LOWER RESPIRATORY TRACT INFECTIONS

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LOWER RESPIRATORY TRACT INFECTIONS

• Prof T Rogers

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PNEUMONIA
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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

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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

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Classification of pneumonia

• Community-acquired
• Hospital-acquired
• Aspiration and anaerobic
• Pneumonia in immunocompromised
• AIDS-related
• Geographically restricted
• Recurrent

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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 lt10 of all respiratory infection cases
  prescribed antibiotics
• Most will be managed in the community

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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

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SYMPTOMS OF PATIENTS WITH COMMUNITY-ACQUIRED
PNEUMONIA()Mc Farlane unpublished

• Cough 92
• Fever 86
• Breathlessness 67
• Pleural pain 62
• Headache 55
• New sputum production 54
• Muscle aches 44
• Nausea/vomiting 48

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COMMUNITY ACQUIRED PNEUMONIA WHATS CAUSING IT?
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MICROBIOLOGICAL CAUSES () OF COMMUNITY ACQUIRED
PNEUMONIA FROM HOSPITAL BASED STUDIES (N3,000)

• CAP Severe CAP
• No cause found 36 33
• Pneumococcus 25 27
• Influenza virus 8 2.3
• Legionella spp. 7 17
• Haem. Influenzae 5 5
• Other viruses 5 8
• Psittacosis/Q fever 3 2
• Gram neg. bacilli 2.7 2
• Staph aureus 2 5

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INVESTIGATIONS FOR DIAGNOSIS OF PNEUMONIA

• Non-invasive blood count, urea, albumin,LFTs,
  sputum gram, chest X-ray, CT scan
• Culture of sputum, blood, pleural fluid
• Serology pneumococcal, Legionella antigen
• Invasive induced sputum, bronchoscopy, open lung
  biopsy

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

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SOME COMPLICATIONS OF PNEUMOCOCCAL SEPSIS

• Bacteraemia (10)
• Empyema (1)
• Meningitis (lt0.5)
• Mortality rates of 10-25
• Splenectomy or asplenia a major risk factor

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Pneumococcal vaccine is recommended for

• Age gt65 years
• Underlying chronic lung disease
• Asplenia
• Alcoholism
• Diabetes mellitus
• Chronic renal failure
• HIV infection

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BTS Guidelinesfor the Management of Community
Acquired Pneumonia in Adults Updated 2004

• www.brit-thoracic.org/guidelines

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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

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VIRUSES THAT CAUSE COMMUNTIY ACQUIRED PNEUMONIA
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INFLUENZA
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OTHER VIRAL CAUSES

• Respiratory syncytial virus (RSV)
• Parainfluenza viruses
• Enteroviruses
• (Cytomegalovirus)

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CAUSES OF ATYPICAL PNEUMONIA

• Mycoplasma pneumoniae
• Chlamydia pneumoniae
• Legionella pneumophila
• Coxiella burnetii

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Mycoplasma pneumoniae

• Has no cell wall, therefore doesnt 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

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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

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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

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RISK FACTORS

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

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Legionnaires disease

• Hyponatremia, confusion, nausea, vomiting,
  abnormal LFTs 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

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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

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Examples of antibiotics for CAI

• Benzylpenicillin
• Penicillin V
• Ampicillin, amoxycillin, Augmentin
• Cefuroxime, cefotaxime, ceftriaxone
• Moxifloxacin (a quinolone)
• Erythromycin, clarythromycin, azithromycin

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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
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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.aureu
s Non-MRSA flucloxacillin 1-2gqds iv rifampicin
600 mg od or bd, po/iv MRSA vancomycin 1gbd iv
(dose monitoring)
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ACID ALCOHOL FAST RODS SUGGESTING TUBERCULOSIS
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KLEBSIELLA PNEUMONIA (RARE)
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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

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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

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HOSPITAL ACQUIRED PNEUMONIA Pseudomonas
aeruginosa
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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

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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

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MAJOR CAUSES OF PNEUMONIA IN IMMUNOCOMPROMISED

• Pneumocystis jiroveci (carinii)
• Cytomegalovirus
• Other respiratory viruses
• Tuberculosis
• Fungi

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Pneumocystis jiroveci(Lung biopsy)
Cyst stage
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NOCARDIOSIS(Cause Nocardia asteroides, acid
fast rod)
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Geographically restricted pneumonias

• Typhoid
• Melioidosis
• Brucellosis
• Endemic mycoses histoplasmosis
• Helminthic paragonimiasis

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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

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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