22/f w pneumonia after a really bad cough

Three weeks ago I had a really really bad cough. So bad in fact that a few days after it started I noticed a soreness in my left rib. It's just over that spot really and it hurts when I yawn or take a deep breath. Prior to that I had a bit of a cold but it did not concern me enough to visit my GP. My mum who's a nurse describes it as the worst cough she has ever seen. The cough was so bad that I ended up vomiting. My GP had put me on Amoxycillin/Clavalunate but my symptoms were not improving much after a week. He also prescribed me some Paracetamol/Codeine (1g/30mg QID) for pain that I have been taking regularly but my pain was still not very well under control. I got chills/rigors just as my course of antibiotics was finishing. The cough had settled slightly by then but the pain was unbearable especially when lying down and taking deep breaths/coughing. I literally couldnt lie down and sleep sitting up on a chair.  Yesterday I started to get a little short of breath so I came to emergency. I was started on roxithromycin and given a shot of ceftriaxone. I've been feeling much better since. This was a two days ago, and im coming in today for my daily shot of ceftriaxone.

*for sake of brevity, abx names have been included in the quote.

Hx: Otherwise well nil issues not on meds.

Ix: CRP 5.1 WCC17.5(14.2) w mature neutrophilia. GGT328 ALT 207 AST 128 ALP 147. CXR n. CT Chest small localized posterior R-LL pneumonia. Sputum culture from ED nad.

O/E: Chest clear. Nil SOB. localized pain in chest when coughing/yawning. stable afebrile.

What was the likely missed diagnosis?

Registrar: This was likely a missed case of Pertussis/Whooping Cough. It tends to spontaneously resolve after 3 weeks anyway. It is treated with macrolides (eg roxithromycin) and by chance she was put on it in Emergency. The pneumonia may have developed after she pulled a muscle and stopped breathing deeply for a period of time. The elevated LFT's are probably from her antibiotic treatment.


Plan: 
Continue abx.
When stable (pain resolved and WCC n) d/c on clarythromycin 250mg BD and cephalexin 500mg tds.
Stop Paracetamol given elevated LFT's.
Start Oxycodone 5mg QID PRN.
Chest physiotherapy as tolerated.

Learning

• TIL: Pertussis can infect adults despite immunization! There are ~7000 cases a year in australia.
• It is a notifiable disease.
• In adults, a very severe cough with no purulent sputum and post cough vomiting is typical even if the "whoop" is not present.
• Pertussis responds to macrolides, with clarythromicin as a first line.
• Chest physio is very important for pneumonia as pleuritic pain can lead to atelectasis