The ultrasound shows a liver abscess in the right lobe and, in view of his travel, an amoebic abscess is a strong possibility. Fortunately, you had sent off an amoebic CFT sample and you ring the reference laboratory urgently. The test is positive (usually positive with an amoebic liver abscess).

Treatment

Treat with metronidazole 800 mg × 3 daily for 10 days followed by diloxanide furoate 500 mg × 3 daily for 10 days. Aspiration of the abscess is only required with failure of medical therapy.

Remember

• Take a careful history: always repeat

• Examine the patient thoroughly: always repeat

• Initial investigations often give a clue to the diagnosis: often need repeating

• Be patient and don’t give antibiotics until diagnosis is made unless the patient is very sick

• Perform invasive and/or expensive investigations only when appropriate, e.g. echo, CT scan/MRI, bone marrow and culture, lymph node/liver biopsy.

Progress.

This man responded quickly to therapy with loss of pain, improvement in appetite and he became apyrexial after 4 days. A repeat ultrasound 3 weeks later still showed a small residual cavity.

What are the most common causes of septicaemia in patients presenting from the community?

The most common organisms isolated are Escherichia coli, Staphylococcus aureus, Streptococcus pneumoniae and pyogenic streptococci – especially group A streptococci. Neisseria meningitidis should not be forgotten as a possible cause of community-acquired sepsis.

In hospital, coagulase-negative staphylococci can also cause sepsis in immunosuppressed patients with IV lines in situ. Wounds, the respiratory tract (especially in ventilated patients) and the urinary tract (in catheterised patients) are other sources of sepsis in hospitalised patients.

What factors predispose to septicaemia?

In both Gram-positive and Gram-negative septicaemia, impaired host defences, surgery or instrumentation (including intravenous cannulae, urinary catheters and mechanical ventilation) predispose to septicaemia (Table 1.2).

Table 1.2 Predisposing factors for septicaemia

What is the differential diagnosis of septic shock?

Non-infective disorders, such as acute myocardial infarction, pulmonary embolism or drug reactions, must be excluded. Toxic shock (e.g. toxic shock syndrome) can also present in a similar manner.

What would be your initial management of this woman and what investigations would you do?

This patient required supportive therapy (e.g. fluid replacement) because she was dehydrated and oxygen was given and inotropes. Broad-spectrum antibiotics were started after blood and urine cultures had been taken. The antibiotic therapy varies according to local hospital policy and the likely focus of infection. This severely shocked patient was transferred to HDU/ITU (see p. 383).

If a urinary tract infection is thought to be the likely source, a broad-spectrum cephalosporin is often appropriate (e.g. cefuroxime) or a quinolone (e.g. ciprofloxacin).

If there is no obvious focus of infection, blind therapy must be broad spectrum and cover streptococci, staphylococci and coliforms.

Suitable choices are:

• A broad-spectrum cephalosporin such as IV cefuroxime or IV cefotaxime or IV ceftriaxone.

• Metronidazole should be added if an anaerobic infection is considered likely.

• A broad-spectrum penicillin with β-lactamase inhibitor (e.g. piperacillin/tazobactam). Gentamicin can be added if the patient is very ill.

• A carbapenem (e.g. imipenem, although this is a restricted antibiotic in many hospitals).

Remember

• If you give gentamicin, remember that you need to monitor serum levels. Combining it with a cephalosporin can potentiate its nephrotoxicity.

• Cefuroxime, ceftriaxone and cefotaxime have fairly good activity against staphylococci and streptococci, as well as against many Gram-negative rods; they have poor activity against Pseudomonas spp. Ceftazidime has poor activity against streptococci and staphylococci but excellent activity against Pseudomonas spp. and other Gram-negative organisms. No cephalosporins are active against Enterococcus spp.

• Cephalosporins are associated with C. difficile diarrhoea and should be avoided if possible.

• If a patient develops sepsis while in hospital it is possible that this is due to resistant organisms, e.g. methicillin-resistant S. aureus (MRSA) or resistant Gram-negative rods.

• If MRSA infection is considered likely and the patient is very sick, add IV vancomycin 1 g × 2 per day (assuming normal renal function) given over at least 100 minutes while awaiting culture results.