Limits...
Efficacy of eleven antimicrobials against a gregarine parasite (Apicomplexa: Protozoa).

Johny S, Merisko A, Whitman DW - Ann. Clin. Microbiol. Antimicrob. (2007)

Bottom Line: Treatment with metronidazole and griseofulvin in host insects significantly reduced gregarine counts, whereas, gregarine counts of insects fed, albendazole, ampicillin, chloramphenicol, fumagillin, quinine, streptomycin, sulfadimethoxine, thiabendazole or tetracycline, were not significantly different from the controls.However, albendazole produced a strong, but non-significant reduction in gregarine count, and streptomycin exhibited a non-significant antagonistic trend.In addition, the insect system described here, provides a simple, inexpensive, and effective method for screening antibiotics.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biological Sciences, Box 4120, Illinois State University, Normal, Illinois, 61790, USA. jshajah@ilstu.edu

ABSTRACT

Background: The Apicomplexa are a diverse group of obligate protozoan parasites infesting a wide range of invertebrate and vertebrate hosts including humans. These parasites are notoriously difficult to control and many species continue to evolve resistance to commercial antibiotics. In this study, we sought to find an effective chemotherapeutic treatment against arthropod gregarines (Apicomplexa), and to identify candidate compounds for testing against other groups of protozoan parasites.

Methods: We tested eleven commercial antibiotics against a gregarine parasite of Romalea microptera grasshoppers. Infected insects were fed daily, lettuce containing known amounts of specific antibiotics. On Days 15 or 20, we measured the number of gregarines remaining in the digestive tract of each grasshopper.

Results: Treatment with metronidazole and griseofulvin in host insects significantly reduced gregarine counts, whereas, gregarine counts of insects fed, albendazole, ampicillin, chloramphenicol, fumagillin, quinine, streptomycin, sulfadimethoxine, thiabendazole or tetracycline, were not significantly different from the controls. However, albendazole produced a strong, but non-significant reduction in gregarine count, and streptomycin exhibited a non-significant antagonistic trend.

Conclusion: Our results confirm that gregarine infections are difficult to control and suggest the possibility that streptomycin might aggravate gregarine infection. In addition, the insect system described here, provides a simple, inexpensive, and effective method for screening antibiotics.

Show MeSH

Related in: MedlinePlus

Life stages of Gregarina sp. infecting Romalea microptera grasshoppers. A. Fresh smear of trophozoite with epimerite; B. Gamonts on conjugation-stained with Heidenhain's iron haemotoxylin ; C. Gametocyst on sporulation (vertical arrow – unsporulated gametocyst, right arrow – coiled spores, inner picture – gametocyst showing sporoducts); D. Fresh spores
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC2214726&req=5

Figure 1: Life stages of Gregarina sp. infecting Romalea microptera grasshoppers. A. Fresh smear of trophozoite with epimerite; B. Gamonts on conjugation-stained with Heidenhain's iron haemotoxylin ; C. Gametocyst on sporulation (vertical arrow – unsporulated gametocyst, right arrow – coiled spores, inner picture – gametocyst showing sporoducts); D. Fresh spores

Mentions: We used an unknown species of Gregarina. Placement into this genus was based on trophozoite with papillae shaped epimerite, early association, and gametocysts dehiscing through multiple sporoduct (Fig. 1A-D) [1,11] (Johny and Whitman, unpubl.). The natural occurrence and host range of this specific parasite is unknown. Indeed, probably more than 95% of the world's gregarine fauna awaits identification [11]. Gregarine gametocysts were collected from the faeces of captive male and female grasshoppers, washed with sterile distilled water 3–5 times, and incubated in air at 30°C under 90% RH [44], until dehiscence occurred. The resulting oocyst coils were disrupted by centrifugation in sterile distilled water at 1000 rpm for 5 minutes, resuspended, and then fed to grasshoppers. The oocyst concentration was determined using a haemocytometer, as per Undeen and Vavra [45].


Efficacy of eleven antimicrobials against a gregarine parasite (Apicomplexa: Protozoa).

Johny S, Merisko A, Whitman DW - Ann. Clin. Microbiol. Antimicrob. (2007)

Life stages of Gregarina sp. infecting Romalea microptera grasshoppers. A. Fresh smear of trophozoite with epimerite; B. Gamonts on conjugation-stained with Heidenhain's iron haemotoxylin ; C. Gametocyst on sporulation (vertical arrow – unsporulated gametocyst, right arrow – coiled spores, inner picture – gametocyst showing sporoducts); D. Fresh spores
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2214726&req=5

Figure 1: Life stages of Gregarina sp. infecting Romalea microptera grasshoppers. A. Fresh smear of trophozoite with epimerite; B. Gamonts on conjugation-stained with Heidenhain's iron haemotoxylin ; C. Gametocyst on sporulation (vertical arrow – unsporulated gametocyst, right arrow – coiled spores, inner picture – gametocyst showing sporoducts); D. Fresh spores
Mentions: We used an unknown species of Gregarina. Placement into this genus was based on trophozoite with papillae shaped epimerite, early association, and gametocysts dehiscing through multiple sporoduct (Fig. 1A-D) [1,11] (Johny and Whitman, unpubl.). The natural occurrence and host range of this specific parasite is unknown. Indeed, probably more than 95% of the world's gregarine fauna awaits identification [11]. Gregarine gametocysts were collected from the faeces of captive male and female grasshoppers, washed with sterile distilled water 3–5 times, and incubated in air at 30°C under 90% RH [44], until dehiscence occurred. The resulting oocyst coils were disrupted by centrifugation in sterile distilled water at 1000 rpm for 5 minutes, resuspended, and then fed to grasshoppers. The oocyst concentration was determined using a haemocytometer, as per Undeen and Vavra [45].

Bottom Line: Treatment with metronidazole and griseofulvin in host insects significantly reduced gregarine counts, whereas, gregarine counts of insects fed, albendazole, ampicillin, chloramphenicol, fumagillin, quinine, streptomycin, sulfadimethoxine, thiabendazole or tetracycline, were not significantly different from the controls.However, albendazole produced a strong, but non-significant reduction in gregarine count, and streptomycin exhibited a non-significant antagonistic trend.In addition, the insect system described here, provides a simple, inexpensive, and effective method for screening antibiotics.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biological Sciences, Box 4120, Illinois State University, Normal, Illinois, 61790, USA. jshajah@ilstu.edu

ABSTRACT

Background: The Apicomplexa are a diverse group of obligate protozoan parasites infesting a wide range of invertebrate and vertebrate hosts including humans. These parasites are notoriously difficult to control and many species continue to evolve resistance to commercial antibiotics. In this study, we sought to find an effective chemotherapeutic treatment against arthropod gregarines (Apicomplexa), and to identify candidate compounds for testing against other groups of protozoan parasites.

Methods: We tested eleven commercial antibiotics against a gregarine parasite of Romalea microptera grasshoppers. Infected insects were fed daily, lettuce containing known amounts of specific antibiotics. On Days 15 or 20, we measured the number of gregarines remaining in the digestive tract of each grasshopper.

Results: Treatment with metronidazole and griseofulvin in host insects significantly reduced gregarine counts, whereas, gregarine counts of insects fed, albendazole, ampicillin, chloramphenicol, fumagillin, quinine, streptomycin, sulfadimethoxine, thiabendazole or tetracycline, were not significantly different from the controls. However, albendazole produced a strong, but non-significant reduction in gregarine count, and streptomycin exhibited a non-significant antagonistic trend.

Conclusion: Our results confirm that gregarine infections are difficult to control and suggest the possibility that streptomycin might aggravate gregarine infection. In addition, the insect system described here, provides a simple, inexpensive, and effective method for screening antibiotics.

Show MeSH
Related in: MedlinePlus