Mycoplasma is considered to be a bacterium, but does not have a cell wall as most bacteria do. Yes, it can respond to some antibiotics such as Tylan, oxytetracycline, erythromycin, and others. Viruses such as Infectious bronchitis or infectious laryngotracheitis, or fungi such aspergillosis, will not respond. Prettypenny has said that they think it is a virus, since it rapidly spread through the flock, and that can be common with infectious bronchitis. It can take several weeks to overcome unless secondary bacterial diseases occur, and one can expect the flock to all be carriers of IB for up to a year.