Epidemiological considerations in studies of microbial adhesion

Epidemiological considerations regarding study design, data collection and analysis, and interpretation of results are fundamental to studies of microbial adhesion, when relevance to the pathogenesis of clinical infection is a goal. The host, an obligate participant in all host-pathogen interactions, is a necessary component of microbial adhesion and thus is explicitly or implicitly included in studies of adhesion. This chapter address the host component of microbial adhesion and specifically its epidemiological aspects (i.e., characteristics of human or microbial populations related to disease causation by adhering microorganisms). The chapter discusses the principles of study design and analysis fundamental to (but not exclusive to) sound epidemiological investigation. Examples are drawn primarily from the literature regarding adhesins of uropathogenic Escherichia coli, but the underlying principles apply equally well to other organisms and other clinical settings. Pitfalls to be avoided include type II statistical errors, inattention to confounding variables, and post hoc hypotheses; absence of internal controls; nonuniform evaluation of subjects; failure to characterize subjects adequately, or to stratify analyses according to important clinical characteristics; inattention to the in vivo relevance of the adhesin or receptor studied, or of the assay system used; and overconcluding from research findings to recommendations for clinical practice.