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Traditionally, generations of physicians have been taught that the evaluation of the febrile hospitalised patient consists of the 'panculture;' that is, microbiological culture of blood, urine, sputum or stool in search of an offending pathogen. Often, these laboratory tests are paired with complementary imaging such as chest or abdominal X-rays in order to elucidate sources of infection. Indeed, it is hard to find a 'competent' physician that has not developed this repertoire during the course of their practice.
Although well established in clinical parlance, the term panculture was formally introduced in the medical literature in the 1990s in response to an article examining blood culture contamination in emergency department settings. 1 Even at this juncture, the phrase introduced palpable anxiety. For example, some termed the practice a 'knee-jerk' response to fever. Others called for the term to be removed from medical discourse. 2 Why the consternation regarding an ostensibly innocuous practice?
The pros and cons of the panculture
As with most medical interventions, the practice of panculture to evaluate fever is associated with benefits and risks. For example, ordering pancultures in a febrile patient allows for retrieval of bacteria from multiple sites, thus informing decision-making with respect to source and severity of infection. In haemodynamically unstable patients or those at high risk of adverse events, the practice also allows for microbiological sampling prior to initiation of broad-spectrum antibiotics which may reduce subsequent yield. Finally, panculture data in association with imaging can inform management beyond diagnosis. For example, the presence of an anaerobic pathogen in blood in association with a right lower-lobe infiltrate helps clinch the diagnosis of aspiration pneumonia, and inform care beyond the management of fever.
Despite these benefits, relying on pancultures in the setting of fever is also problematic for several reasons. First, culture of bodily fluids inherently assumes that all fever is infectious in aetiology. As seasoned clinicians recognise, such is not always the case. Particularly in the hospital setting where infection may be the culprit in as few as 17% of cases, 3 pyrexia secondary to venous thromboembolism, medications, autoimmune disorders and malignancy abound and may be overlooked within a penumbra of cultures. Cultures evaluating fever in the postoperative period (where the oft-quoted '5W' pneumonic for the aetiology of fever is...