Question
A 32-year-old man presents with high-grade fever and abdominal discomfort after returning from travel. Which one of the following statements about Salmonella infections is accurate?
a. Skin rash is seen in nearly every case of enteric fever
b. These bacteria normally exist harmlessly in the human intestine
c. They are strictly obligate anaerobes
d. Pulse rate may be lower than expected for the degree of fever
e. Salmonella typhi is divided into serotypes A, B, and D
Answer:
Pulse rate may be lower than expected for the degree of fever
Explanation (Detailed)
The correct statement refers to relative bradycardia (Faget sign), a classic but not universal feature of typhoid fever caused by Salmonella typhi. Normally, fever increases heart rate (~10 beats/min per 1°C rise), but in typhoid, this expected rise is blunted.
Why others are incorrect:
- Rash in all patients → False. “Rose spots” occur only in ~30–40% cases and are often transient and easily missed.
- Commensal organism → False. Salmonella species are pathogenic, not normal gut flora.
- Strict anaerobes → False. They are facultative anaerobes (can survive with or without oxygen).
- Type A, B, C classification → False for S. typhi. These refer to Salmonella paratyphi (A, B, C), not S. typhi.
Cheat Sheet (Exam Focus)
Organism
- Gram-negative rod
- Facultative anaerobe
- Not part of normal gut flora
Transmission
- Feco-oral route
- Contaminated food/water
Clinical Features (Typhoid)
- Step-ladder fever
- Relative bradycardia (Faget sign)
- Abdominal pain, distension
- Constipation > diarrhoea
- Rose spots (~30–40%)
Investigations
- Blood culture → best early test
- Stool/urine → later supportive
- Widal → unreliable
Treatment
- Ceftriaxone / Azithromycin
- Avoid fluoroquinolones unless sensitive
Complications
- Intestinal perforation
- GI bleed
- Chronic carrier (gallbladder)
- Osteomyelitis (esp. sickle cell)
Flash Cards
Q: What is Faget sign?
A: Relative bradycardia in the presence of fever (classically typhoid).
Q: Is Salmonella part of normal gut flora?
A: No, it is pathogenic.
Q: Oxygen requirement of Salmonella?
A: Facultative anaerobe.
Q: Most reliable early diagnostic test in typhoid?
A: Blood culture.
Q: Which Salmonella species has A, B, C types?
A: Salmonella paratyphi.
MCQs (High-Yield & Challenging)
1. A patient with persistent fever has a pulse-temperature dissociation. Which organism is most likely?
a. Streptococcus pneumoniae
b. Escherichia coli
c. Salmonella typhi
d. Staphylococcus aureus
Answer: c
Explanation: Relative bradycardia is classic for typhoid.
2. Which of the following statements is false regarding Salmonella?
a. Gram-negative bacilli
b. Facultative anaerobes
c. Common commensals in healthy gut
d. Transmitted via contaminated food
Answer: c
Explanation: Salmonella is pathogenic, not commensal.
3. Rose spots in typhoid fever are:
a. Seen in all cases
b. Pathognomonic and persistent
c. Present in about one-third of patients
d. Only seen in severe disease
Answer: c
Explanation: Occur in ~30–40%, transient.
4. Which feature is more typical of typhoid than non-typhoidal Salmonella?
a. Profuse diarrhoea
b. Constipation predominance
c. Rapid onset vomiting
d. Severe dehydration
Answer: b
Explanation: Constipation is more typical in typhoid.
5. Which investigation is most useful in early diagnosis of typhoid?
a. Stool culture
b. Urine culture
c. Blood culture
d. Widal test
Answer: c
Explanation: Blood culture is best early.
6. Which of the following is false regarding Salmonella classification?
a. Based on O and H antigens
b. Includes multiple serotypes
c. Typhi classified as A, B, C
d. Paratyphi has A, B, C types
Answer: c
Explanation: Typhi is not classified as A, B, C.
7. Which complication is classically associated with Salmonella in sickle cell disease?
a. Endocarditis
b. Osteomyelitis
c. Meningitis
d. Pneumonia
Answer: b
Explanation: Salmonella is a common cause of osteomyelitis in SCD.
Summary for Quick Exam Revision
Typhoid fever, caused by Salmonella typhi, is a systemic infection transmitted via the fecal-oral route. The organism is a Gram-negative facultative anaerobe and is not part of normal gut flora. A key clinical clue is relative bradycardia (Faget sign), where pulse rate is lower than expected for fever. Patients commonly present with step-ladder fever, abdominal pain, and constipation rather than diarrhoea. Rose spots are seen in only about one-third of patients. Blood culture remains the gold standard for early diagnosis, while Widal test is unreliable. Treatment includes ceftriaxone or azithromycin, with increasing resistance to fluoroquinolones. Important complications include intestinal perforation, hemorrhage, chronic carriage, and osteomyelitis (especially in sickle cell disease). Salmonella paratyphi—not typhi—is classified into types A, B, and C.