July 10, 2019
2 min read

Rapid musculoskeletal diagnostic panel could improve care of children

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Findings from a retrospective analysis suggested that the use of a rapid musculoskeletal diagnostic panel, or MDP, could have shortened the time it took to identify the cause of infection, provide appropriate antibiotics and reduce the length of stay for children.

“No approved rapid diagnostic platforms currently exist for bone and joint specimens from pediatric patients with acute musculoskeletal infection,” Justin B. Searns, MD, a hospitalist in the division of hospital medicine and pediatric infectious diseases at Children’s Hospital Colorado, and colleagues wrote.

The MDP, which was recently validated in another study, combined three separate tests — the Xpert MRSA/Staphylococcus aureus skin and soft tissue infection (SA SSTI) assay; PCR assays for ermA, ermB and ermC genes to determine clindamycin resistance; and a Kingella kingae PCR assay to identify the rtxA gene. Results from the Xpert MRSA/SA SSTI assay were available within 3 hours, and results for the PCR assays were available by 2 p.m. the following calendar day.

The study included 53 children aged 6 months to 18 years who were admitted to the hospital with symptoms persisting for less than 2 weeks, had bone or joint specimens collected and were administered antibiotic therapy, excluding perioperative antibiotics.

Pathogens were identified in 69.8% of patients (n = 37) who underwent standard culturing techniques and in 13 patients (16%) who received a blood culture. The most commonly identified pathogen was S. aureus (n = 25; 47.2%), and MRSA was identified in 16% of these patients (n = 4). Two patients had clindamycin-resistant S. aureus, and one patient had K. kingae infection.

The MDP identified most children with culture-confirmed S. aureus infection (n = 22; 88%), with three patients having MRSA. When cultured, all three patients were confirmed to have MRSA. Although the MDP identified three isolates as clindamycin resistant, culture showed that one of these isolates was clindamycin susceptible.

According to the researchers, no patients with S. aureus would have been identified with the MDP alone, and only one patient would have had a pathogen found on MDP that would have been missed by standard bacterial culture.

Results showed that MDP would have saved 7 hours to pathogen identification (45.6 hours; interquartile range [IQR] = 23-62) compared with standard microbiology culture techniques (52.5 hours; IQR = 36.1-65.6; P< .001). Additionally, use of the MDP would have improved the time to definitive antibiotic therapy by nearly 22 hours (P < .001) and reduced the hospital length of stay by a median of 26.4 hours (P < .001).

The researchers noted that cost is an important factor when considering a new diagnostic tool like the MDA. Theoretically, the decrease in length of stay would justify its expense, they said.

“Additional prospective studies are needed after effective implementation of the MDP, alongside antimicrobial stewardship partnership, to fully evaluate its effects in a real clinical environment,” Searns and colleagues wrote. – by Katherine Bortz

Disclosures: The authors report no relevant financial disclosures.