Clinical Pharmacology and Therapeutics

COMMONLY PRESCRIBED ANTIBACTERIAL DRUGS 333
Case history
A 70-year-old man with a history of chronic obstructive pulmonary
disease visits his GP in December during a local flu
epidemic. He complains of worsening shortness of breath,
productive cough, fever and malaise. On examination, his
sputum is viscous and green, his respiratory rate is 20 breaths
per minute at rest but, in addition to wheezes, bronchial
breathing is audible over the right lower lobe. The GP prescribes
amoxicillin which has been effective in previous exacerbations
of chronic obstructive pulmonary disease in this
patient. Twenty-four hours later, the patient is brought to
the local Accident and Emergency Department confused,
cyanosed and with a respiratory rate of 30 breaths per
minute. His chest x-ray is consistent with lobar pneumonia.
Question
In addition to controlled oxygen and bronchodilators, which
three antibacterial drugs would you prescribe and why?
Answer
This patient is seriously ill with community-acquired lobar
pneumonia. The previously abnormal chest, the concurrent flu
epidemic and the rapid deterioration suggest Staphylococcus,
but Streptococcus pneumoniae and Legionella are also possible
pathogens. The following antibacterial drugs should be
prescribed:
• Flucloxacillin – active against Staphylococcus and
Gram-positive organisms;
• Cefuroxime – broad spectrum and active against
Staphylococcus;
• Erythromycin – active against Legionella and
Mycoplasma, and also some Staphylococcus and other
Gram-positive bacteria.
Case history
A 20-year-old man presented to his GP during a flu epidemic
complaining of a throbbing headache which was
present when he woke up that morning. He had been
studying hard and was anxious about his exams. Physical
examination was normal and he was sent home with paracetamol
and vitamins. He presented to casualty 12 hours
later with a worsening headache. Examination revealed a
temperature of 39°C, blood pressure of 110/60 mmHg, neck
stiffness and a purpuric rash on his arms and legs which did
not blanch when pressure was applied.
Question
Which antibacterial drugs would you use and why?
Answer
This young man has meningococcal meningitis and requires
benzylpenicillin i.v. immediately.
REMEMBER: Treatment of bacterial meningitis must never
be delayed.
FURTHER READING
British National Formulary, www.bnf.org.