When Was the First Antibiotic-Resistant Bacterium Found?

Antibiotic resistance appeared almost immediately after antibiotics were introduced. In 1940, even before penicillin was used clinically, Abraham and Chain identified a penicillinase enzyme in E. coli that could destroy penicillin. By 1942, penicillin-resistant Staphylococcus aureus strains appeared in hospital patients. By the 1950s, hospital staphylococcal infections were widely penicillin-resistant. Each new antibiotic has followed a similar pattern: tetracycline resistance appeared within 6 years of its introduction, methicillin-resistant S. aureus (MRSA) emerged just 2 years after methicillin was introduced in 1960, and vancomycin resistance was detected 14 years after its use began. The fundamental problem is evolutionary: antibiotics create immense selective pressure, and bacteria reproduce rapidly (some every 20 minutes), allowing resistant mutants to quickly dominate. Horizontal gene transfer (plasmids, transposons) enables resistance genes to spread between unrelated species. Today, pan-resistant "superbugs" resistant to all available antibiotics are emerging with increasing frequency.