What are the two most common antibiotic-resistant bacteria?

The two most common antibiotic-resistant bacteria globally in terms of infections and healthcare burden are methicillin-resistant Staphylococcus aureus, MRSA, and drug-resistant Escherichia coli, particularly extended-spectrum beta-lactamase producing E. coli. MRSA is Staphylococcus aureus that has become resistant to methicillin and many penicillin-type antibiotics, it commonly causes skin and soft tissue infections, wound infections, pneumonia, and bloodstream infections, especially in hospitals but also in community settings, and is very common, with millions of carriers worldwide. Drug-resistant E. coli, especially ESBL-producing and fluoroquinolone-resistant strains, is extremely common because E. coli is the leading cause of urinary tract infections, which affect millions yearly, and resistance makes UTIs harder to treat and prone to recurrence and kidney infection. According to CDC and WHO surveillance, other highly common resistant bacteria include drug-resistant Streptococcus pneumoniae causing pneumonia, and resistant Klebsiella pneumoniae. MRSA and resistant E. coli together account for a large proportion of antibiotic-resistant infections in hospitals and clinics, leading to longer stays, higher costs, and need for stronger antibiotics like vancomycin for MRSA and carbapenems for ESBL E. coli. Prevention includes proper antibiotic use, completing prescribed courses, handwashing, and good ventilation with HEPA filtration to reduce airborne transmission of resistant organisms.