What are the treatment options for invasive Salmonella vs invasive Campylobacter infections?

From the Guidelines

Treatment options for invasive Salmonella and Campylobacter infections differ based on their antimicrobial susceptibility patterns and clinical presentation, with azithromycin being the preferred treatment for Campylobacter infections due to increasing fluoroquinolone resistance, as supported by the most recent and highest quality study 1.

Key Considerations

• Invasive Salmonella infections can be treated with fluoroquinolones like ciprofloxacin (500 mg orally twice daily for 7-14 days) as first-line therapy, with third-generation cephalosporins such as ceftriaxone (1-2 g IV daily) as alternatives when resistance is suspected 1.
• For invasive Campylobacter infections, macrolides are preferred, with azithromycin (500 mg orally daily for 3-5 days) being the treatment of choice due to increasing fluoroquinolone resistance, as demonstrated in a study published in the Journal of Travel Medicine 1.
• Azithromycin has been shown to be superior to levofloxacin in achieving clinical cure in settings with high rates of FQ-resistant Campylobacter spp. 1.
• Supportive care including fluid replacement is essential for both infections, particularly when diarrhea causes significant fluid losses.

Clinical Features and Treatment Duration

• Clinical signs and symptoms of invasive Salmonella and Campylobacter infections include watery, mucoid or bloody diarrhea, abdominal tenderness, fever, and nausea.
• Abdominal pain tends to be particularly severe in Campylobacter enteritis and may mimic appendicitis in Yersinia spp. and Campylobacter spp. infection.
• Treatment duration may need extension in immunocompromised patients or those with complications like endovascular infections or abscesses.
• Blood cultures should be obtained before starting antibiotics, and susceptibility testing is crucial for guiding definitive therapy.

Antibiotic Resistance and Treatment Options

• Fluoroquinolone resistance is increasing in Campylobacter spp., making azithromycin a preferred treatment option 1.
• FQs retain efficacy in much of the developing world, but concerns about reduced benefit due to the likelihood of FQ-resistant Campylobacter spp. or Shigella spp. being the cause of dysentery, as well as significant risk concerns, make azithromycin a better choice 1.
• Rifaximin, a nonabsorbable antibiotic, has demonstrated comparable efficacy to FQs in non-invasive TD caused by diarrheagenic E. coli, but is less effective for the treatment of invasive pathogens 1.

From the FDA Drug Label

INDICATIONS AND USAGE Ciprofloxacin Tablets USP, 250 mg, 500 mg and 750 mg is indicated for the treatment of infections caused by susceptible strains of the designated microorganisms in the conditions and patient populations listed below... Typhoid Fever (Enteric Fever) caused by Salmonella typhi... Infectious Diarrhea caused by Escherichia coli (enterotoxigenic strains), Campylobacter jejuni, Shigella boydii†, Shigella dysenteriae, Shigella flexneri or Shigella sonnei† when antibacterial therapy is indicated.

GRAM-NEGATIVE – ... many strains of Salmonella (including S. typhosa), Shigella and Escherichia coli

The treatment options for invasive Salmonella and invasive Campylobacter infections include:

• Ciprofloxacin for the treatment of Typhoid Fever (Enteric Fever) caused by Salmonella typhi and Infectious Diarrhea caused by Campylobacter jejuni 2
• Ampicillin may be effective against some strains of Salmonella, but its efficacy has not been documented for infections other than those included in the INDICATIONS AND USAGE section 3 Key considerations:
• The choice of antibiotic should be guided by culture and susceptibility testing to ensure the selected antibiotic is effective against the invading organism.
• Local epidemiology and susceptibility patterns may contribute to the empiric selection of therapy in the absence of culture and susceptibility data.

From the Research

Clinical Features and Treatment Options

• Invasive Salmonella and invasive Campylobacter infections are both significant causes of morbidity and mortality worldwide, but the provided evidence primarily focuses on Salmonella infections.
• The clinical features of invasive Salmonella infections include acute febrile illnesses, with typhoidal and nontyphoidal Salmonella enterica serotypes being among the most common bacterial causes in the developing world 4.
• Treatment options for invasive Salmonella infections include antibiotics such as azithromycin, ceftriaxone, ciprofloxacin, and amoxicillin, with azithromycin and ceftriaxone being more effective in treating Salmonella infections based on patient outcomes 5.
• However, antibiotic resistance, particularly to fluoroquinolones, is a significant concern and threatens to undermine treatment success for these infections 4, 6, 7.
• Azithromycin is effective for the management of uncomplicated typhoid fever and may serve as an alternative oral drug in areas where fluoroquinolone resistance is common 7.
• A comparison of treatment responses to azithromycin and ciprofloxacin in uncomplicated Salmonella Typhi infection found that azithromycin was associated with prolonged bacteraemia and fever clearance times compared to ciprofloxacin 8.

Antimicrobial Resistance

• Antimicrobial resistance is a significant concern in the treatment of invasive Salmonella infections, with multidrug resistance, third-generation cephalosporin resistance, and fluoroquinolone non-susceptibility being reported in various regions 6.
• The emergence of antibiotic-resistant Salmonella strains highlights the need for effective and safe therapies, as well as the development of new vaccines and treatment strategies 4, 5, 7.

Treatment Strategies

• The choice of antibiotic treatment for invasive Salmonella infections depends on various factors, including the severity of the infection, the presence of antibiotic resistance, and the patient's clinical condition 5, 7.
• Combination therapies and novel treatment strategies are being explored to address the increasing problem of antimicrobial resistance in Salmonella infections 8.
• Further studies are required to define appropriate azithromycin dosing regimens for enteric fever and to assess novel treatment strategies, including combination therapies 8.