Stool cultures for Shigella spp: improved specificity by using MacConkey agar with xylose.

A total of 678 stool specimens were cultured on four different agars: on xylose-lysine-desoxycholate agar (XLD), MacConkey agar (Mac), MacConkey agar supplemented with xylose (Mac-X), and Hektoen enteric agar (HE). Isolation rates for shigellae were 77% on HE, 86% on Mac and Mac-X, and 91% on XLD. The specificities of the media were 61% for Mac, 75% for HE, and 78% for XLD and Mac-X. After overnight incubation, Mac-X is much easier to read than XLD, which requires incubation for at least 22 hours. Based on these results and also on the practical aspect that incubation for 22-21 hours does not fit well in our schedule, we now use Mac-X whenever shigellae need to be looked for (i.e. mainly patients with recent travel to tropical countries). As compared to our previous procedure the workload in the laboratory could be reduced by about 20%.

Development of resistance to macrolide antibiotics in an AIDS patient treated with clarithromycin for Campylobacter jejuni diarrhea.

In an AIDS patient with diarrhea, identical isolates of Campylobacter jejuni susceptible and, later, resistant to macrolide antibiotics were isolated from feces before and after treatment with clarithromycin. Results of rRNA gene restriction analysis and serotyping suggest that development of resistance rather than simultaneous infection with a susceptible and a resistant strain was responsible for this phenomenon. This is the first report of in vivo development of resistance by Campylobacter jejuni in a patient treated with a macrolide for Campylobacter jejuni infection.

[Effect of ciprofloxacin therapy in duration of bacterial excretion in acute salmonella gastroenteritis]. / Einfluss einer Ciprofloxacin-Therapie auf die Ausscheidedauer bei akuter Salmonellen-Gastroenteritis.

In view of the increasing incidence of non-typhoid salmonellosis, the effect of early treatment with ciprofloxacin on the permanent elimination of salmonella was evaluated. In a prospective study, 14 patients with non-typhoid salmonellosis were treated with 2 x 500 mg/d ciprofloxacin for 10 days within 5 days of onset of symptoms. Relapse occurred in 4/14 (29%) patients 2-3 weeks after termination of therapy. Using sero- and ribotyping, relapse was confirmed and reinfection ruled out in 4/4 patients. Furthermore, ribotyping suggested double infection in one patient. Development of resistance to ciprofloxacin was not observed. We conclude that the use of antimicrobial chemotherapy to treat non-institutional salmonellosis in immunocompetent patients cannot generally be recommended but must be considered carefully in each case. Indications for ciprofloxacin therapy in the treatment of non-typhoid salmonellosis are discussed.

Development of resistance to quinolones in five patients with campylobacteriosis treated with norfloxacin or ciprofloxacin.

Development of resistance to nalidixic acid, norfloxacin and ciprofloxacin was observed in five patients with Campylobacter jejuni or Campylobacter coli infection. From all these patients nalidixic acid- and quinolone-susceptible strains were isolated initially, whereas after therapy with norfloxacin or ciprofloxacin strains resistant to these antibiotics were found. Campylobacter strains from the same patient always belonged to the same species and, with the exception of one case, showed identical rRNA gene restriction (rDNA) patterns. This indicates that double-infection with a susceptible and a resistant strain was not responsible for the phenomenon but rather that the infecting strain rapidly developed resistance following treatment.