In Vitro Activity of a Group of Broad-Spectrum Cephalosporins and Other β-Lactam Antibiotics Against Chlamydia trachomatis

Abstract

Volume 23, no. 3, p. 493, abstract: "The activities of seven broad spectrum cephalosporins, four other ,B-lactam antibiotics, and one monobactam.. . ." should read "The activities of seven broadspectrum cephalosporins and five other 3-lactam antibiotics...." Page 493, column 1, lines 12-14: ".. . we tested seven of the new broad-spectrum cephalosporins, four other ,-lactam antibiotics, and one monobactam... ." should read "... we tested seven of the new broad-spectrum cephalosporins and five other 3-lactam antibiotics...." Page 493, column 2, lines 3-6: ".. . and the monobactam Sch 29,482. Sch 29,482, an oral penem highly resistant to ,-lactamase, has been reported to be highly active... ." should read ".... and Sch 29,482, an oral penem highly resistant to P-lactamase and reportedly highly active...." Page 494, column 1, lines 28-33: "The only other monobactam that has been tested against C. trachomatis is SQ 26,776 (5), which was reported to be inactive, with-100 .g/ml needed to suppress normal inclusions. We found Sch 29,482 to be more active, with a mean MIC of 28 FLg/ml" should read "The mean MIC of Sch 29,482 was 28 ,g/ml."

Affinities of β-Lactams for Penicillin Binding Proteins of Chlamydia trachomatis and Their Antichlamydial Activities

“…However, in agreement with others (8, 9), we observed that representative penicillins (benzylpenicillin, ampicillin, and mecillinam) were more active at both the MIC and MBC than cephalosporins (ceftriaxone and cefotaxime). The carbapenems imipenem and meropenem were also relatively inactive, in agreement with earlier findings on N-formimidoylthienamycin and imipenem (8,9). Mecillinam was the most potent of the ␤-lactams we investigated, having an MBC and an MIC of 0.25 and 0.01 g/ml, respectively (Table 1).…”

“…Since we wanted to determine the minimal concentration of antibiotic that affected chlamydial growth, we used morphological abnormality (Fig. 1) as a criterion for determining MICs, rather than complete inhibition of the development of inclusions, which has been used by others (8,9). Thus, the MICs that we determined (Table 1) are not necessarily directly comparable with those reported in the literature.…”

“…They have a complex development cycle involving infection by elementary bodies (EBs), transformation of EBs into reticulate bodies (RBs), RB division, differentiation of RBs back to EBs, and release of EBs following host cell lysis (18). Penicillin and other ␤-lactam antibiotics inhibit the growth of chlamydiae (1,3,(8)(9)(10)(13)(14)(15)(16) and have been used for the treatment of chlamydial infections, particularly when first-line agents are contraindicated (11,14,19,24,25). Exposure of chlamydiae to penicillin leads to the accumulation of large aberrant RBs, the so-called penicillin forms, which can resume normal development if penicillin is removed (15,16).…”

In vitro activity of clavulanic acid, amoxicillin, and ticarcillin against Chlamydia trachomatis

“…In contrast, with penicillins there are occasional inclusions over a wide range of concentrations (6,10,14,15). This probably accounts for the large discrepancies in published reports of MICs of penicillins (4,6,9,10,(13)(14)(15)(16). In vivo, single-dose penicillin treatment does not usually eradicate C. trachomatis (7, 10), but multiple-dose penicillin treatment often results in negative follow-up cultures for weeks or longer (2,5,7,12).…”

In Vitro Effects of Spectinomycin and Ceftriaxone Alone or in Combination with Other Antibiotics against Chlamydia trachomatis

“…The fractional inhibitory concentration (FIC) index for combinations was calculated as follows (11): Ridit analysis illustrates the relative position of the score of a particular group against an identified distribution of a reference group (20). The analysis was carried out by the calculation function of Excel Table. In each batch of microdilution tests, the MICs of the five antimicrobial agents for strains VR-348B and L3 all fell within the ranges previously observed by other investigators using the same method (10,15,22). The ranges of MICs of spectinomycin, ceftriaxone, erythromycin, ofloxacin, and doxycycline were 128 to 256, 10 to 20, 0.06 to 0.5, 0.25 to 1, and 0.015 to ϳ0.125 g/ml, respectively, in our study.…”