In vitro susceptibilities of Chlamydia pneumoniae isolates from German patients and synergistic activity of antibiotic combinations.

The susceptibilities of six Chlamydia pneumoniae type strains and of six German patient isolates to erythromycin, azithromycin, roxithromycin, clarithromycin, doxycycline, ofloxacin, and rifampin were investigated. MICs and minimal chlamydicidal concentrations were all within the ranges reported previously. Combinations of azithromycin with either ofloxacin, doxycycline, or rifampin, as well as combinations of three antibiotics (rifampin, azithromycin, and ofloxacin or doxycycline), showed synergistic activity against C. pneumoniae.

Parasite/host-interrelationships of the trypanosomatids Trypanosoma cruzi and Blastocrithidia triatomae and the reduviid bug Triatoma infestans: influence of starvation of the bug.

We have investigated the effects of Trypanosoma cruzi and Blastocrithidia triatomae on the life span of starved second/third (L2/3), third/fourth (L3/4), and fourth/fifth instars (L4/5) of Triatoma infestans, which had been infected in the first instar and fed last in the second, third or fourth instar respectively. The intestines and sometimes also the flagellate populations of dead bugs were examined. In uninfected L2/3 a higher relative humidity prolonged the life span. With a maximal survival of 14 months, uninfected L3/4 were the most resistant to starvation, followed by L4/5 and then L2/3. Trypanosoma cruzi reduced the life span of starved L3/4 and L4/5 by only 14% and 17%, respectively. Infection with B. triatomae reduced life spans by 51% (L2/3), 55% (L3/4) and 32% (L4/5). The intestines of dead infected bugs were more likely to contain incompletely-digested blood remnants than those of uninfected bugs; living flagellates occurred in all parts of the intestine, and often the rectal lumen contained more dead flagellates than were found on the rectal wall.

Trypanosoma cruzi: origin of metacyclic trypomastigotes in the urine of the vector Triatoma infestans.

Population density and percentage of the different stages of an established infection of Trypanosoma cruzi were determined for two parts of the excretory system and for the rectum of fifth instars of Triatoma infestans unfed and 4 hr after feeding. These data were also evaluated for feces and urine of the fed bugs. In the first unfed group only small populations of the flagellate occurred in the Malpighian tubules and ampullae and not in all bugs. The three rectal populations (rectal lumen and anterior and posterior rectal wall) consisted of approximately equal numbers. About 10% were spheromastigotes and about 10% were stages intermediate to epimastigotes. Significantly fewer epimastigotes and more trypomastigotes were present on the rectal wall than in the lumen. Two intermediate forms leading to the trypomastigote stage occurred in similar numbers. In nearly all bugs the initial excretion (feces) contained the highest number of flagellates as compared to the following drops of urine. More flagellates were excreted through the urine than were contained in the excretory system of unfed bugs. The population in the feces reflected the percentage of forms present in the rectal lumen of unfed bugs, but in the urine the percentage of trypomastigotes increased up to 100%. Four hours after blood uptake, dissection of bugs still showed parasites in the Malpighian tubules and ampullae; the total number of parasites in the rectum was reduced by more than 50%. This reduction was more pronounced in the rectal lumen and on the posterior rectal wall. In stained smears from all three rectal populations there were rarely spheromastigotes but high percentages of epimastigotes. The intermediate stages leading to trypomastigotes mainly originated from short epimastigotes. Comparison of the T. cruzi populations before and after feeding demonstrates that the trypomastigotes in the urine should originate from the rectal wall, especially from the posterior part.