Suppurative abscess (Trueperella pyogenes)
LEVELS: Highly unlikely; Mild; Already in the herd; Routine; Moderate; Negligible; Some; Needed but not available
| Register id | trueperella_pyogenes |
| Type | bacteria |
| Scientific name | Trueperella pyogenes |
| NCBI taxid | 1661 |
| Evidence | 1 document(s) |
| Assigned | 2026-09-04, against criteria version 093366e352a2 |
Overview
Trueperella pyogenes is part of the normal skin and mucosal flora of pigs, cattle and horses, and is found in discharges from the airway, udder and vulva and in faeces. It causes disease opportunistically, when it invades through damaged skin or mucous membrane rather than by spreading from animal to animal, and it survives freezing and drying when protected in organic matter. In pigs it produces suppuration wherever it lodges. The commonest consequence is economic rather than clinical: abscesses full of creamy pus found in the carcass at slaughter, leading to trimming or condemnation. Deeper infections can be fatal — endocarditis, bronchopneumonia, adhesive peritonitis — and infection of the vertebrae can cause the bone to collapse and compress the spinal cord. Rare human infections have been reported, but the chapter does not attribute them to pigs and the organism is resident flora of ruminants and horses as well.
C1 Zoonotic potential
Likelihood of transmission from pigs to humans
Highly unlikely: Human infection with the agent has never been reported, or has been reported but is not attributed to pig or pork exposure
CONFIRMED by Eric. The assignment reached this level from the evidence, and he has reviewed and ratified it.
Confirmed by Eric. CONFIRMED. REVIEWED ON C1_C2_RECLASSIFICATION.md, 2026-09-04, after the C1/C2 rewording that separated exposure from consequence. Eric marked up every moved cell and reversed his own earlier setting on twenty of the twenty-one: "In almost every case, I agreed with new opinion and reversed my old setting." HIS MARKUP HERE WAS "L1". Reverses his 2026-08-28 level 2. Rare human cases are published but the chapter does not attribute them to pigs, and the organism is resident flora of ruminants and horses too.
Basis. "Rare cases of human infection with T. pyogenes have been reported (Plamondon et al. 2007; Levy et al. 2009)." "Infections with T. pyogenes are found worldwide in ruminants, pigs, and horses. It is part of the skin and mucosal flora of the host species." (ch58 58.13.1, 58.13.2)
How this level was decided
MOVED L2 -> L1, re-read 2026-09-04 AGAINST THE REWORDED LABELS. ch58 58.13: rare human cases are published, but the chapter does not say they came from pigs and the organism is resident flora of ruminants and horses as well. Reported in people, not attributed to pigs.
PREVIOUS ANSWER, kept because the evidence behind it has not changed, only the level boundary: INFERRED. Human infection occurs and is published, but the chapter does not say those cases came from pigs, and the organism is resident flora in ruminants and horses as well. So a pig-sourced route is plausible and would be rare, and nothing in pork production is directed at preventing it -- both clauses of level 2. The inference is in attributing the reported human cases to a pig-type exposure rather than a ruminant one; level 1 would follow if the human cases are taken as unrelated to pigs.
C2 Zoonotic impact
Severity of human illness caused by the agent
Mild: Human illness is usually mild and self-limiting, and serious disease occurs only rarely
Corrected by Eric from no level assigned. Reason: "c2l2, Most human cases are manageable and non-contagious between people"
Basis. "Rare cases of human infection with T. pyogenes have been reported (Plamondon et al. 2007; Levy et al. 2009)." That is the entire human-health content of the section. It does not say what those infections were, how they presented, whether they required treatment, or whether anyone died. (ch58 58.13.1)
How this level was decided
NOT ASSESSED. No level assigned. The folder establishes that humans do get infected, which rules out level 1 -- C2 level 1 means the agent does not cause illness in people, and it plainly does. But every level above 1 is a statement about severity, and the folder contains not one word about the clinical course of human T. pyogenes infection. Assigning level 2, 3 or 4 here would be inventing the finding. THIS MAKES THE ENTRY UNEXPORTABLE, and two published case reports would resolve it.
C3 Herd introduction risk
Effort required to keep the agent out of the herd
Already in the herd: Present in most herds, or carried by pigs themselves, so there is no introduction event to prevent
Basis. "It is part of the skin and mucosal flora of the host species and can be isolated in discharges from the upper respiratory tract, udder, vulva, and feces in infected animals." "Infection is opportunistic, resulting from the invasion of skin or mucous membranes by resident T. pyogenes (Jarosz et al. 2014)." "The organism can survive freezing and drying when protected in organic matter such as discharge." (ch58 58.13.2)
How this level was decided
The chapter states it in the words the level uses: the organism is resident flora and infection results from invasion by the pig own T. pyogenes. There is no introduction event to prevent. Level 1.
C4 Detection difficulty
Difficulty of recognizing and confirming infection
Routine: The disease would be suspected from clinical signs, history and epidemiology in normal practice, and confirmed by tests that local or regional laboratories run routinely
CONFIRMED by Eric. The assignment reached this level from the evidence, and he has reviewed and ratified it.
Confirmed by Eric. CONFIRMED. "l1, routine check by most any laboratory"
Basis. "Trueperella pyogenes infection is the major cause of purulent abscessation and purulent discharges of all types in pigs, and its presence should be strongly suspected in such cases." "Trueperella pyogenes causes creamy, greenish pus on inflamed mucous surfaces... The most noticeable and pathognomonic lesions are abscesses." "Confirmation of T. pyogenes requires the demonstration of the organism in typical lesions by laboratory culture or by real-time qPCR. Pinhead beta-hemolytic colonies on blood agar are suggestive of T. pyogenes, and identification can be confirmed using standard bacteriological procedures or more easily by MALDI-TOF mass spectroscopy." (ch58 58.13.3)
How this level was decided
Both halves of level 1 are met, unusually clearly. The chapter instructs that the agent be strongly suspected from the clinical picture -- purulent abscessation of any kind -- and calls the abscesses pathognomonic. Confirmation is blood agar culture with standard bacteriology or MALDI-TOF, which every regional veterinary diagnostic laboratory runs. Level 1.
C5 Production cost
Financial impact on the infected farm's cost of production
Moderate: Losses measurably increase cost of production but remain manageable within normal farm operations, whether acute, chronic, or associated with endemic disease
Basis. "As a consequence of T. pyogenes infection, carcasses at slaughter may contain unsightly abscesses filled with creamy pus, resulting in economic losses from trimming or condemnation." "Endocarditis, bronchopneumonia, and adhesive peritonitis may be fatal and be associated with fever. Suppurative osteomyelitis generally affects the vertebral bodies, leading to pathological fractures, vertebral collapse, and compression of the spinal cord." "Mortality occurs when damage to an organ becomes life-threatening, as in pyelonephritis in sows. Frequently, abscesses do not cause clinical signs other than loss of condition." "The implementation of needle-free injection systems in market hog production has been reported to increase the occurrence of injection site abscesses in pork carcasses." (ch58 58.13.1, 58.13.3)
How this level was decided
Three cost streams, all stated: carcass trimming and condemnation at slaughter, mortality from endocarditis, peritonitis and sow pyelonephritis, and loss of condition in pigs carrying abscesses without other signs. The chapter also records a management practice that is increasing the carcass losses. That measurably raises cost of production while remaining manageable within normal operations, which is level 3. Level 4 would need losses threatening viability, and the chapter describes a chronic tax rather than a crisis.
C6 Market impact
Duration of material disruption to pork and pig markets
Negligible: Little or no material disruption to supply or demand when disease occurs on one or more farms
CONFIRMED by Eric. The assignment reached this level from the evidence, and he has reviewed and ratified it.
Confirmed by Eric. CONFIRMED. "c6l1, the agent is ubiquitous and a secondary suppurative agent - it is not contagious between pigs or herds. It would not have any effect on markets."
Basis. The section describes carcass abscesses handled by trimming or condemnation at the plant, and an organism that is resident flora of pigs, ruminants and horses worldwide. It records no trade measure, movement control, export restriction or consumer response.
How this level was decided
INFERRED. Carcass abscessation is a disposition matter resolved inside the plant on the day, and the loss falls on the producer rather than on the market. Nothing is reportable, no movement is restricted, and the condition has been endemic throughout the period pork has traded normally. Level 1. NOTE: the loss from trimming and condemnation is real and is scored at C5, where it belongs -- it is a farm cost, not a market disruption.
C7 Treatment potential
Potential for treatment to improve outcomes
Some: Treatment exists but is inconsistent, requires extralabel use, or works only in some circumstances
Basis. "Trueperella pyogenes is sensitive to a wide range of antimicrobial agents, including penicillin and ampicillin. Recent work has shown low levels of resistance to penicillins and other beta-lactam drugs and elevated MICs against tetracyclines (Galan-Relano et al. 2019). Other studies have shown elevated MIC levels against macrolides and aminoglycoside drugs (Dong et al. 2019). Antimicrobial treatments only are poorly effective due to difficulty achieving therapeutic levels in abscesses. Abscesses may be removed surgically where they can be identified in affected individuals." (ch58 58.13.4)
How this level was decided
A textbook level 2. The organism is susceptible to a wide range of drugs in vitro, so treatment exists and is not the problem -- but the chapter states it is poorly effective in practice because antimicrobials cannot reach therapeutic levels inside an abscess, and falls back on surgery. Treatment that exists but works only in some circumstances. There is real room for a treatment that penetrated abscesses to improve outcomes, but not the total absence level 3 requires.
C8 Vaccine availability
Availability of effective vaccines or bacterins
Needed but not available: No effective vaccine is available in the US or has been developed, and the disease would justify vaccinating if one existed
Basis. ch58 58.13.4 states it outright: "Effective vaccines are not available. Prevention requires management to reduce or prevent conditions that predispose to the development of T. pyogenes infections." The same section records that "Antimicrobial treatments only are poorly effective due to difficulty achieving therapeutic levels in abscesses".
How this level was decided
STAYS L3. The chapter names the absence directly, and the justification test is met from the other side: treatment is poorly effective because drugs do not reach abscesses, and the losses are carcass trimming, condemnation and sow mortality, scored at C5 level 3. A preventive would be valuable precisely because the therapeutic is not. Level 3.
Levels and evidence are generated from data/assignments/trueperella_pyogenes.yml; the overview is authored in data/overviews/trueperella_pyogenes.md. Do not hand-edit this page — corrections go in data/assignments/CORRECTIONS.yml.
Quoted material marked Basis is from Zimmerman JJ, Karriker LA, Ramirez A, Schwartz KJ, Stevenson GW, Zhang J, eds. Diseases of Swine, 12th edition. Hoboken: Wiley Blackwell, 2025 — except where another source is named in the quotation itself.