Table 2.

Positivity of the periprosthetic tissue culture and sonication fluid culture

Type of sample	Prosthetic joint infection (n = 32)	Mechanical failure (n = 17)	Aseptic loosening (n = 63)
Periprosthetic tissue culture
1 sample positive	2 (6%)*	2 (12%)†	8 (13%)‡
≥ 2 samples positive	24 (75%)	0	0
Sonication culture
< 50 CFU/mL	2 (3%)§	2 (12%)∥	7 (11%)#
≥ 50 CFU/mL	22 (69%)	0	1 (2%)&

* E. coli (n = 1); coagulase-negative staphylococcus (n = 1); ^†coagulase-negative staphylococci (n = 2); ^‡coagulase-negative staphylococci (n = 2), viridans group streptococcus (n = 1) and P. acnes (n = 5); ^§ P. multocida (n = 1), coagulase-negative staphylococcus (n = 1), both patients received antibiotics before surgery; ^∥coagulase-negative staphylococci (n = 2); ^# P. acnes (n = 7), these cases did not correspond with any positive periprosthetic tissue culture; ^& Corynebacterium sp. (n = 1), growth was considered a contamination during sonication procedure.