In Vitro Efficacy of Six Alternative Antibiotics against Multidrug Resistant Escherichia Coli and Klebsiella Pneumoniae from Urinary Tract Infections

<p><b>INTRODUCTION</b>Increasing resistance in Escherichia coli and Klebsiella pneumoniae to firstline antibiotics makes therapeutic options for urinary tract infections (UTIs) challenging. This study investigated the in vitro efficacies of 6 antibiotics against multidrug resistant (MDR) uropathogens.</p><p><b>MATERIALS AND METHODS</b>Minimum inhibitory concentrations to ceftibuten, cefpodoxime, fosfomycin, mecillinam, temocillin, and trimethoprim were determined against 155 MDR-isolates of E. coli and K. pneumoniae. The presence of extended-spectrum beta-lactamases (ESBL) and plasmid-borne AmpC enzymes was determined by phenotypic testing with genotyping performed by multiplex polymerase chain reaction.</p><p><b>RESULTS</b>Temocillin demonstrated highest susceptibility rates for both E. coli (95%) and K. pneumoniae (95%) when breakpoints for uncomplicated UTIs were applied; however, temocillin susceptibility was substantially lower when "systemic infection" breakpoints were used. Fosfomycin demonstrated the best in vitro efficacy of the orally available agents, with 78% and 69% of E. coli and K. pneumoniae isolates susceptible, respectively. The next most effective antibiotics were ceftibuten (45%) and mecillinam (32%). ESBL and ampC genes were present in 47 (30%) and 59 (38%) isolates.</p><p><b>CONCLUSION</b>This study demonstrated few oral therapeutic options for MDR-uropathogens, with fosfomycin demonstrating the best in vitro activity.</p>

In vitro Activities of Mecillinam Against Clinical Isolates of Enterobacteriaceae / 감염과화학요법

BACKGROUND: Mecillinam, an amidinopenicillin antibiotic, has been used to treat urinary tract infections and bacterial enteritis in many countries. In this study, we evaluated in vitro activity of mecillinam against Enterobacteriaceae isolates from urine, and Salmonella and Shigella isolates from patients with bacterial gastroenteritis. MATERIALS AND METHODS: A total of 308 clinical strains were collected and were comprised of Escherichia coli (n=109), Klebsiella pneumoniae (n=52), Enterobacter spp. (n=30), Serratia marcescens (n=30) and Proteus spp. (n=29) isolated from a university hospital in Korea in 2007, and of Salmonella spp. (n=28) and Shigella spp. (n=30) isolated from Korean diarrheal patients from 2001 to 2006. Antimicrobial susceptibility was tested by Clinical Laboratory Standard Institute (CLSI) agar dilution method. CLSI breakpoint of mecillinam for E. coli urinary tract isolates was applied to all other isolates. RESULTS: In E. coli, rate of susceptibility to ampicillin was 30%, but 99-100% to amikacin and cefotaxime. Most (96%) of E. coli isolates, including extended-spectrum beta-lactamase (ESBL) producers, were susceptible to mecillinam. All ESBL producers, except for one isolate, were inhibited by 128 microg/mL and most of them were resistant to mecillinam. All Salmonella isolates and 27 of 30 Shigella isolates were susceptible to mecillinam. CONCLUSION: Mecillinam was active in vitro against most Enterobacteriaceae, Salmonella, and Shigella isolates except for S. marcescens. Therefore, mecillinam can be a good alternative agent for treating urinary tract infection and bacterial gastroenteritis.

In vitro Activities of Mecillinam Against Clinical Isolates of Enterobacteriaceae / 감염과화학요법

BACKGROUND: Mecillinam, an amidinopenicillin antibiotic, has been used to treat urinary tract infections and bacterial enteritis in many countries. In this study, we evaluated in vitro activity of mecillinam against Enterobacteriaceae isolates from urine, and Salmonella and Shigella isolates from patients with bacterial gastroenteritis. MATERIALS AND METHODS: A total of 308 clinical strains were collected and were comprised of Escherichia coli (n=109), Klebsiella pneumoniae (n=52), Enterobacter spp. (n=30), Serratia marcescens (n=30) and Proteus spp. (n=29) isolated from a university hospital in Korea in 2007, and of Salmonella spp. (n=28) and Shigella spp. (n=30) isolated from Korean diarrheal patients from 2001 to 2006. Antimicrobial susceptibility was tested by Clinical Laboratory Standard Institute (CLSI) agar dilution method. CLSI breakpoint of mecillinam for E. coli urinary tract isolates was applied to all other isolates. RESULTS: In E. coli, rate of susceptibility to ampicillin was 30%, but 99-100% to amikacin and cefotaxime. Most (96%) of E. coli isolates, including extended-spectrum beta-lactamase (ESBL) producers, were susceptible to mecillinam. All ESBL producers, except for one isolate, were inhibited by 128 microg/mL and most of them were resistant to mecillinam. All Salmonella isolates and 27 of 30 Shigella isolates were susceptible to mecillinam. CONCLUSION: Mecillinam was active in vitro against most Enterobacteriaceae, Salmonella, and Shigella isolates except for S. marcescens. Therefore, mecillinam can be a good alternative agent for treating urinary tract infection and bacterial gastroenteritis.

Antibióticos I: betalactámicos: penicilinas o penames / Antibiotics I: betalactamics: penicillins or penames

Entre los 53 años transcurridos desde la introducción de la penicilina al campo de la terapéutica, se ha modificado substancialmente la patología infecciosa; han aparecido cepas microbianas resistentes a algunos antibióticos y se han descubierto nuevos antimicrobianos de espectros más amplios; de efectos más potentes y de mejor tolerancia. Uno de los grupo de antibióticos de mayor utilidad es el de las penicilinas o penames que tienen todas un núcleo 6 aminopenicilánico común y que forman parte de los betalactámicos. En esta revisión se presentan esquemáticamente los espectros de acción, las principales indicaciones clínicas y las dosis habituales de los diversos tipos de penicilinas disponibles

In vitro sensitivity of organisms causing urinary tract infections to four common oral antibiotics and to pivmecillinam

The in-vitro sensitivity to ampicillin, cotrimoxazole, nitrofuratoin, nalidixic acid and mecillinam was determined for 511 organisms isolated from 399 consecutive urine specimens. Urine specimens were divided into those of hospital in-patient origin (group A) and those from comunity patients(group B). Group B organisms were more sensitive than group A organisms. Over 75% of all group B organisms were sensitive to nitrofurantoin, nalidixic acid and mecillinam. Organisms resistant to multiple antibiotics were more frequently isolated from group A catheterized patients and are now less frequently isolated than in 1983. The antibiotic implications of these findings are discussed