Infections due to other Salmonella (ICD-11: 1A09)

1. Introduction

Infections caused by Salmonella species, excluding S. typhi and S. paratyphi, represent one of the most common causes of bacterial gastroenteritis worldwide. These infections, classified under ICD-11 code 1A09, encompass a broad spectrum of clinical manifestations ranging from mild self-limited diarrhea to severe septicemia and extraintestinal focal infections.

The clinical importance of these infections lies not only in their frequency but also in the potential for serious complications, especially in vulnerable populations such as young children, elderly individuals, pregnant women, and immunocompromised patients. Transmission occurs predominantly through ingestion of contaminated food or water, with animal-derived products, especially eggs, poultry, undercooked meats, and unpasteurized dairy products, constituting the main transmission vehicles.

From a public health perspective, these infections represent a significant challenge due to their frequently epidemic nature, capacity for rapid dissemination through the food chain, and substantial economic impact related to outbreaks in commercial establishments and institutions. Increasing antimicrobial resistance in Salmonella strains has also generated growing concern among global health authorities.

Correct coding of these infections is critical for multiple reasons: it enables precise epidemiological tracking of outbreaks, facilitates appropriate allocation of public health resources, ensures appropriate reimbursement in health systems, aids in surveillance of antimicrobial resistance patterns, and contributes to research on infectious disease trends. Clear distinction between non-typhoidal Salmonella infections (code 1A09) and typhoid/paratyphoid fever is essential, as these conditions differ significantly in severity, treatment, and public health implications.

2. Correct ICD-11 Code

Code: 1A09

Description: Infections due to other Salmonella

Parent category: Bacterial intestinal infections

This specific ICD-11 code is designated to classify all infections caused by Salmonella species other than S. typhi or S. paratyphi. The most commonly involved species include S. enteritidis, S. typhimurium, S. newport, S. heidelberg, and S. javiana, among hundreds of other identified serotypes.

Important coding notes: This code should be used to document infection or food poisoning due to any Salmonella species other than S. typhi and S. paratyphi. The term "other Salmonella" refers specifically to non-typhoidal salmonellae, which predominantly cause acute gastroenteritis, although they may occasionally result in bacteremia and extraintestinal infections.

Proper coding requires laboratory confirmation whenever possible, through culture of stool, blood, or other relevant clinical specimens. In the context of confirmed outbreaks, clinically compatible cases may be coded based on epidemiological criteria, even in the absence of individual laboratory confirmation. It is essential to document the specific serotype when identified, as this information is valuable for epidemiological investigations and outbreak tracking, although the specific serotype does not change the primary ICD-11 code.

3. When to Use This Code

Code 1A09 should be applied in specific clinical scenarios where there is evidence of non-typhoidal Salmonella infection:

Scenario 1: Acute gastroenteritis with laboratory confirmation Patient presents with acute diarrhea (often with blood or mucus), fever, abdominal cramping, and nausea, with onset 12 to 72 hours after ingestion of suspected food. Stool culture identifies Salmonella enteritidis. This is the most common and straightforward scenario for use of code 1A09, regardless of the severity of gastrointestinal symptoms.

Scenario 2: Foodborne illness outbreak related to an event Multiple individuals who participated in a social event develop similar gastrointestinal symptoms within a compatible timeframe. Epidemiological investigation identifies contaminated common food, and at least one laboratory sample confirms Salmonella. All clinically compatible cases within the outbreak may receive code 1A09, even those without individual laboratory confirmation.

Scenario 3: Bacteremia due to non-typhoidal Salmonella Immunocompromised patient (for example, with HIV infection, undergoing chemotherapy, or with sickle cell anemia) presents with persistent fever and positive blood culture for Salmonella typhimurium, with or without prominent gastrointestinal symptoms. Code 1A09 remains appropriate and may be supplemented with additional codes to specify the bacteremia and underlying immunosuppressive condition.

Scenario 4: Focal extraintestinal infections Patient develops osteomyelitis, septic arthritis, meningitis, or abscess at another site, with culture from the affected site growing non-typhoidal Salmonella. These complications, although less common, are still coded with 1A09 as the etiological diagnosis, supplemented with a specific code for the site of infection.

Scenario 5: Asymptomatic carrier identified during screening Food handler undergoing routine examination presents with positive stool culture for Salmonella without clinical symptoms. Although controversial in some contexts, code 1A09 may be appropriate to document carrier status, especially if there is a need for follow-up or temporary occupational restrictions.

Scenario 6: Gastroenteritis in a child with dehydration Eight-month-old infant presents with profuse watery diarrhea, fever, and signs of moderate to severe dehydration, requiring hospitalization and rehydration therapy. Subsequent stool culture confirms Salmonella heidelberg. Code 1A09 is used together with codes for dehydration and any other complications present.

4. When NOT to Use This Code

It is crucial to recognize situations where code 1A09 is not appropriate, avoiding coding errors that may compromise epidemiological data:

Typhoid or paratyphoid fever: When culture specifically identifies S. typhi or S. paratyphi, different codes should be used (1A07 for typhoid fever, 1A08 for paratyphoid fever). These conditions represent distinct clinical entities with characteristic systemic presentation, prolonged course, and different treatment implications.

Viral gastroenteritis: Gastrointestinal symptoms without laboratory confirmation of Salmonella should not automatically receive code 1A09. In the absence of bacteriological confirmation or strong epidemiological evidence, nonspecific gastroenteritis requires different codes. Viral gastroenteritis is much more common and generally presents with a shorter course.

Other bacterial intestinal infections: When other pathogens are identified as the cause of gastroenteritis (Campylobacter, Shigella, pathogenic E. coli, Yersinia), specific codes for these agents should be used. Coinfection is possible but uncommon, requiring multiple codes when documented.

Traveler's diarrhea without confirmation: Although Salmonella is a possible cause of traveler's diarrhea, this syndromic diagnosis should not be automatically coded as 1A09 without laboratory confirmation or strong epidemiological evidence specific to Salmonella.

Intestinal colonization without active infection: Incidental detection of Salmonella in stool culture from a patient without current or recent gastrointestinal symptoms, especially if the culture was performed for unrelated reasons, may not justify coding as active infection, depending on the clinical context and purpose of documentation.

5. Step-by-Step Coding Process

Step 1: Assess diagnostic criteria

Ideal diagnostic confirmation is based on the combination of compatible clinical presentation and laboratory confirmation. Characteristic symptoms include diarrhea (watery or bloody), fever, abdominal cramping, nausea and vomiting, typically beginning 12 to 72 hours after exposure. Stool culture remains the diagnostic gold standard, although molecular methods (PCR) are increasingly available.

For suspected cases, it is essential to collect detailed history including food exposures in the preceding 72 hours, contact with animals (especially reptiles, birds, and farm animals), recent travel, and other similar cases in the patient's environment. Physical examination should assess hydration status, presence of fever, and abdominal tenderness.

Laboratory investigations include stool culture (ideally collected before initiating antibiotics), complete blood count frequently showing leukocytosis with left shift, and blood cultures in cases with persistent fever or patients with risk factors for bacteremia. Imaging studies are generally not necessary for uncomplicated gastroenteritis.

Step 2: Verify specifiers

Although code 1A09 does not have formal subcategories in ICD-11, clinical documentation should specify important characteristics: severity (mild, moderate, severe based on dehydration and systemic toxicity), presence of complications (bacteremia, focal infections, severe dehydration), specific serotype when identified, and presence of predisposing conditions.

Duration of symptoms should be documented, as most cases resolve in 4 to 7 days, while persistence beyond 2 weeks may indicate complications or carrier state. Antimicrobial resistance patterns of the isolate, when available, are valuable information that should be recorded.

Step 3: Differentiate from other codes

1A00 (Cholera): Differentiated by identification of Vibrio cholerae, clinical presentation with characteristic profuse watery diarrhea "rice water," rapid severe dehydration, and absence of significant fever. Cholera is epidemiologically distinct, usually associated with areas with inadequate sanitation.

1A01 (Intestinal infection by other bacteria of the genus Vibrio): Requires identification of non-cholerae Vibrio species (V. parahaemolyticus, V. vulnificus). Frequently associated with consumption of seafood, especially in coastal areas. V. vulnificus can cause skin infections and severe septicemia in patients with liver disease.

1A02 (Intestinal infections by Shigella): Distinguished by identification of Shigella spp., tendency to cause more severe dysentery with blood and mucus, higher fever, and lower inoculum necessary to cause disease. Transmission predominantly person-to-person, different from primarily foodborne transmission of Salmonella.

Step 4: Required documentation

Essential checklist for adequate documentation:

• Detailed clinical presentation with specific symptoms and chronology
• Stool culture results with identification of Salmonella species/serotype
• Blood cultures and results when performed
• Relevant food and epidemiological exposures
• Assessment of severity and presence of complications
• Predisposing conditions or relevant comorbidities
• Treatment instituted (supportive care, antibiotics if indicated)
• Antimicrobial resistance pattern when available
• Clinical course and response to treatment

Documentation should be sufficient to justify coding even on retrospective review, including clinical reasoning when laboratory confirmation is not available but code is applied based on epidemiological criteria.

6. Complete Practical Example

Clinical Case

A 34-year-old female patient, previously healthy, presents to the emergency department with a complaint of severe diarrhea for 36 hours. She reports that symptoms began abruptly with abdominal cramping followed by liquid stools, initially watery and subsequently with mucus and blood streaks. She reports having had 12 diarrheal episodes in the last 24 hours, associated with fever of 38.5°C, nausea, and two episodes of vomiting. She denies recent travel or antibiotic use.

Upon detailed questioning about food exposures, the patient mentions having attended a family barbecue three days ago, where she consumed grilled chicken, various salads with eggs and homemade mayonnaise. Three other family members who attended the event developed similar symptoms in the same period.

On physical examination, the patient is in fair general condition, dehydrated (dry mucous membranes, decreased skin turgor), febrile (38.2°C), tachycardic (110 bpm), blood pressure 100/70 mmHg. Abdomen slightly distended, increased bowel sounds, diffusely tender on palpation without signs of peritoneal irritation. No other significant findings on examination.

The following tests were ordered: complete blood count showing leukocytes 13,500/mm³ with 78% neutrophils, normal hemoglobin and platelets; electrolytes showing mild hyponatremia (132 mEq/L) and hypokalemia (3.2 mEq/L); normal renal function; stool culture collected before any intervention.

The patient was treated with vigorous intravenous hydration, electrolyte replacement, and symptomatic medications. Due to the presence of high fever, bloody diarrhea, and leukocytosis, empiric antibiotic therapy with ciprofloxacin was initiated. After 48 hours, stool culture returned positive for Salmonella enteritidis sensitive to ciprofloxacin and other tested antimicrobials.

The patient progressed with progressive improvement of symptoms, reduction in stool frequency, afebrile after 72 hours of treatment. She was discharged from the hospital after 4 days with instructions to complete 7 days of antibiotic therapy, maintain adequate hydration, and return if symptoms worsen.

Step-by-Step Coding

Analysis of criteria:

• Clinical presentation compatible: acute gastroenteritis with bloody diarrhea, fever, systemic symptoms
• Laboratory confirmation: positive stool culture for Salmonella enteritidis
• Supportive epidemiological context: family outbreak related to suspected food
• Exclusion of other diagnoses: specific culture for Salmonella, not S. typhi or S. paratyphi

Code selected: 1A09 - Infections due to other Salmonella

Complete justification: The code 1A09 is appropriate because: (1) there is definitive laboratory confirmation of non-typhoidal Salmonella (S. enteritidis); (2) the clinical presentation is characteristic of non-typhoidal salmonellosis with acute gastroenteritis; (3) there is no evidence of typhoid or paratyphoid fever that would require different codes; (4) the epidemiological context (family outbreak related to food) is typical of non-typhoidal Salmonella infection.

Applicable complementary codes:

• Code for dehydration (5C70 - Volume depletion) to document the complication that prompted hospitalization
• Code for hypokalemia (5C52.1) if considered clinically significant
• Possible Z code for contact with or exposure to communicable disease for affected family members in the same outbreak

Documentation should include the specific serotype (S. enteritidis) and antimicrobial susceptibility pattern for epidemiological purposes, although these do not alter the primary ICD-11 code.

7. Related Codes and Differentiation

Within the Same Category

1A00: Cholera

• When to use: Laboratory identification of Vibrio cholerae O1 or O139, presentation with profuse watery diarrhea ("rice water"), severe dehydration with rapid onset.
• Main difference vs. 1A09: Completely different etiologic agent (Vibrio vs. Salmonella), distinct clinical presentation without significant fever, different epidemiologic pattern generally associated with areas with poor sanitation and contaminated water sources.

1A01: Intestinal infection by other bacteria of the genus Vibrio

• When to use: Culture identifies non-cholerae Vibrio species (V. parahaemolyticus, V. vulnificus, V. alginolyticus). Frequently related to consumption of raw or undercooked seafood.
• Main difference vs. 1A09: Different bacterial genus with distinct microbiological characteristics, strong epidemiologic association with seafood, V. vulnificus can cause wound infections and fulminant septicemia in patients with liver disease.

1A02: Intestinal infections by Shigella

• When to use: Culture identifies Shigella spp. (S. dysenteriae, S. flexneri, S. boydii, S. sonnei). Typical presentation with dysentery (bloody diarrhea with mucus), tenesmus, high fever.
• Main difference vs. 1A09: Different bacterium with distinct pathogenesis, lower infectious inoculum (10-100 organisms vs. thousands for Salmonella), transmission predominantly person-to-person or contaminated water rather than food, greater tendency to cause severe dysentery.

Differential Diagnoses

Campylobacteriosis: Very similar clinical presentation with diarrhea (frequently bloody), fever and abdominal cramps. Differentiation requires specific culture. Campylobacter jejuni is frequently associated with consumption of undercooked poultry.

Infections by enteropathogenic E. coli: Various E. coli pathotypes can cause gastroenteritis. Enterohemorrhagic E. coli (EHEC) can cause similar hemorrhagic colitis. Differentiation requires specific laboratory tests including toxin detection.

Viral gastroenteritis: Norovirus and rotavirus are very common causes of acute gastroenteritis. Generally present with shorter course, less prominent fever, and more significant vomiting than diarrhea. Confirmation requires specific tests for viruses.

8. Differences with ICD-10

In ICD-10, non-typhoidal Salmonella infections were coded under A02, with specific subcategories:

• A02.0: Salmonella enteritis
• A02.1: Salmonella septicemia
• A02.2: Localized Salmonella infections
• A02.8: Other specified Salmonella infections
• A02.9: Unspecified Salmonella infection

ICD-11 simplifies this structure with the single code 1A09, eliminating formal subcategories based on clinical manifestation. This change better reflects clinical reality where the same infection may have multiple manifestations or progress from one form to another.

Major changes in ICD-11: The more simplified structure reduces coding complexity while maintaining sufficient specificity for epidemiological purposes. ICD-11 emphasizes detailed clinical documentation in free text rather than multiple subcodes. Additional codes may be used to specify complications (bacteremia, focal infections) when clinically relevant.

Practical impact: Coders will encounter a more straightforward process without the need to decide between multiple subcategories. Epidemiological data may require analysis of additional clinical documentation to distinguish between uncomplicated gastroenteritis and invasive forms. Health information systems need to be updated to map ICD-10 codes A02.x to ICD-11 1A09, potentially with additional flags to capture details of clinical manifestation.

9. Frequently Asked Questions

How is a definitive diagnosis of Salmonella infection made? Definitive diagnosis requires bacterial isolation through microbiological culture. For gastroenteritis, stool culture is the standard method, ideally collected in the early phases of disease and before antibiotic initiation. For cases with suspected bacteremia, blood cultures should be obtained. Molecular methods (PCR) are increasingly available and can provide faster results, although culture is still necessary for antimicrobial susceptibility testing. In outbreak contexts, clinically compatible cases epidemiologically linked to confirmed cases may be considered probable even without individual confirmation.

Is treatment available in public health systems? Treatment for non-typhoidal salmonellosis is widely available in public health systems globally. Most cases require only supportive therapy with adequate hydration and electrolyte replacement, which are low-cost interventions. Antibiotics, when necessary for severe or complicated cases, include relatively accessible options such as fluoroquinolones, third-generation cephalosporins, and azithromycin. Oral rehydration solutions are extremely cost-effective and widely available. Hospitalization may be necessary for cases with severe dehydration, bacteremia, or high-risk patients, but most patients can be managed on an outpatient basis.

How long do treatment and the disease last? Uncomplicated Salmonella gastroenteritis typically resolves spontaneously in 4 to 7 days without specific antimicrobial treatment. Supportive therapy with hydration should continue until complete symptom resolution. When antibiotics are indicated (severe cases, bacteremia, high-risk patients), the typical course is 5 to 7 days for gastroenteritis and 7 to 14 days for bacteremia. Extraintestinal focal infections may require prolonged treatment for several weeks. Fecal shedding of the bacteria may persist for weeks to months after symptom resolution, although this generally does not require treatment in immunocompetent individuals.

Can this code be used in medical certificates and official documents? Yes, code 1A09 can and should be used in medical certificates, compulsory notification reports, medical leave documents, and other official records when appropriate. For work absence certificates, it is important to specify the necessary duration based on disease severity and type of occupation, particularly for food handlers who may require absence until confirmation of bacterial clearance. Documentation for public health purposes should include details about serotype and possible sources of infection to facilitate outbreak investigation.

What are the main risk factors for severe infection? High-risk groups include infants and young children (especially under 1 year of age), elderly individuals over 65 years, pregnant women, immunocompromised patients (HIV/AIDS, chemotherapy, immunosuppressant use, transplant recipients), patients with sickle cell disease or other hemoglobinopathies, individuals with inflammatory bowel disease, and those with achlorhydria or use of potent antacids. These groups have increased risk of bacteremia, extraintestinal infections, and prolonged course, often justifying antimicrobial treatment even when not indicated in healthy individuals.

How can Salmonella infections be prevented? Prevention is based on safe food handling practices: thoroughly cook meat, poultry, and eggs; avoid consumption of raw or undercooked eggs; separate raw foods from cooked foods; wash hands, utensils, and surfaces after contact with raw foods; refrigerate foods appropriately; avoid consumption of unpasteurized milk and dairy products. Special care with pets, especially reptiles and birds, including rigorous hand washing after contact. When traveling, follow precautions with water and food in high-risk areas. Food handlers with active infection should be removed from work until complete resolution.

When are antibiotics necessary? Antibiotics are not routinely recommended for uncomplicated Salmonella gastroenteritis, as they may prolong the carrier state and contribute to antimicrobial resistance. Clear indications for antimicrobial therapy include: documented or suspected bacteremia, signs of extraintestinal infection, patients with risk factors for invasive disease (listed above), infants under 3 months of age, and severe disease with high fever and systemic toxicity. Antimicrobial selection should be guided by local resistance patterns and, when available, susceptibility testing of the specific isolate.

What is the incubation period and when is a person contagious? The typical incubation period is 12 to 72 hours after exposure, although it can range from 6 hours to several days. Infected individuals may shed Salmonella in feces throughout the symptomatic phase and for weeks after symptom resolution. The average duration of shedding is 4 to 5 weeks in adults, but may be more prolonged in children and occasionally persist for months. Chronic carrier state (shedding for more than 1 year) is rare in non-typhoidal infections, unlike typhoid fever. Hygiene precautions, especially hand washing after toilet use, should be maintained for at least 48 hours after complete resolution of diarrhea.

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Final Note: This article provides guidance for clinical coding based on ICD-11. Appropriate coding requires complete clinical evaluation, adequate diagnostic confirmation, and detailed documentation. Healthcare professionals should always consider the individual clinical context and consult local public health guidelines for case notification and management. Appropriate epidemiological surveillance of Salmonella infections is essential for early detection and outbreak control, protection of public health, and monitoring of antimicrobial resistance trends.

External References

This article was prepared based on reliable scientific sources:

1. 🌍 WHO ICD-11 - Infections due to other Salmonella
2. 🔬 PubMed Research on Infections due to other Salmonella
3. 🌍 WHO Health Topics
4. 📋 CDC - Centers for Disease Control
5. 📊 Clinical Evidence: Infections due to other Salmonella
6. 📋 Ministry of Health - Brazil
7. 📊 Cochrane Systematic Reviews

References verified on 2026-02-04