ABSTRACT
Flesh flies (Diptera: Sarcophagidae) are well known cause of myiasis and their gut bacteria have never been studied for antimicrobial activity against bacteria. Antimicrobial studies of Myroides spp. are restricted to nosocomial strains. A Gram-negative bacterium, Myroides sp., was isolated from the gut of adult flesh flies (Sarcophaga sp.) and submitted to evaluation of nutritional parameters using Biolog GN, 16S rRNA gene sequencing, susceptibility to various antimicrobials by disc diffusion method and detection of metallo â-lactamase genes (TUS/MUS). The antagonistic effects were tested on Gram-negative and Gram-positive bacteria isolated from human clinical specimens, environmental samples and insect mid gut. Bacterial species included were Aeromonas hydrophila, A. culicicola, Morganella morganii subsp. sibonii, Ochrobactrum anthropi, Weissella confusa, Escherichia coli, Ochrobactrum sp., Serratia sp., Kestersia sp., Ignatzschineria sp., Bacillus sp. The Myroides sp. strain was resistant to penicillin-G, erythromycin, streptomycin, amikacin, kanamycin, gentamycin, ampicillin, trimethoprim and tobramycin. These strain showed antibacterial action against all bacterial strains except W. confusa, Ignatzschineria sp., A. hydrophila and M. morganii subsp. sibonii. The multidrug resistance of the strain was similar to the resistance of clinical isolates, inhibiting growth of bacteria from clinical, environmental and insect gut samples. The metallo â-lactamase (TUS/MUS) genes were absent, and resistance due to these genes was ruled out, indicating involvement of other secretion machinery.
Moscas varejeiras (Diptera: Sarcophagidae) são causa conhecida de miíase e as bactérias de seus intestinos nunca foram estudadas quanto à atividade antibacteriana. Estudos antimicrobianos de Myroides spp restringem-se à cepas hospitalares. Uma bactéria Gram negativa, Myroides sp, foi isolada do intestino de moscas varejeiras adultas (Sarcophaga sp) e submetida à avaliação de parâmetros nutricionais pelo sistema BIOLOG GN, ao sequenciamento genético 16S rRNA, à sensibilidade a vários antimicrobianos pelo método de difusão de discos e à detecção dos genes de metalo beta lactamases (TUS/MUS). Os efeitos antagonistas foram testados contra bactérias Gram negativas e Gram positivas isoladas de material clínico humano, amostras ambientais e intestino do inseto. As espécies bacterianas incluíram Aeromonas hydrophila, A. culicicola, Morganella morganii subsp sibonii, Ochrobactrum anthropi, Weissella confusa, Escherichia coli, Ochrobactrum sp, Serratia sp, Kestersia sp, Ignatzschineria sp e Bacillus sp. A cepa Myroides sp foi resistente à penicilina G, eritromicina, estreptomicina, amicacina, canamicina, gentamicina, ampicilina, trimetoprim e tobramicina. Esta cepa apresentou atividade antimicrobiana contra todas as cepas exceto W.confusa, Ignatzschineria sp, A. hydrophila e M. morgani subsp sibonii. A resistência múltipla da cepa foi semelhante à de isolados clínicos, inibindo bactérias das amostras clínicas, ambientais e do intestino do inseto. Os genes de metalo beta lactamases (TUS/MUS) estavam ausentes, excluindo-se a resistência mediada por esses genes, o que indica o envolvimento de um mecanismo alternativo de secreção.
Subject(s)
Animals , Gram-Negative Bacteria/genetics , Gram-Negative Bacteria/isolation & purification , Diptera , Drug Resistance, Microbial , In Vitro Techniques , beta-Lactamases/analysis , Diffusion , MethodsABSTRACT
Mosquitoes are vectors for the transmission of many human pathogens that include viruses, nematodes and protozoa. For the understanding of their vectorial capacity, identification of disease carrying and refractory strains is essential. Recently, molecular taxonomic techniques have been utilized for this purpose. Sequence analysis of the mitochondrial 16S rRNA gene has been used for molecular taxonomy in many insects. In this paper, we have analysed a 450 bp hypervariable region of the mitochondrial 16S rRNA gene in three major genera of mosquitoes, Aedes, Anopheles and Culex. The sequence was found to be unusually A+T rich and in substitutions the rate of transversions was higher than the transition rate. A phylogenetic tree was constructed with these sequences. An interesting feature of the sequences was a stretch of Ts that distinguished between Ae-des and Culex on the one hand, and Anopheles on the other. This is the first report of mitochondrial rRNA sequences from these medically important genera of mosquitoes.
Subject(s)
Animals , Base Sequence , Culicidae/genetics , Evolution, Molecular , Molecular Sequence Data , Phylogeny , Polymerase Chain Reaction , Polymorphism, Genetic , Polymorphism, Restriction Fragment Length , RNA/genetics , RNA, Ribosomal, 16S/genetics , Sequence Analysis, DNA , Species SpecificityABSTRACT
A mechanism suggested to cause injury to the preserved organs in vitro is the generation of oxygen free radicals either during preservation or after transplantation due to reperfusion. Methods to suppress generation of oxygen free radicals may lead to improved methods of organ preservation. In this study, increase in the levels of lipid peroxidation in chick cornea after cryopreservation is reported. Addition of fetal bovine serum (FBS) in cryopreservation medium was found to prevent lipid peroxidation. Addition of FBS was also found to be protective towards corneal viability during cryopreservation.