Flashcards in Microbiology Lower Resp Tract infections Deck (102)
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1
Definition of LRTI:
• Any Infection of the respiratory tract from the vocal cords downwards
• Includes bronchi, bronchioles, alveoli, parenchyma, pleura and pleural cavities.
2
Normal flora of the LRT
• The NORMAL LRT is bacteriologically strile
• Inhaled particles including micro-organisms are trapped by mucus and moved to the URT by epithelial cilia (mucociliary excalator)
3
Abnormal flora of LRT
• Paralysis of cilia
• Excessive volume and/or viscosity of mucus
• Macro-ventiliation: LOC, Paralysis, ventilation, failure to protect LRT
• Failure to cough/loss of swallowing reflex
4
Common colonisers of the LRT and origin
• “Colonisers” of LRT are often from URT such as Haemophilus influenza and Streptococcus pneumonia
5
Iatrogenic causes of change of antibiotics
• Antibiotic therapy will effect URT colonisation.
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Types od LRTI
• Bronchiolitis (not covered) - viral
• Bronchitis (acute and chronic)
• Pneumonia
→ Community-acquired
→ Hospital-acquired
→ Aspiration
→ Immunocomprimised host
• Bronchiectasis
• Lung abscess/Emypema
7
Acute Bronchitis causes
Most are Viral:
• Influenza
• RSV
• Rhinovirus
• Adenovirus
• Parainfluenza virus
Pertusis (bacterial cause)
8
Manifestations with % frequency
• Cough (98%)
• Trouble sleeping (60%)
• Dyspnoea (50%)
• Nasal congestations (50%)
• Rhinorrhoea (50%)
• Sore throat (50%)
• Inability to work (33%)
• Fever (10-20%)
9
Chronic obstructive airway disease – chronic bronchitis clinical definition
• Productive cough for more than 3 months per year for at least 2 years
• Wheezing
• Dyspnoea (shortness of breath)
COPD = chronic bronchitis with airflow limitation. Most chronic bronchitis develops COPD or time.
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Infective exacerbations of chronic bronchitis common
• 1-3 exacerbations per year in COPD patients
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Criteria used
Anthonisen criteria – used to optimising antibiotic selection in COPD patients
Antibiotic therapy indicated if two if:
• Increased breathlessness
• Increased sputum volume
• Increased sputum purulence
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Infective exacerbations of chronic bronchitis % viral/Bacteria
40% of acute exacerbations are viral
→ Patients with COPD may have colonisation of the LRT with organisms normally found in the URT such as H. influenza, M. cattarhalis
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Infective exacerbations of chronic bronchitis treatment
Amoxicillin
Tetracycline
14
Community Acquired required length of stay and causative organisms
< 48 hours in hospital or in community (definition)
Usually bacterial Due to S. Pneumonia and sometimes-other organisms. Sometimes viral in children (always consider TB).
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Community Acquired treatment
Narrow spectrum therapy
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Hospital Acquired stay in hospital and causative organisms
>48 hours in hospital and not intubated on admission (definition)
Due to multi-resistant “hospital flora”
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Hospital Acquired treatment
Broad spectrum agents
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Pneumonia general clinical features
Fever/rigors/sweats
Headache
Confusion (esp. elderly)
Vomiting/diarrhoea
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Pneumonia localised clinical features
Breathlessness
Cough (may be productive)
Haemoptysis
Pleuritic chest pain
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Clinical Syndromes – Aspiration
(Macro aspiration) Inhalation of material, about 10% of community cases
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Predisposition to aspiration
Neurological deficit and commonly affects the posterior segment of right upper lobe
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Aspiration complication
Abscess formation
Can be associated with chemical pneumonitis
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Aspiration prevention
Protection of the airway
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Aspiration treatment
Antibiotics to cover URT flora e.g. penicillin or cephalosporin plus metronidazole.
25
Acute community acquired pneumonia x-ray and the differentials for x-ray findings:
Lots of acute CXR shadowing
Sometimes non-infective e.g. Cardiac failure, chemical (smoke infection), severe infection elsewhere (ARDS)
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Acute-community acquired
Ilness progresses over days to a few weeks
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Chronic-community acquired
Illness progresses over weeks to a months
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Differentials for chronic community acquired pneumonaie
TB is the most important cause
Differential is wide including Vasculitides (non infectious)
Specialist assessment is needed.
29
CAP epi
More common in water
Male/Female ratio 2:1
More common in older people
750,000 cases/year in UK
150,000 consult GP
50,000 hospitalised
10% mortality among hospitalised patients
Up to 50% mortality if severe
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Assessing severity of CAP
CURB-65
Confusion (AMT of 8 or less)
Urea raised >7mmol/l
Resp rate >30/min
Blood pressure:
• Systolid <60 mmhg
65 +
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Additional adverse features of CAP
Hypoxaemia Pa 02 <8 kPa, SaO2, 92%
Bilateral or multilobar involvement on CXR
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CURB65 score assessment
>3 Severe pneumonia (mortality)
=2 Non-severe, (mortality 9-2%, consider admission)
0 of 1 Non severe (mortality 1.5%, treat at home)
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In the community assessment of CAP
CRB-66 scores
>3 Urgent hospital admission
1 or 2 Hospital referral and assessment
0 Treat in community
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Possible organisms related to occupation Health Care worker
MTB
Acute HIV seroconversino with pneumonia (needle sticks)
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Possible organisms related to occupation Veterinarian, farmer, abattoir worker
Coxiella burnetti
36
Possible organisms related to occupation DKA
S. pneumonia
S. aureus
37
Possible organisms related to occupation Alcoholism
S. pneumonia
L. pnuemonaie
S. aureus
38
Possible organisms related to occupation COPD
S. pneumonia
H. influenza
M. catarrhalis
39
Possible organisms related to occupation Solid organ transplant recipient (>3 months)
S. pneumonia
H. influenza
Legionella spp.
Pneumocyctis jiroveci
CMV
Stronglyoides
Sterocoracils
40
Possible organisms related to occupation Sickle cell disease
S. pneumonia
41
Possible organisms related to occupation HIV (CD4+ T – cells <200/ ul)
S.penuomaie
P.jirovci
H. influenza
H. influenza
Cryptococcus neoforms
MTB
Rhodococcus equi
42
Possible organisms related to occupation Air-conditioning
Legioella penumophilia
43
Possible organisms related to occupation After windstorm in area of endermnicity
Coccidioides inmitis
44
Possible organisms related to occupation Outbreak in shlter or jail
S. pneumonia, MTB
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Possible organisms related to occupation Exposure to turkeys, psittacine birds
Chlamydia psittici
46
Possible organisms related to occupation Exposure ro rabbits
Francisella turalensis
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Possible organisms related to occupation Travel to Southeast Asia
Burkolderia pseudomallei
48
Immigrants from high endemic from high prevalence of tuberculosis
MTB
49
Investigations
Saturation
Arterial blood gases
FBC; U + E Cr
CRP (shows progression)
CXR
50
Microbiological
• Serum: stored; use retrospectively to diagnose
• Blood cultures: + ve in 15% of severe cases
• Sputum: shown to be of no clinical value except for TB of legionella
• BAL: Bronchio-alveolar lavage. Optimal sample but only in severe cases since invasive
• Urine: antigen for Legionella/ S. pneumonaie
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Grouping of pneumonia
Atypical and Typical (typical doesn’t mean common)
So much overlap that distinguishing is difficult – related to their response to treatment
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Typical pathogens
Often lobar
Streptococcus pneumonaie
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Typical pathogen treatments
Amoxycillin sensitive
Sometimes macrolide sensitive
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Atypical
Often multisystem, multilobar
→ Mycoplasma, Chlamydia. Coiella, Legionella
Amoxicillin resistant (different to typical)
Macrolide sensitive
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Streptococcus pneumonaie can invade and causes
Can invade(although commensual) and cause :
Pneumoniae
Meningitis
Endocarditis
Bacteraemia (may be only manifestations in toddlers) – viral prodrome
Triad → (rare) Austrins triad primary pneumonia, cholangitis, meningitis
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Streptococcus pneumonaie colonises and transmission
Colonises the nose and transmitted person to person
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Streptococcus pneumonaie sensitive to
Amoxycillin and doxycycline levofloxacin/ noxifloxacin
Penicillin resistance rising although rare in the UK
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Streptococcus pneumonaie significant mortality in which groups
Elderly
Renal Failure
Splenectomy
59
Streptococcus pneumonaie vaccination
Is available against 23 serogroups plus new heptavalent conjugate vaccine.
→ Pneumovax
→ Kednav vaccine (recheck name)
60
Haemophilus infleunzae: Presence
Several serovars resident in the nose
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Haemophilus infleunzae: Transmission and associated with which types of infections
Person to Person (capsule vs non capsular)
→ Capsular strain (a-f) – associated with invasive infection including, meningitis, epiglottis (HiB vaccine effective)
→ Non-capsular strains (generally non invasive disease) → Associated with mucosal infections including, otitis media, sinusitis and exacerbations of COPD (HiB vaccine ineffective)
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Haemophilus infleunzae: Can invade and causes which disease
Pneumonaie
Meningitis
Bacteraemia, Epiglottis
Other (septic arthritis)
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Haemophilus infleunzae: Sensitive to
Amoxicillin
20% are Beta-lactamase positive
Sensitive to cefuroxime and co-amoxiclav
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Haemophilus infleunzae: Requires what for growth
Needs special factors to grow: Haem (X) and NAD (V)
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Mycoplasma pneumonaie:Structure
Lacks classical peptidoglycan cell wall
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Mycoplasma pneumonaie: Resistant to
Beta lactam antibiotics
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Mycoplasma pneumonaie: Sensitive to
Macrolides
Tetracyclines
Quinolones
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Mycoplasma pneumonaie:Cause of
Atypical penumoniae
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Mycoplasma pneumonaie: Epi
Occurs in epidemics every 3-4 years
Transmission human to human
Most common in children and young adults
70
Mycoplasma pneumonaie: Rare complications
Myringitis (middle ear infection) and encephalitis
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Mycoplasma pneumonaie: Diagnosis via
Serology -more likely with PCR
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Legionella pneumophilia Survival
Can survive and multiply inside macrophages
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Legionella pneumophilia Presentation
Legionella can cause mild disease (Pontiac fever) or severe pneumonia with multi-organ failure (legionnaires disease)
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Legionella pneumophilia Epi
>50% of cases associated with travel
Cooling towers
Air conditioning systems
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Legionella pneumophilia Diagnosis via
Antigen detection and serology and culture
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Legionella pneumophilia Treatment
Macrolides/quinolones +/- nifampicin
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Chlamydophilia pneumonaie and Chlamydophilia psittaccii Description
Obligate intracellular parasites
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Chlamydophilia pneumonaie and Chlamydophilia psittaccii Sensitive to
Macrolides
Tetracyclines
Quinolones
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Chlamydophilia pneumonaie and Chlamydophilia psittaccii C.pneumoniae prognosis
Self-limiting and mild. Human to human transmission
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Chlamydophilia pneumonaie and Chlamydophilia psittaccii C.psittacii can cause
Severe pneumonia associated with birds of all sorts.
Occupational disease of poultry processing industry
81
Coxiella burnetti: Causes
Q fever – contact with animals
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Coxiella burnetti: Spread by
Airbourne, through infected milk, faeces and urine of farm animals
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Coxiella burnetti:Can causes
Severe pneumonia
84
Coxiella burnetti:Diagnosis is by
Serology (Phase 1 and 2 antibodies)
85
Coxiella burnetti: Treatment
Best with tetracyclines
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Management of Pneumonaies: CAP non severe
Amoxicillin 500 mg-1.0gs (home treated)
87
Management of Pneumonaies: CAP non sever and alternative HAP
Amoxicillin 500 mg-1.0gs
Oral:
Amoxicillin 500 mg-1.0gs
Erythromycin 500 mg
Clarithromycin 500mg
IV:
Ampicillin or nezylpenicillin
88
Management of HAP alternative
Fluoroquinolone with some enhanced pneumococcal activity e.g. levofloxacin
IV:
Levofloxacin
89
Management of
CAP alternative
Erythromycin 500 mg
Clarithromycin 500mg
90
Ventilatory associated pneumonia →
• Gram negatives more common
• Similar paths to hospital acquired pneumonia
• Broad spectrums use
91
Pneumonia in immunocompromised: Description
1. Different groups vary in susceptibility to micro-organisms e.g. neutropenia, HIV, Organ transplantation, steroid treatment.
2. Lack of neutrophils predisposes to Gram negatives e.g. Coliforms, Pseudomonas and Gram positive eg. staph and virdidans streptococci.
3. Lack of appropriate T-cells predisposes to intracellular pathogens (e.g. Mycobacterium spp.)
92
Pneumonia in immunocompromised: Treatment:
• Can be difficult
• Strenous attempts should be made to help identify offending pathogens e.g. use of CT scan, bronchoscopy, BAL, needle biopsy
• Treatment may have to cover a wide range of pathogens
• Recovery of neutrophil function/T-cell defect will improve prognosis
• Prophylaxis required in selected patients
93
Pnenumocysitis jiroveci
• HIV related illness
• Occurs with CD4<200
• Fungus: Pneumocysitis
• Pneumonia, onset over several days → weeks
• Important cases of deaths in AIDS
94
Pnenumocysitis jiroveci treatment
• Refractory to normal antibiotics
• Responds to co-triamoxole (Septrin) + steroids
• Prophylaxis given CD4<200
95
Pnenumocysitis jiroveci Diagnosis requires
• Sputum sputa or BAL sample
• Analysed by Cytology
• Pneumocysitis
96
Complications of pneumonia
Parapneumonic effusion
Empyema
Lung abcessess
97
Parpneumonic effusion
Reactive, not infected
pH>7.2
Manage conservatively
98
Empyema
Infected
pH <7.2
Needs drainage and surgery
99
Lung abscesses
May be due to aspiration, pneumonia, haematogenous spread (IV drug users) or malignancy
100
Aspiration organisms
Polymicrobial
101
Haematogenous abscess usually due to
Staph
102
