Which of the following pairs of bacteria have among the highest reported resistance percentages to principal clinical antibiotics?

• A. Escherichia coli and Klebsiella pneumoniae
• B. Salmonella Typhi and Campylobacter
• C. Pseudomonas and Enterococcus
• D. Staphylococcus and Streptococcus

Answer: (B)

The main idea here is that certain bacteria show very high resistance to the antibiotics doctors rely on, and public-health surveillance often highlights enteric pathogens with particularly large resistance percentages. Salmonella Typhi and Campylobacter are two classic examples that consistently have high proportions of isolates not susceptible to principal clinical antibiotics. Salmonella Typhi has historically acquired multi-drug resistance to first-line drugs (such as ampicillin, chloramphenicol, and trimethoprim-sulfamethoxazole) and, in many regions, resistance to fluoroquinolones as well. Campylobacter frequently exhibits substantial resistance to fluoroquinolones and, in some areas, rising resistance to macrolides. Taken together, these resistance patterns lead to among the highest reported resistance percentages for major therapeutic antibiotics in surveillance data. While other pathogens like E. coli, Klebsiella, Pseudomonas, Enterococcus, Staphylococcus, and Streptococcus have notable resistance issues, the combination of widespread and historically well-documented multi-drug resistance in these two enteric pathogens makes them stand out in terms of the highest reported resistance percentages.