Therefore, to facilitate timely diagnosis of infections in patients with secondary immunodeficiency caused by the etiologies other than HIV, in the current study we intend to construct mathematical models that are based on certain lab test results including complete blood count (CBC), C-reactive protein (CRP), procalcitonin (PCT), erythrocyte sedimentation rate (ESR) and culture results from various body fluids, to help clinicians predict the most likely pathogens and then rapidly start empirical antibiotics before the culture results return in this patient population. This evidence concerns the gene CRP and infection.