When Lab Cultures Come Up Empty: The Hidden Burden of Infections That Defy Diagnosis in Artificial Joints

For the millions of people worldwide who live with artificial hips and knees, few complications are as feared as a periprosthetic joint infection. When bacteria colonize the surface of an implant, the consequences can include repeated operations, months of intravenous antibiotics, lasting functional decline, and enormous healthcare costs. Yet a substantial fraction of these infections present clinicians with a maddening paradox: every clinical sign points to infection, but the laboratory cultures that should reveal the culprit organism come back stubbornly, inexplicably negative. A new umbrella review published in the Journal of Bone and Joint Infection has now pulled together the best available review-level evidence on this elusive condition, and its findings reveal a field riddled with uncertainty, where even the most basic question, how often these culture-negative infections occur, remains surprisingly difficult to answer.

The research team, led by Guido Bocchino of the Catholic University of the Sacred Heart in Rome and including internationally recognized infection specialists such as Javad Parvizi, conducted what is known as an umbrella review. Rather than analyzing individual patient studies, this approach synthesizes existing systematic reviews and meta-analyses, offering a bird’s-eye view of where the published evidence converges and where it falls apart. The researchers searched major bibliographic databases in December 2025, following the PRISMA 2020 reporting guidelines, and ultimately included nine reviews: three systematic reviews and six systematic reviews with meta-analyses. To guard against the double-counting that plagues this type of synthesis, they built a citation matrix of all primary studies and calculated a corrected covered area of 9.4 percent, indicating moderate overlap among the reviews, a finding that shaped how cautiously they interpreted the aggregated numbers.

The headline statistic is striking in its variability. Reported prevalence of culture-negative periprosthetic joint infection ranged from 11.0 percent to 63.6 percent across the included reviews, with a mean of 33.6 percent and a median of 32.5 percent. In other words, depending on which review you consult, somewhere between one in nine and nearly two in three prosthetic joint infections fail to yield a positive culture. The authors attribute this wild spread to differences in patient populations, diagnostic definitions, microbiological workflows, and pre-analytical factors, meaning everything that happens to a specimen before it reaches the culture plate. One large quantitative review reported culture-negative proportions of 38.7 percent across 30 studies, while another meta-analysis found just 11 percent, a gap that underscores how much case mix and laboratory protocol can shift the apparent burden of the disease.

Among the factors driving culture negativity, one stood out repeatedly: prior antibiotic exposure. When patients receive antimicrobial therapy before surgical samples are collected, the drugs suppress bacterial growth in culture even though the infection persists. The reviews that quantified this risk factor reported antibiotic pretreatment in the range of 53 to 64 percent of culture-negative cases, lending strong support to a long-standing principle of antimicrobial stewardship: whenever clinically feasible, antibiotics should be withheld until diagnostic specimens have been obtained. The review also found that culture-negative infections were reported more frequently in the knee than in the hip, accounting for 64.1 percent of cases in the subset of data where joint-specific breakdown was available, and that most studies relied on the Musculoskeletal Infection Society criteria to define the condition, with smaller numbers using Infectious Diseases Society of America or International Consensus Meeting definitions, a patchwork that itself contributes to the heterogeneity.

Into this diagnostic vacuum has stepped a new generation of culture-independent molecular tools, and the umbrella review devoted considerable attention to their performance. Five of the nine included reviews evaluated molecular diagnostics, with next-generation sequencing approaches dominating the landscape. Metagenomic next-generation sequencing, which sequences all genetic material in a specimen without targeting specific organisms, appeared in four of the five molecular-enabled reviews, while targeted sequencing, PCR-based assays, and 16S rRNA sequencing each featured in one. Importantly, no single specimen type emerged as sufficient on its own: synovial fluid, periprosthetic tissue, and sonication fluid, the liquid produced by bathing a removed implant in ultrasound to dislodge biofilm bacteria, were all recurrently evaluated, often in combination, reflecting the understanding that molecular yield depends heavily on sampling strategy.

The diagnostic accuracy figures are impressive on paper. Where meta-analytic estimates were available, pooled sensitivity for molecular methods ranged from 0.81 to 0.93, and pooled specificity ranged from 0.92 to 0.97. In a direct platform comparison, metagenomic next-generation sequencing achieved a sensitivity of 89 percent and a specificity of 92 percent, while targeted next-generation sequencing traded a slightly lower sensitivity of 84 percent for a higher specificity of 97 percent. But the review is equally clear about the caveats. Raw pathogen detection rates among culture-negative cases varied enormously, from 9 percent to 100 percent across individual studies, with pooled summaries clustering around 52 to 54 percent. One review reported shotgun metagenomics detecting pathogens in 43.9 percent of cases while citing upper estimates near 82 percent for sequencing and 90 percent for synovial PCR in selected datasets. The overall false-negative proportion across the evidence base was 21.2 percent, meaning roughly one in five infections still slips past even the most advanced molecular assays.

Perhaps the most revealing finding concerns what molecular testing actually finds when cultures fail. In the one review that detailed post-molecular pathogen attribution, a remarkable proportion of culture-negative infections, around 46 percent, turned out to be fungal, predominantly Candida species, and the assays detected fastidious or atypical organisms including mycobacteria, Cutibacterium acnes, Brucella, and Coxiella burnetii. These are organisms that either grow slowly, require special culture conditions, or are suppressed by prior antibiotics, and their detection supports a conclusion that has been gaining traction in the field: culture-negative status usually reflects microbiological blind spots rather than the absence of any pathogen. Many infections that initially fail to grow in culture later become culture-positive on repeat sampling, suggesting that the true culprit was simply missed the first time around.

Treatment of these infections remains an exercise in empiricism. Because no organism is identified, antibiotic selection relies on guesswork rather than culture-guided targeted therapy. The review found that two-stage exchange, in which the infected implant is removed, an antibiotic-loaded spacer is placed, and a new prosthesis is implanted only after a course of antibiotics, was the most frequently described surgical strategy, accounting for 68.0 percent of the 2,336 extractable procedures across three reviews. Debridement with implant retention accounted for 21.7 percent, and one-stage exchange for 10.3 percent. Vancomycin and cephalosporins were the most commonly mentioned agents, typically providing broad Gram-positive coverage with additional Gram-negative activity, and systemic therapy after revision was often reported as approximately six weeks. Yet dosing, duration, and spacer composition were so inconsistently reported that the authors could not determine whether a two-week antibiotic holiday between stages improves outcomes, a question that recent consensus recommendations have addressed by suggesting continuous therapy may be preferable, particularly for immunocompromised patients.

Outcomes add another layer of complexity. The largest extractable dataset reported an overall failure rate of 19.0 percent for culture-negative infections, with a 95 percent confidence interval of 17.1 to 20.9 percent, while another review found pooled infection control of 79.2 percent. Other syntheses reported treatment success ranging from roughly 70 to 100 percent after two-stage exchange, a spread so wide that direct comparison becomes nearly meaningless. The authors attribute this to inconsistent outcome definitions, differing surgical protocols, and follow-up durations that ranged from three months to ten years. Methodological quality, assessed with the AMSTAR 2 instrument, was similarly variable, with confidence limited by incomplete protocol reporting, variable assessment of publication bias, and insufficient discussion of heterogeneity.

The takeaway from this ambitious synthesis is a call for both humility and better science. Molecular diagnostics, especially next-generation sequencing, are genuinely promising adjunctive tools that can unmask pathogens in a meaningful share of culture-negative cases, but they do not eliminate false negatives, cannot replace phenotypic susceptibility testing, and must be interpreted in the context of prior antibiotics, specimen type, contamination risk, and the overall clinical picture. The authors argue that the first priority remains optimizing conventional culture: obtaining multiple tissue specimens and synovial fluid before antibiotics are given, using appropriate transport and media, prolonging incubation to at least fourteen days, and employing sonication or blood culture bottles where available. Until rigorous primary studies with standardized definitions and reporting are conducted, culture-negative periprosthetic joint infection will remain what it has long been: a common, consequential, and stubbornly opaque challenge at the intersection of surgery and microbiology.

Subject of Research: Culture-negative periprosthetic joint infection: prevalence, molecular diagnostics, treatment, and evidence limitations

Article Title: Culture-negative periprosthetic joint infection: an umbrella review of prevalence, diagnostic strategies, treatment, and methodological limitations

Article References: Bocchino, G., Maccauro, G., Zampoli, A., Papalia, R., Indelli, P. F., Pérez-Prieto, D., & Parvizi, J. (2026). Culture-negative periprosthetic joint infection: an umbrella review of prevalence, diagnostic strategies, treatment, and methodological limitations. Journal of Bone and Joint Infection, 11(4), 479-488. https://doi.org/10.5194/jbji-11-479-2026

Image Credits: AI Generated

DOI: 10.5194/jbji-11-479-2026

Keywords: periprosthetic joint infection, culture-negative infection, next-generation sequencing, metagenomics, joint arthroplasty, molecular diagnostics, antibiotic stewardship, two-stage exchange, biofilm, sonication, umbrella review, orthopedic surgery