Legionellosis in patients with HIV infection

Atypical bacterial pneumonia in the HIV-infected population

Human immunodeficiency virus (HIV)-infected individuals are more susceptible to respiratory tract infections by other infectious agents (viruses, bacteria, parasites, and fungi) as their disease progresses to acquired immunodeficiency syndrome. Despite effective antiretroviral therapy, bacterial pneumonia (the most frequently occurring HIV-associated pulmonary illness) remains a common cause of morbidity and mortality in the HIV-infected population. Over the last few decades, studies have looked at the role of atypical bacterial pneumonia (i.e. pneumonia that causes an atypical clinical presentation or responds differently to typical therapeutics) in association with HIV infection. Due to the lack of available diagnostic strategies, the lack of consideration, and the declining immunity of the patient, HIV co-infections with atypical bacteria are currently believed to be underreported. Thus, following an extensive database search, this review aimed to highlight the current knowledge and gaps regarding atypical bacterial pneumonia in HIV. The authors discuss the prevalence of Chlamydophila pneumoniae, Mycoplasma pneumoniae, Coxiella burnetii, Legionella species and others in the HIV-infected population as well as their clinical presentation, methods of detection, and treatment. Further studies looking at the role of these microbes in association with HIV are required. Increased knowledge of these atypical bacteria will lead to a more rapid diagnosis of these infections, resulting in an improved quality of life for the HIV-infected population.

Legionella pneumonia and HIV: case reports and review of the literature

Although Legionnaires' disease occurs more commonly in patients with some degree of immunosuppression (diabetes, chronic lung disease, end stage renal disease, cancer, etc.), it has been infrequently described in patients infected with human immunodeficiency virus (HIV) and AIDS. Some studies suggest that pneumonia caused by Legionella tends to present with more severe clinical features and complications in the HIV-infected population. The use of antibiotic prophylaxis or the association of severe pneumonia with other pathogens may account for under diagnosis of the disease. We diagnosed five cases of Legionella pneumonia in patients with HIV infection at our institution during a 1-year period. The cases seen ranged in severity, regardless of the CD4(+) counts of the patients. Based on our observations, it seems impossible to discern whether HIV infection is an additional risk factor for Legionnaires' disease. We describe those five cases and review the available literature.

Streptococcus pneumoniae and Legionella pneumophila pneumonia in HIV-infected patients

We compared the epidemiological data, clinical features and mortality of community-acquired pneumonia (CAP) by Streptococcus pneumoniae and Legionella in HIV-infected patients and determined discriminative features. An observational, comparative study was performed (January 1994 to December 2004) in 15 HIV patients with CAP by Legionella and 46 by S. pneumoniae. No significant differences were observed in delay until initiation of appropriate antibiotic therapy. Smoking, cancer and chemotherapy were more frequent in patients with Legionella pneumonia (p=0.03, p=0.00009 and p=0.01). Patients with Legionella pneumonia had a higher mean CD4 count (p=0.04), undetectable viral load (p=0.01) and received highly active antiretroviral therapy more frequently (p=0.004). AIDS was more frequent in patients with S. pneumoniae pneumonia (p=0.03). Legionella pneumonia was more severe (p=0.007). Extrarespiratory symptoms, hyponatraemia and increased creatine phosphokinase were more frequent in Legionella pneumonia (p=0.02, p=0.002 and p=0.006). Respiratory failure, need for ventilation and bilateral chest X-ray involvement were of note in the Legionella group (p=0.003, p=0.002 and p=0.002). Mortality tended to be higher in the Legionella group (6.7 vs 2.2%). In conclusion, CAP by Legionella has a higher morbimortality than CAP by S. pneumoniae in HIV-infected patients. Detailed analysis of CAP presentation features allows suspicion of Legionnaires' disease in this subset.

Legionelosis e infección por el virus de la inmunodeficiencia humana: ¿infección oportunista?

BACKGROUND AND OBJECTIVE

Legionella infections are not frequent in HIV-infected patients, although clinical manifestations and outcome are particularly severe in this subset. This manuscript analyzes the clinical features and immunological situation of HIV-infected patients with Legionnaires' disease (LD).

PATIENTS AND METHOD

The clinical files of HIV-infected patients diagnosed with LD from 1983 to December 2003 were reviewed. The incidence of hospital-acquired Legionella pneumonia (HALP) from 1997-2000 in HIV-infected patients was compared with that of non infected patients.

RESULTS

Eighteen patients were included. 72.2% were diagnosed by the Legionella urinary antigen assay. The incidence of HALP in HIV-infected and non infected patients was 0.3 and 0.25/1000 admissions/year, respectively (p = 0.42). 83.3% received appropriate antibiotic treatment at the Emergency department. The mean lymphocyte CD4 count was 348.1/microl, 53.8% had an undetectable viral load and 64.7% were on antiretroviral therapy. 72.2% were smokers, 38.8% had cancer and 16.7% were on chemotherapy. 93.8% had cough, 75% dyspnea, 62.5% extrarespiratory symptoms, 76.5% increased AST, 50% increased CK and 56.3% hyponatremia. Moreover, 50% developed bilateral pulmonary infiltrates, 83.3% respiratory failure and 22.2% died.

CONCLUSIONS

Although LD is not more frequent in HIV-infected than in non infected patients, its clinical severity suggests that it is an opportunistic infection.

Legionnaires disease and HIV infection

STUDY OBJECTIVES

To compare the outcome of Legionnaires disease (LD) in patients with and without HIV infection.

DESIGN

Retrospective review of clinical charts.

SETTING

Six hundred-bed university hospital.

PATIENTS

We studied the clinical findings of 64 patients without HIV and 15 patients with HIV. Patients with a serologic diagnosis only were not included. Patients with previous immunosuppressive therapy or transplant recipients were excluded from the former group. In the HIV group, the mean CD4 cell count was 347.5/ microL, plasma viral load was undetectable in 50% of the patients, and only one patient (7%) was receiving cotrimoxazole as prophylaxis against Pneumocystis carinii at the time of pneumonia. No differences were observed in the two groups with respect to community or nosocomial acquisition, delay in the initiation of appropriate treatment, the use of macrolides or fluoroquinolones, and Fine score in cases of community-acquired LD.

RESULTS

Univariate analysis showed that time to apyrexia was longer, and respiratory symptoms, bilateral infiltrates in chest radiograph, hyponatremia, increase in aspartate aminotransferase and creatine phosphokinase (CK), and respiratory failure were more frequent in the HIV group. Mortality was greater in patients with HIV, achieving a statistically significant value of 20%; however, multivariate analysis only confirmed these differences with respect to the increase in CK.

CONCLUSIONS

LD has a more severe clinical presentation and worse evolution in patients with HIV.

Evaluation of the Winthrop-University Hospital criteria to identify Legionella pneumonia

STUDY OBJECTIVE

To measure the ability of a set of clinical parameters, the Winthrop-University Hospital (WUH) criteria, to identify Legionella pneumonia while discriminating against bacteremic pneumococcal pneumonia at the time of hospitalization for community-acquired pneumonia (CAP).

DESIGN

Retrospective case-control study.

SETTING

An urban county hospital and a tertiary-care Veterans Affairs hospital.

PATIENTS

Thirty-seven patients with Legionella pneumonia (diagnosed by a positive result of a urinary Legionella antigen test) and 31 patients with bacteremic pneumococcal pneumonia. A subgroup of patients with all required laboratory criteria were studied further.

RESULTS

The WUH criteria correctly identified 29 of 37 patients with Legionella pneumonia (sensitivity, 78%; 95% confidence interval [CI], 61 to 90%), while successfully excluding legionellosis in 20 of 31 patients with bacteremic pneumococcal pneumonia (specificity, 65%; 95% CI, 45 to 80%). The positive and negative predictive values, adjusted for a relative prevalence of 1:3 between Legionella and Streptococcus pneumoniae bacteremia, were 42% (95% CI, 25 to 61%) and 90% (95% CI, 74 to 97%), respectively. In the subgroup analysis, the WUH criteria were successful in identifying 20 of 23 patients with Legionella pneumonia (sensitivity, 87%; 95% CI, 65 to 97%), while excluding legionellosis in 9 of 18 patients with bacteremic pneumococcal pneumonia (specificity, 50%; 95% CI, 27 to 73%). The adjusted positive and negative predictive values for a 1:3 relative prevalence were 37% (95% CI, 20 to 59%) and 92% (95% CI, 62 to 98%), respectively. The predictive values were changed in the directions expected for an increased relative prevalence of 1:1. The areas under the receiver operating characteristic curves were 0.72 +/- 0.06 for the entire study group and 0.68 +/- 0.09 for the subgroup.

CONCLUSIONS

Although the WUH criteria discriminated fairly well between cases (mean +/- SE) and control subjects, the sensitivity is not high enough to exclude legionellosis confidently. These results suggest that empiric therapy for Legionella pneumonia should be included in the initial antibiotic regimen for hospitalized patients with CAP.

Lung abscess caused by Legionella micdadei

We describe a case of lung abscess caused by sporadic infection with Legionella micdadei in a patient with AIDS. L micdadei infection can be very difficult to diagnose because the organism stains only weakly Gram negative, requires special culture media, and is not detectable with some direct fluorescent antibody tests that are directed only at Legionella pneumophila. Since it can stain acid fast, it may be confused with mycobacteria. The abscess was successfully treated using antibiotics and percutaneous catheter drainage.

Medical management of AIDS patients. Bacterial and fungal infections

The rapid and thus far generally inexorable rise in HIV infections has led to a series of opportunistic infection that includes those caused by bacteria, yeasts, and members of the Eumycetes. The infections range in prevalence from occasional to highly prevalent, in severity from trivial to fatal, and in anatomic areas involved from local to disseminated. They occur as isolated, concurrent, or sequential infections with regard to other opportunistic diseases. Some vary in their geographic distribution. They may be newly acquired or reactivated and occur early or late in the course of HIV infection. Bacterial infections are usually easily treated, although they frequently disseminate and often recur after seemingly appropriate treatment. In contrast, all but the mildest fungal infections are difficult to treat and even more difficult or impossible to eradicate. The diagnosis of bacterial and fungal infections begins with clinical suspicion and involves relatively standard methodology. Treatment of the systemic mycoses and some bacterial infections in HIV infected patients is punctuated by exaggerated side effects of therapy, frequent relapses, and the need for maintenance suppressive therapy.