Unique H. Influenzae Infection Emerges in Atlanta's HIV Population

By Megan Brooks

December 26, 2019

NEW YORK (Reuters Health) - There was a significant increase in cases of invasive nontypeable Haemophilus influenzae (NTHi) infection among the HIV population in Atlanta from 2017 to 2018, a surveillance study has found.

Two unique but genetically related clonal strains were identified and were associated with septic arthritis among young black men who have sex with men with HIV, the investigators report in JAMA.

"The occurrence of invasive disease often leading to septic arthritis in a population of young men with similar demographic and clinical features (i.e. young black men who have sex with men, the majority living with HIV and in geographic proximity) is atypical for this pathogen and suggests the possibility of transmission within social networks," first author Dr. Lauren Collins, a physician at Emory University School of Medicine in Atlanta, told Reuters Health by email.

"Given our findings that many of the men with clonal infection reported a history of sexually transmitted infections and nontypeable H. influenzae commonly colonize the upper respiratory tract, we were intrigued by the possibility of sexual transmission," said Dr. Collins. "Prior studies have also demonstrated genital tract colonization with nontypeable H. influenzae in men and women. Further work is warranted to determine whether clonal strains may have been transmitted via orogenital contact."

Among 533 adults with invasive NTHi infection in Atlanta from 2008 to 2018, 60 occurred in adults with HIV infection. Among these individuals, the incidence of invasive NTHi infection was 41.7 cases per 100,000) in 2017-2018 - significantly greater than from 2008 to 2016 when the incidence was 9.6 per 100,000. Among those without HIV, the incidence was 1.1 per 100,000 from 2008-2018.

Septic arthritis was the most commonly identified clinical syndrome, occurring in 32% of those with HIV with clonal invasive NTHi infection compared with no cases among persons with HIV without clonal isolates and in fewer than 1% of cases among adults without HIV.

"While our findings were in metropolitan Atlanta, as we have seen with many emerging infections, the likelihood of continued geographic spread is high," co-investigator Dr. Monica M. Farley, a physician at Emory University School of Medicine and the Atlanta VA Hospital, told Reuters Health by email.

In addition, the occurrence of invasive NTHi infection in black HIV-infected MSM group "underscores the shifting epidemiology of invasive H. influenzae during the postvaccine era from H. influenzae serotype b toward NTHi infection," the investigators note in their article.

"The study reminds us that old pathogens can change and adapt and we need to be alert to new manifestations or new populations at risk," Dr. Farley, who serves as academic principal investigator of the Georgia Emerging Infections Program (EIP) funded by the US Centers for Disease Control and Prevention (CDC), added in her email.

The investigators suggest clinicians consider invasive NTHi infection in the differential diagnosis of febrile illness or sepsis with bone or joint complaints occurring among persons with HIV, men who have sex with men or both.

Dr. Farley said this study also demonstrates "the power of population-based surveillance paired with new genomic tools to detect these changes. But the original observation by astute clinicians was an essential part of this investigation, which was then facilitated by strong partnerships between clinicians, clinical investigators and public health epidemiologists."

SOURCE: http://bit.ly/2ZpQoTG JAMA, online December 20, 2019.