Bacterial Respiratory Tract Infections Flashcards
What are the typical organisms which cause community acquired pneumonia?
- Streptococcus pneumonia (gram pos diplococci, most common cause of CAP)
- Haemophilus Influenzae (gram neg cocobacilli)
- Moraxella catarrhalis
What are the atypical causes of community acquired pneumonia?
- Mycoplasma pneumonia
- Legionella pneumonia
- Chlamydophila pneumoniae
- Chlamydophilia psttaci
CCLM
What are the risk factors for streptococcus pneumonia?
- Alcohol and smoking abuse
- Asthma
- Co-infection with other substance
- Immunosupression
What is the treatment for S.pneumoniae?
1st line - Amoxicillin/benzylpenicillin
2nd line/pen allergy - Clarithromycin/ ceftriaxone,
Durations 5 days for mild, 7-10 days for mod-severe.
What are the features of haemophilus influenzae?
- Occurs in older people and people with underlying lung disease.
- Haemophilus influenzae B vaccine means most infections are caused by non-typeable which can colonise the URT too.
- Grown on chocolate agar with growth factors X and V
What is the treatment for H.influenzae?
1st line - Co-amoxiclav due to risk of beta lactamses
2nd Line/pen allergy - Ceftriaxone (macrolides/tetracyclines?)
Duration 7-10 days
Describe features and treatment of Moraxella catarrhalis
It is a frequent cause of infective exacerbations of COPD which is gram negative.
Treatment is mainly via co-amoxiclav or doxycycline for 5-10 days
Describe features of mycoplasma pneumoniae and the presentation
- Smallest living bacterium which lacks a cell wall. Very difficult to grow so don’t normally use cultures, instead diagnosed via PCR from sputum/throat swab.
- Clinically presents with fever, haemolysis, Guillain-Barre syndrome, erythema multiforme, cardiac abnormalities and arthritis/arthralgia
What is the treatment for mycoplasma pneumoniae?
Due to the lack of cell wall, the beta lactams are ineffective. So 1st line is clarithromycin (5 days), 2nd line is doxycycline (7-14 days)
Describe aetiology and presentation of legionella pneumophilia
- Arises from aerosols from water so hot water should be kept above 50 degrees and cold water below 20.
- Atypical cause so can cause extra respiratory symptoms before the respiratory symptoms
How is the diagnosis of legionella pneumophilia made and what is the treatment?
Diagnosis - Culture, serology or urine antigen test
Treatment - It is intracellular so beta lactams don’t work. So 1st line is levofloxacin, 2nd line is clarithromycin. Duration 10-14 days.
What are the causative organisms for hospital acquired pneumonia?
- Enterobacterales (Klebsiella, E.coli or enterobacter)
- Pseudomonas aeruginosa
- S.Aureus
- Acinetobacter (ventilator acquired)
- Stenotrophomonas (ventelator acquired)
What is the microbiology involved in the diagnosis of hospital acquired pneumonia?
Different chrome agar plates or oxidase test. Chrome agar can also be used to determine other factors
What are the signs and symptoms of hospital acquired pneumonia?
Symptoms - Fever, cough/sputum, chest pain, insidious/abrupt onset, non resp symptoms.
Signs - Dull percussion, coarse crepitations and increased vocal resonance.
What is the clinical assessment scoring system used in pneumonia?
CURB65 score. Used to determine whether patient requires hospital admission.
C - Confusion,
U - Urea over 7
R - Respiratory rate over 30
B - BP. Diastolic under 60 or systolic under 90.
65 - Age over 65
