mycoplasma pirum mycoplasma pirum mycoplasma pirum is a species of bacteria in the genus mycoplasma. this genus of bacteria lacks a cell wall around their cell membrane. without a cell wall, they are unaffected by many common antibiotics such as penicillin or other beta-lactam antibiotics that target cell wall synthesis. mycoplasma are the smallest bacterial cells yet discovered, can survive without oxygen and are typically about 0.1 µm in diameter. mycoplasma pirum scientific classification domain: bacteria phylum: mycoplasmatota class: mollicutes order: mycoplasmatales family: mycoplasmataceae genus: mycoplasma species: m. pirum binomial name mycoplasma pirumdel giudice et al. 1985 it has been isolated from those who immune systems are compromised. it has been isolated from those being treated for hiv infection. the type strain is hrc 70-159 = atcc 25960 = nctc 11702. its natural host is unknown.