Respiratory infections Flashcards by B M

What are parameters of CURB65 score?

Confusion
Urea >7
RR >30
BP - systolic <90 or diastolic <60
Age >65

not validated for use in immunocompromsied patientd

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What is risk of mortality for these CURB65 score?

0 or 1

3-5

0 or 1 - low risk, community treatment

2 - intermediate 3-15% risk mortality. Consider hospital care

3-5 - high risk. >15% mortality. May need ITU support

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How long can legionella urinary antigen test remain positive?

Can remain positive for few weeks, even after being antibiotics. So can still be useful as diagnostic tool

only detects serotype 01

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When should we suspect atypical pathogens?

in outbreak settings

infections in otherwise healthy individuals

atypicals - legionella, mycoplasma, chlamydia spp

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Patients with COPD.

What are indications for long term antibiotic prophylaxis?

frequent exacerbations with sputum production

prolonged exacerbations

exacerbations requiring hospitalization

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What are risks of influenza in pregnancy?

miscarriage
small-for-gestational age

increased risk of severe infection requiring ITU support

risk of secondary bacterial infection

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21 year old returns from Saudia Arabia, with fever, cough, SOB.

CXR shows bilateral pulmonary infiltrates

What are potential diagnoses?

MERS-CoV
SARS-CoV

Hanta virus pulmonary syndrome

influenza - including avian influenza

Legionella
Mycoplasma
Coxiella burnetti
Chlamydia spp

Cryptococcus
Histoplasma
Tularaemia
Melioidosis

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21 year old returns from Saudia Arabia, with fever, cough, SOB.

CXR shows bilateral pulmonary infiltrates

Tests positive for influenza. What are next steps?

Continue respiratory precautions

send for flu typing - assess for H5N1 or H7N9

treat with oseltamivir 75mg BD 5 days

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in TB treatment, when is it considered

MDR-TB

XDR-TB

MDR-TB - if resistant to both isoniazid and rifampicin

XDR-TB - resistant to above, plus fluoroquinolone, plus injectable e.g amikacin

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What are quick tests which can give idea about TB resistance in sample?

Gene Xpert (Cepheid) firstly confirms M. TB present

sputum processed to detect major mutation in rpoB, which accounts for 98% resistance against rifampicin

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42 year old man with 18 weeks history of cough. CXR normal

Suspect pertussis.

Patient has had all vaccinatons in childhood
Wife is 36 weeks pregnant

How to diagnose pertussis?

Nasopharyngeal culture/ PCR

Pertussis IgG - if raised can suggest recent infection, as long as not immunised in past year

Clinical diagnosis - “whoop” cough or paroxysms of cough, for >14 days

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42 year old man with 18 weeks history of cough. CXR normal

Suspect pertussis.

Patient has had all vaccinatons in childhood
Wife is 36 weeks pregnant

What is treatment?

Antibiotics reduce transmission, and so mostly used as public health measure

azithromycin 5 days
co-trimoxazole 14 days

no benefit is started after 21 days of symptoms

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42 year old man with 18 weeks history of cough. CXR normal

Suspect pertussis.

Patient has had all vaccinatons in childhood
Wife is 36 weeks pregnant
Children aged 6 + 8 at home

What prophylaxis is recommended for family?

Prophylaxis for all household contacts, who have had contact within 21 days of patient, and at risk e.g health conditions, pregnant, unvaccinated. Combination of antibiotics and vaccination

Do not need prophylaxis if had vaccine booster within past 5 years

Children vaccinated ages 2, 3, 4 months - would not require antibiotic prophylaxis, as vaccinated
Unvaccinated, or no recent vaccination - give antibiotics, and vaccinate
Pregnant mother - erythromycin safer in pregnancy. Mother should have had pertussis booster during pregnancy

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Patient with pertussis

What are treatment options with someone with protracted cough?

Very little evidence, but these have been tried -

corticosteroids
b-eta agonists
antihistamines
pertussis immunoglobulin

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What are benefits of using Taz/ gent in neutropenic sepsis?

Normally neutropenic as on chemotherapy, so at risk of certain organisms

Antibiotics will cover most organisms including pseudomonas

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Patient with AML. Presents SOB - treated for neutropenic sepsis

CT chest shows patchy consolidation bilaterally, nodules, and halo sign

What are possible diagnoses?

Non-infective -
pulmonary oedema
leukaemic infiltration
drug toxicity

Viral -
Influenza
RSV
parainfluenza
adenovirus
CMV

Chlamydia
Mycoplasma
Legionella

PCP
Cryptococcal
Nocardia

Aspergillus - nodules, halo sign, air crescent, all suggest angioinvasive aspergillus infection

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How to diagnose pulmonary aspergillus infection?

BAL

culture for fungi

Beta-2-glucan
galactomannan

aspergillus PCR
PCP PCR

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What is treatment of choice for pulmonary aspergillus?

Voriconazole

Ambisome

capsofungin

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23 year old with CF.

Increase SOB.

Known colonised with pseudomonas and staph aureus

Recent sputum grew Stenotrophomonas maltophilia

What is the significance of this?

Stenotrophomonas maltophilia was originally classified as a pseudomonas, and is an environmental bacteria found in soil. Gram negative, non-fermenter

Resistant to beta-lactams and carbapenems

recognised as opportunistic pathogen in immunocompromised

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Patient with CF, what bacteria do we need to look for in sputum?

These species require special testing

pseudomonas

S maltophilia

Haemophilus influenzae

Staph aureus

Burkholderia

Aspergillus

Fungi

If sputum culture psoitive, difficult to know if this organism is colonising airway, or causing infection

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in CF patients, inhaled antibiotics can be used

What are examples of this?

What are benefits?

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Colistin
tobramycin
aztreonam
levofloxacin
amikacin

antibiotics get directly to site of infection - higher concentration
less systemic side effects

What is rationale behind isolating CF patients on hospital admission?

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Reduce their risk of exposure to infections

CF patient may have multidrug resistant organism e.g pseudomonas, so prevents spread of this

Cryptococcus can cause pulmonary infection in immunocompromised.

What are two species?

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C neoformans - associated bird droppings

C gattii - associated with trees and surrounding soil

Any patient with pulmonary cryptococcus should have lumbar puncture to see if any CNS involvement. As this influences duration of treatment

What is treatment for cryptococcal infection?

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Ambisome and flucytosine

fluconazole maintenance for 6-12 months

Blood culture machine flags positive, but no organism seen on gram stain. Patient being treated for LRTI What is possible explanation?

Strep pneumoniae do not culture well. Bacteria die, and do not gram stain well Consider sending streptococcal urinary antigen test to clarify

How to differentiate strep pneumoniae from other streptococci biochemically?

Gram pos cocci alpha-haemolysis susceptibility to optochin - viridans group strep are resistant

Which organisms are most common cause of sinusitis/ otitis media?

Strep pneumoniae Haemophilus influenzae Moraxella catarrhalis

Which organisms cause otitis externa?

staph aureus pseudomonas relatively benign condition, but can become malignant otitis externa, and spread from ear to temporal bone. Occurs in diabetics/ immunocompromised

What are most common causes of conjunctivits?

Adenovirus HSV VZV Strep pneumoniae Haemophilus influenzae Moraxella catarrhalis Chlamydia trachomatis - neonates

Epiglottitis is life threatening emergency, usually children? What are common causes?

Haemophilus influenzae - most common Strep pneumoniae Staph aureus incidence decreasing with use of Hib vaccine

Which viruses cause "common cold"

rhinoviruses enteroviruses coronaviruses adenoviruses

Which viruses cause croup?

parainfluenza is most common cause RSV influenza parainfluenza metapneumovirus croup is severe URTI seen in children RSV most common cause bronchiolitis

What are benefits of antibiotics in GAS pharyngitis?

Reduce risk of sequelae Reduce durations of symptoms Reduce transmissibility e.g between school children

Why does GAS infection in throat/ skin have different outcomes for long term sequeale?

>150 types of GAS, with different M antigen on cell wall M1/ M3 associated rheumatic fever M12/ M49 associated glomerulonephritis rheumatic fever only follows after pharyngitis, and never after skin infection. This is thought to be due to different M type causing infection. Occurs 1-5 weeks after initial infection glomerulonephritis can occur after pharyngitis/ cellulitis

GAS pharyngitis What is cause of associated skin rash?

Scarlet fever Due to Streptococcal pyrogenic exotoxin (SPE) A-C, having a super-antigen effect

GAS What is included in Centor score? score used in pharyngitis symptoms for 3 days or less score out of 5

Age <13 Exudate on tonsils Lymphadenopathy Cough Temp >38.0 degC

Child with GAS confirmed, and starting treatment. Who requires close contact prophylaxis?

No prophylaxis - close contacts asymptomatic Symptomatic contacts should be treated

What is treatment of GAS?

Amoxicillin Erythromycin Azithromycin

CAP Blood culture positive What are features to help classify colony as strep pneumoniae? gram catalase haemolysis optochin susceptibility

gram pos catalase neg haemolysis - alpha optochin susceptibility - susceptible

Sputum culture What are cut offs for neutrophils and epithelial cells per low powered field?

>25 neutrophils <10 epithelial cells high epithelial cell number suggests oropharyngeal contamination,. So difficult to assess if organism causing infection or not

What is are the major virulence factors of strep pneumoniae?

polysaccharide capsule - allows it to evade phagocytosis pneumolysin - acts on alveoli causing direct damage leading to oedema/ inflammation

What are steps to help prevent pneumococcal infection?

23-valent polysaccharide vaccine prophylactic antibiotics for those who cannot have vaccine/ vaccine wont work e.g splenectomy

Patient with three pneumoccocal infections in 2 months. Each treated with antibiotics. What are possible explanations for this?

Wrong diagnosis - unlikely in this case Wrong treatment - resistance Wrong treatment - duration of treatment too short Complication - abscess not adequately penetrated by antibiotics Re-infection - possible common source. Less likely with pneumococcal

Bordetella pertussis is bacteria, but blood tests often reveal lymphocytosis. Why is this?

Pertussis disease is mediated by toxins Lymphocytes increase in response to toxins Lymphocytosis is classical feature of pertussis infection

What are diagnostic tests for pertussis?

Often based on clinical history Sputum/ NPA taken within first 14 days - culture and PCR

What are three stages of pertussis infection?

catarrhal - similar flu like symptoms to any URTI paroxysmal convalescent

Pertussis disease is toxin mediated. What are benefits of antibiotics?

Reduce bacterial load, which reduces symptom duration, and transmission rate

What is treatment of pertussis? When does it need to be started?

Macrolides need to start treatment within 21 days

Pertussis From public health perspective, how long do children need to be off school?

Children with suspected, epidemiologically linked or confirmed pertussis should be excluded from schools or nurseries for five days from commencing appropriate/ recommended antibiotic therapy or for 21 days from onset of symptoms (in those who are not treated)

When is pertussis vaccine given?

8 weeks 12 weeks 16 weeks causing most severe disease in young children, so given early DTaP/IPV/Hib/HepB combination vaccine

Pertussis What are hospital infection control policies?

droplet precautions - highly communicable until had 5 days of antibiotics or until 21 days after symptom onset

Respiratory infections Flashcards

(51 cards)