PABA Allergy and Baba Overdose

PABA (para-aminobenzoic acid) is a natural substance that is sometimes used in sunscreen products. It is also found in a number of medications and foods, and may be used to treat certain disorders. People may have reactions to PABA, including a skin allergy and an overdose. This article discusses how to prevent and manage these reactions.

We performed a radiosynthesis of [11C]PABA using a commercially available Grignard precursor and subsequent quenching in aqueous HCl. The radiochemical purity of the resulting product was >99% at the end of the synthesis, and a 35% decay-corrected radiochemical yield was achieved.

The labeled PABA was incorporated into several major human pathogens, including Staphylococcus aureus and E. coli (both gram-positive), but not into Salmonella, Pseudomonas aeruginosa, or Mycobacteria (all gram-negative). It was also able to differentiate living from heat-killed bacteria in an in vivo murine myositis model, using simultaneous intramuscular inoculation of live and heat-killed E. coli at different sites in the left deltoid muscle to induce infection and sterile inflammation.

As demonstrated in Supp Fig 4, [11C]PABA specifically accumulated in the infected left deltoid muscle, but not in the contralateral heat-killed inoculation site or normal muscle. This is consistent with results from dynamic PET-CT studies that have been reported for [18F]FDG in the same model, indicating that PABA is a potential tracer to distinguish living from heat-killed bacteria in vivo.