ABSTRACT
Crematogaster ants use their contact venoms to compete with other ants. Although those venoms are used primarily as repellent and toxic secretions, they may have other functions. The present study aimed to test the antibacterial property of abdominal venom of three neotropical Crematogaster ant species (C. distans, C. pygmaea and C. rochai) against gram-negative (Escherichia coli and Pseudomonas aeruginosa) and gram-positive (Enterococcus faecalis and Staphylococcus aureus) bacteria. Sterile filter paper was soaked with C. distans, C. pygmaea or C. rochai crude venom and placed on an agar dish that was inoculated with bacterial suspensions. The agar dish was incubated overnight at 37ºC and examined for zones of growth inhibition. For each tested venom and bacterial strain, three venom concentrations were used, with six replicates for each concentration: 1, 2 and 4 DGE (Dufour's gland equivalent). The venom of C. pygmaea, but not those of C. rochai and C. distans, inhibited the growth of all tested gram-positive and gram-negative bacterial strains. This is the first evidence of antibacterial properties of contact venoms in Crematogaster ants and it supports the claim that ant venoms are multifunctional. It is hypothesized that only C. pygmaea venom showed antibacterial activities due to its nesting habits.
ABSTRACT
Crematogaster ants use their contact venoms to compete with other ants. Although those venoms are used primarily as repellent and toxic secretions, they may have other functions. The present study aimed to test the antibacterial property of abdominal venom of three neotropical Crematogaster ant species (C. distans, C. pygmaea and C. rochai) against gram-negative (Escherichia coli and Pseudomonas aeruginosa) and gram-positive (Enterococcus faecalis and Staphylococcus aureus) bacteria. Sterile filter paper was soaked with C. distans, C. pygmaea or C. rochai crude venom and placed on an agar dish that was inoculated with bacterial suspensions. The agar dish was incubated overnight at 37ºC and examined for zones of growth inhibition. For each tested venom and bacterial strain, three venom concentrations were used, with six replicates for each concentration: 1, 2 and 4 DGE (Dufour's gland equivalent). The venom of C. pygmaea, but not those of C. rochai and C. distans, inhibited the growth of all tested gram-positive and gram-negative bacterial strains. This is the first evidence of antibacterial properties of contact venoms in Crematogaster ants and it supports the claim that ant venoms are multifunctional. It is hypothesized that only C. pygmaea venom showed antibacterial activities due to its nesting habits.
ABSTRACT
ABSTRACT The aim of this study was to determine the antimicrobial resistance of 43 Escherichia coli strains isolated from the Santo Antonio weir (Fortaleza, CE, Brazil) from January to April 2007. Susceptibility tests performed with 8 antimicrobials indicated that 67.5% of the strains were susceptible to all of them. Resistance to tetracycline (25.6%), sulfazotrim (18.6%), nalidixic acid (9.3%), and ciprofloxacin (4.7%) was observed. The strains did not show resistance to betalactamics. Nine strains (21%) were multiresistant, the resistance being chromosome (78%) and plasmid (56%) mediated. The presence of resistant bacteria may be related to antimicrobials in the sewage discharged into the weir, and the inappropriate use of this body of water may pose human health risks.
RESUMO Este trabalho objetivou caracterizar a resistência antimicrobiana de 43 cepas de Escherichia coli isoladas do açude Santo Anastácio (Fortaleza, CE), durante os meses de janeiro a abril de 2007. As cepas foram submetidas a testes de suscetibilidade a oito antimicrobianos, tendo 67,4% delas apresentado sensibilidade a todos. Observou-se resistência à tetraciclina (25,6%), ao sulfazotrin (18,6%), ao ácido nalidixíco (9,3%) e a ciprofloxacina (4,7%). Nenhuma resistência foi observada aos betalactâmicos. Nove (21%) cepas apresentaram multirresistência, com um percentual de 78% para resistência cromossômica e 56% para resistência plasmidial. A presença de bactérias resistentes pode estar relacionada ao lançamento de antimicrobianos nas águas através de esgotos, sendo que o uso inadequado dessas águas pode comprometer a saúde da população.