Isolation of Legionella maceachernii from an immunocompromised patient with severe underlying lung disease

Lung abscess caused by Legionella species: implication of the immune status of hosts

Legionella pneumonia typically presents as lobar pneumonia with multiple-lobe involvement, but Legionella lung abscess is rare. To identify the predisposing factors for Legionella abscess, we analyzed 62 of the 79 case reports on Legionella abscess found in literature; 28 (45.2%) were of hospital-acquired infection and 28 (45.2%), community-acquired infection. Seventeen patients (27.4%) died. L. pneumophila serogroup 1 was the most common, but other serogroups of L. pneumophila, L. micdadei, L. bozemanii, L. dumoffii, and L. maceachernii were also isolated from the abscess. Corticosteroids were administered for underlying diseases to 43 (69.4%) patients. Peripheral neutrophil counts were higher in patients with abscess than in those with only pulmonary infiltration. In certain cases, Legionella abscess developed during neutropenia recovery. However, lymphocyte counts were low in most cases. Clinical factors like corticosteroid treatment, which causes impaired cellular immunity and subsequent neutrophil accumulation in the lesion, might function as predisposing factors for Legionella abscess.

Legionella maceachernii soft tissue infection

Soft tissue infection caused by Legionella spp. is rare. Infection due to Legionella maceachernii has only been described in 5 cases and none of them had soft tissue infection; they were immunocompromised hosts who presented with pneumonia. To our knowledge, this is the first case report of L. maceachernii soft tissue infection.

Legionella maceachernii pneumonia in a patient with HIV infection

We report a case of fatal Legionella maceachernii pneumonia in a 49 year-old man with HIV infection and review the 3 previous reported cases, all of which occurred in individuals with underlying immune defects. Infection with L. maceachernii was attributable to the deaths of all cases. Issues related to the clinical aspects, laboratory identification of this unusual species, and detection of Legionnaires' diseases are discussed.

Systemic lupus erythematosus in the intensive care unit

SLE causes significant morbidity and mortality by multisystem organ involvement. Infections are the leading cause of morbidity and mortality in patients with SLE. Meticulous exclusion of infection is mandatory in patients with SLE, because infections may masquerade as exacerbation of underlying disease; and the immunosuppression used to treat severe forms of exacerbation of lupus can have catastrophic consequences in patients with infections. Corticosteroids are the first-line therapy for most noninfectious complications of SLE, with various adjuvant immunosuppressive agents such as cyclophosphamide being increasingly used in combination with plasmapheresis. Some recent series have shown an improved survival rate, but this improvement needs to be confirmed by further studies. Controlled trials comparing various therapeutic options are lacking, and optimal therapy has not been defined.

Infections in systemic lupus erythematosus and rheumatoid arthritis

Patients with systemic lupus erythematosus have a higher infection rate than the general population. It is estimated that at least 50% of them will suffer a severe infectious episode during the course of the disease. Improvements in the control of the disease are discussed in this article.

Legionella and community-acquired pneumonia: a review of current diagnostic tests from a clinician's viewpoint

Many physicians are unaware of the limitations of the available tests for diagnosing infections with Legionella organisms. Geographic differences in the importance of nonpneumophila Legionella species as pathogens are underrecognized, in part because available diagnostic tests are biased toward the detection of pneumophila serogroup 1. Routine laboratory practices reduce the likelihood of culturing Legionella species from clinical isolates. Failure of seroconversion is common, particularly with nonpneumophila species; even when seroconversion occurs, it may take much longer than 4 weeks. Urinary antigen testing has insufficient sensitivity to affect clinical management in most regions of the United States, as it can reliably detect only L. pneumophila serogroup 1 infections. Polymerase chain reaction-based techniques offer hope of providing highly sensitive, rapid diagnostic tests for all Legionella species, but limitations in the current tests will make validating them difficult.