Coli and the health department recommended adding bleach to it. 

@Ivan Chavez if you really want to go above and beyond: clean out gutters, inspect all appliances (or at least those you provide) ice and vinegar in the disposal, check stove elements and use oven cleaner, run vinegar or bleach through the washer, vinegar or bleach in the dishwasher, clean the dishwasher strainer, check light bulbs in vent hood and change charcoal filter, electrical system check-make sure gfci work with a tester (not the button), check all bulbs, fans, and outlets, plumbing check for leaking toilets, dripping p traps under the sinks, you can also check resistance on electrical water heater elements to make sure they aren't busted.

@Luke TrovingerLots and lots of bleach and dish soap with hot water.Also PH balanced cleaners you can buy at Home Depot will take out urine smell.

Is it at the spray with bleach and all is well stage or is it extensive and will take hiring a specialist? 

I warn my tenants not to use bleach on the quartz or put hot things on it, just to make sure. 

If vacant you need to:what is cost of dumpsters vs buying a pick up or finding some hauler to throw away all the demolition  secure and board up and add cameras, get roof bids, order roof parts, roof needs to get on the house ASAPclean out dry wall, everything fabric throw away, cut up and remove carpet, mop the studs and floor with bleach and water solution (5% bleach), inspect electrical - maybe some shorts or problems, order flooring for kitchen and baths and new kitchen cabinets (measure like you are OCD ten times), how is the sub flooring?

I go to take a look and scrub it off with a bleach and baking soda paste.

A bunch of Iranians have died drinking methanol and bleach to cure it.

Your best bet would be to clean it with bleach.

For example, you can't give a holiday gift to only who you think are good tenants because one of them would post "Thanks Sam for the $25 AMC movies GC my boy friend and I saw Avengers last night xoxo" then your other tenants who didn't get a GC will feel left out.I visit my properties once a month for regular maintenance, mostly for little stuff, like changing AC filters, test smoke alarm batteries, test GFCI receptacles, pour bleach down AC condensate drain lines, exercise water supply stop valves, feel under any drains to check leakage, test water heater T&P valves, etc etc etc...they do not need to be done monthly but that's what I do at each property.