Outpatient Parenteral Antimicrobial Treatment (OPAT)

Abstract

Outpatient parenteral antimicrobial therapy (OPAT) is the provision of intravenous (IV) antibiotics to patients in the community or an ambulatory care setting. It was first used to treat children with cystic fibrosis in the 1970s but did not become part of adult services in the UK until the 1990s. OPAT facilitates hospital admission avoidance and decreased lengths of inpatient stay. It is associated with high levels of patient satisfaction. Recent clinical guidelines on the provision of OPAT services in the UK and US have recently been published Skin and soft tissue infections (SSTIs), in particular lower limb cellulitis, are the commonest medical conditions referred to OPAT services. Patients are typically treated for three to five days with IV antibiotics but patients with lymphoedema or underlying skin conditions typically require longer courses. Increasingly, multidrug-resistant urinary tract infections (UTIs) may be treated in the community with IV antibiotics, although oral options such as fosfomycin are now available. Patients with bone and joint infection invariably require prolonged parenteral antibiotic courses, whether this be vertebral osteomyelitis or native or prosthetic joint infection. Other less common examples, where careful patient selection is required, include infected diabetic foot ulcers (with or without osteomyelitis), infective endocarditis, empyema, liver, and tubo-ovarian and brain abscesses. Patients are recruited on the basis of clinical syndromes (e.g. lower limb cellulitis) or laboratory referral (e.g. multidrug-resistant UTIs). Active recruitment (e.g. attendance at acute assessment unit board rounds or orthopaedic multidisciplinary teams, MDTs) compared to passive recruitment (waiting for clinical referrals) increases the yield of patients. The suitability of a patient to receive treatment out of hospital or in an ambulatory care setting needs careful assessment and is dependent upon age, comorbidities, and severity of infection. OPAT also requires patients to engage actively and reliably with therapy. Therefore, IV drug users and patients with serious mental health problems are generally not suitable. Commonly used antibiotics are those given once daily as these reduce nursing time, although some nursing teams can administer IV antibiotics up to three times per day. It is imperative to take a drug allergy history and seek an alternative class of antibiotics when a patient complains of severe penicillin allergy.