Roxithromycin in Lyme borreliosis: discrepant results of an in vitro and in vivo animal susceptibility study and a clinical trial in patients with erythema migrans.

A new semisynthetic macrolide roxithromycin was evaluated for its potential use in the treatment of Lyme borreliosis. Using a macro-dilution broth technique, Borrelia burgdorferi was shown to be susceptible to roxithromycin with a minimal bactericidal concentration (MBC) of 0.06-0.25 microgram/ml. A systemic B. burgdorferi infection was established in gerbils; a dosage of greater than or equal to 25 mg/kg/day roxithromycin for 10 days eliminated the infection. A single blind, randomized multicenter study was performed to evaluate the efficacy of roxithromycin 150 mg b.i.d. versus phenoxymethyl-penicillin 1 g b.i.d. for 10 days in patients with uncomplicated erythema migrans. The study was interrupted when 19 patients had enrolled because of five treatment failures. All 5 patients had received roxithromycin; three patients had persisting or recurrent erythema migrans, one developed a secondary erythema migrans-like lesion and severe arthralgia and one developed neuroborreliosis. B. burgdorferi was isolated from skin biopsies after roxithromycin therapy from two patients with persistent erythema migrans and both isolates were still highly susceptible to roxithromycin (MBC = 0.03 microgram/ml). No treatment failures were seen in 10 patients treated with phenoxymethyl-penicillin. Roxithromycin is thus not recommended for treatment of Lyme borreliosis.

Darkening of haemoglobin in simulated, continuously agitated aerobic blood cultures: an early indicator of bacterial growth.

The change of purple oxyhaemoglobin to the darker reduced haemoglobin and methaemoglobin was used as an initial visual growth indicator in continuously agitated, aerobic Colorbact bottles after inoculation with a broad assortment of aerobic and facultatively anaerobic bacteria previously isolated from blood cultures. Growth of all the faster growing strains could be detected by darkening of the blood cultures within a 24 h period of agitation, after they had stood unshaken for eight h. The darkening was accompanied by consumption of O2 and acidification of the fluid media. The slower growing bacteria were detected by turbidity. This growth detection method is easy, quick, inexpensive and reliable, and is especially promising for application in clinical microbiological departments which daily receive blood cultures from peripheral hospitals.

Colorbact, a visually read blood culture system using darkening of haemoglobin in aerobic blood cultures as an early growth indicator, compared with Bactec 6A and 7A.

Colorbact-A (aerobic), a blood culture system using darkening due to oxygen reduction and acidification of haemoglobin as an initial growth indicator during the first day of incubation of continuously agitated, aerobic blood cultures, was compared with the 24 h agitated aerobic Bactec 6A in 1767 consecutive paired cultures. Both systems were examined simultaneously twice daily during the first two days and once daily the next five days of incubation. In addition, during the agitation period Colorbact-A was observed for darkening four to five times during day duty between 8 a.m. and 4 p.m. The final seven days detection rate found by Colorbact-A using observation for darkening during initial agitation was similar to the rate found by Bactec 6A for both clinically significant strains and "contaminants", but Colorbact-A was significantly faster (p less than 0.001) in finding clinically significant strains. Colorbact-AN (anaerobic) was more rapid (p less than 0.01) and yielded more positive cultures than the anaerobic Bactec 7A. The Colorbact system was flexible, inexpensive, reliable and especially promising for laboratories which receive blood cultures from other hospitals once daily, as many positive cultures can be found immediately on arrival undisturbed by agitation during transport.

Isolation of hyaluronic acid from cultures of streptococci in a chemically defined medium.

A haemolytic streptococcus (Lancefield's group A) has been cultivated in a chemically defined medium. About 300 mg hyaluronic acid of a high degree of purity was isolated per litre of this culture.