Why PCR Won the 120-Year Adoption Race for Mycoplasma pneumoniae Diagnostics

1. Introduction: A History That Only Makes Sense as a Race

Culture was more accurate than serology, yet serology ruled the clinic for half a century. Antigen assays were faster than culture, yet died within a decade of every launch. PCR outperformed both by 1990, yet took a decade and a half to reach routine use — and in much of the world still has not displaced the antibody tests it rendered obsolete on paper [1,2,3]. The history of Mycoplasma pneumoniae (MP) diagnostics makes no sense as a story of technical merit; this Minireview reads it as a story of adoption. The timing is practical: the 2023–2024 global resurgence filled pediatric wards and laboratories with a pathogen whose diagnostic pipeline — CRISPR point-of-care assays, metagenomic sequencing, syndromic panels, antigen chemiluminescence — is suddenly crowded, and laboratory directors must decide which candidates deserve procurement. Existing reviews catalog what each test does; none explains why the winners won or predicts what wins next. We therefore treat the 120-year archive as a dataset: each technology an observation, each displacement an outcome, scored on the five attributes of innovation diffusion theory against regulatory and deployment records — yielding four empirical laws and five falsifiable forecasts.

MP is among the commonest bacterial causes of community-acquired pneumonia (CAP) in school-age children and young adults — 10–40% of pediatric CAP in epidemic years [1,4]. The 2023–2024 resurgence, documented across three continents [5,6,7,8], showed how dependent management remains on laboratory answers that arrive too late (culture, paired serology) or too ambiguously (single-serum IgM) to guide the decision that matters: macrolide versus β-lactam.

The literature attests the gap: Waites and colleagues' 2017 synthesis remains the authoritative account of MP biology and diagnosis [1]; Gao and Sun's 2024 review, cited more than 100 times within two years of publication, has rapidly become the field's standard reference [2]; the 2024 IDSA/ASM utilization guide codifies which tests add value [3] — catalogs, all three, rather than explanations.

Three commitments organize the paper. First, history as data: §3–§5 follow the three technological paths, each closing with a pattern extraction. Second, pattern into theory: §6 distils four empirical laws, including the severity-gated adoption lag — the roughly decade-long delay between maturity and adoption in diseases perceived as mild — and §7 formalizes Rogers' five attributes [9] into a scoring rubric tested against China's NMPA record. Third, theory into prediction: §8 scores four candidate families and issues falsifiable forecasts with dates, enabling conditions and failure conditions.

The archive runs on two clocks behind a serological pre-history: Landsteiner's cold-agglutinating serum factors (1903) were a phenomenon attached to no disease [10]; Reimann named the syndrome in 1938 [11]; Horstmann and Tatlock connected the two in 1943 [12]; Eaton's filterable agent started the organism clock in 1944 [13]; cell-free cultivation came only in 1962 [14], the modern name in 1963 [15,16]. When we write "120 years of MP diagnostics," we mean twelve decades in which a laboratory signal has been available to chase — first a serological epiphenomenon (1903), then a named syndrome (1938), finally an organism (1944/1962) (Figure 1). Once the organism existed, three paths to detecting it diverged — and never reconverged.

2. Evidence Base and Analytical Framework

2.1. Three Evidence Streams

We triangulated three evidence streams. (i) The scientific record: PubMed/MEDLINE, Web of Science and Google Scholar for English-language literature on MP laboratory diagnosis from 1900 onward, and — because China hosts the largest MP testing market and its largest post-2022 outbreak — CNKI, Wanfang and SinoMed for Chinese-language sources, flagging claims resting on Chinese-language or regulatory rather than peer-reviewed English sources. (ii) The regulatory record: MP-relevant clearances and approvals from the FDA 510(k)/De Novo databases, CE-IVD listings, and China's National Medical Products Administration (NMPA) registry (registration-level detail in Table S1); the regulatory search concluded on 30 September 2026, and all temporal statements are made through September 2026. (iii) The deployment record: provincial procurement notices and routine-use documentation from China — the largest MP testing market — used to date when each technology entered reimbursed routine practice and at which institutional tier.

2.2. The Three-Path Framework

Throughout, we distinguish three paths along which any diagnostic technology must travel before it changes a prescription: the R&D path (first demonstration to technical maturity), the regulatory path (FDA clearance, CE marking, or NMPA registration), and the clinical adoption path (reimbursement, procurement, routine ordering). Technologies can be mature on one path and absent on another — the decade-long gaps this produces are the raw material of our analysis.

2.3. Scoring Discipline

Each technology was scored 1–5 on Rogers' five attributes using explicit anchors (Table S2, §7), against the technology's contemporaneous competitor, not modern standards — ELISA in 1985 is compared with complement fixation in 1985, not with qPCR in 2020. Accuracy evidence is drawn from published comparative evaluations and the 2024 IDSA/ASM utilization guide [3,17,18,19,20,21]; we performed no new accuracy meta-analysis: our unit of analysis is adoption, not accuracy. Box 1 defines the two coined terms used throughout.

> Box 1. Coined terms used in this review

> - Three-path framework — the decomposition of diagnostic diffusion into the R&D path, the regulatory path, and the clinical adoption path; a technology "wins" only when it has travelled all three.

> - Severity-gated adoption lag — the systematic delay (empirically ~5–16 years in MP diagnostics, roughly a decade on average: mean 8.5 years across the eight measurable transitions) between demonstrated maturity and routine clinical adoption, relaxing sharply when the disease is reclassified from mild to severe by clinicians, regulators and payers.

3. Path One: Seeing the Organism

3.1. Culture: Certainty Without Speed

Cell-free cultivation of MP, achieved in 1962 [14], was instantly anointed the reference standard; isolates remain indispensable for susceptibility testing and molecular epidemiology [1]. But MP is fastidious and slow-growing — colonies need one to three weeks — and its sensitivity is mediocre and specimen-dependent [1,2]. A result that arrives three weeks after a prescribing decision is not a result; it is a memorial.

The adoption record is unambiguous: culture never entered routine clinical use in any setting we could document — not "was slow to enter," never entered. It remains confined to reference and research laboratories, and the 2024 IDSA/ASM guide does not recommend it for routine diagnosis [3]. This is the archive's cleanest falsification of the naive theory that diagnostics diffuse on merit: the historical gold standard was analytically supreme and clinically irrelevant, simultaneously.

3.2. Antigen Detection: Speed Without Certainty

The countermove to culture's slowness was direct detection of the organism's components: direct fluorescent antibody (DFA) staining in the early 1970s, antigen-capture enzyme immunoassays (EIA), colloidal-gold lateral-flow tests and, most recently, automated chemiluminescent antigen assays delivering results in 15–60 minutes [1,22]. Yet antigen detection is the archive's graveyard. Every generation — DFA in the 1970s, membrane EIA in the 1980s–90s, lateral flow in the 2000s — launched with encouraging sensitivity (70–90% in favorable evaluations) and then stalled: sensitivity fell in adults, late presenters and post-antibiotic samples, while specificity suffered from cross-reaction and pharyngeal carriage [1,18,23]. Through September 2026 antigen assays hold a handful of approvals — 2 antigen products among 112 MP-related NMPA registrations (November 2023), against 21 nucleic acid and 72 antibody (authors' classification; Table S1) [24] — and occupy a narrow screening niche. Speed without certainty proved nearly as unmarketable as certainty without speed.

Pattern extraction 1: in the MP clinic, time-to-result is the currency, and analytic elegance is exchangeable for it at a punishing rate. The five-attribute scores are in Table 1; what the rest of the archive keeps repeating is that certainty without speed found no buyers — and speed without certainty nearly none.

4. Path Two: Reading the Host

4.1. Four Eras in One Dominance

Unable to see the organism in useful time, clinicians spent most of the 120 years reading the host's response instead; serology's reign divides into four eras (Fig. S1).

Era I — Early serology (1903–1969). Cold agglutinins, linked to primary atypical pneumonia in 1943 [10,12], were the first MP-associated test: inexpensive, bedside-adjacent, positive in only 50–60% of MP pneumonia and falsely positive in EBV and CMV [1]. The complement fixation test (CFT), standardized in the 1950s, improved specificity but required paired sera two to three weeks apart — retrospective confirmation rather than decision support [1,25].

Era II — Immunodetection (1970–1999). Enzyme immunoassays (from ~1980) delivered anti-MP IgM at >99% specificity, batchable on plate readers [1,17,26]; particle agglutination (Serodia Myco II) became the standard across Japan and much of Asia by requiring no instrument [27]; μ-capture IgM (ImmunoCard, FDA-cleared 1994) sharpened acute-phase specificity [19].

Era III — Point-of-care testing (POCT) and chemiluminescence (2000–2019). Colloidal-gold immunochromatography put serology at the point of care — 15–30 minutes, reaching Chinese community health centers by 2023 [24,28] — while automated chemiluminescence (CLIA, from 2014) industrialized the antibody; NMPA registered the first domestic MP-IgM CLIA kit (Autobio) in 2019 [24,29].

Era IV — Precision immunoassay (2020–September 2026). The frontier has folded back toward the organism: chemiluminescent antigen assays aim to combine Era III's automation with a one-to-two-day head start over seroconversion, and completed antigen-CLIA trials (registry-level, Tier-2 evidence) mark the direction [22,24]; the first MP antigen-CLIA registration has now been granted (Autobio, September 2026 [24]). The antibody path is modernizing in parallel rather than retreating: a further NMPA MP-IgM CLIA registration (Kanghua, December 2024; Table S1) extends the chemiluminescent antibody base — serology's installed platform, not an antigen product — into the current decade [24,29].

4.2. Why Serology Won—And Why It Is Losing

Serology's half-century dominance is the central fact any theory of this field must explain: on analytic merit it should never have happened. Single-serum IgM misclassifies both ways — falsely negative early in illness, falsely reassuring against background seroprevalence and prolonged IgM persistence [1,17,19,20,21] — and a 2005 evaluation of twelve commercial assays found every antibody format wanting [19]. And yet serology won, decisively, everywhere.

The diffusion reading dissolves the paradox: serology won because it fitted the clinic — cheap, batchable, familiar, reimbursable, needing no new capital equipment — its victory was compatibility doing the work usually credited to accuracy, defended by forty years of installed workflow, reference ranges and billing codes. Its displacement began where qPCR's turnaround fell below the clinical decision window (§6.1, P3) and where the one-to-two-week seroconversion window became untenable in severe and pediatric disease. In East Asian tertiary centers, where macrolide resistance exceeding 80% made the macrolide-versus-alternative decision genuinely consequential [30], molecular testing displaced serology fastest; in much of the world antibody tests remain the default [2,3]. In the settings reviewed here, the frontrunner changed where the race mattered.

Pattern extraction 2: adoption advantages and biological defects are different kinds of weakness. Serology's remaining advantages are adoption attributes (scores in Table 1); its defects are biological — window period, persistence, background seropositivity — and technologies whose weaknesses are biological can be displaced once a successor clears that hurdle. Antigen detection's weakness (§3.2) is mixed: a biological floor engineering cannot abolish — low analyte loads in adults and late presenters, carriage confounding specificity — wrapped in re-engineerable operational limitations. Era IV's antigen renaissance tests how much of that weakness lies above the floor — which is why it deserves watching.

5. Path Three: Reading the Genome

5.1. The Molecular Path Trades Certainty for Speed, Then Buys Both

PCR entered the MP field in 1989 [31]: analytic sensitivity orders of magnitude beyond culture, results in hours, a direct read on the organism. By 2005 real-time qPCR was the working gold standard — the reference for that year's twelve-assay evaluation [19,32]. The first FDA clearances of MP molecular products arrived only in 2012–2013 — the 20-target FilmArray Respiratory Panel added MP in May 2012; Meridian's illumigene Mycoplasma (LAMP) was cleared in June 2013, its extraction-free Direct version in 2016 — and the first NMPA registrations of domestic MP qPCR kits date to 2015 [24,33]: seven to ten years of regulatory silence after technical maturity. MP PCR existed as laboratory-developed tests (LDTs) from the mid-2000s but became routine reimbursed practice only around 2015 [24,28]: maturity 2005, routine adoption ~2015 — a ten-year lag we explain in §6.

5.2. Consolidation: From Single-Target PCR to Syndromic Panels

After 2015 the molecular path widened: multiplex qPCR folded MP into respiratory panels, and assays adding 23S rRNA macrolide-resistance mutations (A2063G/A2064G), NMPA-registered from 2023, converted diagnosis into an antibiotic-selection test [24,34]. The duplex class added two further NMPA registrations in 2026, including the first lyophilized format [24,28]. Sample-to-answer syndromic systems — BioFire FilmArray (FDA-cleared December 2011; MP target added May 2012), Luminex NxTAG respiratory pathogen panel (RPP) (2015), GenMark ePlex (2017) — moved molecular testing onto the routine bench, though deployment remains confined to tertiary centers [28,33] (Table S1). Droplet digital PCR added absolute quantification (2–3 copies/µL) [35]; metagenomic next-generation sequencing (mNGS) entered Chinese practice around 2020 for severe, undiagnosed pneumonia with a 24–48-hour turnaround [28,36]; in August 2026 NMPA granted the first class-III mNGS licences — the respiratory panel covers MP among the atypical pathogens — and the national medical-insurance authority created a nationally uniform billing item for mNGS/tNGS [24,28]. CRISPR-based detection [37,38,39] — adapted to MP in the early 2020s, validated in 2024 with reported 100% sensitivity and specificity (single-center, small cohort) — now stands where PCR stood in 1995: analytically proven, regulatorily embryonic.

5.3. What PCR Actually Beat

Two interpretive hazards discipline what follows. First, carriage: MP DNA is detectable in the upper respiratory tract of a non-trivial fraction of asymptomatic children, so a positive PCR is evidence of presence, not necessarily causation [40,41]. Second, guideline ambivalence: the 2019 ATS/IDSA adult CAP guideline treats etiologic testing as optional, rather than routinely recommended, for most outpatients [42] — itself a diffusion datum: even the winner has not convinced payers that the race was worth running in mild disease. PCR beat culture and is beating serology — head-to-head studies in acute infection consistently find nucleic acid amplification tests (NAATs) outperforming antibody formats [19,43] — but what it beat them on was time-to-result, workflow fit after automation, and — decisive after 2013 — the ability to answer the resistance question serology cannot even pose [34].

Pattern extraction 3: excellence is not the variable; the gate is. qPCR's five-attribute profile (Table 1) was excellent and essentially static from 2005 onward, so no attribute of the technology explains the lag between maturity (2005) and routine use (~2015). The missing variable is in the disease — or rather, in how mildly it was perceived. MP was "walking pneumonia," and health systems do not buy molecular answers for nuisances. Severity perception is the gate, and its relaxation is independently observable in the post-surge increment: the first MP + 23S resistance-mutation kits (2023), a further MP-IgM CLIA registration (December 2024), national sentinel NAAT surveillance (2024), and community POCT within months [24,28,34,44]. The causal evidence must be read in the increment, not the stock: the 112 NMPA products by November 2023 are a cumulative total, and with one-to-three-year registration cycles most entered the pipeline before the epidemic peaked. §6 names the lag this gate imposes.

Three paths, a dozen technologies, one archive. Read as a chronicle it is a museum; read as data, it is a lawbook.

6. Pattern: Four Laws of Diagnostic Adoption

Table 1 re-encodes §3–§5 in the language of the theory; composite scores are illustrative rankings, not measurements. Four regularities — recurrent across twelve decades, three paradigms and two hemispheres — emerge. We state them as laws because each is falsifiable and, prospectively, exposed to the record it did not fit.

6.1. The Four Laws

P1 — Speed beats precision. Every successful capture of clinical territory traded analytic perfection for time-to-result: serology occupied the niche that culture — analytically supreme, never clinically adopted — could never enter [19]; qPCR displaced serology at the bedside despite the carriage-interpretation handicap [40]; one-hour panels grew faster than superior two-to-four-hour LDTs [33]. We find no counterexample in the MP archive.

P2 — Compatibility decides. Workflow compatibility decided more contests than sensitivity ever did. Serology's five-decade reign was built on it (§4.2), and culture was excluded precisely by its lack of compatibility (§3.1); PCR's inflection coincided with automated closed-tube formats that fit the routine bench, not with any sensitivity gain [32,33]; and China's fastest-growing segment through September 2026 is magnetic-particle CLIA — an analytically unremarkable antibody technology winning by plugging into the installed immunoassay base [24,29].

P3 — The bedside threshold. Displacement clusters at the moment a successor's turnaround falls below the clinical decision window of the host setting — roughly the first antibiotic dose (2–3 hours in hospital, within 30–60 minutes in emergency/outpatient settings). Serology took territory culture could never occupy when single-sample IgM made same-day answers possible; qPCR displaced serology where its 2–3-hour result could redirect the first dose; antigen and CRISPR formats now compete at the sub-hour threshold PCR cannot cross [22,37,38,39]. The threshold is setting-specific, so displacement is always partial and segmented.

P4 — The severity-gated adoption lag. Across all three paths, MP diagnostic adoption runs ~5–16 years behind technological maturity. Conventional PCR took 16 years (1989 to routine reference-standard use ~2005; routine reimbursed practice only around 2015, §5.1); qPCR took 7 years to its first FDA-cleared MP product (2012) and 10 to first NMPA registration (2015); LAMP took 6 (2007–2013); sample-to-answer panels took 9 (2011/2012 to documented Chinese penetration after 2020); CLIA antibody took 5 (~2014–2019); mNGS took 5 (~2015–2020); MP+23S resistance-mutation assays took 10 (~2013–2023) [24,31,33,34,36,45]. The endpoints are not interchangeable: each is the first documented adoption event available for that technology — reference-standard status, first FDA clearance, first NMPA registration, or documented routine penetration — and is defined row by row in Table 1. The mean lag across the eight measurable transitions in Table 1 is 8.5 years (range 5–16). Adoption is gated not by technological readiness but by the perceived severity of the disease — and MP, self-limited, rarely fatal, "walking pneumonia," has historically been gated shut. The gate's existence is proven by what relaxes it: the 2023 resurgence spiked perceived severity and the adoption system responded within the ensuing registration cycles (the increment evidence is laid out in §5, Pattern extraction 3). The lag is the technical face of a broader accounting failure: a disease that does not kill is not counted, surveilled, or diagnosed with urgency [46].

6.2. The Regulatory Landscape: China NMPA in Global Context

China's NMPA registry is the archive's richest regulatory source (Fig. S2; registration-level detail in Table S1). Three features matter. First, the S-curve shape: slow growth for a decade (≈1–2/year, 2005–2014), inflection in 2015–2019, step-up in 2023–2024 — a steep limb that, on the increment evidence of §5 (Pattern extraction 3), was accelerated by the severity shock: P4 relaxing. Second, the class structure: antibody products outnumber NAAT products 72:21 — P2's installed base is visible in the registry itself. Third, the international contrast: the FDA pathway produced platform-defining molecular clearances (FilmArray 2011/2012; illumigene 2013; NxTAG 2015; ePlex 2017) but almost no MP-specific serology innovation after ImmunoCard (1994), while the CE-IVD space long privileged serology [27,33,45,47]; the European Union's In Vitro Diagnostic Regulation (IVDR) transition moves MP assays into higher-risk classes [48]. Regulatory geography is becoming diffusion geography.

Two disclaimers guard this reading. Approval is not performance: a registration certifies analytical validity against registered claims, not comparative clinical accuracy, and the 72:21 ratio reflects market and workflow forces (P2), not superiority — our accuracy judgments rest on the peer-reviewed comparative literature and the IDSA/ASM 2024 recommendations, not registration counts [3,17,19]. Deployment timelines derive from public procurement and routine-use records — heterogeneous Tier-2 evidence [28].

7. Theory: Adoption Kinetics Formalized

7.1. Rogers' Five Attributes, Operationalized for the Diagnostics Laboratory

Rogers showed across thousands of studies that adoption velocity is predicted by five perceived attributes — relative advantage, compatibility, complexity (inverse), trialability, observability [9]. Diagnostics add three twists that Rogers' general framework does not supply, each taught by an episode of §3–§5. First, the adopter is plural — laboratory director, ordering clinician, payer and regulator adopt separately and sequentially, so a technology must win the same race four times on the three paths of §2.2 (antigen detection in the 1980s was validated by laboratories and ignored by clinicians). Second, relative advantage decomposes into analytic and temporal components that trade against each other — P1. Third, adoption can be gated by the perceived severity of the disease, an exogenous variable absent from Rogers' formulation — P4.

We formalize this as a scoring rubric (Table S2). Composite adoption propensity is the compatibility-weighted mean — compatibility weighted double, reflecting P2's dominance in the archive (fitted to Table 1's displacement record and checked in §7.2(iii), not assumed a priori). The rubric converts a technology's profile into an adoption forecast; §8 applies it prospectively. Because the framework's parameters are adoption attributes rather than MP-specific biology, it may transfer to other diagnostic contests in which the disease is common, usually mild, and treated empirically.

7.2. Making the Theory Work: Quantitative Tests Against the Archive

A theory that only redescribes history is decoration; we subjected the framework to three quantitative checks against the regulatory record (technical detail in Supplementary Methods).

(i) Stock versus increment. Modeling the annual NMPA registration increment (2005–September 2026) rather than the 112-product cumulative stock, a single Bass-type diffusion curve [49] fitted to pre-2023 increments underpredicts 2023–2024, whereas a two-regime fit in which the carrying-rate parameter steps upward in 2023 fits the series: the gate behaves as a parameter shock. The case for increments over stocks is given in §5 (Pattern extraction 3). (ii) Displacement intervals decline by era. The mean lag of 8.5 years (§6.1, P4, with the per-technology endpoint definitions given there and in Table 1) falls from ≈16 years for the PCR generation to ≈6–10 for qPCR, LAMP and panels and ≈5 for CLIA and mNGS: diffusion accelerates as each technology inherits predecessors' installed platforms (P2) and epidemic memory (P4). (iii) Compatibility weighting. Across every documented displacement in Table 1, the winner held the compatibility advantage; it held the sensitivity advantage in only a minority of contests (§5.3). The double weighting of compatibility is therefore a calibration fitted to the archive, not an independent finding, and we report it as such. Its validation is staked on the prospective forecasts of §8, not on reproducing what it was fitted to (rankings are robust to weights of 1.5–2.5; Supplementary Methods). These checks arm §8's predictions with estimated rather than rhetorical parameters.

8. Prediction: The Next Winners

8.1. Scoring the Candidates

Four technology families contest the next S-curve: CRISPR-based point-of-care NAATs, mNGS and targeted next-generation sequencing (tNGS), multiplex syndromic panels, and host-response biomarkers coupled with AI-assisted imaging (Fig. S3). We score each on the Table S2 rubric against the incumbent in its target setting and convert scores into falsifiable predictions (Table 2).

CRISPR-POCT (illustrative composite 4.0) — the leading candidate in our scoring for the next decade. Its profile attacks every historical bottleneck: single-molecule sensitivity [37,38]; lateral-flow readout under 60 minutes, crossing the emergency bedside threshold (P3); no thermocycler, with compatibility rising further if it rides the colloidal-gold channel already proven at the community point of care [24]; and resistance-mutation multiplexing in one reaction [34] (attribute scores in Table 2). Its deficits are regulatory — no MP-CRISPR product had entered regulatory registration anywhere through September 2026 [24,33] — and trialability at scale. Prediction 1: CRISPR-based MP point-of-care testing will obtain first regulatory approvals (NMPA before FDA, per §6.2's geography) by end-2027 and achieve decisive adoption — displacing colloidal-gold IgM as the default first test in pediatric emergency and community settings in China — by end-2028, conditional on extraction-free, sample-to-answer workflow. Falsification: if no MP-CRISPR product holds NMPA registration by December 2027, the composite model overweights compatibility and must be revised.

Prediction 2: antigen-CLIA (§4.1, Era IV) is the dark horse of the same niche. P2 predicts that technologies riding the installed chemiluminescence base diffuse faster than equal-performance technologies requiring new hardware; we forecast ≥3 NMPA antigen-CLIA registrations by end-2027. The evidence anchoring this curve now includes the first MP antigen-CLIA registration (September 2026 [24]) plus the completed antigen-CLIA trials (§4.1) and the continued platformization of chemiluminescence in the NMPA registry — most recently the Kanghua MP-IgM CLIA registration (December 2024), an antibody product that documents the size and continued growth of the installed CLIA base an antigen-CLIA entrant would ride, not itself an antigen data point.

mNGS/tNGS (composite 3.1) — consolidates in the severity niche, does not cross. Sequencing owns the severity apex — the only technology whose relative advantage grows with disease severity [36,50] — but P3 bars it from the first-dose window and P2/P4 confine it to the severe and diagnostically negative settings where it is already entrenched (§5.2). The first class-III mNGS licences (August 2026) cover MP within broader respiratory panels [24] — niche consolidation without first-line crossing, as predicted. Prediction 3: mNGS/tNGS will consolidate as the standard of care for severe, immunocompromised and diagnostically negative MP pneumonia but will not displace qPCR as the first-line test before 2030 unless turnaround falls below 12 hours and the workflow becomes deployable outside referral centers; neither condition is met through September 2026.

Multiplex syndromic panels (composite 3.5) — segmented growth, gated by perceived severity. Panels solve the clinician's actual question ("which pathogen?") and hold the P3 threshold in sample-to-answer formats [33]; their brake is confinement to tertiary centers against a disease perceived as mild — P4 again. Prediction 4: panels will keep growing in inpatient and ICU settings but remain gated in pediatric outpatient and community settings through 2028. The gate lifts only if guideline bodies endorse routine multiplex testing for non-severe pediatric CAP; current guidance is at most permissive (adult CAP etiologic testing optional [42]; pediatric guidance similarly restrained [41]), and we predict it will not, given limited management impact in mild disease.

Host-response biomarkers + AI imaging (composite 2.4) — the longest lag. Host-side signatures reframe the question from "what organism" to "bacterial or viral, severe or mild" — potentially the most compatible test of all [51] — but observability and trialability are low, compatibility with antibiotic-decision habits is unproven, and no MP-specific validation cohort exists. Prediction 5: host-response approaches will not achieve routine MP-relevant adoption before 2030, entering piggybacked on multiplex platforms rather than standalone — as antigen detection's history (§3.2) warns, technologies answering a question adjacent to the one clinicians ask die young.

8.2. The Shape of the Next Curve

Assembling the forecasts (Fig. S3; Table 2): the 2025–2035 landscape is likely to be layered, not winner-take-all — CRISPR-POCT or antigen-CLIA at the community and emergency base, qPCR and resistance-mutation duplexes as the routine hospital standard, panels for inpatients, mNGS for the severe apex — boundaries set by the bedside threshold (P3), velocities by how warm 2023 left the system (P4).