And for many cases it works, though Baytril isn't exactly broad spectrum any more. If the OP were going with Baytril + Fortaz or Baytril + Naxcel to target both gram-pos and gram-neg bacteria then I could see the point.
The OP also described this as a "lingering RI", and if the snake has had Baytril treatments for it in the recent past, the bacteria that are left are very likely resistant. Or, in a worse scenario, the underlying cause may be viral and not bacterial; several of the PMV's can present as on-again off-again RI's before the snake eventually succumbs to the disease.