Is a Clostridioides difficile (C. diff) infection with a negative Nap (nucleic acid amplification) test for the 027 strain present?

From the Guidelines

A negative result for C. difficile NAP 027 strain does not rule out the possibility of C. difficile infection caused by a different strain, and clinical assessment of the patient's symptoms, white blood cell count, and kidney function remains essential for determining disease severity and appropriate management. The patient may still have C. difficile infection caused by a different strain, which still requires appropriate treatment. According to the 2019 update of the WSES guidelines for management of Clostridioides (Clostridium) difficile infection in surgical patients 1, standard treatment for non-severe C. difficile infection typically includes oral vancomycin 125 mg four times daily for 10 days or fidaxomicin 200 mg twice daily for 10 days. For severe infections, oral vancomycin is preferred.

Key Considerations

• The absence of the NAP1/027 strain may suggest a better prognosis, but clinical assessment is still essential for determining disease severity and appropriate management.
• Infection control measures should still be implemented regardless of the strain to prevent transmission.
• Repeat testing after a first negative sample during the same diarrheal episode may be useful only in selected cases with ongoing clinical suspicion during an epidemic situation or in cases with high clinical suspicion during endemic situations 1.
• Nucleic acid amplification tests (NAAT) for C. difficile toxin genes appear to be sensitive and specific and may be used as a standard diagnostic test for CDI, but the use of NAATs has limitations, including the inability to distinguish between C. difficile colonization and active disease 1.

Diagnostic Approach

• The diagnosis of CDI should be based on clinical signs and symptoms in combination with laboratory tests, and stool testing should only be performed on diarrheal stools from at-risk patients with clinically significant diarrhea (≥ 3 loose stools in 24 h) with no obvious alternative explanation 1.
• Typing is useful to differentiate C. difficile strains and to obtain epidemiological information, and PCR-ribotyping can be used to identify the NAP1/027 strain 1.

Treatment

• Standard treatment for non-severe C. difficile infection typically includes oral vancomycin 125 mg four times daily for 10 days or fidaxomicin 200 mg twice daily for 10 days 1.
• For severe infections, oral vancomycin is preferred 1.

Infection Control

• Infection control measures should still be implemented regardless of the strain to prevent transmission 1.

From the Research

C diff nap 027 negative

• The term "C diff nap 027 negative" refers to a strain of Clostridium difficile that is negative for the NAP1/B1/027 ribotype, which is known for being hypervirulent and having a high recurrence rate 2.
• Studies have shown that early fecal microbiota transplantation can be an effective treatment for CD027 infections, with a significantly reduced mortality rate compared to treatment with antibiotics alone 3.
• Other treatment options for CD027 infections include the use of vancomycin plus tigecycline, which has been shown to be effective in some cases 4.
• Fecal microbiota transplantation has also been shown to be effective in treating recurrent CDI, including cases caused by the NAP1/B1/027 strain 5, 6.
• The prevention of recurrent CDI is an important area of research, with various interventions being studied, including antibiotics, fecal microbiota transplantation, monoclonal antibodies, and probiotics 6.

Treatment Options

• Fecal microbiota transplantation: has been shown to be effective in treating CD027 infections and recurrent CDI 3, 5, 6.
• Vancomycin plus tigecycline: has been shown to be effective in some cases of CD027 infections 4.
• Antibiotics: such as fidaxomicin, have been shown to be effective in preventing recurrent CDI 6.
• Monoclonal antibodies: such as actoxumab and bezlotoxumab, have been shown to be effective in preventing recurrent CDI 6.

Recurrence and Mortality

• The NAP1/B1/027 strain of C. difficile is known for having a high recurrence rate and mortality rate 2.
• Early fecal microbiota transplantation has been shown to significantly reduce the mortality rate in CD027 infections 3.
• Recurrent CDI is a significant problem, with frequent recurrences associated with increased morbidity and mortality, high healthcare costs, and lower quality of life 6.