LOWER RESPIRATORY TRACT INFECTIONS Prof T Rogers

PNEUMONIA

THE IMPORTANCE OF PNEUMONIA A major killer in both developed and developing countries Accounts for more deaths than other infectious diseases Mortality rates vary but can be as high as 25% A major cause of death in children in developing countries Incidence here (?) 2-5/1000 population

PNEUMONIA Neither radiological or microbiological criteria are specific for predicting the cause of pneumonia A better approach is to first consider the clinical circumstances under which pneumonia acquired Add the clinical background of the particular patient…

Classification of pneumonia Community-acquired Hospital-acquired Aspiration and anaerobic Pneumonia in immunocompromised AIDS-related Geographically restricted Recurrent

COMMUNITY-ACQUIRED PNEUMONIA: INTRODUCTORY POINTS More common at the extremes of age Twice as common in winter months A General Practitioner is likely to see up to 10 cases per yr Represent <10% of all respiratory infection cases prescribed antibiotics Most will be managed in the community

TYPES OF COMMUNITY ACQUIRED PNEUMONIA In a previously healthy individual Here the infection may have been acquired by droplet spread from another Alternatively, in patients with underlying diseases endogenous colonizing bacteria may be the cause These are more likely to be resistant to first-line antibiotics

SYMPTOMS OF PATIENTS WITH COMMUNITY-ACQUIRED PNEUMONIA(%) [Mc Farlane unpublished] Cough92 Fever86 Breathlessness67 Pleural pain62 Headache55 New sputum production54 Muscle aches44 Nausea/vomiting48

COMMUNITY ACQUIRED PNEUMONIA: WHAT’S CAUSING IT?

MICROBIOLOGICAL CAUSES (%) OF COMMUNITY ACQUIRED PNEUMONIA FROM HOSPITAL BASED STUDIES (N=3,000) CAPSevere CAP No cause found3633 Pneumococcus2527 Influenza virus82.3 Legionella spp*.717 Haem. Influenzae55 Other viruses58 Psittacosis/Q fever32 Gram neg. bacilli2.72 Staph aureus*25

INVESTIGATIONS FOR DIAGNOSIS OF PNEUMONIA Non-invasive: blood count, urea, albumin,LFT’s, sputum gram, chest X-ray, CT scan Culture of sputum, blood, pleural fluid Serology: pneumococcal, Legionella antigen Invasive: induced sputum, bronchoscopy, open lung biopsy

TYPICAL GRAM APPEARANCE OF Strep pneumoniae IN SPUTUM GRAM POSITIVE CHAINS DIPLOCOCCI

Streptococcus pneumoniae (pneumococcus) A gram positive coccus that grows in short chains Alpha haemolytic on blood agar Identified by its susceptibility to optochin Polysaccharide capsule confers pathogenicity-at least 80 serotypes There are multivalent vaccines for prevention of pneumococcal disease

SOME COMPLICATIONS OF PNEUMOCOCCAL SEPSIS Bacteraemia (10%+) Empyema (1%) Meningitis (<0.5%) Mortality rates of 10-25% Splenectomy or asplenia a major risk factor

Pneumococcal vaccine is recommended for: Age >65 years Underlying chronic lung disease Asplenia Alcoholism Diabetes mellitus Chronic renal failure HIV infection

BTS Guidelines for the Management of Community Acquired Pneumonia in Adults Updated

Treatment Home treated-Amoxicillin 500mg or 1 g tds PO (or admitted for social reasons) Hospital treated Amoxicillin 500mg or 1 g PO plus erythromycin 500mg qds po Hospital treated severe Co-amoxiclav 1.2 g tds and erythromycin 500mg qds I/v, +/- rifampicin

VIRUSES THAT CAUSE COMMUNTIY ACQUIRED PNEUMONIA

INFLUENZA

OTHER VIRAL CAUSES Respiratory syncytial virus (RSV) Parainfluenza viruses Enteroviruses (Cytomegalovirus)

CAUSES OF ‘ATYPICAL’ PNEUMONIA Mycoplasma pneumoniae Chlamydia pneumoniae Legionella pneumophila Coxiella burnetii

Mycoplasma pneumoniae Has no cell wall, therefore doesn’t respond to beta lactams Causes atypical pneumonia in adolescents and young adults Dry hacking cough, low grade fever, headache feature Isolation by culture of the organism is difficult therefore diagnosis is confirmed by a high CFT or rising titre of specific antibodies Cold agglutinins also typical Macrolides or tetracyclines most active

Chlamydia pneumoniae An obligate intracellular bacterium Causes mild pneumonia but may cause protracted symptoms Sore throat, hoarseness, URT symptoms feature Serological diagnosis rather than culture Tetracyclines, macrolides, quinolones active

Legionnaires’ disease A severe pneumonia due to Legionella pneumophila Can be community or hospital acquired Organism is acquired from environmental sources eg, humidified air conditioning, showers Usually attacks debilitated individuals

RISK FACTORS Male sex Advanced age Cigarette smokers Alcoholism Chronic lung disease Immmunosuppression, malignancy

Legionnaires’ disease Hyponatremia, confusion, nausea, vomiting, abnormal LFT’s a feature Diagnosis often confirmed by urinary antigen test (specific for serogroup 1) Can be cultured on special media Must be notified to Public Health as it can cause outbreaks Most active antibiotics are: macrolides, quinolones, rifampicin

Antibiotic Treatment of Community Acquired Pneumonia The priority is to cover pneumococcus Penicillin, amoxycillin, cephalosporins, new quinolones and macrolides have all been used as monotherapy Choice will be influenced by local resistance rates for pneumococcus

Examples of antibiotics for CAI Benzylpenicillin Penicillin V Ampicillin, amoxycillin, Augmentin Cefuroxime, cefotaxime, ceftriaxone Moxifloxacin (a quinolone) Erythromycin, clarythromycin, azithromycin

PATHOGEN PREFERRED THERAPY S pneumoniae amoxicillin 500 mg – 1.0 ga tds po or benzylpenicillin 1.2 g qds iv M pneumoniae C pneumoniae erythromycin 500 mg qds po or iv or clarithromycin 500 mg bd po or iv C psittaci/C burnetii tetracycline 250 mg – 500 mg qds po or 500 mg bd iv Legionella spp. clarithromycin 500 mg bd po or iv ± rifampicin c 600 mg od or bd, po/ iv

Hinfluenzae Non- B-lactamase-producing: amoxicillin 500 mg tds po or ampicillin 500 mg qds iv B-lactamase-producing: co-amoxiclav 625 mg tds po or 1.2 gtds iv Gram negative enteric bacilli cefuroxime 1.5 g tds or cefotaxime 1-2g tds iv or ceftriaxone 2g od iv (Comment: the table in the 2001 version incorrectly stated bd) P.aeruginosa ceftazidime 2g tds iv plus gentamicin or tobramycin (dose monitoring) S.aureus Non-MRSA: flucloxacillin 1-2gqds iv ±rifampicin 600 mg od or bd, po/iv MRSA: vancomycin 1gbd iv (dose monitoring)

ACID ALCOHOL FAST RODS SUGGESTING TUBERCULOSIS

KLEBSIELLA PNEUMONIA (RARE)

COMMUNITY ACQUIRED PNEUMONIA IN INFANTS AND CHILDREN Group B streptococcus and E coli cause pneumonia in neonates RSV an important pathogen in infants Bordetella pertussis (cause of whooping cough) important in young children As is Haemophilus influenzae type b

SOME FEATURES OF NOSOCOMIAL PNEUMONIA Often ventilator associated, therefore seen in ITU most commonly Due to both endogenous organisms and others acquired by cross infection MRSA, gram negatives predominate High associated mortality because of co- morbidity and antibiotic resistance

HOSPITAL ACQUIRED PNEUMONIA: Pseudomonas aeruginosa

TREATMENT OF HOSPITAL ACQUIRED PNEUMONIA Will depend on the local epidemiology of the unit/hospital Often require good cover for MRSA and gram negative enterobacteria Therefore vancomycin and carbapenem or Tazocin may be used

PNEUMONIA IN THE IMMUNOCOMPROMISED HOST Cause depends on the underlying immunodeficiency More likely to present as a diffuse interstitial pneumonia Treatment often empirical as establishing the cause is often difficult

MAJOR CAUSES OF PNEUMONIA IN IMMUNOCOMPROMISED Pneumocystis jiroveci (carinii) Cytomegalovirus Other respiratory viruses Tuberculosis Fungi

Pneumocystis jiroveci (Lung biopsy) Cyst stage

NOCARDIOSIS (Cause: Nocardia asteroides, acid fast rod)

Geographically restricted pneumonias Typhoid Melioidosis Brucellosis Endemic mycoses: histoplasmosis Helminthic: paragonimiasis

Recurrent pneumonia May be caused by local bronchial or pulmonary abnormality Obstruction due to eg, foreign body, carcinoma, lymph node Chronic obstructive lung disease: bronchiectasis Neurological disorders: motor neurone disease Structural: tracheo-oesophageal fistula Aspiration (alcoholics): anaerobic organisms Immunodeficiency state: hypogammaglobulinaemia

EMPYEMA May arise as an acute complication of pneumonia Characterised by collection in pleural cavity, malaise, fever, pleuritic pain, leucocytosis Chronic empyema usually occurs after failure to diagnose or treat adequately an acute empyema May be loculated, or associated with a broncho-pleural fistula Organisms are those causing the original pneumonia, or anaerobes Treat by drainage of the collection and antibiotics after microbiological findings