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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.

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Mean ± SE number of gregarines in the guts of Romalea microptera grasshoppers (combination of animals dissected on Days 16 and 20) after treatment with different antimicrobials. Numbers above bar represents n. *Means significantly different from control group (ANOVA protected Tukey's HSD test, α = 0.05).
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Figure 2: Mean ± SE number of gregarines in the guts of Romalea microptera grasshoppers (combination of animals dissected on Days 16 and 20) after treatment with different antimicrobials. Numbers above bar represents n. *Means significantly different from control group (ANOVA protected Tukey's HSD test, α = 0.05).

Mentions: The mean densities of gregarines (pooled data for Days 15 and 20) for the different treatment groups are presented in Figure 2. Grasshoppers treated with metronidazole (ANOVA followed by Tukey HSD test, P < 0.01) and griseofulvin (ANOVA followed by Tukey HSD test, P < 0.05) exhibited significantly lower gregarine counts than control insects (Fig. 2). No other treatments were significantly different from the control; however, albendazole treatment exhibited a strong, but non-significant trend for reduced gregarine count (P > 0.05; Fig. 2). In contrast, a non-significant antagonistic trend was observed in the streptomycin treatment, which showed higher gregarine counts in comparison to the control (P > 0.05) (Fig. 2). Of the 98 animals dissected in Fig. 2, 1 control, 1 fumagillin-, 2 griseofulvin- and 4 metronidazole-treated animals lacked gregarines in their guts.


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

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

Mean ± SE number of gregarines in the guts of Romalea microptera grasshoppers (combination of animals dissected on Days 16 and 20) after treatment with different antimicrobials. Numbers above bar represents n. *Means significantly different from control group (ANOVA protected Tukey's HSD test, α = 0.05).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 2: Mean ± SE number of gregarines in the guts of Romalea microptera grasshoppers (combination of animals dissected on Days 16 and 20) after treatment with different antimicrobials. Numbers above bar represents n. *Means significantly different from control group (ANOVA protected Tukey's HSD test, α = 0.05).
Mentions: The mean densities of gregarines (pooled data for Days 15 and 20) for the different treatment groups are presented in Figure 2. Grasshoppers treated with metronidazole (ANOVA followed by Tukey HSD test, P < 0.01) and griseofulvin (ANOVA followed by Tukey HSD test, P < 0.05) exhibited significantly lower gregarine counts than control insects (Fig. 2). No other treatments were significantly different from the control; however, albendazole treatment exhibited a strong, but non-significant trend for reduced gregarine count (P > 0.05; Fig. 2). In contrast, a non-significant antagonistic trend was observed in the streptomycin treatment, which showed higher gregarine counts in comparison to the control (P > 0.05) (Fig. 2). Of the 98 animals dissected in Fig. 2, 1 control, 1 fumagillin-, 2 griseofulvin- and 4 metronidazole-treated animals lacked gregarines in their guts.

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