Clinical images: Bacterial infections

Dr Philip Marazzi outlines some common and interesting bacterial presentations.


This 78-year-old woman had had chronic lymphocytic leukaemia for several years. She developed a rash without the features suggestive of those commonly seen in general practice. She was referred to a dermatologist, who diagnosed cutaneous TB. There was no obvious abnormality on her chest X-ray and no history of travel to areas where she might have picked up the infection. She was treated with antituberculous chemotherapy for six months and the infection resolved.

Perianal abscess

This 63-year-old developed two perianal abscesses. He was admitted to hospital for incision and drainage. Luckily, there were no complications such as fistula formation. Following his discharge, the practice nurses helped with his dressings and he made a full recovery. There was no obvious underlying cause found, such as any immunosuppressant medication, inflammatory bowel disease, diabetes mellitus or HIV/AIDS.

Septic arthritis

This 88-year-old woman was living in a care home. A visit was requested as she had apparently developed cellulitis. In fact, when seen, it was clear that there was more going on. She was pyrexial and unwell, complaining of severe pain in her knee. She was admitted to hospital, where she was found to have septic arthritis, with Staphylococcus aureus grown in blood cultures and aspirate from her swollen knee. She was treated aggressively and recovered.

Infected lymph node

This 77-year-old man had metastatic colon cancer. This included significant lymphadenopathy in his groin. One of these glands became necrotic and infected while he was having chemotherapy. His blood was checked and he was not neutropaenic. He was treated with antibiotics with only very limited effectiveness. He was admitted to hospital for incision and drainage, and initially improved, but then deteriorated rapidly and died.


This elderly man developed an abscess on the back of his neck. It had been growing for a few days before he presented, at which time it was already draining pus. It was formally incised and drained. He was given oral flucloxacillin. This helped to clear any residual infection within the soft tissue surrounding the abscess, allowing it to settle completely. It was not his first skin infection and he was tested to ensure that he was not diabetic, but his results were normal.


Sore throats remain extremely common and it is a challenge to identify the few patients who have bacterial rather than viral infections. If swabs are taken, a proportion of these will grow streptococci sensitive to penicillin. The result will not be available for two to three days. This patient had enlarged, inflamed tonsils with exudates. He was unwell and had been feverish for several days. A throat swab did subsequently grow a group A Strep and penicillin V was prescribed.

Infected PEG line

This 63-year-old woman had carcinoma of the larynx. Her treatment involved radiotherapy to the neck, resulting in significant nutritional problems. A percutaneous endoscopic gastrostomy (PEG) tube was inserted to allow her to have enteral nutrition. Unfortunately, she developed recurrent infections at the skin site. These were treated with oral antibiotics. She continued to complain of a deep subcutaneous pain, and the possibility of an abscess was raised. Investigation failed to reveal this. She managed until she could take food orally again and the tube was removed.

Acne vulgaris

Acne vulgaris is not simply a bacterial infection, but there is an element of infection in this multifactorial condition. In addition to sebum overproduction and hormonal factors, the skin is colonised with the commensal bacterium Propionibacterium acnes. It is known that antibacterials are efficacious partly because of their antibacterial activity, as well as their effect on other aspects of skin physiology, such as reduction in sebum production.

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