Chest Infections

1. Chest Infections Lawrence Pike

2. Chest Infections • Acute bronchitis • Acute exacerbation of chronic bronchitis • Community acquired pneumonia

3. Acute bronchitis • Acute bronchitis is typically self-limiting lasting 7 to 14 days. • Usually caused by adenovirus, rhinovirus or influenza virus. • Bacteria rarely cause acute bronchitis, however, they may act as secondary invaders following a viral infection. Bacteria implicated include Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis and occasionally Staphylococcus aureus (especially during influenza epidemics).

4. Acute exacerbation of chronic bronchitis • Increased purulent sputum, worsening cough, pyrexia and increased breathlessness. • Haemophilus influenzae, Streptococcus pneumoniae and Moraxella catarrhalis are commonly grown from sputum samples.

5. Community acquired pneumonia • An acute lower respiratory tract infection with purulent sputum, cough, fever, breathlessness combined with signs on examination and changes on chest x-ray. • Usual bacteria implicated • include Streptococcus pneumoniae (most common), Haemophilus influenzae, Moraxella catarrhalis and occasionally Staphylococcus aureus (especially during influenza epidemics). • Atypical infections • include those caused by Mycoplasma pneumoniae, Chlamydia pneumoniae, Chlamydia psittaci and Legionella pneumoniae.

6. Incidence • 17% of all 'acute' consultations are for acute respiratory infections • In previously healthy subjects acute bronchitis is usually self-limiting in nature. However, around 5% are pneumonias • Acute exacerbation of chronic bronchitis is associated with viral infections in 50% of cases. • Mycoplasma pneumoniae occurs in epidemics with a 4-year cycle. It is most common in children

7. Symptoms and Signs • Clinical presentations range from cough without sputum or chest signs, to an illness characterised by expectoration of mucopurulent sputum, fever, dyspnoea, pleuritic chest pain and diffuse or focal signs in the chest. • Consider pneumonia in any patient, of any age, with cough and dyspnoea, tachypnoea and pleuritic chest pain; and/or focal signs in the chest, especially if they are systemically unwell. • Legionella pneumonia should be considered if risk factors such as recent travel or recent repair of plumbing are present.

8. Differential Diagnosis • Influenza • Congestive cardiac failure • Chronic obstructive airways disease • Pulmonary embolism • Acute pulmonary oedema • Chest infection with underlying malignancy • Subdiaphragmatic pathology: e.g. cholecystitis, pancreatitis, perforated duodenal ulcer, subphrenic/hepatic abscess

9. Should I use an antibiotic ? • Cough may persist for 2 to 3 weeks after presentation and is unlikely to resolve or improve more quickly as a result of antibiotic therapy. • Unnecessary use of an antibiotic may cause resistance of organisms to the drug and increased patient expectations of antibiotics for future minor illness. Antibiotics may also cause side-effects. • Resistance of Streptococcus pneumoniae to penicillin V has increased from 0.3% in 1989 to 7.5% in 1996; and to erythromycin has increased from 3.3% in 1989 to 11.8% in 1996.

10. Should I use an antibiotic ? • To minimise resistance, it is important to prescribe only when appropriate and necessary. • Antibiotics may be of benefit if two or preferably three of the following are present: • increased sputum volume • purulent sputum • dyspnoea. • In childrentheprobability of a viral cause is higher than in adults.

11. Should I use an antibiotic ? • Antibiotic therapy should be considered for the following groups:1. Reduced resistance to infection.2. Co-existing illness, diabetes, congestive cardiac failure, asthma.3. History of previous persistent mucopurulent cough.4. Clinical deterioration.

12. Which Antibiotic? • Most cases of bacterial chest infection in the community remain sensitive to amoxycillin • If treatment with amoxycillin shows no improvement within 48 hours, erythromycin should be substituted. • Erythromycin is first choice if an atypical organism is suspected. However, azithromycin or clarithromycin may be more active than erythromycin against Haemophilus influenzae and also have less GI upset.

13. Which Antibiotic? • For exacerbations of chronic bronchitis • Amoxycillin or a Tetracycline (and erythromycin in pencillin allergy) are appropriate first choices if any antibiotic is to be used. • 5% of Streptococcus pneumoniae and 5% of Haemophilus influenza strains are tetracycline-resistant. 15% H. influenza strains are amoxycillin-resistant.

14. Which Antibiotic? • Pneumonia in a previously healthy chest - amoxycillin is still the first choice antibiotic. • If Staphylococcus aureus is suspected e.g. after influenza or measles - add flucloxacillin. Staphylococcal pneumonia requires treatment for 2 to 3 weeks, then, if symptoms persist, seek advice from a specialist. • If Mycoplasma pneumoniae (consider this during an outbreak) or Legionella infection suspected (e.g. recent travel), use erythromycin. Legionella pneumonia, will require a prolonged course of antibiotic until proven resolution, and admission should be strongly considered or specialist advice sought in all cases. Erythromycin is the historical drug of choice, although the newer macrolides may be an alternative.

15. Which Antibiotic? • Chlamydia infections- use a tetracycline or erythromycin for 10 to 14 days. • Quinolones (Ciprofloxacin, Ofloxacin) have poor activity against Streptococcus pneumoniae and should not be used as single agents in "blind therapy" of chest infections. • First generation cephalosporins, e.g. cephalexin, are not an appropriate choice for lower respiratory infections. • Co-amoxiclav should be considered if B-lactamase resistant strains are locally a problem - consult local protocols - or for treatment of pneumonia during influenza epidemics.