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In this article, we show how a particular biomarker comes into being in an emergency department in a hospital in Copenhagen, Denmark. We explore the contextual becoming of this biomarker, suPAR, through interviews with nurses and physicians and through relational ontology. We find that as a prognostic biomarker suPAR is challenged in it becoming as an object for clinical practice in the emergency department by the power of diagnostic practices and the desire for experience-based scripts that quickly enable the clinician to reach the right diagnosis. Although suPAR is enacted as a promising triage strategy suggesting a low or high risk of disease, the inability to rule out specific diagnoses and producing the notion of secure clinical actions make its non-specificity and prognostic character problematic in clinical practices. Specific diagnostic criteria versus prognostic interpretation and non-specificity risk profiling challenges the way healthcare workers in an emergency department understand the tasks they are set to solve and how to solve them. We discuss how the becoming of suPAR is strengthened through enactments of specificity and engagement in triage strategies and we reflect on it's becoming through new diagnostic practices with the need to accommodate diagnostic ambiguity. [ABSTRACT FROM AUTHOR]

Sulpha agents, which act by inhibiting the enzyme dihydropteroate synthase (DHPS), are used widely for the treatment and prophylaxis of Pneumocystis carinii pneumonia (PCP). Recently, we have shown that mutations in the dihydropteroate synthase (DHPS) gene of Pneumocystis carinii f.sp hominis are associated with failure of sulpha prophylaxis and increased mortality in HIV-1 positive patients with PCP, suggesting that DHPS mutations may cause sulpha resistance. To facilitate detection of DHPS mutations we developed a restriction fragment length polymorphism (RFLP) assay, detecting mutations at codon 55 and 57 of the P. carinii DHPS gene. The RFLP-assay was compared with direct DNA sequencing on 27 PCP isolates from HIV-1 positive patients with a mixture of wildtype and mutant DHPS types. In all samples the RFLP-assay correctly identified wildtype or DHPS mutation at codon 55 or 57. Combined with DNA extraction by a Chelex-based method, this method can be performed within 1 d and allows a fast, cost-efficient and reliable method of detection of DHPS mutations in P. carinii. [ABSTRACT FROM AUTHOR]