Transcript Document 7218895

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
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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[Mc Farlane unpublished]
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Cough
Fever
Breathlessness
Pleural pain
Headache
New sputum production
Muscle aches
Nausea/vomiting
92
86
67
62
55
54
44
48
COMMUNITY ACQUIRED PNEUMONIA:
WHAT’S CAUSING IT?
MICROBIOLOGICAL CAUSES (%) OF
COMMUNITY ACQUIRED PNEUMONIA FROM
HOSPITAL BASED STUDIES (N=3,000)
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No cause found
Pneumococcus
Influenza virus
Legionella spp*.
Haem. Influenzae
Other viruses
Psittacosis/Q fever
Gram neg. bacilli
Staph aureus*
CAP
Severe CAP
36
25
8
7
5
5
3
2.7
2
33
27
2.3
17
5
8
2
2
5
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:
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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
2004
www.brit-thoracic.org/guidelines
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
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Respiratory syncytial virus (RSV)
Parainfluenza viruses
Enteroviruses
(Cytomegalovirus)
CAUSES OF ‘ATYPICAL’
PNEUMONIA
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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
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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
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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
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 comorbidity 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
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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
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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