Although it is hoped they can provide some guidance in developed countries there are some important distinctions in this environment and individual recommendations may not be as applicable this website in this setting. The early chapters of these guidelines consider the most common presentations of OI disease such as respiratory, gastrointestinal

and neurological disease. These chapters are followed by chapters on specific organisms such as Candida spp, herpes simplex virus and varicella zoster virus, whilst the final chapters discuss special circumstances such as pregnancy, the use of the intensive care unit, the investigation of unwell patients with fever of undetermined origin and management of imported infections. Each section contains specific information on the background, epidemiology, presentation, treatment and prophylaxis of OIs. Since the advent of the era of highly active antiretroviral therapy (HAART) the incidence of ‘classic’ opportunistic infections such as Pneumocystis jirovecii and Mycobacterium avium complex has dramatically fallen [3]. The relative

contribution of infections that have not formerly been regarded as ‘opportunistic’ has increased. These include community-acquired pneumonia, Clostridium difficile infection and Cobimetinib influenza A virus (IAV) infection. The distinction between ‘opportunistic’ and ‘non-opportunistic’ infection is becoming blurred. HIV-seropositive individuals are often less immunocompromised than in the era before HAART. Increasingly it is subtle differences in the susceptibility to, or severity of, infections commonly encountered in immunocompetent individuals that are observed in individuals living with HIV. Recent findings suggest that the strains of pneumococci, a pathogen not regarded as ‘opportunistic’, which are most prevalent in individuals living with HIV behave as ‘opportunistic’ infections [4]. We accept some infections, such as IAV infection, included in these guidelines are not

‘opportunistic’, even using this more relaxed view but believe the current concerns relating to IAV infection and evidence IMP dehydrogenase that disease may be more severe in some HIV-seropositive individuals [5] justify their inclusion in these guidelines. Further information on the role of antiretroviral therapy is also discussed (see below). In the appendices there is an A–Z of drugs used in the management of opportunistic infections. This is intended as a guideline but readers are advised to follow the discussion of dosing and the evidence for specific treatments provided in the text. In some cases alternative treatments are provided in the appendix. These are not discussed in the text and these are mainly of historical interest and readers should be aware that these are not, in general, supported by the evidence base for treatments discussed in the text.