Modification and duration of therapy for suspected bloodstream infection associated with an intravenous catheter
The results of culture and susceptibility testing guide ongoing therapy for suspected bloodstream infection associated with an intravenous catheter. In many cases (depending on the local resistance epidemiology among S. aureus isolates), infections are due to methicillin-susceptible strains of S. aureus and treatment can be simplified to using an antistaphylococcal beta-lactam antibiotic (eg flucloxacillin or cefazolin) – see Methicillin- and penicillin- susceptible S. aureus bacteraemia. If gentamicin or tobramycin was added to the empirical regimen, review the need for ongoing therapy at 48 to 72 hours. After 72 hours, if no gram-negative pathogens have been isolated from the initial samples, gram-negative bacteraemia is less likely – stop gentamicin or tobramycin and seek expert advice.
The duration of therapy depends on the virulence of the pathogen and patient factors (eg immune compromise, presence of prosthetic material, indication for the intravenous catheter) – seek expert advice.
If the infection is caused by a pathogen with low virulence (eg a coagulase-negative staphylococcus), bacteraemia can resolve quickly after removal of the infected intravenous catheter. If persistent bacteraemia and endocarditis are excluded, prolonged antibiotic therapy may not be required. Seek expert advice on the duration of therapy, with consideration of:
- the patient’s clinical status
- the context of the infection (eg associated with a peripheral versus central intravenous catheter, or a short-term versus long-term intravenous catheter; whether patient has immune compromise).
If infection is caused by a more virulent pathogen (eg Staphylococcus aureus, a Candida species1), continue therapy after the device is removed. Treatment duration may need to be prolonged in these cases, since persistent bacteraemia is more common, and deep-seated infectious complications are more likely (such as infective endocarditis, osteomyelitis or endophthalmitis); further investigations are required.