The Limitations of Gram-stain Microscopy of Synovial Fluid in Concomitant Septic and Crystal Arthritis

Abstract

The incidence of concurrent septic and crystal arthritis may be higher than previously thought. Synovial fluid samples in concomitant septic and crystal arthritis are significantly less likely to have a positive Gram-stain at microscopy than in cases of an isolated septic arthritis. We would advise the clinician to maintain a high index of suspicion for septic arthritis in these patients.

Neutrophils: Beneficial and Harmful Cells in Septic Arthritis

“…The CpG DNA can bind to Toll-like receptor 9 (TLR9) in immune cells, leading to the production of cytokines such as IL-1β, TNF, IL-6 and IL-12 [ 62 , 63 ]. Some studies showed that intra-articular injection of S. aureus CpG DNA can induce arthritis in mice [ 64 , 65 ].…”

“…Antibiotic therapy is started ideally after synovial fluid samples have been obtained [ 64 ]. Gram stains of synovial fluid are helpful when positive, but they are not always sensitive enough for the diagnosis of septic arthritis [ 65 ]. Patients should be treated empirically for septic arthritis when synovial fluid leukocyte counts exceed 50,000 cells/mm 3 , although gout and pseudogout also commonly present with leukocyte counts of this magnitude [ 66 ].…”

Performances du ratio lactate/glucose synovial pour le diagnostic d’arthrite septique

“…Si elle reste une étape essentielle pour l'identification du pathogène, la mise en culture du liquide synovial est une démarche longue qui retarde l'instauration d'une antibiothérapie ciblée (10). La coloration de Gram est une méthode rapide mais qui présente une sensibilité limitée pour détecter l'infection bactérienne, à savoir d'environ 45 à 50 % (4,(11)(12)(13). La culture du liquide synovial peut être négative dans 20 % des cas et nécessite un délai pouvant aller jusqu'à 72 heures.…”

Performance of a new rapid diagnostic test the lactate/glucose ratio of synovial fluid for the diagnosis of septic arthritis

“…Even though they are the essential means to identify a pathogen, synovial fluid cultures are time-consuming and consequently targeted antibiotic treatment are delayed(10). Gram staining is a fast, but not very efficient method with only 45 to 50% of sensitivity to detect bacterial infection (4,(11)(12)(13). The synovial fluid culture can be negative in 20% of cases, and can take up to 72 hours.…”