Antimicrobial susceptibility of Campylobacter jejuni subsp. jejuni assessed by E-test and double dilution agar method in Southern Chile

Abstract

Campylobacter jejuni subsp. jejuni is one of the most frequent causes of infectious diarrhea in both, developed and developing countries (Fernández 1992, Allos & Blaser 1995. Although C. jejuni subsp. jejuni diarrhea is a self-limited disease, in some clinical instances it is necessary the prescription of antibiotics, being erythromycin the drug of choice (Allos & Blaser 1995). For several years however, higher levels of resistance to this drug, as well as to others, such as tetracycline and fluoroquinolones, have been reported in several countries (Taylor & Courvalin 1988).The information on bacteriological, biological, pathogenical, clinical and epidemiological aspects of C. jejuni subsp. jejuni generated in South America is vast and valuable (Fernández 1992). However, the susceptibility patterns of this bacterium have not been well defined in this geographical region.The aim of this study was to determine the susceptibility patterns of C. jejuni subsp. jejuni clinical strains, to six antimicrobial agents, in Southern Chile by using two quantitative methods.A total of 108 C. jejuni subsp. jejuni strains submitted in this study, had been isolated and identified from pediatric diarrheic stools specimens using standard procedures between March 1996 and December 1997. Strains were stored at -35ºC in freezing medium until analyzed. Staphylococcus aureus ATCC 25923 and Escherichia coli and E. coli ATCC 25922 were used as control strains.The antimicrobial susceptibility patterns of the strains under study were determined by means of the E-test and the double dilution agar method (Baker et al. 1991).To perform the E-test, several colonies of each strain, obtained from a fresh culture in blood agar plate, were suspended in 5 ml of Mueller-Hinton broth to achieve a turbidity equal to the 0.5 Mac Farland standard. The suspensions were inoculated with sterile swabs onto 150 mm diameter MuellerHinton 5% sheep blood agar plates and after the agar surfaces were allowed to dry, six E-test strips were applied on each plate. Plates were incubated at 37ºC for 48 h under microaerobic conditions and inhibitory concentrations were read at the point where the elliptical zone of inhibition intersected the E-test strip.For the agar dilution method, Mueller-Hinton agar plates containing serial twofold dilutions of each antimicrobial agent from 0.125 to 128 µg/ ml were prepared. Inocula of the strains were prepared diluting 1:10 each bacterial suspension made in Mueller-Hinton broth with a turbidity equal to the 0.5 Mac Farland standard. Plates were inoculated with a multipoint replicator delivering spots of 4This work received financial support from grants S-97-21 DID-UACH and FONDECYT 1980920. + Corresponding

Tetracycline Resistance of Chilean Campylobacter Jejuni Strain Bank from Humans, Cattle and Chickens

“…In the South of Chile, low percentages (2 %) of tetracycline resistance in C. jejuni isolated from hens and human has been described [11,12]. In contrast, in the present study in Metropolitan region, 45 (29 %) out of 153 strains tested were resistant to this antibiotic.…”

Resistance to erythromycin of Campylobacter jejuni and Campylobacter coli isolated from animals and humans

“…High percentage (24.1%) of thermophilic Campylobacter strains resistant to erythromycin isolated from humans in developed countries is a surprising fact, having in mind a strict control of antibiotic use in human and veterinary medicine in these countries. In some countries, for example Chile and Egypt, have not documented the resistance to erythromycin in strains isolated from humans (Fernández et al, 2000;Putnam et al, 2003). Lower level of resistance to erythromycin, ranging from 3.4 to 9.1% was reported by authors from Australia, India, USA, Brasil and Belgium (Alfredson et al, 2003;Aquino et al, 2002;Gupta et al, 2004;Jain et al, 2005;Vlieghe et al, 2008).…”

Susceptibilidad antimicrobiana de Campylobacter jejuni aislado de coprocultivos en Santiago de Chile

“…Los datos obtenidos en este estudio demuestran que nuestro país no es ajeno a esa realidad, ya que 32,4% de las cepas aisladas en nuestro laboratorio fueron resistentes a ciprofloxacina. Esta cifra representa un cambio en el patrón de resistencia si consideramos que, en aislados realizados entre los años 1996 y 1997 en el sur de Chile, Fernández y cols, reportaron 100% de susceptibilidad a ciprofloxacina 18 , aunque la presencia de este tipo de resistencia ya había sido detectada en 1996 27 . Las quinolonas tienen dos sitios blanco en las bacterias gramnegativas: un sitio principal (ADN girasa o topoisomerasa II) y un sitio secundario (topoisomerasa IV).…”