Antimicrobial multiresistance of Shigella sp strains in a semi rural community of north Santiago

Appropriate antimicrobial therapy shortens the duration of Shigellosis and significantly reduces the risk of transmission. Shigella strains resistant to common antimicrobials have increased during the past years, determining the need for a periodic surveillance, to guide effective therapy. Aim: To r eport the results of a surveillance program in a rural community near Santi ago (Colina), for Shigella infections. Material and methods: Between 1995 a nd 1997, stool samples from 3,534 episodes of diarrhoea, that occurred in C olina, were obtained. Two hundred twenty six Shigella strains were isolated and studied for susceptibility to amplicin (AM), amoxicililin/clavulanic a cid (AMC), cotrimoxazole (STX), chloramphenicol (CAF), tetracycline (TET), furazolidine (FU), ciprofloxacine (CIPR), nalidixic acid (AC NAL), gentamyc in (GENT) and cefotaxime (CFTX). Results: Shigella flexnerii represented 13 4 of 226 Shigella strains isolated. All strains were susceptible to CIPR, A C NAL, GENT and CFTX. Yearly variation of resistant patterns to other antim icrobials were observed for these strains. Resistance to AM varied from 56 to 76% to AMC from 25 to 56%, to STX from 21 to 47% to CAF from 36 to 69%, to TET from 44 to 78% and to FU from 9 to 18%. Overall resistance was highe r during 1997. All 85 strains of S sonnei were susceptible to CIPR, AC NAL and CFTX. Resistance throughout the years varied from 56 to 88% for AM, fro m 0 to 28% for AMC, from 44 to 53% for STX, from 11 to 40% for CAF, from 11 to 42% for TET and from 5 to 11 % for FU. Overall resistance was also high er during 1997, except for AM and STX. Seven S hoydii strains were isolated , only during 1995. All seven were resistance to AM and TET and none were r esistance to FU. CIPR. AC NAL and CFTX. Two strains was resistance to AMC. STX and CAF. Conclusions: Antimicrobial resistance patterns of Shigella sp isolated in Colina have increased from 1995 to 1997, specially for commonly used antimicrobials. Resistance remains low for furazolidine and all strai ns remain susceptible to quinolones.