Klebsiella pneumoniae
LEVELS: Highly unlikely; Moderate; Already in the herd; Laboratory-dependent; Moderate; Negligible; Some; Available, or not needed
| Register id | klebsiella_pneumoniae |
| Type | bacteria |
| Scientific name | Klebsiella pneumoniae |
| NCBI taxid | 573 |
| Evidence | 1 document(s) |
| Assigned | 2026-09-04, against criteria version 093366e352a2 |
Overview
Klebsiella pneumoniae is a normal inhabitant of the pig's digestive tract and is also common in the environment — in soil, in water and especially in sawdust, which suits it well enough to multiply in. Occasionally it causes septicaemia in one- to four-week-old piglets, which are found dead or collapsed and blue, and it can cause severe toxic mastitis in sows. Why these outbreaks start is not known. Mortality is usually low, one or two piglets per litter and under 5% overall, though outbreaks with far higher losses have been reported in Australia; a herd problem typically runs for a few weeks up to about three months and then stops. Nothing about the lesions identifies it — they look like septicaemia caused by Streptococcus suis, Actinobacillus suis, erysipelas or E. coli — so it is diagnosed by culture, which is straightforward. K. pneumoniae causes serious infections in people, but human disease is far too widespread to be attributed to pigs and the organism is not regarded as a zoonotic agent in this context.
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
Basis. "Klebsiella pneumoniae is a cause of various human opportunistic infections, including pneumonia, meningitis, urinary tract infections, and neonatal septicemia, but it is not considered a zoonotic agent." (ch58 58.7.1)
How this level was decided
The chapter answers C1 in one sentence: not a zoonotic agent. Human K. pneumoniae disease is real and common but is not acquired from pigs, which is the dead-end pattern Eric ruled on for chikungunya -- an agent that reaches people by another route entirely scores level 1 here. NOTE: the section also raises horizontal transfer of AMR genes from pig to human isolates. That is not the agent reaching humans from pigs, and the criterion it would have fed -- contribution to AMR -- was deleted from the framework on 2026-08-25, so it does not lift this level.
C2 Zoonotic impact
Severity of human illness caused by the agent
Moderate: Clinically important illness is common and may require medical treatment or hospitalization, but death or permanent disability is uncommon
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 "L3". Reverses his 2026-08-28 level 1, which he had reached on attribution -- "the source of the disease in people would almost never be [pigs]". C2 now grades the agent, and Klebsiella pneumonia and sepsis require hospitalisation. Level 3 rather than 4 follows his own S. aureus rule: the drug-resistant and hypervirulent strains are the minority, so the general risk rating applies.
Basis. "Klebsiella pneumoniae is a cause of various human opportunistic infections, including pneumonia, meningitis, urinary tract infections, and neonatal septicemia." "Hundreds of mobile AMR genes have been found in K. pneumoniae, and its role in antimicrobial-resistant infections in other species such as humans is well described." (ch58 58.7.1)
How this level was decided
RE-SCORED 2026-09-04. C2 now grades the severity of the illness the agent causes in a person, independent of how the person was exposed -- the 2026-09-01 pig-attribution reading is reversed, and C1 alone carries the source question. Returns to the level it held before 2026-09-01. Pneumonia and sepsis requiring hospitalisation. Level 3 rather than 4 on Eric's own S. aureus rule -- "not all S.aureus are drug resistant so need to avoid the temptation to put this as l4. l3 is suitable for a more general risk rating" -- which applies identically to a genus whose hypervirulent and carbapenem-resistant strains are the minority.
PREVIOUS ANSWER, written under the pig-attribution reading: MOVED L3 -> L1 on 2026-09-01, and Eric had already written the reason into his own C2 ruling before the criterion was rescoped: "I think the source of the disease in people would almost never be attributed to pigs or pork (though no good data to support this)". Human Klebsiella infection is common, serious and overwhelmingly nosocomial or endogenous. Moved by the 2026-09-01 C2 rescoping, which Eric accepted: "i accept the c2_review changes". C2 now grades the severity of illness acquired FROM PIGS, so an entry whose pig is a dead-end host has no pig-attributable illness to grade. THE LEVEL MUST NOT BE READ AS A FINDING THAT THE AGENT IS MILD -- it records that pigs are not a source.
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. "Klebsiella pneumoniae is a commensal of the porcine digestive tract and is present in the environment, both in soil and water sources. It is frequently found in sawdust, which is an ideal environment for survival and multiplication." "The reasons for the emergence of outbreaks of K. pneumoniae septicemia in piglets are unknown." (ch58 58.7.1, 58.7.3)
How this level was decided
Already carried by the pigs themselves as a gut commensal, so there is no introduction event to prevent -- level 1. Outbreaks are emergences from existing carriage and from bedding, not incursions, which is why the chapter can say their cause is unknown rather than tracing them to a source. NOTE: soil, water and sawdust are also reservoirs outside the pig industry, and read strictly the C3 escalation rule would make that level 4. Scored level 1 because commensal carriage means the introduction question does not arise at all. The same tension is scored the other way on chlamydia_spp, where the second reservoir is ruminants and birds rather than the inanimate environment. One ruling settles both.
C4 Detection difficulty
Difficulty of recognizing and confirming infection
Laboratory-dependent: The presentation does not point to this disease specifically, but local or regional laboratories can confirm it with a validated assay once it is suspected
CONFIRMED by Eric. The assignment reached this level from the evidence, and he has reviewed and ratified it.
Confirmed by Eric. CONFIRMED. "l2, straightforward to diagnose and easy to grow"
Basis. "Lesions are nonspecific and similar to those observed in septicemia due to other bacteria such as Streptococcus suis (Chapter 57), Actinobacillus suis (Chapter 43), Erysipelothrix rhusiopathiae (Chapter 48), or E. coli (Chapter 49)." "Culture is required for confirmation. K. pneumoniae is easily isolated in abundant pure culture from various tissues using standard aerobic culture on blood agar." (ch58 58.7.2)
How this level was decided
The chapter gives both halves explicitly. Lesions are non-specific against four common septicaemias, so the presentation does not point here -- not level 1. Confirmation is standard aerobic culture on blood agar with abundant pure growth, which any local or regional laboratory runs. Level 2, and about as clean an example of the level as the batch contains.
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. "Klebsiella septicemia infrequently occurs in preweaned 1- to 4-week-old piglets. Piglets are found dead or recumbent and cyanotic." "Overall mortality is variable but usually low (less than 5%), and within-litter mortality is also variable and usually low, with one to two piglets dying per litter. However, cases with mortality as high as 100% have been reported in Australia." "The duration of herd disease varies from a few weeks to as long as 12 weeks." "sows presenting with a severe toxic mastitis." (ch58 58.7.2)
How this level was decided
Pre-weaning mortality of one to two piglets per litter sustained for up to twelve weeks is a measurable increase in cost of production, and severe toxic mastitis in sows adds to it. It remains manageable within normal farm operations -- the chapter describes herds working through it, sometimes without intervention. Level 3. The 100% mortality reports from Australia are the rare extreme the general rule says should not set the score.
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 is correct, no historical evidence thus far that diagnoses of the agent in pigs has had any effect on markets"
Basis. The section describes sporadic pre-weaning septicaemia confined to affected units in the UK and Australia, and explicitly states the organism is not zoonotic. It records no trade measure, movement control, export restriction or consumer response.
How this level was decided
INFERRED. A non-zoonotic, non-reportable septicaemia of suckling piglets does not reach the market -- affected pigs die before weaning, nothing enters the food chain, and no regulatory response is triggered. Level 1.
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. "All of the isolates have an innate resistance to beta-lactams and most have shown in vitro sensitivity to other antimicrobials tested. However, occasional isolates with resistance to multiple antimicrobials have been detected." "interventions included antimicrobial treatment of remaining piglets in affected litters... Some of these interventions resulted in cessation or reduction in mortality. However, in the absence of untreated control groups, their efficacy cannot be assessed since the disease was sometimes self-limiting on farms without interventions." (ch58 58.7.3)
How this level was decided
Treatment is available and is used, ruling out level 3, but the chapter is unusually frank that its efficacy is unproven -- innate beta-lactam resistance, multidrug-resistant isolates appearing, and field interventions whose apparent success cannot be separated from spontaneous resolution. Treatment that exists but is inconsistent is level 2.
C8 Vaccine availability
Availability of effective vaccines or bacterins
Available, or not needed: Effective vaccines are widely available in the US or secured for national outbreak response, or the disease does not clinically or economically justify vaccinating
CONFIRMED by Eric. The assignment reached this level from the evidence, and he has reviewed and ratified it.
Confirmed by Eric. CONFIRMED AT LEVEL 1. "c8l3 is correct, but again there is no economic imperative to develop or use a vaccine given the disease's current low significance in pigs" Eric, 2026-08-28: "all seven to L1". Re-ruled after the C8 rewording of the same day. His 2026-08-27 words are unchanged and are quoted above in full -- what has moved is the level they map to. He wrote each of them to say that no vaccine is NEEDED here, and level 3 was then the only place a missing vaccine could go, so the reasoning and the level contradicted each other. The reworded level 1 holds exactly what he was describing: no vaccine exists, and the disease does not justify one. Recorded as a confirmation of the reworded pass rather than an override, because the pass now agrees with him.
Basis. ch58 58.7.3 names isolate typing, antimicrobials, creep feed and iron, and no vaccine. Eric, 2026-08-27: "there is no economic imperative to develop or use a vaccine given the disease's current low significance in pigs".
How this level was decided
MOVED L3 -> L1 by the rewording. Sporadic pre-weaning septicaemia confined to affected units, non-zoonotic, cause of outbreaks unknown. He named the absence of economic imperative directly, which is the reworded level 1 second clause.
Levels and evidence are generated from data/assignments/klebsiella_pneumoniae.yml; the overview is authored in data/overviews/klebsiella_pneumoniae.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.