bacilio - bacillus
cepa - stock, strain, root.
en biologнa se usa el tйrmino'strain'

Buena suerte.

Cepas - просто племя, илил более
подходит штамм, а bacilos - бацилл.

Saludos de Gabor.

Bacillus is a rod-shaped bacteria; as your text is about tuberculosis, it is Koch's bacillus, the Russian for it is микобактерия туберкулёза, туберкулёзная палочка, бактерия Коха (these are synonims).
Cepas de bacillas should be translated into Russian as бациллярный штамм or бактериальный штамм, which is one and the same.
Email me if you have problems with viewing cyrillics, I'll send you a Word file
Greetings
Natalia