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May 15, 2019

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Journal Club

In this feature, a panel of IDSA members identifies and critiques important new studies in the current literature that have a significant impact on the practice of infectious diseases medicine.

  • Is Vancomycin Really Preferred Over Metronidazole for Mild C. difficile Infection?
  • Marijuana for People Living with HIV and Chronic Pain

For a review of other recent research in the infectious diseases literature, see “In the Literature,” by Stanley Deresinski, MD, FIDSA, in each issue of Clinical Infectious Diseases.

 

Manie Beheshti, MD.jpg

Is Vancomycin Really Preferred Over Metronidazole for Mild C. difficile Infection?

Reviewed by A. Krishna Rao, MD, MS

Clostridioides (formerly Clostridium) difficile infection (CDI) can present with severe disease leading to death, and frequently recurs even after initial cure. For mild disease, prior studies suggested metronidazole was noninferior to vancomycin for achieving sustained cure (resolution of diarrhea at end of treatment without recurrence ~1 month after treatment). Recently updated IDSA guidelines, however, upon reviewing evidence from five randomized controlled trials (RCTs), conclude that vancomycin is superior for sustained cure, even in mild CDI.

A new retrospective, two-phase study conducted by Appaneal et al. and reported in Clinical Infectious Diseases compares metronidazole and vancomycin with respect to treatment failure (all-cause mortality or recurrence 30 days post-treatment). In the first phase, they included 3,656 patients from 125 Veteran’s Affairs medical centers with mild CDI (white blood cell count < 15,000 cells/µL and serum creatinine < 1.5 mg/dL) treated with metronidazole. Failure occurred in 374 patients, and a multivariable analysis identified several predictors (e.g., age ≥ 65 years and low serum albumin). In the second phase, they used these predictors of failure alongside predictors of metronidazole vs. vancomycin treatment to develop a propensity score, used to match metronidazole treated patients to 115 vancomycin treated patients. There was no significant difference in failure noted between the matched cohorts.

While one may be tempted to conclude from this study’s results that metronidazole is noninferior to vancomycin for mild CDI, several limitations preclude this. It is retrospective, and the sample size was small. The cohorts were matched in part on predictors of failure and then compared with respect to failure, with the investigators finding no difference—a somewhat circular chain of reasoning. Finally, even if there is no mortality difference, this study does not evaluate sustained cure, which favors vancomycin based on data from five RCTs. However, both here and in prior studies, many patients do achieve good results with metronidazole for treatment of CDI. Given that vancomycin is disruptive to the microbiome and its use associates with selection for resistance (e.g., Enterococcus), future studies that identify which subgroups can be successfully treated with metronidazole would be useful.

(Appaneal et al. Clin Infect Dis. Published online: Dec. 18, 2018.)

 

Marijuana for People Living with HIV and Chronic Pain

Reviewed by Lauren Richey, MD, MPH, FIDSA

As the availability of medical marijuana in the United States continues to expand, medical providers are interested in determining its role and efficacy in chronic pain. HIV and/or AIDS is a qualifying diagnosis in most states that allow medical marijuana but very little data exists to assess its efficacy. A new study published in the Journal of Acquired Immune Deficiency Syndromes assessed marijuana use as it relates to pain severity and changes in opioid prescriptions among people living with HIV (PLWH).

The authors analyzed data from a large ongoing prospective cohort of PLWH and chronic pain embedded within the Centers for AIDS Research Network of Integrated Clinical Systems. These sites are medical homes where enrolled patients’ information is collected from the medical record and from patient responses to standardized questions on pain and substance use collected every 4 to 6 months. The sites included clinics in Massachusetts, Alabama, California, North Carolina, and Washington. Patients were followed for 1 year following their initial pain assessment. Patients with moderate pain for over 3 months were defined as having chronic pain. Outcomes were changes in reported pain and initiation or discontinuation of opioids during the study period.

There were 433 PLWH in the study; 72 percent had no marijuana use in the past 3 months. The authors found that neither increases nor decreases in marijuana use were associated with changes in pain severity in study participants. They also found that marijuana use at the index visit was not associated with lower odds of opioid initiation or higher odds of opioid discontinuation. Limitations included a small sample size, only 1 year of data, inability to quantify the marijuana dose, and the inclusion of only initiation and discontinuation of opioids as opposed to increases or decreases in the dose.

The decision to recommend marijuana for chronic pain needs to be considered within the context of potential harms and limited evidence for benefits at this time. More studies are needed to assess the role of marijuana for chronic pain in PLWH.

(Merlin et al. J Acquir Immune Defic Syndr. Published online: February 20, 2019.)

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For a review of other recent research in the infectious diseases literature, see “In the Literature,” by Stanley Deresinski, MD, FIDSA, in each issue of Clinical Infectious Diseases:

May 15

  • Autoimmune Encephalitis After Herpes Simplex Encephalitis
  • Prevention of Infections of Cardiac Implantable Electronic Devices
  • Pneumonia, Empyema due to Listeria

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