Fig. 1

Diagram of the Natural Histories of Pb and MRSA Exposure. The natural history of Pb exposure and selection for antibiotic resistance in Staphylococcus aureus that colonize individuals in this study population could work in several ways. a The individual is exposed to Pb first, and is then exposed to MRSA and MSSA. The Pb prevents colonization by MSSA, but not MRSA. b The individual is colonized by MRSA and/or MSSA first, and is then exposed to Pb. The Pb selects for antibiotic resistance by killing MSSA and leaving MRSA behind. c MRSA and/or MSSA is exposed to Pb in the environment. The Pb exposure selects for antibiotic resistance in the environment. The individual is then exposed to both MRSA and Pb from the same source. Abbreviations: MRSA – Methicillin-resistant Staphylococcus aureus; MSSA – Methicillin susceptible Staphylococcus aureus; Pb – Lead