Clinical Overview of extensively drug-resistant Salmonella Newport with an NDM-1 gene

What to know

  • An extensively drug-resistant strain of Salmonella Newport with an NDM-1 gene has been associated with an outbreak linked to moringa powder capsules. This is the first documented outbreak of Salmonella with an NDM-1 gene in the United States.
  • If antibiotics are needed, infection with this strain may not be treatable with commonly recommended antibiotics or with carbapenem antibiotics, including meropenem.
  • Tailor antibiotic treatment to antimicrobial susceptibility testing results when possible.
Medical illustration of drug-resistant, nontyphoidal, Salmonella bacteria.

Overview

CDC has detected a strain of Salmonella Newport with unusual and highly concerning antimicrobial resistance. Whole genome sequencing analysis of clinical samples from ill people in an outbreak linked to Rosabella moringa powder capsules predicts that most of the bacteria are extensively drug resistant (XDR). Antimicrobial susceptibility testing to confirm resistance is currently underway.

  • Most people with Salmonella infection recover without antibiotics. If antibiotics are needed, infections with this strain may not be treatable with commonly recommended antibiotics and may require a different antibiotic choice.
  • XDR Salmonella are resistant to all first-line and alternative antibiotics commonly recommended for the treatment of Salmonella infections.
  • This strain also might be resistant to multiple β-lactam antibiotics, including meropenem and other carbapenems, because it carries an NDM-1 carbapenemase gene.

Diagnosis

  • Obtain appropriate cultures (e.g., stool, urine, blood).
    • If Salmonella is identified by a culture-independent diagnostic test (CIDT), a follow-up culture is recommended to obtain an isolate for antimicrobial susceptibility testing.
    • Serologic testing is unreliable and not advised.
  • Order antimicrobial susceptibility testing of the Salmonella isolate to guide the choice of antibiotic if antibiotics are needed.

Reminder

Report all laboratory-confirmed Salmonella infections, following guidance from your local or state health department.

Patient management

Keep in mind

At present, CDC and professional societies do not have evidence-based recommendations for treating infection with XDR Salmonella with carbapenemase genes.

Treatment recommendations

  • Limit use of antibiotics for patients with acute diarrheal illness to those with clinical indications.
  • Consider the resistance profile of this strain (XDR Salmonella Newport with an NDM-1 gene) when selecting empiric treatment for patients who consumed Rosabella moringa powder capsules in the 7 days before illness began.
    • Infection with this strain may not be treatable with amoxicillin-clavulanic acid, ampicillin, azithromycin, ceftriaxone, ciprofloxacin, meropenem, and trimethoprim-sulfamethoxazole.
    • Clinical breakpoints to determine resistance have not been established for azithromycin, but most isolates carry a macrolide resistance gene that typically correlates with an elevated minimum inhibitory concentration (>32 µg/ml).
  • Tailor antibiotic treatment to antimicrobial susceptibility testing (AST) results when available.
    • Consult with a clinical microbiologist regarding AST options when isolates are resistant to normally reported drugs.

Considerations for XDR or complicated infection

Tip

Consider consultation with an infectious disease specialist for management of patients with XDR or complicated Salmonella infection. Patients receiving antibiotics should be monitored for treatment failure.

Patient counseling

  • Advise patients that they can take steps to prevent the spread of disease.
  • Advise patients about returning to work based on local and state health department recommendations.
    • Some health departments require a negative stool test before a person can return to work in a high-risk setting (such as food preparation, childcare, or healthcare) after a Salmonella infection.

Resources

Treatment guidance

Selected publications

CDC data

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Content Source:
National Center for Emerging and Zoonotic Infectious Diseases (NCEZID)