Microbiology Lower Resp Tract infections Flashcards Preview

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Flashcards in Microbiology Lower Resp Tract infections Deck (102)
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1
Q

Definition of LRTI:

A
  • Any Infection of the respiratory tract from the vocal cords downwards
  • Includes bronchi, bronchioles, alveoli, parenchyma, pleura and pleural cavities.
2
Q

Normal flora of the LRT

A
  • 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
Q

Abnormal flora of LRT

A
  • 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
Q

Common colonisers of the LRT and origin

A

• “Colonisers” of LRT are often from URT such as Haemophilus influenza and Streptococcus pneumonia

5
Q

Iatrogenic causes of change of antibiotics

A

• Antibiotic therapy will effect URT colonisation.

6
Q

Types od LRTI

A
•	Bronchiolitis (not covered) - viral
•	Bronchitis (acute and chronic)
•	Pneumonia
→ Community-acquired
→ Hospital-acquired
→ Aspiration
→ Immunocomprimised host
  • Bronchiectasis
  • Lung abscess/Emypema
7
Q

Acute Bronchitis causes

A
Most are Viral:
•	Influenza
•	RSV
•	Rhinovirus
•	Adenovirus
•	Parainfluenza virus

Pertusis (bacterial cause)

8
Q

Manifestations with % frequency

A
  • Cough (98%)
  • Trouble sleeping (60%)
  • Dyspnoea (50%)
  • Nasal congestations (50%)
  • Rhinorrhoea (50%)
  • Sore throat (50%)
  • Inability to work (33%)
  • Fever (10-20%)
9
Q

Chronic obstructive airway disease – chronic bronchitis clinical definition

A

• 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.

10
Q

Infective exacerbations of chronic bronchitis common

A

• 1-3 exacerbations per year in COPD patients

11
Q

Criteria used

A
Anthonisen criteria – used to optimising antibiotic selection in COPD patients
Antibiotic therapy indicated if two if:
•	Increased breathlessness
•	Increased sputum volume
•	Increased sputum purulence
12
Q

Infective exacerbations of chronic bronchitis % viral/Bacteria

A

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

13
Q

Infective exacerbations of chronic bronchitis treatment

A

Amoxicillin

Tetracycline

14
Q

Community Acquired required length of stay and causative organisms

A

< 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).

15
Q

Community Acquired treatment

A

Narrow spectrum therapy

16
Q

Hospital Acquired stay in hospital and causative organisms

A

> 48 hours in hospital and not intubated on admission (definition)
Due to multi-resistant “hospital flora”

17
Q

Hospital Acquired treatment

A

Broad spectrum agents

18
Q

Pneumonia general clinical features

A

Fever/rigors/sweats
Headache
Confusion (esp. elderly)
Vomiting/diarrhoea

19
Q

Pneumonia localised clinical features

A

Breathlessness
Cough (may be productive)
Haemoptysis
Pleuritic chest pain

20
Q

Clinical Syndromes – Aspiration

A

(Macro aspiration) Inhalation of material, about 10% of community cases

21
Q

Predisposition to aspiration

A

Neurological deficit and commonly affects the posterior segment of right upper lobe

22
Q

Aspiration complication

A

Abscess formation

Can be associated with chemical pneumonitis

23
Q

Aspiration prevention

A

Protection of the airway

24
Q

Aspiration treatment

A

Antibiotics to cover URT flora e.g. penicillin or cephalosporin plus metronidazole.

25
Q

Acute community acquired pneumonia x-ray and the differentials for x-ray findings:

A

Lots of acute CXR shadowing

Sometimes non-infective e.g. Cardiac failure, chemical (smoke infection), severe infection elsewhere (ARDS)

26
Q

Acute-community acquired

A

Ilness progresses over days to a few weeks

27
Q

Chronic-community acquired

A

Illness progresses over weeks to a months

28
Q

Differentials for chronic community acquired pneumonaie

A

TB is the most important cause
Differential is wide including Vasculitides (non infectious)
Specialist assessment is needed.

29
Q

CAP epi

A
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
30
Q

Assessing severity of CAP

A
CURB-65
Confusion (AMT of 8 or less)
Urea raised >7mmol/l
Resp rate >30/min
Blood pressure:
•	Systolid <60 mmhg
65 +
31
Q

Additional adverse features of CAP

A

Hypoxaemia Pa 02 <8 kPa, SaO2, 92%

Bilateral or multilobar involvement on CXR

32
Q

CURB65 score assessment

A

> 3 Severe pneumonia (mortality)
=2 Non-severe, (mortality 9-2%, consider admission)
0 of 1 Non severe (mortality 1.5%, treat at home)

33
Q

In the community assessment of CAP

A

CRB-66 scores
>3 Urgent hospital admission
1 or 2 Hospital referral and assessment
0 Treat in community

34
Q

Possible organisms related to occupation Health Care worker

A

MTB

Acute HIV seroconversino with pneumonia (needle sticks)

35
Q

Possible organisms related to occupation Veterinarian, farmer, abattoir worker

A

Coxiella burnetti

36
Q

Possible organisms related to occupation DKA

A

S. pneumonia

S. aureus

37
Q

Possible organisms related to occupation Alcoholism

A

S. pneumonia
L. pnuemonaie
S. aureus

38
Q

Possible organisms related to occupation COPD

A

S. pneumonia
H. influenza
M. catarrhalis

39
Q

Possible organisms related to occupation Solid organ transplant recipient (>3 months)

A
S. pneumonia
H.  influenza
Legionella spp.
Pneumocyctis jiroveci
CMV
Stronglyoides
Sterocoracils
40
Q

Possible organisms related to occupation Sickle cell disease

A

S. pneumonia

41
Q

Possible organisms related to occupation HIV (CD4+ T – cells <200/ ul)

A
S.penuomaie
P.jirovci
H. influenza
H. influenza
Cryptococcus neoforms
MTB
Rhodococcus equi
42
Q

Possible organisms related to occupation Air-conditioning

A

Legioella penumophilia

43
Q

Possible organisms related to occupation After windstorm in area of endermnicity

A

Coccidioides inmitis

44
Q

Possible organisms related to occupation Outbreak in shlter or jail

A

S. pneumonia, MTB

45
Q

Possible organisms related to occupation Exposure to turkeys, psittacine birds

A

Chlamydia psittici

46
Q

Possible organisms related to occupation Exposure ro rabbits

A

Francisella turalensis

47
Q

Possible organisms related to occupation Travel to Southeast Asia

A

Burkolderia pseudomallei

48
Q

Immigrants from high endemic from high prevalence of tuberculosis

A

MTB

49
Q

Investigations

A
Saturation
Arterial blood gases
FBC; U + E Cr
CRP (shows progression) 
CXR
50
Q

Microbiological

A
  • 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
51
Q

Grouping of pneumonia

A

Atypical and Typical (typical doesn’t mean common)

So much overlap that distinguishing is difficult – related to their response to treatment

52
Q

Typical pathogens

A

Often lobar

Streptococcus pneumonaie

53
Q

Typical pathogen treatments

A

Amoxycillin sensitive

Sometimes macrolide sensitive

54
Q

Atypical

A

Often multisystem, multilobar
→ Mycoplasma, Chlamydia. Coiella, Legionella
Amoxicillin resistant (different to typical)
Macrolide sensitive

55
Q

Streptococcus pneumonaie can invade and causes

A

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

56
Q

Streptococcus pneumonaie colonises and transmission

A

Colonises the nose and transmitted person to person

57
Q

Streptococcus pneumonaie sensitive to

A

Amoxycillin and doxycycline levofloxacin/ noxifloxacin

Penicillin resistance rising although rare in the UK

58
Q

Streptococcus pneumonaie significant mortality in which groups

A

Elderly
Renal Failure
Splenectomy

59
Q

Streptococcus pneumonaie vaccination

A

Is available against 23 serogroups plus new heptavalent conjugate vaccine.
→ Pneumovax
→ Kednav vaccine (recheck name)

60
Q

Haemophilus infleunzae: Presence

A

Several serovars resident in the nose

61
Q

Haemophilus infleunzae: Transmission and associated with which types of infections

A

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)

62
Q

Haemophilus infleunzae: Can invade and causes which disease

A

Pneumonaie
Meningitis
Bacteraemia, Epiglottis
Other (septic arthritis)

63
Q

Haemophilus infleunzae: Sensitive to

A

Amoxicillin
20% are Beta-lactamase positive
Sensitive to cefuroxime and co-amoxiclav

64
Q

Haemophilus infleunzae: Requires what for growth

A

Needs special factors to grow: Haem (X) and NAD (V)

65
Q

Mycoplasma pneumonaie:Structure

A

Lacks classical peptidoglycan cell wall

66
Q

Mycoplasma pneumonaie: Resistant to

A

Beta lactam antibiotics

67
Q

Mycoplasma pneumonaie: Sensitive to

A

Macrolides
Tetracyclines
Quinolones

68
Q

Mycoplasma pneumonaie:Cause of

A

Atypical penumoniae

69
Q

Mycoplasma pneumonaie: Epi

A

Occurs in epidemics every 3-4 years
Transmission human to human
Most common in children and young adults

70
Q

Mycoplasma pneumonaie: Rare complications

A

Myringitis (middle ear infection) and encephalitis

71
Q

Mycoplasma pneumonaie: Diagnosis via

A

Serology -more likely with PCR

72
Q

Legionella pneumophilia Survival

A

Can survive and multiply inside macrophages

73
Q

Legionella pneumophilia Presentation

A

Legionella can cause mild disease (Pontiac fever) or severe pneumonia with multi-organ failure (legionnaires disease)

74
Q

Legionella pneumophilia Epi

A

> 50% of cases associated with travel
Cooling towers
Air conditioning systems

75
Q

Legionella pneumophilia Diagnosis via

A

Antigen detection and serology and culture

76
Q

Legionella pneumophilia Treatment

A

Macrolides/quinolones +/- nifampicin

77
Q

Chlamydophilia pneumonaie and Chlamydophilia psittaccii Description

A

Obligate intracellular parasites

78
Q

Chlamydophilia pneumonaie and Chlamydophilia psittaccii Sensitive to

A

Macrolides
Tetracyclines
Quinolones

79
Q

Chlamydophilia pneumonaie and Chlamydophilia psittaccii C.pneumoniae prognosis

A

Self-limiting and mild. Human to human transmission

80
Q

Chlamydophilia pneumonaie and Chlamydophilia psittaccii C.psittacii can cause

A

Severe pneumonia associated with birds of all sorts.

Occupational disease of poultry processing industry

81
Q

Coxiella burnetti: Causes

A

Q fever – contact with animals

82
Q

Coxiella burnetti: Spread by

A

Airbourne, through infected milk, faeces and urine of farm animals

83
Q

Coxiella burnetti:Can causes

A

Severe pneumonia

84
Q

Coxiella burnetti:Diagnosis is by

A

Serology (Phase 1 and 2 antibodies)

85
Q

Coxiella burnetti: Treatment

A

Best with tetracyclines

86
Q

Management of Pneumonaies: CAP non severe

A

Amoxicillin 500 mg-1.0gs (home treated)

87
Q

Management of Pneumonaies: CAP non sever and alternative HAP

A
Amoxicillin 500 mg-1.0gs 
Oral:
Amoxicillin 500 mg-1.0gs
Erythromycin 500 mg
Clarithromycin 500mg

IV:
Ampicillin or nezylpenicillin

88
Q

Management of HAP alternative

A

Fluoroquinolone with some enhanced pneumococcal activity e.g. levofloxacin

IV:
Levofloxacin

89
Q

Management of

CAP alternative

A

Erythromycin 500 mg

Clarithromycin 500mg

90
Q

Ventilatory associated pneumonia →

A
  • Gram negatives more common
  • Similar paths to hospital acquired pneumonia
  • Broad spectrums use
91
Q

Pneumonia in immunocompromised: Description

A
  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
Q

Pneumonia in immunocompromised: Treatment:

A
  • 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
Q

Pnenumocysitis jiroveci

A
  • HIV related illness
  • Occurs with CD4<200
  • Fungus: Pneumocysitis
  • Pneumonia, onset over several days → weeks
  • Important cases of deaths in AIDS
94
Q

Pnenumocysitis jiroveci treatment

A
  • Refractory to normal antibiotics
  • Responds to co-triamoxole (Septrin) + steroids
  • Prophylaxis given CD4<200
95
Q

Pnenumocysitis jiroveci Diagnosis requires

A
  • Sputum sputa or BAL sample
  • Analysed by Cytology
  • Pneumocysitis
96
Q

Complications of pneumonia

A

Parapneumonic effusion
Empyema
Lung abcessess

97
Q

Parpneumonic effusion

A

Reactive, not infected
pH>7.2
Manage conservatively

98
Q

Empyema

A

Infected
pH <7.2
Needs drainage and surgery

99
Q

Lung abscesses

A

May be due to aspiration, pneumonia, haematogenous spread (IV drug users) or malignancy

100
Q

Aspiration organisms

A

Polymicrobial

101
Q

Haematogenous abscess usually due to

A

Staph

102
Q

Rare causes of lung abscess

A

Klebsiella pneumonia

Pseudomonas aeruginosa and fungi

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