Most common cause of non gonococcal arthritis?

ANSWER: (A) S. aureusREF: Harrison's 18th Ed Ch. 334The hematogenous route of infection is the most common route in all age groups, and nearly every bacterial pathogen is capable of causing septic arthritis.In infants, group B streptococci, gram-negative enteric bacilli, and S. aureus are the most common pathogens.Since the advent of the Haemophilus influenzae vaccine, the predominant causes among children < 5 years of age have been S. aureus, Streptococcus pyogenes (group A Streptococcus), and (in some centers) Kingella kingae.Among young adults and adolescents, N. gonorrhoeae is the most commonly implicated organism. S. aureus accounts for most nongonococcal isolates in adults of all ages; gramnegative bacilli, pneumococci, and B-hemolyticstreptococci'particularly groups A and B but also groups C, G, and F are involved in up to one-third of cases in older adults, especially those with underlying comorbid illnesses.