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Medicine year 1 semester 2 > Case 8- staph and strep > Flashcards

Case 8- staph and strep Flashcards

1
Q

S.aureus toxin mediated diseases

A

1) Scalded skin syndrome
2) Food poisoning
3) Toxic shock syndrome

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2
Q

S.aureus - scalded skin syndrome

A

There is disseminated desquamation of the epithelium (flaky skin) in the infants, blisters with no organisms or leukocytes

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3
Q

S.aureus - food poisoning

A

After consumption of fodd contaminated with heat stable enterotoxin, there is a rapid onset of severe vomiting, diarrhoea, and abdominal cramping. Lasts for 24 hours

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4
Q

S.aureus - toxic shock

A

Multisystem intoxication characterised initially by fever, hypotension and a diffuse macular erythematous rash. There is a high mortality rate without prompt antibiotic therapy

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5
Q

S.aureus - Suppurative infections

A 
Impetigo
Folliculitis
Furuncles and Carbuncles
Bacteraemia and endocarditis
Pneumonia and empyema
Osteomyelitis
Septic arthritis
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6
Q

S.aureus - Impetigo

A

Localised cutaneous infections characterised by pus filled vesicles on an erythematous base. Superficial infection of the skin. Caused by S.aureus and occasionally S.pyogenes. Most common in children due to poor hand hygiene. Crusty lesions form consisting of dried serum, blood, bacteria and cellular debris through the eroded epidermis. Topical fusidic acid is the most common treatment. Oral Flucloxacillin can be used for more widespread infections.

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7
Q

S.aureus - folliculitis

A

Impetigo involving hair follicles

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8
Q

S.aureus - furuncles or boils

A

Large, painful or pus filled cutaneous nodules

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9
Q

S.aureus - carbuncles

A

A group of furuncles with extensions into the subcutaneous tissue with evidence of systemic disease (fever, chills, bacteremia)

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10
Q

S.aureus - bacteraemia and endocarditis

A

Spread of bacteria in the blood from a focal point of infection. Endocarditis is characterised by damage to the endothelial lining of the heart

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11
Q

S.aureus - pneumonia and empyema

A

Consolidation and abscess formation in the lungs, Normally in the very young, elderly or patient with a recent or underlying pulmonary disease. You have a severe form of necrotising penumonia with septic shock and high mortality. Empyema is a collection of pus in the pleural cavity

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12
Q

S.aureus - osteomyelitis

A

Destruction of bones particularly the metaphyseal area of long bones

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13
Q

S.aureus- septic arthritis

A

Painful erythematous joint with a collection of purulent material in the joint space. Often linked to underlying joint disease, joint prostheses, IV drug abuse, alcoholism and diabetes. You will need to be admitted to hospital and treated with IV antibiotics.

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14
Q

Staphylococcus- wound infection

A

Characterised by erythema and pus at the site of traumatic or surgical wound. Infection with foreign bodies are caused by both S.aureus and coagulase negative staphylococci

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15
Q

Staphylococcus- urinary tract infection

A

Dysuria and pyuria in sexually active women (staphylococcus saprophyticus) in patients with urinary catheters (other coagulase negative staphylococci) or following seeding of the urinary tract by bacteraemia (S.aureus)

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16
Q

Staphylococcus- catheter and shunt infection

A

A chronic inflammatory response to the bacteria coating a catheter or shunt (normally with coagulase negative staphylococci)

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17
Q

Staphylococcus- prosthetic device infection

A

Chronic infection of a device characterised by localised pain and mechanical failure of the device (most commonly with coagulase-negative staphylococci)

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18
Q

Treatment for staph infections

A

Flucloxacilin

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19
Q

S.aureus

A

A gram positive cocci. 20-25% of normal flora. Causes opportunistic infection when it enters the blood stream especially if the host is compromised- skin break, catheter, surgical wound and immunocompromised

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20
Q

Cutaneous infections

A

impetigo, folliculitis, furuncle and carbuncle

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21
Q

Suppurative infection

A

Production of pus

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22
Q

Cellulitis

A

Infection of the skin, mostly caused by S.aureus but can be caused by streptococci. Tends to be deeper in Erysipelas and can get into the subcutaneous tissue. There are less defined borders. Swollen, painful and red. Can get pus at the site the bacteria entered the skin. It is a spreading bacterial infection of the skin

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23
Q

Erysipelas

A

A skin infection. Swollen, painful and red. In the face its more likely to be erysipelas then cellulitus. A more superficial form of cellulitis dermis in the upper subcutaneous tissue. Has a more uniform appearance with defined edges. Mainly caused by Streptococcus pyogenes.

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24
Q

Risk factors for cellulitus / erysipelas

A

Immunosuppresion, leg ulcers and minor skin injuries

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25
Q

Symptoms of erysipelas / cellulitus

A

Can feel systemically unwell with fever, malaise or rigors, particularly with erysipelas. Complications are that it can lead to local necrosis, abscess and sepsis.

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26
Q

Class 1 treatment for erysipelas / cellulitus

A

Class 1- Patient afebrile (not feverish) and healthy other than cellulitis- use oral flucloxacillin alone. If there is exposure to river or sea water you should seek advice

27
Q

Class 2 treatment for erysipelas / cellulitus

A

Class 2- patient is febrile (feverish) and ill, or comorbidity, admit for IV treatment or use outpatient parenteral antimicrobial therapy.

28
Q

Class 3 treatment for erysipelas / cellulitus

A

Class 3- if toxic (showing signs of sepsis) admit into hospital

29
Q

Why are prosthetic device infection so dangerous?

A

Bacteria can colonise the surface of a pacemaker, the bacteria grow very slowly as antibiotics work best against rapidly growing bacteria it is hard to remove them. The bacteria can drop of the pacemaker and spread to distant sites. The bacteria can release an extracellular matrix, this is a protective layer which stops bacteria from being attacked by antibiotics. Can cause continuous infections as it is hard to completely get rid of the S.aureus. Often the only way to treat it is to replace the device. Recurrent Bacteraemia (bacteria remains in the blood stream).
S.epidermis causes oppurtunistic infections. S.saprophyticus causes UTI’s.

30
Q

How to classify strep

A

Can be classified in the haemolytic properties (how they effect red blood cells) and the serological properties. To determine haemolytic properties you grow the bacteria on a blood agar, its the first methord of classification

31
Q

Strep- alpha haemolytic

A

Alpha- haemolytic streptococci causes haemoglobin to change colour (green-ish)

32
Q

Strep- beta haemolytic

A

Beta-haemolytic lyse red blood cells

33
Q

Strep- gamma haemolytic

A

No change

34
Q

What is the basis for the strep serological classifications?

A

How they react to testing kits. What differentiates them is their cell wall polysaccharides and how they react with antibiotics

35
Q

The serological types of alpha- hemolytic

A

1) Pneumoniae

2) Viridians

36
Q

The serological types of beta- hemolytic

A

1) Pyogenes (group A)

2) Agalactiae (group B)

37
Q

The serological types of alpha- hemolytic

A

1) Enterococcus- normal part of bowel flora, causes problems in wounds

38
Q

Diseases causes by strep.pyogenes (group A) suppurative infections

A

1) Pharyngitis
2) Scarlet fever
3) Pyoderma
4) Erysipelas
5) Cellulitis
6) Necrotising fascitis
7) Streptococcal toxic shock syndrome
8) Laryngitis, pneumoniae

39
Q

Diseases causes by strep.pyogenes (group A) non- suppurative infections

A

1) Rheumatic fever

2) Acute glomerulonephritis

40
Q

Diseases caused by streptococus agalactiae (group B)

A

1) Early onset neonatal disease
2) Late onset neonatal disease
3) Infections in pregnant women
4) Bacteremia, pneumonia, bones and joint infection

41
Q

Diseases causes by streptococcus pneumoniae

A

1) Pneumonia
2) Meningitis
3) Bacteremai

42
Q

Pharyngitis

A

Reddened pharynx with exudates (cells and blood vessels) generally present. Cervical lymphadenopathy can be prominent. Rapid onset sore throat which can cause severe pain when swallowing. Important to diagnose quickly as strep throat can cause Rheumatic fever and Rheumatic heart disease.

43
Q

Scarlet fever

A

A diffuse erythematous/ micropapillary rash which begins on the chest and spreads to the extremities, complication of streptococcal pharyngitis. Causes by toxins, you get flushed cheeks

44
Q

Pyoderma

A

Localised skin infection with vesicles progressing to pustules, no evidence of systemic disease

45
Q

Necrotising fasciitis

A

Deep infection of the skin that involves destruction of muscle and fat. Rapidly progressing and fatal, treated with IV antibiotics

46
Q

Early onset neonatal disease

A

Within 7 days of birth, infected new-borns develop signs and symptoms of pneumonia, meningitis and sepsis

47
Q

Late onset neonatal disease

A

More then one week after birth, neonates develop signs and symptoms of bacteraemia with meningitis

48
Q

Strep pyogenes

A

A chain of gram positive cocci. Group A strep.pyogenes is present in normal flora and is an opportunistic pathogen in compromised individuals. Can affect seemingly healthy individuals. The mortality rate for the infections are 0.1% You can have more severe and infectious diseases which have a mortality rate of 25%

49
Q

Strep throat

A

You get enlarged and painful tonsils, it is very quick and there tends to be pus on the throat

50
Q

Main cause of impetigo and cellulitis

A

S.aureus

51
Q

How is group A: Streptococcus pyogenes spead

A

There is a reservoir in the skin and nasopharynx. It is spread by droplet inhalation and direct contact. It is then followed by colonisation which is facilitated by the action of protein Fm, Lipotechoic acid and M antigen. This allows for the strep.pyogenes to bind to the pharyngeal mucosa as the proteins are found in the cell wall of the bacteria. Colonisation may be asymptomatic but it can be symptomatic.

52
Q

What is the fever pain index used for?

A

The FEVERPAIN index can be used to determine if it’s a bacterial infection instead of viral. Can also be diagnosed using a rapid antigen test

53
Q

The FeverPAIN score

A

The FeverPAIN criteria are: score 1 point for each (maximum score of 5)
• Fever over 38°C.
• Purulence (pharyngeal/tonsillar exudate).
• Attend rapidly (3 days or less)
• Severely Inflamed tonsils
• No cough or coryza
0 or 1 is associated with a 13% to 18% likelihood of isolating streptococcus. A score of 2 or 3 is associated with a 34% to 40% likelihood of isolating streptococcus. A score of 4 or 5 is associated with a 62% to 65% likelihood of isolating streptococcus.

54
Q

How to cure Pharyngitis

A

Phenoxymethylpenecillin

55
Q

Acute rheumatic fever

A

A post strep complication. When you get an autoimmune reaction against your own tissue. It is caused by cross reactivity between M-proteins and human cell surface proteins. The M-proteins and human cell surface proteins are very similar so when you have an immune reaction against the M-proteins your own proteins can get mistakenly damaged

56
Q

Symptoms of rheumatic fever

A

Normally occurs 1-5 weeks after streptococcal pharyngitis. Causes a fever, rash, carditis, arthritis and CNS manifestations. 80% of symptoms go within 10 weeks.

57
Q

Rheumatic heart disease

A

1 in 3 people with acute rheumatic fever will develop rheumatic heart disease. This will cause permanent damage to cardiac valve tissue, dizziness, chest pain, shortness of breath, tiredness and heart failure. The symptoms can be life long.

58
Q

Strep.pneumoniae

A

Most common cause of community acquired pneumoniae. It is a gram positive diplococci. It is present in the nasopharynx of healthy individuals. It is an opportunistic pathogen which causes disease in compromised individuals. It is alpha-haemolytic. There are 90 different disease-causing serotypes, the serotypes are determined by the way they react to antibodies.

59
Q

How is strep pneummoniae spread

A

Infections can be exogenous (by droplets from a carrier). Infections can also be from an endogenous route (the bacteria residing in your own nasal pharynx), this will be during an immunocompromised period

60
Q

What does strep pneumoniae cause

A

It causes pneumococcal diseases like:
• Otitis media which is linked to ear infection.
• Pneumococcal Bacteraemia- bacteria in the blood stream, very invasive.
• Pneumococcal sepsis
• Pneumococcal Meningitis- the second biggest cause of meningitis after N.meningitidis B (menB).

61
Q

Pneumococcal meningitis

A

Causes meningitis which is infection of the brain. A gram positive bacteria

62
Q

Treatment for pneumococcal meningitis

A

It is treated with penicillin (beta-lactam) initially, however, Beta-lactam resistant strains are now emerging. If suspect antibiotic resistance prescribe Cephalosporins and Vancomycin.

63
Q

Vaccine for meningitis

A

There is a vaccine with the trade name Prevanar 13. It is given in a single dose which covers 13 different serotypes, given at 2 years and in the over 65. The vaccine covers 96% of infections.

64
Q

What is the biggest cause of sepsis

A

Pneumonia

Medicine year 1 semester 2 (61 decks)

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