Top Infectious Disease News of the Week—December 2, 2018

#5: Decontaminants Don't Cut Bloodstream Infection Risk in Ventilated ICU Patients

The use of digestive and oral decontaminants in patients in the intensive care unit (ICU) who are mechanically ventilated and who have moderate to high antibiotic resistance is not associated with a reduction in ICU-acquired bloodstream infections caused by multidrug-resistant gram-negative bacteria.

According to the results of a randomized clinical trial conducted by investigators in the Netherlands and published in the Journal of the American Medical Association (JAMA), when compared with standard care, the use of chlorhexidine (CHX) 1% mouthwash, selective oropharyngeal decontamination (SOD), and selective digestive tract decontamination (SDD) made no discernible difference in whether patients developed bloodstream infections from multidrug-resistant gram-negative bacteria.

The baseline standard care routine involved chlorhexidine body washing and a hand hygiene improvement program, the authors noted.

Read about blood stream infection risk in ventilated ICU patients.

#4: Consequences of the Opioid Epidemic: Decade of Research Shows Spike in Drug Use-Associated Infective Endocarditis

As the opioid crisis grew into a national epidemic, the rate of drug use-associated infective endocarditis hospitalizations and valve surgeries increased more than 12-fold in one US state, according to a decade of research published this week in the Annals of Internal Medicine.

Investigators tracked instances of drug use-associated infective endocarditis in North Carolina over a 10-year period, from 2007 to 2017, and found that annual hospitalizations attributed to the condition increased from 0.92 to 10.95 per 100 000 persons. The rate of drug use-associated infective endocarditis requiring surgery increased from 0.10 to 1.38 per 100,000 persons.

The results also indicated a shift in the profile of infective endocarditis patients, one that investigators categorized as “dramatic.” The median age of patients with drug use-associated infective endocarditis was 33 years, compared with 56 for regular infective endocarditis. Patients tended to be female (47% vs. 33%) and white (89% vs. 63%).

Read about the spike in infective endocarditis.

3: Fractional Yellow Fever Vaccine Dose Remains Protective After a Decade

A new study shows a fractional dose of yellow fever vaccine is not just a good stop-gap measure, but can actually provide long-term protection.

Yellow fever is an incurable, highly fatal acute hemorrhagic viral disease spread by mosquitoes. It gets its name from the fact that in some patients, the disease is accompanied by jaundice. Other symptoms include fever, headaches, muscle pain, fatigue, and vomiting. According to the World Health Organization (WHO), as many as half of the people who become infected with the virus will die from it. The virus is currently endemic in Africa, Central America, and South America.

The good news is that there is a highly effective vaccine that can prevent yellow fever. The bad news is that vaccine supplies are often lacking in affected areas. Thus, when an outbreak occurs, local officials are frequently left scrambling to find sufficient vaccine supplies.

Read about the protection of a fractional yellow fever dose after a decade.

#2: Low Microbiota Diversity Prior to Bone Marrow Transplant Linked to Higher Risk for Complications

Intestinal microbiota diversity is critical for keeping harmful bacteria from dominating gut which can results in severe microbiota injury and treatment complications in patients with cancer.

In a new study, presented today, December 3, in an oral abstract session at the 60th Annual American Society of Hematology Annual Meeting in San Diego, California, investigators determined that individuals who had lower microbiota diversity in their intestine prior to a bone marrow transplant had a higher risk for post-transplant complications such as graft-versus-host disease or death.

“Patients who went into the BMT process with a gut flora that was already disrupted had a higher risk of death after the transplant,” Marcel van den Brink, MD, PhD, chief of Memorial Sloan Kettering’s (MSK) Division of Hematologic Malignancies and senior author of the study, said in a recent statement said. “The thing that we keep coming back to is that preserving the commensal flora in the microbiome is good for transplant patients.”

Read about the link between low microbiota diversity and transplant complications.

#1: Is Natural Long-Term HIV Suppression Possible for More Patients?

Typically, people with HIV must rely on antiretroviral therapy to keep their viral levels down. However, a tiny handful of people have a natural ability to keep their viral load low without medication. Investigators at Johns Hopkins University School of Medicine recently published a paper highlighting their findings after studying 2 patients with HIV who have the rare ability to achieve viral suppression in the absence of antiretroviral therapy.

One patient, termed an “elite suppressor,” carries the genetic marker HLA-B*57. This gene allows him to maintain low viral levels without ever having taken antiretroviral therapy. The second patient, termed a “post-treatment controller,” did take antiretroviral therapy for several years but has not done so for the past decade and a half. He has no genetic markers that offer any natural protection against HIV, yet he too is able to keep his viral levels at an undetectable level. Both patients are middle-aged African-American men.

In the normal course of the disease, HIV invades immune cells called CD4+ T cells, where it replicates and eventually enters the bloodstream. Another type of immune cell, the CD8+ T cell, can kill off the infected CD4+ T cells if it’s early enough in the process; however, most CD8+ T cells are overpowered by the sheer volume of CD4+ T cells, and fail to stop the cells’ replication. As the cells replicate, they tend to mutate, meaning that HIV cells found in a single patient’s body today are likely to be different than HIV cells found in his or her body several years ago.

The investigators, however, made a different discovery when examining the HIV cells culled from the patients over a period of several years. After studying the virus isolated from the post-treatment controller in 2010 and again in 2017 (when the virus was tested 2 separate times, 6 months apart), the team found that the cells were nearly identical 7 years later. And after comparing cells isolated from the elite suppressor in 2017 with those isolated from him in 2013, the investigators again discovered that all of the virus cells were nearly identical.

The implication of the near-identical cells detected, even years later, is that the virus actually cloned itself. The cloned viruses formed a reservoir in CD4+ T cells, never entering the bloodstream. The investigators hypothesize that, when it comes to these patients, their own CD8+ T cells could be major players in keeping their viral loads under control. When the research team culled CD8+ T cells from the 2 patients and combined them with their own HIV-infected CD4+ T cells, the virus remained suppressed. When the team combined other peoples’ CD8+ T cells with the 2 patients’ HIV-infected CD4+ T cells, however, the low viral levels could not be maintained.

Read about the potential of natural long-term HIV suppression.