Three days later the patient started to get some pain in her ear and noticed that the top of her ear was starting to swell. She hoped it would settle down but after two more days the pain was severe and the upper part of her pinna was now very swollen and red. She attended the Emergency Department who diagnosed a severe infection of her outer ear, admitted her for IV Flucloxacillin (a great choice normally for skin infections) and removed the ear ring. As the ring was removed a large quantity of pus poured out of the piercing hole. This was collected in a sterile universal container and sent to the microbiology laboratory. A Gram stain of the pus showed lots of Gram-negative bacilli.
The next day a Pseudomonas aeruginosa was growing from the pus sample. As the Microbiologist was checking his emails he noticed an alert from Public Health England about a potential community outbreak of Pseudomonas ear infection associated with ear piercing. “Hmmm, this is probably not a coincidence” thought the Microbiologist. The patient was therefore notified to Public Health England and the isolate was sent to the Reference Laboratory for typing to see whether this patient was part of the outbreak.
Pseudomonas and ears
If you are a regular reader of the bug blog you will know that P. aeruginosa in otitis externa is a pet irritation of mine (see the blog). Most external ear infections are caused by Staphylococcus aureus as for any other type of skin and soft tissue infection however when the cartilage of the pinna is involved P. aeruginosa becomes the main pathogen. In fact P. aeruginosa perichondritis following ear piercing is a classic microbiology exam scenario. There are a couple of reasons why P. aeruginosa is the main pathogen for perichondritis following ear piercing:
- It is able to survive in liquid detergents and antiseptics which are sometimes used to clean equipment involved in ear piercing
- It produces enzymes e.g. proteases and elastases which are able to directly damage the cartilage of the pinna
The initial management of Pseudomonas perichondritis is surgical, under the Ear, Nose and Throat (ENT) surgeons, as many of these patients require full drainage of pus to prevent the infection extending deeper into the ear which unchecked could progress to malignant otitis externa, a severe and life-threatening infection. Any ear ring (or other type of piercing) involved in the infection should be removed as soon as possible.
Anti-pseudomonal antibiotics should be started but should not unnecessarily delay surgical evaluation. The antibiotic choice for P. aeruginosa can be difficult as many antibiotics are not active against it. In addition it is rather ingenious or “competent” in that it can acquire new genetic mechanisms of resistance very easily (see earlier blog). I tend to empirically treat serious infections with two unrelated anti-pseudomonals, at least until I know for certain that the bacterium is sensitive e.g. beta-lactam PLUS aminoglycoside or beta-lactam PLUS fluoroquinolone. If I really want good soft tissue penetration, as in this case, I would tend to go for the latter combination as although Gentamicin has excellent activity it does not get into tissue very well and is not very good at treating abscesses (the acidic nature of the abscess prevents Gentamicin getting into the bacterium).
Antibiotics usually active against P. aeruginosa include:
- Beta-lactams e.g. Piptazobactam, Ceftazidime, Meropenem, Imipenem
- Aminoglycosides e.g. Gentamicin, Amikacin, Tobramycin
- Fluoroquinolones e.g. Ciprofloxacin (the only oral anti-pseudomonal)
- Polymyxins e.g. Colistin
- Mono-bactams e.g. Aztreonam
The current outbreak
So far there have been two clusters of 26 cases of related P. aeruginosa infection identified within the UK since mid-July 2016; one in the East Midlands and another in the South East. So far the source is unclear but given the geographical distribution of cases it is likely that a product supplied to tattoo and piercing studios is contaminated with P. aeruginosa rather than a more localised problem. The Public Health England investigation is currently focusing on a potentially contaminated aftercare spray product.
Twenty four hours later our patient was still in a lot of pain and had a large amount of swelling of her upper ear. She was taken to theatre where the surgeons had to remove a large area of necrotic cartilage and soft tissue leaving the patient with a large piece of her ear missing which will require plastic surgery reconstruction in the future. The patient was eventually discharged with PO Ciprofloxacin for 14 days and an appointment to see the plastic surgeons in a few months’ time to discuss options for reconstructing her ear. The typing results did not confirm that the patient was part of the community outbreak. Needless to say the patient has been put off having anymore piercings done and has in fact removed all of her other piercings as well.