It is safe to say that almost any antivirus will detect the major infections, but
no antivirus detects all the exploits as they change every few milliseconds. However, Apple conducts rigorous virus detection on everything in the app store, ClamX AV uses the latest open-source signature database, and AUM has a good reputation, but there are virtually NO Apple viruses in any of the databases because there aren't any. Therefore, they can only detect Windows exploits. Additionally,
Apple Platform Security among other things detects and quarantines any known exploits that get through. Some AV apps supposedly detect unknown viruses, but their success rate is virtually nil, and they have a high rate of false hits.
My suspicion is you are a victim of the latter, and I would not be concerned about the single report.
