In vitro activity of a group of broad-spectrum cephalosporins and other beta-lactam antibiotics against Chlamydia trachomatis

Abstract

The activities of seven broad spectrum cephalosporins, four other ,-lactam antibiotics, and one monobactam against Chlamydia trachomatis were measured in a cell culture system. The minimal inhibitory concentration offour of the seven cephalosporins was .-128 ,ug/ml; those of the other three were from 16 to 32 ,ug/ml. Of the other agents, only mecillinam had activity against C. trachomatis comparable to that reported for ampicillin (minimal inhibitory concentration, <0.5 ,ug/ml).A single dose of penicillin or ampicillin as commonly used in the treatment of uncomplicated gonococcal urethritis will usually not eradicate a concurrent chlamydial infection (5). Repetitive dosage is more effective; thus, amoxicillin given for 10 days eradicated Chlamydia trachomatis in 48% of men with chlamydial urethritis (2) and, given for 14 days, eradicated these organisms from the cervixes of pregnant women (E. R. Alexander, personal communication). To assess the potential activity of other ,Blactam antibiotics, we tested seven of the new broad-spectrum cephalosporins, four other Plactam antibiotics, and one monobactam against five C. trachomatis strains in a cell culture system.McCoy cells treated with cycloheximide were used. The cells were grown in Eagle minimal essential medium to which 10% inactivated fetal calf serum, 2 mM glutamine, and 5% glucose were added. No antibiotics or antifungal agents except those under investigation were included in the medium. Seven-day-old monolayers were treated with trypsin and resuspended in medium to a concentration of 3 x 10 cells per ml. The cells were seeded onto 96-well microtiter plates with a volume of 0.2 ml per well and incubated at 35°C for 24 h.One isolate of C. trachomatis, H/UW-4, which is well adapted to conditions in the laboratory; four clinical isolates from patients with urethritis, neonatal conjunctivitis, and from the cervix were used in our studies. These isolates had been passed three to five times in cells free of antibiotics.The antimicrobial agents evaluated were moxalactam, cefmenoxime, cefotaxime, ceftriaxone, cefoperazone, N-formimidoyl thienamycin, cefsulodin, mecillinam, piperacillin, mezlocillin, azlocillin, and the monobactam Sch 29,482. Sch 29,482, an oral penem highly resistant to J-lactamase, has been reported to be highly active against both ,-lactamase-positive and -negative strains of Neisseria gonorrhoeae and Haemophilus influenzae (C. Thornsberry and C. N. Baker, Program Abstr. Intersci. Conf. Antimicrob. Agents Chemother. 21st, Chicago, Ill., abstr. no. 747, 1981).The various antimicrobial agents were supplied as powders, solubilized according to instructions from the manufacturer, and diluted in medium containing 2 j±g of cycloheximide per ml before use. One-day-old monolayers were inoculated with 0.1 ml of the test strain dilution to yield 103 to 104 inclusion-forming units per ml.The plates were then centrifuged for 60 min at 2,000 x g at 25°C. After inoculation and centrifugation, the medium was aspirated and the wells were overlaid with 0.2-ml p...

Chlamydia pneumoniae and Atherosclerosis: Critical Assessment of Diagnostic Methods and Relevance to Treatment Studies

“…The success of the cephalosporin regimens supports concerns about the specificity of the serologic criteria since these antibiotics have no or poor activity against Chlamydia spp. in vitro (50). A number of subsequently published treatment studies have claimed microbiologic eradication, despite the fact that cultures were not done (54).…”

Simkania negevensis, an Example of the Diversity of the Antimicrobial Susceptibility Pattern among Chlamydiales

“… a Shown are the MICs of various antibiotics against members of the Chlamydiales orders ( 5 , 6 , 8 , 10 , 11 , 21 – 24 ). This table was adapted from reference 8 with permission.…”

“… Chlamydiales members lack the traditional peptidoglycan (PG) layer. However, partial susceptibility to β-lactams is observed among Chlamydia spp., which are known to form aberrant bodies when treated with penicillin derivatives ( 10 ), while W. chondrophila is susceptible to high doses of fosfomycin ( 11 ). Aberrant bodies represent enlarged forms of the bacterium, due to abnormal division despite persisting DNA replication ( 11 ).…”