Understanding Salmonella: Types, Features, and Treatment

Salmonella encompasses typhoidal and non-typhoidal subtypes, each with distinct clinical features and disease implications.

### Understanding Salmonella: Key Insights for Microbiology Exams
* 🔬 Salmonella is a **gram-negative rod** that is **motile**, **acid labile**, **oxidase negative**, **facultative intracellular**, and **non-lactose fermenting**, encompassing multiple subtypes including **typhoidal** and **non-typhoidal types**.
* 🦠 The Vi antigen **prevents phagocytosis**, allowing Salmonella to **evade immune responses**, while the flagella contributes to **motility** and the Type 3 secretion system, which is **crucial for its pathogenicity**.
* ⚠ An important distinction between Salmonella and Shigella is that **Shigella lacks flagella**, which is a **key feature to remember for exams**.
* 🍽 Non-typhoidal Salmonella is primarily associated with **food-borne gastroenteritis** linked to reptiles, amphibians, poultry, and eggs, presenting with symptoms such as **diarrhea, potentially bloody**.
* 🌡 Typhoidal Salmonella causes typhoid fever, characterized by **early constipation**, **rose-colored spots on the abdomen**, and complications like **septic shock** and **hepatosplenomegaly**, with chronic carriers at risk for **gallbladder cancer**.
* 🩸 Patients with sickle cell disease face an **increased risk of osteomyelitis** due to the interplay of Salmonella's pathophysiology and the complications associated with sickle cell, including **capillary occlusion**.
* 💊 Treatment for non-typhoidal Salmonella is usually **supportive**, while typhoidal Salmonella is treated with **fluoroquinolones**, or **ceftriaxone plus azithromycin** if resistance is present.
* 📚 Remembering the **key features and associated risks of Salmonella** is crucial for success on exams like the **USMLE and COMLEX**.

Salmonella

Dirty Medicine

Salmonella is a gram-negative, motile, acid-labile, oxidase-negative, facultative intracellular, and non-lactose fermenting rod.

Salmonella is an umbrella term for multiple subtypes, notably typhoid and non-typhoid (NTS).

Typhoid and non-typhoid Salmonella cause different diseases.

Salmonella causes gastroenteritis and colitis.

Flagella promotes motility and a Type 3 secretion system, allowing attachment to and insertion into non-phagocytic cells (unlike Shigella).

Endotoxin targets the neurovascular system, decreasing circulating neutrophils.

Salmonella enters through intestinal epithelium M cells, reaching Peyer's patches and disseminating through the reticuloendothelial system.

Mnemonics: VI prevents phagocytosis; flagella relates to the Type 3 secretion system.

Clinical Features: Non-Typhoidal vs. Typhoidal Salmonella

Non-typhoidal Salmonella: food-borne gastroenteritis, +/- bloody diarrhea; associated with reptiles, amphibians, poultry, and eggs.

Typhoidal Salmonella (Typhoid fever): early constipation, non-specific GI symptoms, rose-colored spots on the abdomen, and potentially pea soup diarrhea; complications include septic shock, hepatosplenomegaly, and meningitis.

Typhoidal Salmonella is stored in the gallbladder of chronic carriers, increasing gallbladder cancer risk.

Increased risk of osteomyelitis in sickle cell patients due to decreased liver and spleen function, capillary occlusion of the GI system, and dissemination through the reticuloendothelial system.

Non-typhoidal Salmonella: usually supportive treatment. Typhoidal Salmonella: fluoroquinolones (or ceftriaxone plus azithromycin if fluoroquinolones are contraindicated or resistance is present).