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Flashcards in Microbiology Lower Resp Tract infections Deck (102):
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.

6

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.

10

Infective exacerbations of chronic bronchitis common

• 1-3 exacerbations per year in COPD patients

11

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

12

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

13

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).

15

Community Acquired treatment

Narrow spectrum therapy

16

Hospital Acquired stay in hospital and causative organisms

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

17

Hospital Acquired treatment

Broad spectrum agents

18

Pneumonia general clinical features

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

19

Pneumonia localised clinical features

Breathlessness
Cough (may be productive)
Haemoptysis
Pleuritic chest pain

20

Clinical Syndromes – Aspiration

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

21

Predisposition to aspiration

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

22

Aspiration complication

Abscess formation
Can be associated with chemical pneumonitis

23

Aspiration prevention

Protection of the airway

24

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)

26

Acute-community acquired

Ilness progresses over days to a few weeks

27

Chronic-community acquired

Illness progresses over weeks to a months

28

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

30

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 +

31

Additional adverse features of CAP

Hypoxaemia Pa 02 <8 kPa, SaO2, 92%
Bilateral or multilobar involvement on CXR

32

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)

33

In the community assessment of CAP

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

34

Possible organisms related to occupation Health Care worker

MTB
Acute HIV seroconversino with pneumonia (needle sticks)

35

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

45

Possible organisms related to occupation Exposure to turkeys, psittacine birds

Chlamydia psittici

46

Possible organisms related to occupation Exposure ro rabbits

Francisella turalensis

47

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

51

Grouping of pneumonia

Atypical and Typical (typical doesn’t mean common)
So much overlap that distinguishing is difficult – related to their response to treatment

52

Typical pathogens

Often lobar
Streptococcus pneumonaie

53

Typical pathogen treatments

Amoxycillin sensitive
Sometimes macrolide sensitive

54

Atypical

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

55

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

56

Streptococcus pneumonaie colonises and transmission

Colonises the nose and transmitted person to person

57

Streptococcus pneumonaie sensitive to

Amoxycillin and doxycycline levofloxacin/ noxifloxacin

Penicillin resistance rising although rare in the UK

58

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

61

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)

62

Haemophilus infleunzae: Can invade and causes which disease

Pneumonaie
Meningitis
Bacteraemia, Epiglottis
Other (septic arthritis)

63

Haemophilus infleunzae: Sensitive to

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

64

Haemophilus infleunzae: Requires what for growth

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

65

Mycoplasma pneumonaie:Structure

Lacks classical peptidoglycan cell wall

66

Mycoplasma pneumonaie: Resistant to

Beta lactam antibiotics

67

Mycoplasma pneumonaie: Sensitive to

Macrolides
Tetracyclines
Quinolones

68

Mycoplasma pneumonaie:Cause of

Atypical penumoniae

69

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

71

Mycoplasma pneumonaie: Diagnosis via

Serology -more likely with PCR

72

Legionella pneumophilia Survival

Can survive and multiply inside macrophages

73

Legionella pneumophilia Presentation

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

74

Legionella pneumophilia Epi

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

75

Legionella pneumophilia Diagnosis via

Antigen detection and serology and culture

76

Legionella pneumophilia Treatment

Macrolides/quinolones +/- nifampicin

77

Chlamydophilia pneumonaie and Chlamydophilia psittaccii Description

Obligate intracellular parasites

78

Chlamydophilia pneumonaie and Chlamydophilia psittaccii Sensitive to

Macrolides
Tetracyclines
Quinolones

79

Chlamydophilia pneumonaie and Chlamydophilia psittaccii C.pneumoniae prognosis

Self-limiting and mild. Human to human transmission

80

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

82

Coxiella burnetti: Spread by

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

83

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

86

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

Rare causes of lung abscess

Klebsiella pneumonia
Pseudomonas aeruginosa and fungi

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