Resistance of Escherichia coli to trimethoprim (TMP)-sulfamethoxazole remains at 3%-8% at many medical centers within the United States. In this study a 44% resistance rate was observed among E. coli isolated at a pediatric hospital in Santiago, Chile, and a 40% resistance rate at a general teaching hospital in Bangkok, Thailand. Most isolates were from urinary tract infections and showed high-level resistance (minimal inhibitory concentration of TMP greater than 1,000 micrograms/ml). Nineteen of 35 isolates tested transferred resistance to TMP; most cotransferred resistance to streptomycin and sulfonamides. Dihydrofolate reductase type I was detected by gene probing in 14 of 35 strains. Subsequent investigations in Brazil, Honduras, and Costa Rica revealed that this high rate of resistance was not an isolated phenomenon.

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We have examined the resistance of Pseudomonas pseudomallei biofilm cells to ceftazidime and cotrimoxazole. A large number of these biofilm cells remained viable at 12 and at 24 h, except in the biofilm treated with 200 times the MIC of ceftazidime. The inherent resistance of P. pseudomallei biofilms to conventional antibiotics may explain the lack of success in the treatment of the chronic manifestations of this bacterial infection.

The study included 172 patients, aged 0-15 years, for whom at least 1 nonfecal, nonurinary specimen was culture-positive for nontyphoidal Salmonella. Ninety-five percent had positive blood cultures. Immunocompromising diseases were found in 19% of 74 infants and 77% of 98 children. Associations between the study factors and outcomes, as localized infection or death, were assessed by logistic regression analysis. Thirty-three patients had localized infections. An adjusted risk factor for development of localized infections was an age of <12 months (P=.003). There were 17 deaths. The case-fatality rates were 43% and 10% for immunocompromised and 5% and 0% for nonimmunocompromised infants and children, respectively. Adjusted risk factors for death were age of <12 months (P=.006), inappropriate antimicrobial therapy (P=.014), meningitis or culture-proven pneumonia due to nontyphoidal Salmonella (P=.004), and immunocompromised status (P<.001). The clinical courses and prognoses for infants and children with extraintestinal infection due to nontyphoidal Salmonella can be categorized into 4 groups according to the characteristics of age (infants vs. children) and host status (immunocompromised vs. nonimmunocompromised).