Necrotic Enteritis in Broilers: Linking Intestinal Lesions with Laboratory Diagnosis

A broiler may arrive for postmortem examination with a distended, fragile small intestine covered by a dirty-looking membrane. Such lesions can strongly suggest necrotic enteritis (NE), but the veterinarian still needs to connect what is seen grossly with laboratory detection of Clostridium perfringens. 

The value of diagnosis lies in bringing these two pieces together: What does the intestine look like, and can C. perfringens be demonstrated reliably? 

Start with the intestinal lesion^[1] 

NE lesions are most commonly found in the jejunum and ileum, although the duodenum and ceca can also be affected. The small intestine may appear thin, friable, and distended with gas. A characteristic tan-orange pseudomembrane can cover the mucosal surface, producing the familiar “dirty Turkish towel” appearance. 

A diphtheritic or pseudomembranous membrane is particularly common in the jejunum and may also extend into the duodenum, ileum, or ceca. 

These findings provide an important clinical direction, but the postmortem picture should be interpreted together with laboratory findings rather than treated as the only basis for diagnosis. 

Look beyond the obvious intestinal lesion^[1] 

Not every consequence of NE is confined to the intestinal wall. Subclinical disease has been linked with hepatitis and cholangiohepatitis. A distended gallbladder containing flocculent material has also been described. 

This matters during postmortem examinations. When intestinal changes are relatively subtle, associated hepatobiliary abnormalities may provide an additional reason to investigate C. perfringens and NE. 

Where does culture fit? 

Laboratory detection can begin with intestinal samples that are homogenized and serially diluted before inoculation onto selective media. Anaerobic enrichment can also be performed using pre-reduced cooked meat medium, followed by culture on selective formulations. 

Tryptose sulfite cycloserine (TSC) and sulfite polymyxin sulfadiazine (SFP) media can assist detection. On TSC, C. perfringens produces characteristic black colonies because of sulfite reduction, while an egg-yolk halo reflects lecithinase activity^[1],[2],[3]. 

Presumptive colonies can then be evaluated using Gram staining, capsule staining, colony characteristics and biochemical testing to support identification^[1]. 

The limitation is practical: culture and plate counting can be time-consuming, particularly when a rapid diagnostic decision is needed. 

PCR can add speed and sensitivity^[1],[4] 

Molecular testing provides another route to detecting C. perfringens. Conventional PCR can identify the organism more rapidly than culture, while real-time PCR provides greater detection capacity. 

The difference is particularly relevant when bacterial concentrations are low. Conventional PCR detected approximately 2–3 log10 concentrations, whereas real-time PCR extended detection to approximately 5–6 log10 concentrations. 

Real-time PCR also showed a high correlation with culture and lower relative standard deviation, supporting more consistent and reproducible quantification. 

These methods therefore offer complementary value: culture provides organism recovery and phenotypic information, while PCR can provide faster and more sensitive detection. 

Make the lesion and laboratory result tell the same story^[1] 

A practical NE investigation should bring the findings together: 

• Gross examination: Assess the jejunum, ileum and other affected intestinal segments for friability, gas distension, and pseudomembranous lesions. 
• Additional lesions: Look for hepatobiliary changes that may accompany subclinical disease. 
• Culture: Use selective anaerobic methods and evaluate characteristic colonies. 
• Identification: Support presumptive colonies with staining and biochemical characteristics. 
• Molecular detection: Consider conventional or real-time PCR when faster or more sensitive detection is required. 

Clinical Bottom Line 

The diagnosis of NE becomes more useful when the gross lesion and laboratory evidence are interpreted together. The characteristic intestinal appearance can raise suspicion, while culture and molecular methods can provide additional evidence for C. perfringens involvement. 

For the practicing veterinarian, the goal is not simply to find black colonies or obtain a positive PCR result. It is to connect the laboratory finding with the intestinal pathology and the clinical picture of the flock.

References:

1. Fathima S, Hakeem WG, Shanmugasundaram R, Selvaraj RK. Necrotic enteritis in broiler chickens: a review on the pathogen, pathogenesis, and prevention. Microorganisms. 2022 Sep 30;10(10):1958. https://www.mdpi.com/2076-2607/10/10/1958
2. Wu SB, Rodgers N, Choct M. Optimized necrotic enteritis model producing clinical and subclinical infection of Clostridium perfringens in broiler chickens. Avian diseases. 2010 Sep 1;54(3):1058-65. https://www.researchgate.net/profile/Shu-Biao-Wu/publication/47427451
3. Samples CM. Isolation, identification and characterization of clostridium perfringens from cooked meat-poultry samples and in silico biomodeling of its delta enterotoxin. Delta. 2010 Sep;4(2):028. https://www.researchgate.net/profile/Sinosh-Skariyachan/publication/20333540. https://www.researchgate.net/profile/Sinosh-Skariyachan/publication/203335401
4. Wu SB, Rodgers N, Choct M. Real-time PCR assay for Clostridium perfringens in broiler chickens in a challenge model of necrotic enteritis. Applied and environmental microbiology. 2011 Feb 1;77(3):1135-9. https://journals.asm.org/doi/pdf/10.1128/aem.01803-10