Acute Bacterial Arthritis and Waiting for Culture Results
Two hundred thirty-one patients were admitted for joint complaints and had a synovial fluid culture from December 10, 2010, to September 18, 2013. Of these, 94 patients met the inclusion criteria (Table 1). The subjects ranged in age from 26 to 93 years; 54% of them were male. Approximately three-fourths of subjects had at least 1 risk factor for septic arthritis. The most commonly affected joint was the knee (62 cases), followed by the wrist (10 cases). The other affected joints, in decreasing frequency, were hip, ankle, elbow, shoulder, and first metacarpophalangeal.
The overall positivity rate was 22.3% (21/94) (Table 2). Interestingly, none of the patients in the low-risk group had a positive synovial fluid culture after 5 days of incubation. On the other hand, 28.7% (21/73) of the high-risk patients showed growth with a mean time to positivity of 36.65 ± 27.13 hours. The earliest growth was noted after 3 hours of incubation. While half of the positive synovial culture results were detected within a day of incubation, growth was observed at up to 90 hours of incubation.
The most common organism was methicillin-resistant Staphylococcus aureus followed by methicillin-sensitive S. aureus (MSSA). There were 2 isolates of coagulase-negative Staphylococcus. Almost all methicillin-resistant S. aureus isolates showed growth by 24 hours, with the remaining one turning positive at 44.6 hours of incubation.
The 5 synovial fluid cultures that turned positive between 48 and 90 hours grew MSSA, Enterococcus faecalis, and coagulase-negative Staphylococcus (Table 3).
Results
Two hundred thirty-one patients were admitted for joint complaints and had a synovial fluid culture from December 10, 2010, to September 18, 2013. Of these, 94 patients met the inclusion criteria (Table 1). The subjects ranged in age from 26 to 93 years; 54% of them were male. Approximately three-fourths of subjects had at least 1 risk factor for septic arthritis. The most commonly affected joint was the knee (62 cases), followed by the wrist (10 cases). The other affected joints, in decreasing frequency, were hip, ankle, elbow, shoulder, and first metacarpophalangeal.
The overall positivity rate was 22.3% (21/94) (Table 2). Interestingly, none of the patients in the low-risk group had a positive synovial fluid culture after 5 days of incubation. On the other hand, 28.7% (21/73) of the high-risk patients showed growth with a mean time to positivity of 36.65 ± 27.13 hours. The earliest growth was noted after 3 hours of incubation. While half of the positive synovial culture results were detected within a day of incubation, growth was observed at up to 90 hours of incubation.
The most common organism was methicillin-resistant Staphylococcus aureus followed by methicillin-sensitive S. aureus (MSSA). There were 2 isolates of coagulase-negative Staphylococcus. Almost all methicillin-resistant S. aureus isolates showed growth by 24 hours, with the remaining one turning positive at 44.6 hours of incubation.
The 5 synovial fluid cultures that turned positive between 48 and 90 hours grew MSSA, Enterococcus faecalis, and coagulase-negative Staphylococcus (Table 3).