Case 8- staph and strep

Question 1

S.aureus toxin mediated diseases

Answer 1

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

Question 2

S.aureus - scalded skin syndrome

Answer 2

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

Question 3

S.aureus - food poisoning

Answer 3

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

Question 4

S.aureus - toxic shock

Answer 4

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

Question 5

S.aureus - Suppurative infections

Answer 5

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

Question 6

S.aureus - Impetigo

Answer 6

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.

Question 7

S.aureus - folliculitis

Answer 7

Impetigo involving hair follicles

Question 8

S.aureus - furuncles or boils

Answer 8

Large, painful or pus filled cutaneous nodules

Question 9

S.aureus - carbuncles

Answer 9

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

Question 10

S.aureus - bacteraemia and endocarditis

Answer 10

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

Question 11

S.aureus - pneumonia and empyema

Answer 11

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

Question 12

S.aureus - osteomyelitis

Answer 12

Destruction of bones particularly the metaphyseal area of long bones

Question 13

S.aureus- septic arthritis

Answer 13

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.

Question 14

Staphylococcus- wound infection

Answer 14

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

Question 15

Staphylococcus- urinary tract infection

Answer 15

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)

Question 16

Staphylococcus- catheter and shunt infection

Answer 16

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

Question 17

Staphylococcus- prosthetic device infection

Answer 17

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

Question 18

Treatment for staph infections

Answer 18

Flucloxacilin

Question 19

S.aureus

Answer 19

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

Question 20

Cutaneous infections

Answer 20

impetigo, folliculitis, furuncle and carbuncle

Question 21

Suppurative infection

Answer 21

Production of pus

Question 22

Cellulitis

Answer 22

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

Question 23

Erysipelas

Answer 23

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.

Question 24

Risk factors for cellulitus / erysipelas

Answer 24

Immunosuppresion, leg ulcers and minor skin injuries

Question 25

Symptoms of erysipelas / cellulitus

Answer 25

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

Question 26

Class 1 treatment for erysipelas / cellulitus

Answer 26

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

Question 27

Class 2 treatment for erysipelas / cellulitus

Answer 27

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

Question 28

Class 3 treatment for erysipelas / cellulitus

Answer 28

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

Question 29

Why are prosthetic device infection so dangerous?

Answer 29

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.

Question 30

How to classify strep

Answer 30

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

Question 31

Strep- alpha haemolytic

Answer 31

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

Question 32

Strep- beta haemolytic

Answer 32

Beta-haemolytic lyse red blood cells

Question 33

Strep- gamma haemolytic

Answer 33

No change

Question 34

What is the basis for the strep serological classifications?

Answer 34

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

Question 35

The serological types of alpha- hemolytic

Answer 35

1) Pneumoniae | 2) Viridians

Question 36

The serological types of beta- hemolytic

Answer 36

1) Pyogenes (group A) | 2) Agalactiae (group B)

Question 37

The serological types of alpha- hemolytic

Answer 37

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

Question 38

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

Answer 38

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

Question 39

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

Answer 39

1) Rheumatic fever | 2) Acute glomerulonephritis

Question 40

Diseases caused by streptococus agalactiae (group B)

Answer 40

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

Question 41

Diseases causes by streptococcus pneumoniae

Answer 41

1) Pneumonia 2) Meningitis 3) Bacteremai

Question 42

Pharyngitis

Answer 42

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.

Question 43

Scarlet fever

Answer 43

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

Question 44

Pyoderma

Answer 44

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

Question 45

Necrotising fasciitis

Answer 45

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

Question 46

Early onset neonatal disease

Answer 46

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

Question 47

Late onset neonatal disease

Answer 47

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

Question 48

Strep pyogenes

Answer 48

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%

Question 49

Strep throat

Answer 49

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

Question 50

Main cause of impetigo and cellulitis

Answer 50

S.aureus

Question 51

How is group A: Streptococcus pyogenes spead

Answer 51

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.

Question 52

What is the fever pain index used for?

Answer 52

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

Question 53

The FeverPAIN score

Answer 53

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.

Question 54

How to cure Pharyngitis

Answer 54

Phenoxymethylpenecillin

Question 55

Acute rheumatic fever

Answer 55

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

Question 56

Symptoms of rheumatic fever

Answer 56

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

Question 57

Rheumatic heart disease

Answer 57

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.

Question 58

Strep.pneumoniae

Answer 58

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.

Question 59

How is strep pneummoniae spread

Answer 59

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

Question 60

What does strep pneumoniae cause

Answer 60

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).

Question 61

Pneumococcal meningitis

Answer 61

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

Question 62

Treatment for pneumococcal meningitis

Answer 62

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

Question 63

Vaccine for meningitis

Answer 63

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.

Question 64

What is the biggest cause of sepsis

Answer 64

Pneumonia