Ultrastructural Analysis of the Effects of Penicillin and Chlortetracycline on the Development of a Genital Tract Chlamydia

Abstract

The developmental cycle of a genital tract Chlamydia (MRC-1 /G) growing in irradiated monkey kidney cell monolayers was analyzed by electron microscopy. Growth was essentially similar to that of C. psittaci and ocular isolates of C. trachomatis. Penicillin (50 units/ml) interfered with the growth cycle by producing greatly enlarged initial bodies which sometimes measured 3 Am instead of the normal 1 to 1.3 ,um in diameter. In contrast to penicillin, chlortetracycine (10 ,g/ml) did not grossly distort morphology of the initial body but had a definite inhibitory effect on the formation of elementary bodies depending upon the time postinfection the antibiotic was added. If added 24 hr or later postinfection, typical inclusions containing elementary bodies were formed. When administered 18 hr postinfection, the transition of initial bodies to elementary bodies was prevented, and the inclusion was much smaller when examined at 48 hr in comparison to a control without chlortetracycline. Addition of the drug at 6 or 12 hr postinfection resulted in very small inclusions which contained only one or two chlamydiae of an initial body type. It was not possible to detect chlamydiae when chlortetracycline was added immediately after adsorption (0 hr), and cells were examined by light and electron microscopy at 48 hr.

Characterization of In Vitro Chlamydia muridarum Persistence and Utilization in an In Vivo Mouse Model of Chlamydia Vaccine

“…The use of penicillin to examine ultrastructural changes has been used in other strains of Chlamydia . The findings in our study were similar to those seen by others using C. trachomatis and C. psittaci , with the development of aberrant bodies (ABs) after the addition of penicillin and the return of inclusions with a normal appearance after its withdrawal. Recently, C. muridarum persistence was examined using amoxicillin and demonstrated the formation of aberrant bodies by 36 hr post‐infection, consistent with our penicillin G model.…”

Drosophila melanogaster S2 cells: a model system to study Chlamydia interaction with host cells

“…Furthermore, treatment of L2-infected S2 cells with penicillin resulted in enlarged RBs (unpubl. data), similar to the changes reported in mammalian cells (Matsumoto and Manire, 1970;Kramer and Gordon, 1971). The fact that IncG was produced and localized to the inclusion suggests that Chlamydia was metabolically active and modified the inclusion as it does during mammalian infection.…”

Electron microscopic evidence of persistent chlamydial infection following treatment

“…3 Apparently cleared, unculturable chlamydial infections can be induced to recur following immunosuppressive therapy 4 or an intervening gonococcal infection. 5 This has most convincingly been demonstrated in vitro where treatment with cytokines such as interferon (IFN)-γ or tumour necrosis factor (TNF)-α 6-8 or antibiotics 9,10 or nutrient deprivation 11 have all led to significant alterations in reticulate body (RB) morphology. Of critical importance is that, although the altered RB will not typically replicate in vitro , when the cytokine or antibiotic is removed, or nutrients restored, the altered RB reverts to a normal morphology and resumes its full metabolic activity.…”