1A09.0) - Salmonella Enteritis: Complete Clinical Coding Guide

1. Introduction

Salmonella enteritis represents one of the most prevalent gastrointestinal infections worldwide, constituting an important public health problem that affects millions of people annually. This condition results from the ingestion of food or water contaminated by bacteria of the genus Salmonella, excluding strains responsible for typhoid and paratyphoid fever, which have distinct specific coding.

The clinical relevance of this pathology transcends individual discomfort, representing a significant challenge for epidemiological surveillance systems and sanitary control. Inadequate conditions in animal husbandry, transport, slaughter, and commercialization of domestic animals substantially contribute to the dissemination of this bacterium in the food supply chain, making prevention a complex multisectoral effort.

From a public health perspective, Salmonella enteritis is frequently associated with foodborne outbreaks that can affect entire communities, requiring rigorous epidemiological investigation and immediate containment measures. Morbidity and mortality, although generally low in healthy populations, can be significant in vulnerable groups such as infants, elderly individuals, pregnant women, and immunocompromised patients.

Precise coding using ICD-11 code 1A09.0 is fundamental for various purposes: it enables appropriate epidemiological tracking, facilitates antimicrobial resistance studies, aids in resource planning in health services, supports food safety policies, and ensures appropriate reimbursement in health systems. Correct documentation is also essential for identifying outbreak patterns and implementing effective preventive measures.

2. Correct ICD-11 Code

Code: 1A09.0

Description: Enteritis due to Salmonella

Parent category: 1A09 - Infections due to other Salmonella

Official definition: This code classifies poisonings caused by ingestion of food containing Salmonella species, excluding Salmonella typhi and Salmonella paratyphi, which are responsible for specific enteric fevers. The definition emphasizes the role of inadequate conditions in raising, transporting, slaughtering, and marketing domestic animals in the dissemination of this bacterium through the food supply chain.

Code 1A09.0 belongs to the chapter on infectious and parasitic diseases of ICD-11, specifically within intestinal bacterial infections. This classification reflects the primarily gastrointestinal nature of the infection, distinguishing it from systemic manifestations caused by other Salmonella species.

It is important to understand that this code applies specifically to acute gastroenteritis caused by non-typhoidal Salmonella, characterized mainly by intestinal symptoms such as diarrhea, nausea, vomiting, and abdominal pain. Proper coding requires diagnostic confirmation, either through compatible clinical evidence in appropriate epidemiological context, or ideally through laboratory confirmation via stool culture.

The hierarchical structure of ICD-11 allows this code to be used both independently and in combination with additional codes that specify complications, severity, or particular circumstances of the infection, providing flexibility in clinical documentation without compromising diagnostic accuracy.

3. When to Use This Code

The code 1A09.0 should be applied in specific clinical scenarios where there is clear evidence of enteritis caused by non-typhoidal Salmonella. Below, we present detailed practical situations:

Scenario 1: Acute Gastroenteritis with Laboratory Confirmation A patient presents with watery or bloody diarrhea of sudden onset, fever, nausea, vomiting, and abdominal cramping. Stool culture confirms the presence of Salmonella enteritidis. This is the ideal scenario for application of code 1A09.0, as there is definitive microbiological confirmation. Documentation should include the specific laboratory result, identified species when available, and the temporal correlation between symptoms and diagnostic confirmation.

Scenario 2: Documented Epidemiological Outbreak During investigation of a foodborne outbreak in a commercial establishment, multiple patients develop gastrointestinal symptoms after consumption of specific foods. Even without individual laboratory confirmation in all cases, patients with compatible clinical presentation and documented exposure to the implicated food may receive code 1A09.0, especially when other outbreak cases had laboratory confirmation. Documentation should include reference to the investigated outbreak and established epidemiological link.

Scenario 3: Characteristic Clinical Presentation with Food Exposure Patient reports consumption of raw or undercooked eggs, inadequately prepared poultry products, or other high-risk foods, developing profuse diarrhea, moderate fever (38-39°C), nausea, and vomiting 12 to 72 hours later. Even without immediate laboratory confirmation, code 1A09.0 may be appropriate when the clinical-epidemiological context is strongly suggestive, especially in settings with limited diagnostic resources. Documentation should detail the food exposure and compatible clinical characteristics.

Scenario 4: Enteritis with Complications in Vulnerable Population An infant or elderly patient develops gastroenteritis with significant dehydration, persistent fever, and positive culture for Salmonella. Code 1A09.0 is applied for the primary infection and may be complemented with additional codes for dehydration, electrolyte disturbances, or other complications. Documentation should specify both the infection and its clinical consequences.

Scenario 5: Asymptomatic Carrier Identified on Screening A food handler undergoing periodic examination has a positive stool culture for Salmonella without active symptoms. Although controversial, code 1A09.0 may be considered with appropriate qualifiers indicating carrier status, especially when there are public health implications. Documentation should clarify the absence of symptoms and diagnostic context.

Scenario 6: Recurrence or Prolonged Infection Patient with persistent gastrointestinal symptoms for more than one week, with culture confirming Salmonella. Although most cases are self-limited, some patients develop prolonged infection. Code 1A09.0 remains appropriate, with additional documentation regarding symptom duration and severity, especially important to justify specific therapeutic interventions.

4. When NOT to Use This Code

It is fundamental to recognize situations where code 1A09.0 is not appropriate, avoiding coding errors that may compromise epidemiological data and administrative processes:

Typhoid and Paratyphoid Fever: Infections caused by Salmonella typhi or Salmonella paratyphi should be coded with specific codes from category 1A07 (Typhoid fever) or 1A08 (Paratyphoid fever). These present distinct clinical manifestations, with prolonged fever, prominent systemic manifestations, and clinical course different from typical enteritis. Differentiation is crucial as treatment, prognosis, and public health measures differ substantially.

Gastroenteritis of Other Etiologies: When culture identifies other pathogens such as Campylobacter, Shigella, pathogenic E. coli, or enteric viruses, specific codes for these agents should be used. The clinical presentation of gastroenteritis may be similar regardless of the agent, making laboratory confirmation essential for accurate coding.

Bacteremia or Extraintestinal Salmonella Infections: When Salmonella is isolated from blood, cerebrospinal fluid, joints, or other extraintestinal sites, different codes are necessary to reflect the invasive nature of the infection. These manifestations, although less common, represent serious complications that require a distinct therapeutic approach.

Unspecified Gastroenteritis: In the absence of etiological confirmation and without epidemiological context strongly suggestive of Salmonella, codes for unspecified infectious gastroenteritis should be used. Premature coding as Salmonella enteritis without adequate evidence compromises the utility of epidemiological data.

Food Poisoning by Preformed Toxins: Conditions caused by preformed bacterial toxins in food (such as staphylococcal poisoning or Bacillus cereus) have different clinical presentation, with much more rapid onset and absence of significant fever. These require specific coding for non-infectious food poisoning.

5. Step-by-Step Coding Process

Step 1: Assess Diagnostic Criteria

The first fundamental step is to establish the diagnosis of Salmonella enteritis through appropriate clinical and laboratory criteria. The evaluation should include:

Detailed Clinical History: Investigate symptom onset, characterizing the typical incubation period of 12 to 72 hours after exposure. Question about consumption of high-risk foods, including eggs and egg products, poultry, meats, unpasteurized dairy products, and animal exposure. Document the nature and intensity of symptoms: frequency and characteristics of bowel movements, presence of blood or mucus, fever, nausea, vomiting, and abdominal pain.

Physical Examination: Assess signs of dehydration, including skin turgor, mucous membranes, heart rate, and blood pressure. Examine the abdomen for tenderness on palpation, distension, or other relevant findings. Check body temperature, considering that moderate fever is common.

Laboratory Confirmation: Ideally, request stool culture with specific agent identification. Stool culture remains the gold standard, allowing identification of Salmonella species and serotype, as well as antimicrobial susceptibility testing when necessary. In some contexts, rapid molecular tests may be available.

Epidemiological Context: Consider whether there are known outbreaks in the community, related cases, or documented exposures that strengthen diagnostic suspicion even before laboratory confirmation.

Step 2: Verify Specifiers

After establishing the diagnosis, assess characteristics that may require additional documentation:

Disease Severity: Classify as mild (tolerable symptoms, adequate oral hydration), moderate (significant symptoms, possible need for intravenous hydration), or severe (severe dehydration, bacteremia, need for hospitalization). This classification influences therapeutic decisions and may require additional codes.

Duration of Symptoms: Document whether the presentation is acute (less than 7 days), prolonged (7-14 days), or persistent (more than 14 days). Most cases resolve in 4-7 days, but variations justify specific documentation.

Complications Present: Identify complications such as severe dehydration, electrolyte disturbances, bacteremia, reactive arthritis, or other manifestations that require additional coding.

Special Population: Note whether the patient belongs to a risk group (infants, elderly, pregnant women, immunocompromised), as this may influence management and prognosis.

Step 3: Differentiate from Other Codes

Carefully compare with differential diagnoses:

Versus Other Bacterial Gastroenteritis: Although clinical presentations may overlap, characteristics such as presence of abundant blood (more common in Shigella), intense colicky abdominal pain (suggestive of Campylobacter), or absence of fever (possible in enterotoxigenic E. coli) may guide diagnosis. Laboratory confirmation is definitive.

Versus Typhoid Fever: Typhoid fever presents with prolonged and progressive fever, prominent systemic manifestations, hepatosplenomegaly, and less evident gastrointestinal symptoms initially. The distinction is crucial as treatment and prognosis differ significantly.

Versus Viral Gastroenteritis: Viral gastroenteritis (norovirus, rotavirus) generally has more abrupt onset, greater vomiting component, less prominent fever, and shorter duration. Epidemiological context (outbreaks in closed environments) and seasonality may aid in clinical differentiation.

Step 4: Necessary Documentation

Adequate documentation should include:

Mandatory Checklist:

Date of symptom onset and duration
Detailed description of clinical presentation
History of food or epidemiological exposure
Laboratory test results, especially stool culture
Salmonella species identified when available
Assessment of severity and presence of complications
Treatment instituted and clinical response
Relevant coexisting conditions

Ideal Clinical Record: "Patient presents with acute gastroenteritis onset 48 hours ago, characterized by liquid diarrhea (6-8 bowel movements/day), fever of 38.5°C, nausea, and occasional vomiting. Reports consumption of undercooked eggs three days before symptom onset. Physical examination reveals mild dehydration, diffusely tender abdomen without signs of peritoneal irritation. Stool culture positive for Salmonella enteritidis. Diagnosis: Salmonella enteritis (ICD-11: 1A09.0). Treatment: oral hydration, supportive measures, guidance on hygiene and transmission prevention."

6. Complete Practical Example

Clinical Case

Initial Presentation: A 35-year-old previously healthy patient seeks medical care with a complaint of severe diarrhea for two days. He reports that symptoms began abruptly with nausea, followed by vomiting and frequent liquid bowel movements, initially watery and subsequently with streaks of blood. He reports fever measured at home of 38.8°C, chills, intense abdominal cramps, and progressive weakness. He denies recent travel but mentions having attended a social event three days ago where he consumed egg-based preparations, including homemade mayonnaise and mousse.

Evaluation Performed: On physical examination, the patient appears in fair general condition, moderately dehydrated (dry mucous membranes, decreased skin turgor), axillary temperature of 38.3°C, heart rate of 98 bpm, blood pressure 110/70 mmHg. Abdomen slightly distended, increased bowel sounds, diffusely tender on palpation without signs of peritoneal irritation or palpable masses. Remainder of examination without significant abnormalities.

Initial laboratory tests show slightly elevated leukocytes (12,000/mm³), normal renal function with mild hemoconcentration. A stool sample was collected for culture and fecal leukocyte testing. Parasitological examination was negative, but stool culture after 48 hours revealed growth of Salmonella enteritidis sensitive to tested antimicrobials.

Subsequent epidemiological investigation identified three other participants from the same social event with similar symptoms, and analysis of samples from served foods confirmed Salmonella contamination in egg-based preparations.

Diagnostic Reasoning: The clinical presentation characterizes acute bacterial gastroenteritis, with compatible incubation period (approximately 72 hours), typical symptoms of invasive enteritis (fever, bloody diarrhea, abdominal pain), and strongly suggestive epidemiological history (consumption of high-risk foods at an event with other cases). Laboratory confirmation with isolation of Salmonella enteritidis definitively establishes the etiological diagnosis.

The presentation does not suggest severe systemic disease or extraintestinal complications. Moderate dehydration is an expected consequence of the diarrheal illness, not constituting an uncommon complication. The patient does not belong to a risk group for severe disease.

Coding Justification: This case meets all criteria for application of code 1A09.0: microbiological confirmation of non-typhoidal Salmonella, characteristic clinical manifestations of enteritis, appropriate epidemiological context (documented food exposure), and absence of systemic manifestations suggesting another diagnostic category.

Step-by-Step Coding

Criteria Analysis:

Etiological confirmation: Positive culture for Salmonella enteritidis ✓
Primary gastrointestinal manifestations: Diarrhea, vomiting, abdominal pain ✓
Exclusion of typhoid/paratyphoid fever: Species is not S. typhi or S. paratyphi ✓
Adequate documentation: History, examination, complete laboratory ✓

Primary Code Selected: 1A09.0 - Salmonella Enteritis

Complete Justification: Code 1A09.0 is most appropriate as the patient presents with confirmed non-typhoidal Salmonella infection with primarily intestinal manifestations. The identified species (S. enteritidis) is one of the leading causes of Salmonella gastroenteritis worldwide, frequently associated with contaminated eggs and poultry products.

The clinical presentation is typical: incubation period of 12-72 hours, watery diarrhea initially progressing to bloody, moderate fever, prominent gastrointestinal symptoms. There is no evidence of bacteremia or extraintestinal manifestations requiring different coding.

Applicable Complementary Codes:

Code for moderate dehydration (5C72.1): documents present complication that influenced management
Z code for exposure to contaminated food at social event: provides epidemiological context
Code for source of infection (foodborne outbreak): relevant for epidemiological surveillance

Final Documentation: "Primary Diagnosis: Salmonella Enteritis (1A09.0). Etiological agent: Salmonella enteritidis confirmed by stool culture. Secondary Diagnosis: Moderate dehydration (5C72.1). Exposure: Consumption of contaminated foods at social event with documented outbreak. Treatment: Intravenous hydration, supportive measures, guidance on transmission prevention. Course: Clinical improvement after 48 hours, discharge with guidance and outpatient follow-up."

7. Related Codes and Differentiation

Within the Same Category

1A09 - Infections due to other Salmonella (parent category): This category encompasses all Salmonella infections except typhoid and paratyphoid fever. Code 1A09.0 is the specific subcategory for enteritis, but other codes within 1A09 may include systemic or extraintestinal manifestations of non-typhoidal Salmonella.

1A07 - Typhoid Fever: Caused specifically by Salmonella typhi, characterized by prolonged fever, severe systemic manifestations, possible involvement of multiple organs. Differentiation is essential: while 1A09.0 represents primarily intestinal self-limited infection, 1A07 indicates severe systemic disease requiring mandatory antibiotic therapy and frequent hospitalization.

1A08 - Paratyphoid Fever: Caused by Salmonella paratyphi (types A, B, C), presents with clinical picture similar to typhoid fever, but generally less severe. The distinction from 1A09.0 is based on the etiologic agent and pattern of clinical manifestations.

Differential Diagnoses

1A03 - Shigellosis: Also causes bloody diarrhea (dysentery), but generally with more pronounced tenesmus, smaller fecal volume, and higher fever. Definitive distinction requires culture, but clinical and epidemiological characteristics may suggest one or the other diagnosis.

1A04 - Other specified bacterial gastroenteritis: Includes infections by Campylobacter, pathogenic E. coli, Yersinia, among others. Differentiation from 1A09.0 depends essentially on laboratory confirmation, although some clinical characteristics may be suggestive.

1A00 - Cholera: Characterized by profuse watery diarrhea of "rice water" type, rapid severe dehydration, generally without fever or significant abdominal pain. Epidemiological context (endemic areas, outbreaks) and distinctive clinical presentation aid in differentiation.

1A20 - Viral gastroenteritis: Caused by norovirus, rotavirus, enteric adenovirus. Generally present with more abrupt onset, vomiting more prominent than diarrhea initially, less significant fever, and shorter duration (24-48 hours). Seasonality and epidemiological context (outbreaks in closed environments) are important clues.

How to Distinguish Clearly: Precise differentiation between Salmonella enteritis and other gastroenteritis is based primarily on laboratory confirmation through stool culture. Clinically, some characteristics may guide: incubation period (longer in Salmonella than in food poisoning from toxins), presence of moderate fever (less common in viral gastroenteritis), progression from watery to bloody diarrhea (suggestive of invasive pathogens such as Salmonella or Shigella), and epidemiological context (type of food implicated, outbreak pattern).

8. Differences with ICD-10

Equivalent ICD-10 Code: In ICD-10, Salmonella enteritis is coded as A02.0 (Salmonella enteritis), within category A02 (Other Salmonella infections).

Main Changes in ICD-11: The transition to ICD-11 brought important structural modifications in the organization of Salmonella infections:

Enhanced Hierarchical Structure: ICD-11 uses a more flexible alphanumeric system (1A09.0) compared to the ICD-10 system (A02.0), allowing greater granularity and future expansion without complete restructuring.

More Detailed Definitions: ICD-11 incorporates into the code definition itself important epidemiological aspects, such as the role of animal breeding, transport, and commercialization conditions in bacterial dissemination. This contextualization was less explicit in ICD-10.

Better Differentiation: The separation between enteric fevers (typhoid and paratyphoid) and other Salmonella infections is clearer in the ICD-11 structure, with distinct categories (1A07, 1A08 versus 1A09), facilitating precise coding.

Post-Coordination Capability: ICD-11 allows greater flexibility in adding specifiers and extensions to main codes, enabling more detailed documentation of severity, complications, and epidemiological context without the need for completely separate codes.

Practical Impact of These Changes: For healthcare professionals, the transition represents the need to become familiar with the new coding structure, but offers significant advantages. Greater clarity in definitions reduces coding ambiguity, improving the quality of epidemiological data. The more flexible structure facilitates capture of clinically relevant information that was difficult to code in ICD-10.

For epidemiological surveillance systems, ICD-11 offers more granular and contextualized data, improving the ability to track outbreaks, identify contamination sources, and evaluate public health interventions. Compatibility with electronic health systems has also been improved, facilitating data integration and analysis.

9. Frequently Asked Questions

1. How is Salmonella enteritis diagnosed? Definitive diagnosis requires stool culture with isolation of the Salmonella bacterium. The patient must provide a stool sample, preferably before starting antibiotic therapy, which is processed in a microbiology laboratory. Results are generally available within 48-72 hours. Rapid molecular tests (PCR) are increasingly available, offering results within hours, but culture remains important for antimicrobial susceptibility testing. Clinically, diagnosis can be suspected based on characteristic symptoms (diarrhea, fever, abdominal pain) and history of food exposure, but laboratory confirmation is essential for accurate coding.

2. Is treatment available in public health systems? Yes, treatment for Salmonella enteritis is widely available in public health systems. Most cases require only supportive measures: adequate hydration (oral or intravenous depending on severity), electrolyte replacement, and symptomatic control of nausea and fever. These treatments are accessible and low-cost. Antibiotics are generally not necessary in uncomplicated cases, being reserved for patients with severe disease, bacteremia, or high-risk groups. When indicated, appropriate antibiotics (fluoroquinolones, third-generation cephalosporins) are available in essential medication formularies of public health systems.

3. How long does treatment last? Treatment duration varies according to severity. Uncomplicated cases resolve spontaneously within 4-7 days with supportive measures alone. Hydration should be maintained throughout the symptomatic period. When antibiotic therapy is necessary, typical duration is 5-7 days for uncomplicated intestinal infection. Cases with bacteremia or extraintestinal complications may require prolonged treatment of 10-14 days or longer. Immunocompromised patients may require more prolonged therapy. It is important to complete the prescribed course even after symptom improvement to prevent recurrence and reduce the risk of carrier state.

4. Can this code be used in medical certificates? Yes, code 1A09.0 can and should be used in medical certificates when appropriate. Salmonella enteritis frequently causes temporary disability for work activities due to debilitating symptoms such as frequent diarrhea, vomiting, fever, and weakness. Typical time off work is 3-7 days, which may be prolonged in severe cases. It is important to specify in the certificate both the descriptive diagnosis ("Salmonella enteritis") and the ICD-11 code, facilitating administrative processing. Additionally, food handlers and healthcare professionals may require prolonged time off until complete resolution of symptoms and, in some contexts, negative follow-up cultures, due to transmission risk.

5. Is it necessary to notify cases of Salmonella enteritis to health authorities? In many jurisdictions, confirmed cases of Salmonella enteritis are subject to mandatory reporting to public health authorities, especially when associated with outbreaks. Notification allows epidemiological investigation, identification of contamination sources, implementation of control measures, and prevention of secondary cases. Healthcare professionals should be familiar with local reporting regulations. Even in places where individual notification is not mandatory, outbreaks or clusters of cases should always be reported to allow appropriate public health response.

6. Can patients continue shedding the bacterium after symptom resolution? Yes, fecal shedding of Salmonella can persist for weeks after clinical resolution. Approximately half of patients continue shedding the bacterium for 4-5 weeks after infection, and a small proportion may become chronic carriers (shedding for more than one year). This fact has important implications for transmission prevention: patients should maintain rigorous hand hygiene, especially after toilet use and before handling food, even after symptom improvement. Food handlers and healthcare professionals may require negative cultures before returning to high-risk activities.

7. Is there a vaccine available against Salmonella enteritis? There is no vaccine available against non-typhoidal Salmonella, which causes enteritis coded as 1A09.0. Existing Salmonella vaccines are specific for S. typhi (typhoid fever) and do not provide protection against other serotypes. Prevention of Salmonella enteritis is based on food safety measures: adequate cooking of food (especially eggs, poultry, and meat), avoiding consumption of raw or undercooked products, pasteurization of milk and dairy products, proper hygiene in food handling, and sanitary control in the food production chain.

8. What are the possible complications of Salmonella enteritis? Although most cases are self-limited, complications can occur, especially in vulnerable groups. The most common include severe dehydration with electrolyte disturbances, requiring hospitalization and intravenous hydration. Bacteremia occurs in a small percentage of cases, potentially leading to focal infections in bones, joints, meninges, or endocardium. Reactive arthritis may develop weeks after intestinal infection, causing joint pain and inflammation. Post-infectious irritable bowel syndrome is reported in some patients, with persistent intestinal symptoms after resolution of acute infection. These complications require appropriate additional codes beyond 1A09.0.

Conclusion: The ICD-11 code 1A09.0 for Salmonella enteritis represents an essential tool for accurate documentation of this important cause of infectious gastroenteritis. Appropriate coding requires clear understanding of diagnostic criteria, differentiation of similar conditions, and appropriate documentation of clinical and epidemiological context. Healthcare professionals should familiarize themselves with the nuances of this code, its appropriate application, and its differences from ICD-10, ensuring quality data that support epidemiological surveillance, clinical research, and public health policies aimed at prevention and control of this foodborne infection.

External References

This article was prepared based on reliable scientific sources:

🌍 WHO ICD-11 - Salmonella Enteritis
🔬 PubMed Research on Salmonella Enteritis
🌍 WHO Health Topics
📋 CDC - Centers for Disease Control
📊 Clinical Evidence: Salmonella Enteritis
📋 Ministry of Health - Brazil
📊 Cochrane Systematic Reviews

References verified on 2026-02-04

Salmonella Enteritis

Share