E. COLI - COLIFORM MASTITIS
LEVELS: Highly unlikely: No controls necessary; Highly unlikely: No evidence of non-foodborne zoonotic transmission; Highly effective: Routine on-farm biosecurity measures are effective in preventing farm-to-farm transmission; Moderate: Clinical signs not unique but existing tests available at local/regional laboratory(s); Moderate: Manageable losses related to endemic (population) or chronic (individual) occurrence; Negligible: Little or no market disruption when disease occurs on one or more farms; High risk: Resistance to antibacterial or antiviral treatments is, or can be expected to be a common problem; Minimal risk: Antibacterial or antiviral treatments rarely occur, or are typically limited to short-course individual animal therapy; Available but with uncertain efficacy: Limited treatments available in US or are only effective in some situations; No availability: Effective vaccines not currently available in the US (or have not been developed); Not feasible: Eradication extremely unlikely
OVERVIEW
Coliform mastitis (CM) in swine refers to inflammation of the mammary glands associated with fever and reduced milk production, typically occurring within 12-48 hours postpartum. CM is the main clinical sign of postpartum dysgalactia syndrome (PPDS). E. coli is the most important causative agent, though other coliforms (Citrobacter, Enterobacter, Klebsiella) may also be involved. The average incidence is 13% at the herd level. External contamination of nipples with feces or oral microbiota of nursing piglets provides the source of infection, which ascends through the teat canal (galactogenous route). The sow's teat duct lacks muscular sphincters, facilitating bacterial entry. Clinical signs include pyrexia (39.3-40.5°C), listlessness, anorexia, sternal recumbency, and hypogalactia. Affected glands may be reddened, swollen, and firm. Disease is typically self-limiting (2-3 days) as bacteria generally disappear 1-6 days after parturition. The most important economic impact is mortality and growth retardation in piglets due to reduced milk availability. CM behaves as a non-contagious infection of endogenous origin with great heterogeneity of isolates even within one sow. No effective vaccines are available; prevention focuses on farrowing house hygiene and minimizing stress.
FOODBORNE ZOONOTIC TRANSMISSION POTENTIAL
Level: Highly unlikely: No controls necessary
E. coli causing coliform mastitis in sows are not foodborne zoonotic pathogens. These strains are opportunistic infections of the mammary gland without documented human disease transmission through pork consumption.
NON-FOODBORNE ZOONOTIC TRANSMISSION POTENTIAL
Level: Highly unlikely: No evidence of non-foodborne zoonotic transmission
Coliform mastitis strains are not zoonotic. The fecal-origin E. coli causing mastitis in sows are opportunistic infections without documented transmission to or disease in humans.
EFFECTIVENESS OF ON-FARM BIOSECURITY IN PREVENTING FARM-TO-FARM TRANSMISSION
Level: Highly effective: Routine on-farm biosecurity measures are effective in preventing farm-to-farm transmission
CM is a non-contagious, endogenous infection: (1) Non-contagious: "Like CM, nonspecific UTI behaves like a noncontagious infectious disease of endogenous origin"; (2) Fecal source: "External contamination of the nipples with feces or by the oral microbiota of the neonatal piglet is a potential source of infection"; (3) Strain heterogeneity: "great heterogeneity of isolates...may be cultured...between distinct glands of individual sow, or even between subcomplexes within one gland"; (4) Environmental management: Farrowing house hygiene controls exposure.
DIFFICULTY OF DETECTING AND CONFIRMING INFECTION
Level: Moderate: Clinical signs not unique but existing tests available at local/regional laboratory(s)
Diagnosis requires laboratory confirmation: (1) Clinical suspicion: Pyrexia, hypogalactia, affected glands "reddened, swollen, and firm"; (2) No rapid farm test: "A reliable rapid test for use on the farm is not available"; (3) Milk cytology: "cytological examination allows differentiation between healthy and mastitic complexes at least during the first 48 hours"; threshold >5 × 10^6 cells/mL with >70% PMN; (4) Culture: "Culture of the secretion may be necessary"; individual complexes must be sampled, not pooled; (5) Ultrasound: "Ultrasonography can be used for diagnosis."
FINANCIAL IMPACT ON FARM'S COST OF PRODUCTION
Level: Moderate: Manageable losses related to endemic (population) or chronic (individual) occurrence
CM causes moderate economic impact: (1) Piglet losses: "The most important adverse economic effect of CM in sows is the mortality and growth retardation in piglets due to pain in affected teats and dysgalactia"; (2) Herd incidence: "average incidence of 13% at the herd level"; (3) Self-limiting: Disease typically resolves within 2-3 days; (4) Up to 80% of dysgalactic sows: "may have gross lesions of mastitis."
EFFECT ON DOMESTIC OR EXPORT MARKETS
Level: Negligible: Little or no market disruption when disease occurs on one or more farms
No trade implications: (1) Not regulated: CM is not a reportable or trade-restricted disease; (2) Sow-level disease: Does not affect market pigs; (3) Indirect effects: Impact is through piglet losses and growth retardation.
PATHOGEN'S ABILITY TO DEVELOP AND SPREAD RESISTANCE
Level: High risk: Resistance to antibacterial or antiviral treatments is, or can be expected to be a common problem
E. coli in CM share resistance patterns: (1) Heterogeneous susceptibility: "Antimicrobial therapy is complicated by the heterogeneous pattern of antimicrobial susceptibility of individual isolates not only within a herd but also within a sow"; (2) Same AMR concerns: As other porcine E. coli.
AMR DEVELOPMENT DRIVEN BY DISEASE MANAGEMENT
Level: Minimal risk: Antibacterial or antiviral treatments rarely occur, or are typically limited to short-course individual animal therapy
CM treatment contributes to antimicrobial use: (1) Treatment timing: "therapeutic measures are usually not undertaken before the sow shows signs of dysgalactia"; (2) Empirical selection: Limited value of sensitivity testing in individual cases due to strain heterogeneity; (3) Self-limiting: Short disease course limits antimicrobial duration.
AVAILABILITY OF EFFECTIVE TREATMENT OPTIONS
Level: Available but with uncertain efficacy: Limited treatments available in US or are only effective in some situations
Treatment options exist: (1) Antimicrobials: "Amoxicillin, tylosin, and potentiated sulfonamides administered parenterally are indicated"; "enrofloxacin and cefquinome" also effective; (2) NSAIDs: "Therapy with nonsteroidal anti-inflammatory drugs, such as meloxicam (0.4 mg/kg BW), is indicated"; (3) Self-limiting disease: "treatment may at best shorten the period of underfeeding of the piglets"; (4) Susceptibility variation: Heterogeneous patterns complicate optimal selection.
AVAILABILITY OF EFFECTIVE VACCINES OR BACTERINS
Level: No availability: Effective vaccines not currently available in the US (or have not been developed)
No vaccines available: (1) No protective immunity: "An episode of CM apparently does not result in protection against homologous reinfection"; (2) Strain heterogeneity: Multiple different strains even within one sow makes vaccination impractical; (3) Prevention focus: Hygiene and environmental management.
FEASIBILITY OF ERADICATING THE DISEASE FROM THE US
Level: Not feasible: Eradication extremely unlikely
Eradication is not feasible: (1) Endogenous origin: Fecal microbiota is the source; (2) Ubiquitous E. coli: Normal intestinal flora; (3) Risk factor management: Focus is on reducing contamination and stress at farrowing.