Weight faltering and new cough in an infant with cystic fibrosis
An 8-month-old girl with cystic fibrosis, diagnosed on newborn screening and homozygous for F508del, attends the CF clinic. She was breastfed and has been on pancreatic enzymes since diagnosis. Over the last 2 months her weight has fallen from the 50th to the 9th centile. For 10 days she has had a new cough, worse at night and with physiotherapy, but no fever. She is feeding slightly less but still taking 6 breastfeeds daily; stools are more frequent and looser. Examination: respiratory rate 42, oxygen saturation 97% in air, mild subcostal recession, coarse crackles at the right base, no fever, ear temperature 36.8°C. A throat swab taken 3 months ago grew Staphylococcus aureus. You are covering a busy clinic and must decide whether to treat, investigate, or admit.
1. What is your assessment and immediate plan?
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This looks like a mild pulmonary exacerbation with nutritional faltering, not just routine CF care. New daily cough, increased work of breathing, focal crackles, and looser stools in a child with CF suggest increased airway infection and possibly pancreatic insufficiency. I would obtain an oropharyngeal swab for bacterial culture (and consider viral PCR), review enzyme dose and adherence, and calculate energy intake. I would start airway clearance twice daily, salbutamol before physiotherapy if wheezy, and oral antibiotics covering S. aureus and H. influenzae, typically flucloxacillin or co-amoxiclav according to local guidance. I would not delay treatment for a chest radiograph, although a film may help if focal signs persist. Admission is not mandatory if feeding and oxygen saturation are adequate, but I would arrange early review, weight monitoring, and dietitian input. The CF team should be informed the same day because early aggressive treatment preserves lung function.
2. How do you decide between oral antibiotics at home and intravenous antibiotics in hospital?
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The decision between oral and intravenous antibiotics hinges on severity and trajectory, not on the swab result alone. Oral treatment is reasonable here: oxygen saturation 97%, no fever, taking most feeds, mild recession, and no vomiting. Intravenous therapy and admission would be indicated for increasing respiratory distress, oxygen saturation below 92%, poor feeding or dehydration, fever with systemic upset, focal consolidation, or failure to improve after 48–72 hours of oral treatment. I would also admit if the family cannot reliably administer physiotherapy or return for review.
At home I would give clear return precautions, a 2-week course according to local policy, and a follow-up appointment within 1 week with repeat weight and swab. If the swab grows Pseudomonas aeruginosa, this changes the antibiotic choice and may prompt admission, so the culture result must be reviewed rather than filed.