Streptococci

Question 1

What is the etymology of streptococcus pyogenes

Answer 1

Etymology:Gr. n.puon(Latin transliterationpyum), discharge from a sore, pus; Gr. suff.-genes(from Gr. v.gennaô), producing; N.L. masc. adj.pyogenes, pus-producing.

Question 2

Detail the microbiology of streptococcus pyogenes

gram, shape, aerobe, movement?

Answer 2

• Gram positive cocci in chains
• Facultative anaerobe - grows in the presence and absence of oxgyen
• Group A streptococcus GAS in clincical settings (Lancefield grouping)
• Non-motile (doesn’t have flagella)
• may rarely be found in the upper respiratory tract

Question 3

Is it a commensal or Pathogen?

Answer 3

Rarely isolated from healthy skin. Can colonise upper respiratory tract of humans

Invasive infections are associated with >25% mortality

Question 4

What are the organisms virulence factors

Answer 4

Bacterial capsule (in invasive infections) to evade the immune systems

Exotoxin production - damages host cell structures

Immune evasion and dissemination

Question 5

Which infections do GAS cause

Answer 5

Sore Throat (Bacterial pharyngitis) 
Impetigo (sometimes)
Scarlet fever 
Cellulitis 
Necrotising fasciitis (Rare) Revisit in year 4

Question 6

What is cellulitis

Answer 6

An acute infection of the skin involving the dermis and subcutaneous tissues

Question 7

How does a patient become infected with cellulitis

Answer 7

Causative agent enters via a break in skin
Cut, graze
Burn
Bite (e.g.) spider, dog, horse fly
Skin ulcer
Skin condition – e.g., eczema, psoriasis

Question 8

What are the signs and symptoms of cellulitis

Answer 8

Skin becomes red, hot, swollen, tender, painful
Commonly affects legs
Blisters (sometimes)

Question 9

What are the risk factors for cellulitis

Answer 9

Obesity
Poorly managed diabetes - blood flow compilcations leading to a less efective immune response
IV drug use - if the needles are unhygenic
Previous cellulitis history
Swimming! Bodies of water may harbour bacteria
Smoking

Question 10

Where are the areas of the body which are endogenous carriers of Gp A streptococci

Answer 10

Interdigital toe spaces
Vagina
Anus

Question 11

What are the complictions of poorly managed cellulitis

Answer 11

Spread of infection to other body sites (blood, muscle, bone); Lymphoedema; Recurrent cellulitis

Question 12

What are the differential diagnoses (things which may present similarly to cellulitis but arent)

Answer 12

Eczema (In particular varicose eczema) Eczema doesnt have a changing border
Lymphoedema - isnt hot to the touch
Allergic reaction - isn’t so localised

All of the above conditions will have a history

Question 13

How do we manage mild cellulitis with no systemic toxicity (in the community)

Answer 13

Pain management (paracetamol, ibuprofen)
Adequate fluid intake

High dose oral antibiotic (7-14d)
Phenoxymethylpenicillin (clarithromycin/clindamycin)

Refer if facial cellulitis, severe (rapidly spreading, fever, change in mental state), patient is very young (< 1 yo)
Hospital admission – IV Benzylpenicillin (Vancomycin)

Question 14

What is the pharmacists role in mild cellulitis management

Answer 14

• Pick up on any danger symptoms and advise patient accordingly
• OTC pain relief if appropriate e.g. Paracetamol / Ibuprofen (this shouldn’t delay antibiotic prescribing)
• If leg affected keep it raised

Public health

• Treating skin wounds
• Hand hygiene
• Keep skin moisturised (emollients in eczema, psoriasis) and therefore manage risk factors

Question 15

What is GAS

Answer 15

Group A Streptococcus (pyogenes)

Question 16

Give some of the aetiology of strep throat

transmission, age, time of year, medical conditions, medication

Answer 16

-Transmission
Droplets in the air /direct contamination of wound
-Age
Young (5-15 years)
-Time of year (Spring, Autumn)
-Medical conditions (immunosuppression)
HIV/AIDS
Leukaemia
Asplenia
Aplastic anaemia
-Medication (immunosuppressive)
Chemotherapy, Carbimazole, DMARDs etc

Question 17

What are the signs (what a practitioner can see) and symptoms (what the patient can feel) of strep throat

Answer 17

• Swollen tonsils
• Painful, tender
• Discomfort when swallowing

Question 18

What other things can present like step throat

Answer 18

Glandular fever
Viral infection (presents witha fever)

Cancer
Persistent sore throat (typically in over 45s and history of smoking)

Quinsy (peritonsillar abscess)
Painful collection of pus (usually one-sided)

Epiglottitis
Inflammation of epiglottis - typically seen in children 2-6 (rare now in britain due to vaccination) Is a medical emergency

Question 19

How do we manage strep throat

Answer 19

Often no treatment required

OTC- analgesics / anaesthetic & antibacterial lozenges /sprays/ mouthwashes

Antibiotics (Fever and pain)
Phenoxymethylpenicillin; qds, 5-10d OR Clarithromycin; bds, 5d)

Systemically very unwell - difficulty breathing, medical emergency -> Hospitalisation

Question 20

What is the pharmacists role around strep throat

Answer 20

Check Patient Medical Record for any ADRs (around 1 in 10 people have a penicillin allergy)
Eliminate any danger symptoms
Recommend appropriate OTC products to manage symptoms
Non-medicated lozenges and local anaesthetic mouthspray not supported by evidence

Public health
Maintain good hygiene
Wash hands regularly
Cover your mouth when coughing (with a tissue)

Question 21

What are the signs and symptoms of scarlet fever

Answer 21

Initial flu-like symptoms

- High temperature
- Sore throat 
- Swollen neck glands

Eventual rash (sandpaper-like) development

May develop strawberry tongue - often has a white coating

Question 22

What is the causative agent of scarlet fever

Answer 22

Streptococcus A - exotoxin mediated. It can evolve from strep throat or a wound

Question 23

Who does scarlet fever usually affect

Answer 23

Children 10 and under (not newborns though due to maternal antibodies)

Question 24

How do we manage scarlet fever

Answer 24

-Suspected but person otherwise well
Phenoxymethyl penicillin (PenV), qds, 10 days
Dose dependant on age
Azithromycin if pen allergic 
once a day, 5 days
-Manage pain and itching
- this can go on to cause cellulitis

Hospital admission if:

• Pre-existing valvular heart disease
• Immunocompromised
• Suspect severe complication (e.g.) toxic shock syndrome

Question 25

What is the pharmacists role

Answer 25

Public health Highly infectious, easily spread -Wash hands Trap aerosols in tissues – bin it kill it Symptom management Pain, fever management (paracetamol, ibuprofen) Itching (calamine lotion, antihistamines) Scarlet fever is a notifiable disease - PHE needs to know

Question 26

What is the microbiology of Streptococcus pneumoniae | gram, motility, capsule type, where it lives

Answer 26

- Gram positive coccus (its a diplococcus) - > 90 capsular types reported - Non-infectious forms typically non-capsulated - Non motile (no flagella) - Normal inhabitant of URT (both transiently and chronically) - Nasal cavity - Pharynx - Nasopharynx - 20-50% children - 5-20% adults

Question 27

How long can Streptococcus pneumoniae last in the environment

Answer 27

Up to 4 weeks and can be carried from person to person

Question 28

What is community acquired pneumonia

Answer 28

- A pneumonia acquired outside of the hospital setting or onset within 48h of hospital admission - Frequently caused by S. pneumoniae (other causes leigonaires disease, micoplasma bacteria) - 5th leading cause of mortality (Europe)

Question 29

What ar the risk factors for CAP

Answer 29

Smoking - paralysed scilia Contact with children Poor oral hygiene *Age (>65y)* - innate defences are less effective Alcohol abuse - damages innate defence mechanisms

Question 30

How do people become carriers for strep. pneumo.

Answer 30

Pneumococci can be (transiently) carried in the nasopharynx Typically acquire via asymptomatic nasal colonisation. The infection process follows this path: ``` Negatively charged capsule expression reduces entrapment in the innate defence mechanism mucous Intimate association to host cells following down regulation of capsule Neutrophil influx (1-3 d post colonisation). This often initiates clearance of the bacterium However, if clearance doesnt fully occur carrier state persists (d14) ```

Question 31

How do patients move from carrier state to becoming infected with strep pmeuno.

Answer 31

In some cases, there is a switch from carriage to invasive infection. More common in over 65s. The bacteria move from the nasopharynx to the lower respiratory tract Initially mild irritation of upper airway Short incubation period (1-3d) Fever, malaise Dyspnoea, shaking chills Productive cough (purulent discharge) May progress to acute respiratory failure or death (if untreated)

Question 32

Which cells are involved in the initial response to strep. pneum. infection

Answer 32

Macrophages - initial response If this fails there is neutrophil recruitment to the area. This leads to inflammation in the LRT lungs. This can be removed by a healthy individuals immune system

Question 33

Which virulence factors does SP have to enable it to infect the host

Answer 33

1. Polysaccharide Capsule - Sp virulence is associated with capsule thickness - it works through a charge interference, it has a very similar charge to the phagocytic cells hence pushes them away - High surface charge interferes with phagocyte interactions - Reduces complement deposition at bacterial surface 2. Pneumolysin - Pore forming toxin produced by lysed bacterial cells - Innate defence inhibition (can damage scillia) - Induction of cytokine release adding to the inflammatory resopnse

Question 34

How do we manage SP and designate the severity of the disease

Answer 34

Severity assessment in adults with symptoms suggestive of CAP is determine through (i) clinical judgement and (ii) CRB-65 scoring 1 point given for each of following prognostic features - Confusion - Respiratory rate (≥30 breaths/min) - Blood pressure (diastolic ≤60 mmHg or systolic <90 mmHg). - Age ≥65y Scores (risk of death) 0 = Low (< 1% risk of mortality) 1 or 2 = Intermediate (1-10% risk of mortality) 3 or 4 = High (> 10% risk of mortality) need urgent hospital admision

Question 35

What management do we use for patients with a low CRB-65 score

Answer 35

LOW (score = 0) Consider community management Amoxicillin (500mg, tds, 5d, oral) Alternative options are doxycycline (atypicals?) or clarithromycin (pen allergy)

Question 36

What management do we use for patients with a moderate CRB-65 score

Answer 36

MODERATE (score = 1 or 2) Consider hospital assessment Amoxicillin WITH (if atypical suspected) clarithromycin or erythromycin (in pregnancy) Doxycycline and clarithromycin if pen allergy Local antibiotic policy may also apply

Question 37

What management do we use for patients with a severe CRB-65 score

Answer 37

SEVERE (score = 3 or 4) Urgent hospital admission Hospital admission, IV antibiotics common NICE (Sep 2019) = Co-amoxiclav WITH clarithromycin OR erythromycin (if pregnant) Local antibiotic policy may also apply

Question 38

What can pharmacists do to limit the spread od CAP

Answer 38

Smoking cessation information Patient education on pneumonia - leaflets, nhs website Self management strategies – rest, analgesia, adequate fluid intake. Vaccination information OTC cough medication not recommended - they dont work in this setting

Question 39

What is the difference between a bacterial developed pneumonia and a covid aquired pneumonia

Answer 39

Prior exposure to covid case | A productive cough is associated with bacterial infections (covid is dry)