid - Con: Less sensitive – so may miss some cases
How does serology work?
Look for antibodies in serum to streptococcal toxins= indirect evidence of streptococcal
infection
Look for antibodies in serum to streptococcal toxins= indirect evidence of streptococcal
infection
* Anti-streptolysin O titre (ASOT)
* Anti-DNAse B
Name 2 antibodies detected by serology
Look for antibodies in serum to streptococcal toxins= indirect evidence of streptococcal
infection
* Anti-streptolysin O titre (ASOT)
* Anti-DNAse B
When is serology most useful?
Most useful for supporting diagnosis of immune complications which only happen some weeks
after initial infection
