Recurring and Emerging Questions Related to Management of HIV-Related Opportunistic Infections
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Opportunistic Infections Volume 26 Issue 3 September 2018 Perspective Recurring and Emerging Questions Related to Management of HIV-Related Opportunistic Infections The incidence of HIV-related opportunistic infections (OIs) has dramatically Society of America (IDSA) OI guide- declined with the ability to achieve viral suppression and immune recon- lines are accessed online. During the stitution with potent antiretroviral therapy. However, a large number of period from March 1, 2017, to Feb- patients remain at risk for OIs because they are diagnosed at late stages of ruary 28, 2018, adult OI guidelines HIV disease, fail to stay in treatment, or fail to maintain viral suppression. were accessed more than 420,000 Clinicians should remain vigilant for OIs and for changes in recommended times; of these, approximately 72,000 management strategies. Issues that often arise in this regard include how to page views were for Pneumocystis interpret polymerase chain reaction diagnostic results in individuals with HIV jiroveci pneumonia (PCP), 45,000 for infection; whether primary prophylaxis for Mycobacterium avium complex tuberculosis drug dosing, 28,000 for is still needed; whether clinicians should screen asymptomatic patients for toxoplasmosis, and 25,000 for Myco- cryptococcal antigen; and need for amphotericin B in treatment regimens bacterium avium complex (MAC). for cryptococcal meningitis. This article summarizes a presentation by Henry Masur, MD, at the IAS–USA continuing education program held in Washing- Most-Asked Questions about OIs ton, DC, in April 2018. Very few controlled trials related to Keywords: HIV, opportunistic infections, Pneumocystis pneumonia, PCP, Myco- the diagnosis, therapy, or prevention bacterium avium, MAC, Toxoplasma, cryptococcal meningitis, PCR, diagnostics of OIs are currently being performed, in contrast to the numerous studies Despite the success of current anti- approximately 1100 to approximately performed in the 1980s and 1990s. The retroviral therapy (ART) in reducing 350 over the last 10 years. However, guidelines currently rely on observa- the burden of HIV-related opportunis- the prevalence and incidence in this tional data from patients with HIV tic infections (OIs), a large number of district remain unacceptably high. As infection, and experience in other individuals living with HIV infection of 2016, the overall prevalence of HIV patient populations that are plausibly present late in HIV disease or do not infection was 1.9%, including rates of applicable to patients with HIV infec- maintain viral suppression and thus 0.9% among whites, 3.1% among Afri- tion. Thus some of the recent changes remain at risk for opportunistic dis- can Americans, and 1.2% among His- in the guidelines are based on obser- eases. Management of OIs is thus still panics/Latinos. Data from 2016 indicate vational data from patients with HIV relevant for practitioners who care for that among individuals with known infection, and some of the recommen- this patient population. HIV infection, only 63% are virally sup- dations are extrapolated from other pressed, with only 47% of youth with patient populations. HIV Epidemic in Washington, DC HIV infection being virally suppressed (Figure 1). Thus, there remains a large Polymerase Chain Reaction (PCR)- Based Diagnosis The current state of the HIV epidemic patient population with low or declin- in Washington, DC, provides an exam- ing CD4+ cell counts who are suscep- For the management of HIV-related ple of the ongoing risk of OIs in current tible to OIs. From 2011 to 2015, 21% of OIs, clinicians must be aware that patient populations. The good news in newly diagnosed individuals had CD4+ microbiology laboratories are changing Washington, DC, is that, thanks to the cell counts below 200/µL at diagnosis; their testing platforms dramatically. efforts of many funding agencies, fed- at 1 year after diagnosis, 50% of these When organisms are grown in conven- eral and local health administrations, patients still had counts below 200/µL. tional media, any growth can often clinics and hospitals, and health care be identified by genus and species practitioners, the annual number of within a few hours by techniques such newly recognized cases of HIV infection Surrogate Markers for Incidence of OIs in Recent Years as Matrix Assisted Laser Desorption/ in this district has been reduced from Ionization/Time of Flight Mass Spec- In the absence of hard data on inci- trometry (MALDI-TOF) Other speci- Dr Masur is Clinical Professor of Medicine dence of OIs in recent years, there are mens are tested by qualitative nucleic at George Washington University School of some indices that can provide an idea acid amplification methods that are Medicine in Washington, DC. He is Cochair of the scope of the problem of HIV- extremely sensitive for minute quan- of the National Institutes of Health-Centers for Disease Control and Prevention-Infec- related OIs. One such metric is how tities of organisms and are highly tious Disease Society of America Guidelines often the National Institutes of Health specific for identifying organisms for the Management of HIV-Related Oppor- (NIH)-Centers for Disease Control and accurately. Thus, the clinician is get- tunistic Infections in Adults and Adolescents. Prevention (CDC)-Infectious Disease ting information faster, and can obtain 79 IAS–USA Topics in Antiviral Medicine 14,000 500 450 12,000 400 10,000 350 300 8,000 250 6,000 200 Number of Cases 4,000 Number of Youths 150 100 2,000 50 0 0 Living Ever linked to Retained in Retained in Virally Living Ever linked to Retained in Retained in Ever virally Virally in DC HIV care any care in any care in supressed in in DC HIV care any care in any care in supressed supressed in (98%) 2016 (76%) 2016: >1 2016 (63%) (95%) 2016 (77%) 2016: >1 (57%) 2016 (47%) medical visit medical visit (56%) (53%) Figure 1. Contact with HIV care and viral suppression among known individuals (left) and youth (right) with HIV infection in Washington, DC (DC) in 2016. Adapted from the DC Health Annual Epidemiology and Surveillance Report, 2017.10 far more sensitive testing, often with is a nasopharyngeal swab (not nasal contaminate lower respiratory speci- concurrent information about whether swab) so that cells in the posterior mens) with respiratory viruses, or with specific resistance-associated genes retropharynx are collected. The Bio- MAC, Cryptococcus, or Pneumocystis. are present. Thus, the data coming to fire upper respiratory panel tests for a Thus, because PCR is ultrasensitive clinicians must be interpreted with number of bacteria such as Bordetella, compared with conventional smears analytic approaches that are consider- Chlamydophila pneumonia, and Myco- and cultures, a negative PCR test is con- ably different from interpretations that plasma pneumonia, and several viruses vincing evidence that the pathogen is clinicians made when diagnoses were such as influenza, parainfluenza, coro- not present. A positive result, however, established based on smears of bio- navirus and adenovirus. If the speci- must be evaluated in the context of the logic fluids and tissues, conventional men is positive for coronavirus, for clinical situation, and what other path- cultures, antigen detection assays, and example, how much confidence is there ogens or processes are concurrently serum antibody tests. For example, that the identified agent is the cause of present. Some pathogens that can col- increasingly, laboratories are not per- the patient’s syndrome? onize the airways of an individual with forming immunofluorescence assays Coronavirus may be present in very HIV infection, including herpes simplex for PCP, with diagnoses being primarily small quantities and represent coloniza- virus, cytomegalovirus (CMV), MAC, and based on PCR assays. tion following an acute infection days Candida, are so rarely the cause of pul- The question is whether the detec- or weeks before, depending on the monary dysfunction in persons with tion of an organism in respiratory sam- patient’s immune status (ie, some HIV infection, even those with very low ple, stool, cerebrospinal fluid (CSF), or immunosuppressed persons can shed CD4+ cell counts, that they should be blood is an indication that the identi- a respiratory virus for many months considered as extremely unlikely etio- fied organism is causing the syndrome after an acute infection). If coronavirus logic agents for pulmonary dysfunction. of concern rather than being detected is the only pathogen detected, the cli- Conventional cultures can detect as a bystander/colonizer or contami- nician might assume that coronavirus colonizers as well, but conventional nant. For instance, when bronchoalve- has caused the clinical illness, assum- cultures are not as sensitive as PCR. olar lavage fluid is tested by the Biofire ing the clinical illness is compatible Thus, when the cultures are positive, Platform (Salt Lake City, Utah), does the with what is known about a corona- the quantity of organisms present is detection of an organism provide the virus infection. However, the patient more likely to indicate causality; the clinician with assurance that Pneumo- may in fact be infected with an organ- same is true for a smear. In addition, in cystis is the causative organism? ism not tested for by this platform, or contrast to PCR, conventional cultures Consider a scenario in which a 35- missed by this specimen or by a pro- can be quantitative or semiquantitative, year-old patient recently diagnosed cess that is not due