What management and investigations are appropriate for a patient with suspected bacterial proctitis, a history of perineal hernia and abdominal aortic aneurysm, who has presented to a general practitioner (GP) after discharge from hospital?

Management of Suspected Bacterial Proctitis in General Practice

For a patient with suspected bacterial proctitis presenting to your GP clinic, perform a digital rectal examination after taking a focused history, obtain urine culture and inflammatory markers if systemically unwell, start empiric broad-spectrum antibiotics covering gram-positive, gram-negative, and anaerobic organisms if there are signs of systemic infection or surrounding soft tissue involvement, and refer urgently to colorectal surgery or gastroenterology depending on severity and your clinical suspicion of the underlying cause. 1, 2

Initial Clinical Assessment

History and Physical Examination

• Collect a focused medical history specifically asking about: rectal pain, discharge, bleeding, fever, recent hospitalization, immunosuppression status, inflammatory bowel disease history, and any history of prior perianal abscess or fistula 1, 2
• Perform a complete digital rectal examination to identify: tenderness, induration, fluctuance suggesting abscess, palpable cord-like structures suggesting fistula, and assess sphincter tone 1, 2
• Given the patient's history of perineal hernia and abdominal aortic aneurysm, be particularly vigilant as perineal infections can seed AAA grafts through bacterial translocation, with one case series showing 10% prevalence of bacterial translocation in AAA patients and significantly increased septic morbidity 3

Laboratory Investigations

If the patient appears systemically well without fever or signs of sepsis:

• Routine laboratory tests are not required for uncomplicated proctitis 1
• Consider urine culture only if urinary symptoms are present 1

If the patient has signs of systemic infection (fever, tachycardia, hypotension):

• Obtain immediately: complete blood count, serum creatinine, C-reactive protein, procalcitonin, and lactate 1
• Check serum glucose and hemoglobin A1c to identify undetected diabetes, which increases infection risk 1, 2
• Obtain blood cultures before starting antibiotics if bacteremia is suspected 4

Antibiotic Decision Algorithm

When to Start Antibiotics

Start empiric antibiotics if ANY of the following are present:

• Signs of sepsis (fever, tachycardia, hypotension, altered mental status) 1, 4
• Surrounding soft tissue infection or cellulitis 1, 5
• Immunocompromised state (diabetes, steroids, chemotherapy) 1
• Given this patient's AAA, have a lower threshold to start antibiotics due to risk of graft seeding through bacterial translocation 6, 3

Do NOT routinely use antibiotics if:

• The patient is systemically well with localized symptoms only 1
• No signs of soft tissue extension or systemic involvement 1

Antibiotic Regimen

If antibiotics are indicated, use broad-spectrum coverage:

• The regimen should cover gram-positive, gram-negative, and anaerobic organisms 1, 5
• Base selection on: patient's clinical condition, individual risk for multidrug-resistant organisms (recent hospitalization, prior antibiotics), and local resistance patterns 1
• Start antibiotics within 1 hour if septic shock is present, or within 8 hours if systemically unwell but stable 4
• Duration: 3-5 days after adequate source control if surgical drainage is performed 1, 4

Imaging Considerations

Imaging is NOT routinely needed for typical proctitis, but consider if: 1, 2

• Suspected abscess that is not clinically obvious
• Atypical presentation or concern for inflammatory bowel disease
• Suspected perforation or peritonitis
• Do not delay treatment to obtain imaging if the patient is unstable 1, 4

Referral Strategy

Urgent Referral (Same Day) to Emergency Department or Colorectal Surgery:

• Any signs of sepsis or hemodynamic instability 1, 4
• Suspected perianal abscess requiring drainage 1, 5
• Suspected Fournier's gangrene (crepitus, rapidly spreading erythema, systemic toxicity) 1
• Given the AAA history, any concern for infected aneurysm or systemic infection warrants urgent surgical evaluation 6

Routine Referral to Colorectal Surgery:

• Suspected fistula-in-ano (recurrent perianal pain, discharge, history of prior abscess) 2
• Chronic or recurrent proctitis not responding to initial management 2
• Atypical features suggesting Crohn's disease (lateral fissures, multiple fistulas) 2

Referral to Gastroenterology:

• Suspected inflammatory bowel disease 2
• Need for endoscopic evaluation if infectious proctitis is suspected but not improving 2

Critical Pitfalls to Avoid

• Never delay antibiotics while waiting for culture results if the patient has signs of systemic infection 4
• Do not probe for fistulas during acute infection as this causes iatrogenic complications 1
• Do not assume all proctitis is benign—in this patient with AAA, consider that perineal infections can lead to mycotic aneurysm infection with catastrophic consequences 6, 3
• Do not miss Crohn's disease by assuming all perianal disease is simple infection—atypical features warrant gastroenterology referral 2
• Do not continue antibiotics beyond 5 days if adequate source control is achieved, as this increases resistance without improving outcomes 4

Outpatient Management (If Systemically Well)

If the patient has no signs of sepsis and examination suggests uncomplicated proctitis:

• Dietary modifications: increase fiber and water intake 1
• Topical anesthetics and oral analgesics for pain control 1
• Close follow-up within 48-72 hours to reassess 1
• Clear return precautions: fever, worsening pain, inability to urinate, spreading erythema 1