Worse Outcomes From Legionella Pneumonia in Individuals With Advanced HIV

Previous results stated that Legionella pneumonia characteristics may not differ in individuals with HIV and individuals who do not have HIV, however this may not be relevant in patients with advanced HIV and low CD4+ T-cell counts, according to a Letter to the Editor published in Clinical Infectious Diseases.

A recent report by Cilloniz, et al¹ was the first retrospective case-control study of Legionella pneumonia in patients with HIV from 3 Spanish hospitals that compared Legionella pneumonia disease severity, treatment, and outcomes between people with HIV and healthy individuals. Results showed no different between case patients and controls in pneumonia severity scores, antimicrobial regimens, and the need for admission to intensive care units.

Results of this study were consistent with the report of the South Bronx Legionella outbreak,² which suggested over-representation of HIV in individuals who became clinically ill with Legionella and found that the mortality rate did not differ between individuals with HIV and individuals without. In contrast, a study by Wolter, et al,³ evaluated patients with Legionella infection and with known HIV status from sites in South Africa and concluded that compared with uninfected individuals, people living with HIV had higher case-fatality rates (0% vs 20%, respectively). Further, unlike the Cilloniz study, only 24% of patients with Legionella received appropriate antibiotic therapy.

Although the Cilloniz study was a stepping stone to better understand Legionella infection in individuals with HIV, the results may not be applicable to people living with HIV with advanced disease and low CD4+ T-cell counts. Most of the participants with HIV in this study had well-controlled illness with a median CD4+ T‑cell count of 335/µL, which represents individuals with a relatively conserved immune state. Since their immune status was intact, treatment regimens in case patients and controls were similar and included appropriate empirical coverage for Legionella, which may explain the low rates of intensive care unit admission and favorable outcomes seen in patients with HIV. People with HIV with a CD4+ T-cell count <200/µL are often not targeted by empirical antimicrobial therapy even when opportunistic infections in these individuals are of significant concern and require atypical bacterial pneumonia agents.

In summary, the Letter to the Editor writers concluded that, “Therefore, the findings by Cilloniz et al., may be relevant for people with HIV receiving treatment who have preserved CD4 T-cell counts, but may not hold true for patients who are profoundly immunocompromised but should not be generalized to conclude that the clinical presentation and outcomes do not differ between HIV and non-HIV individuals.”

References

1. Cilloniz C, Miguel-Escuder L, Pedro-Bonet ML, et al. Community-acquired Legionella pneumonia in HIV-infected adult patients: a matched case-control study. Clin Infect Dis. 2018;67(6):958-961.

2. Weiss D, Boyd C, Rakeman JL, et al. A large community outbreak of Legionnaires’ disease associated with a cooling tower in New York City, 2015. Public Health Rep. 2017;132(2):241-250.

3. Wolter N, Maimuna C, Cohen C, et al. Legionnaires’ Disease in South Africa, 2012–2014. Emerg Infect Dis. 2016;22(1):131-133.

4. Head BM, Keynan Y. Similar outcomes of Legionella pneumonia in treated HIV infection [published online October 15, 2018]. Clin Infect Dis. doi:0.1093/cid/ciy892/5130853