Atypical pneumonias. Clinical diagnosis and empirical treatment

The incidence of acute renal failure and high mortality rate in elderly patients hospitalized with community acquired pneumonia

Community acquired pneumonia is associated with high mortality and health care costs, especially in old age. The clinical presentation of pneumonia in the elderly may be asymptomatic or atypical. One of the known complication is an acute kidney injury. The purpose of our study was to estimate the incidence of this complication in elderly patients hospitalized with pneumonia in our geriatric hospital. From a group of 180 elderly patients hospitalized with community-acquired pneumonia 34.4 % developed acute kidney injury. In this group, 51.6 % of patients died compared to 14.4 % in the group of patients without acute kidney injury (p < 0.001). The lower level of e-GFR was significantly associated with mortality (p < 0.001): out of seven patients with e-GFR level of 15-29 mg/mmol, five patients died (71.4 %). Elderly patients with community-acquired pneumonia suffering acute kidney injury experienced worse in-hospital outcomes; mortality rate was significantly higher in our study. We found a relationship between low level of e-GFR and mortality. Clinicians should be alert for early detection and prevention of kidney injury in patients admitted with pneumonia.

Myositis and acute kidney injury in bacterial atypical pneumonia: Systematic literature review

BACKGROUND

Bacterial community-acquired atypical pneumonia is sometimes complicated by a myositis or by a renal parenchymal disease. Available reviews do not mention the concurrent occurrence of both myositis and acute kidney injury.

METHODS

In order to characterize the link between bacterial community-acquired atypical pneumonia and both myositis and a renal parenchymal disease, we reviewed the literature (United States National Library of Medicine and Excerpta Medica databases).

RESULTS

We identified 42 previously healthy subjects (35 males and 7 females aged from 2 to 76, median 42 years) with a bacterial atypical pneumonia associated both with myositis (muscle pain and creatine kinase ≥5 times the upper limit of normal) and acute kidney injury (increase in creatinine to ≥1.5 times baseline or increase by ≥27 μmol/L above the upper limit of normal). Thirty-six cases were caused by Legionella species (N = 27) and by Mycoplasma pneumoniae (N = 9). Further germs accounted for the remaining 6 cases. The vast majority of cases (N = 36) presented a diffuse myalgia. Only a minority of cases (N = 3) were affected by a calf myositis. The diagnosis of rhabdomyolysis-associated kidney injury was retained in 37 and that of acute interstitial nephritis in the remaining 5 cases.

CONCLUSION

Bacterial atypical pneumonia may occasionally induce myositis and secondary kidney damage.

Clinical predictors for Legionella in patients presenting with community-acquired pneumonia to the emergency department

Background

Legionella species cause severe forms of pneumonia with high mortality and complication rates. Accurate clinical predictors to assess the likelihood of Legionella community-acquired pneumonia (CAP) in patients presenting to the emergency department are lacking.

Methods

We retrospectively compared clinical and laboratory data of 82 consecutive patients with Legionella CAP with 368 consecutive patients with non-Legionella CAP included in two studies at the same institution.

Results

In multivariate logistic regression analysis we identified six parameters, namely high body temperature (OR 1.67, p < 0.0001), absence of sputum production (OR 3.67, p < 0.0001), low serum sodium concentrations (OR 0.89, p = 0.011), high levels of lactate dehydrogenase (OR 1.003, p = 0.007) and C-reactive protein (OR 1.006, p < 0.0001) and low platelet counts (OR 0.991, p < 0.0001), as independent predictors of Legionella CAP. Using optimal cut off values of these six parameters, we calculated a diagnostic score for Legionella CAP. The median score was significantly higher in Legionella CAP as compared to patients without Legionella (4 (IQR 3–4) vs 2 (IQR 1–2), p < 0.0001) with a respective odds ratio of 3.34 (95%CI 2.57–4.33, p < 0.0001). Receiver operating characteristics showed a high diagnostic accuracy of this diagnostic score (AUC 0.86 (95%CI 0.81–0.90), which was better as compared to each parameter alone. Of the 191 patients (42%) with a score of 0 or 1 point, only 3% had Legionella pneumonia. Conversely, of the 73 patients (16%) with ≥4 points, 66% of patients had Legionella CAP.

Conclusion

Six clinical and laboratory parameters embedded in a simple diagnostic score accurately identified patients with Legionella CAP. If validated in future studies, this score might aid in the management of suspected Legionella CAP.

Q Fever Community-Acquired Pneumonia in a Patient With Crohn’s Disease on Immunosuppressive Therapy

Community-acquired pneumonia (CAP) may be caused by typical or atypical pathogens. The three most common zoonotic atypical pathogens are Chlamydophila psittaci (psittacosis), Francisella tularensis (tularemia), and Coxiella burnetii (Q fever). Atypical CAPs are suggested by a distinctive pattern of extrapulmonary organ involvement. Zoonotic CAP may be differentiated from nonzoonotic CAP (Chlamydia pneumoniae, Mycoplasma pneumoniae, Legionnaire's disease) by a recent zoonotic vector contact history. Zoonotic atypical CAP occurs sporadically, but not randomly, and require close association with the appropriate zoonotic vector to transmit the infection. CAP accompanied by the extrapulmonary finding of splenomegaly in a normal host limits differential diagnostic possibilities to Q fever and psittacosis. Splenomegaly does not occur with other typical or atypical CAP. Another common extrapulmonary finding occurs with some atypical pneumonias, that is, Q fever, psittacosis, and Legionnaire's disease is early mild/transient elevations of serum transaminases indicative of (hepatic) extrapulmonary organ involvement. The case presented is a middle-aged man with longstanding Crohn's disease who was further immunosuppressed by chronic prednisone therapy. The patient presented with CAP and extrapulmonary findings, that is, splenomegaly and increased serum transaminases. He denied recent contact with birds or animals. Because Crohn's disease and Q fever CAP may be accompanied by splenomegaly, the cause of his splenomegaly was a diagnostic dilemma. The patient was treated with levofloxacin. Serologic tests for atypical pathogens (Q fever, psittacosis, Legionnaire's disease, C. pneumoniae, and M. pneumoniae) were ordered. Enzyme-linked immunosorbent assay serology for Q fever was positive with elevated acute immunoglobulin-M (phase II) titers. Re-questioning of the patient revealed a recent exposure to a neighbor's parturient cat, providing the necessary zoonotic vector contact history for Q fever. The patient responded to levofloxacin, which resulted in resolution of the patient's symptoms, right lower lobe pneumonia, and splenomegaly. Because a prior abdominal computed tomography scan indicated no splenomegaly and his splenomegaly resolved with antimicrobial therapy, the splenomegaly was related to Q fever CAP.

The atypical pneumonias: clinical diagnosis and importance

The most common atypical pneumonias are caused by three zoonotic pathogens, Chlamydia psittaci (psittacosis), Francisella tularensis (tularemia), and Coxiella burnetii (Q fever), and three nonzoonotic pathogens, Chlamydia pneumoniae, Mycoplasma pneumoniae, and Legionella. These atypical agents, unlike the typical pathogens, often cause extrapulmonary manifestations. Atypical CAPs are systemic infectious diseases with a pulmonary component and may be differentiated clinically from typical CAPs by the pattern of extrapulmonary organ involvement which is characteristic for each atypical CAP. Zoonotic pneumonias may be eliminated from diagnostic consideration with a negative contact history. The commonest clinical problem is to differentiate legionnaire's disease from typical CAP as well as from C. pneumoniae or M. pneumonia infection. Legionella is the most important atypical pathogen in terms of severity. It may be clinically differentiated from typical CAP and other atypical pathogens by the use of a weighted point system of syndromic diagnosis based on the characteristic pattern of extrapulmonary features. Because legionnaire's disease often presents as severe CAP, a presumptive diagnosis of Legionella should prompt specific testing and empirical anti-Legionella therapy such as the Winthrop-University Hospital Infectious Disease Division's weighted point score system. Most atypical pathogens are difficult or dangerous to isolate and a definitive laboratory diagnosis is usually based on indirect, i.e., direct flourescent antibody (DFA), indirect flourescent antibody (IFA). Atypical CAP is virtually always monomicrobial; increased IFA IgG tests indicate past exposure and not concurrent infection. Anti-Legionella antibiotics include macrolides, doxycycline, rifampin, quinolones, and telithromycin. The drugs with the highest level of anti-Legionella activity are quinolones and telithromycin. Therapy is usually continued for 2 weeks if potent anti-Legionella drugs are used. In adults, M. pneumoniae and C. pneumoniae may exacerbate or cause asthma. The importance of the atypical pneumonias is not related to their frequency (approximately 15% of CAPs), but to difficulties in their diagnosis, and their nonresponsiveness to beta-lactam therapy. Because of the potential role of C. pneumoniae in coronary artery disease and multiple sclerosis (MS), and the role of M. pneumoniae and C. pneumoniae in causing or exacerbating asthma, atypical CAPs also have public health importance.

Atypical pneumonia in active patients: clues, causes, and return to play

Atypical pneumonias can affect young, otherwise healthy individuals who have close contact with one another, such as athletes in team sports. Symptoms, which often progress gradually, may mimic an upper respiratory tract infection. Mycoplasma, chlamydia, and legionella organisms, along with certain viruses, are the usual atypical pneumonia agents, and antimicrobial therapies are recommended. Because complications, though rare, can be protracted, affect athletic performance, and result in sudden death, return-to-play guidelines should be cautious and patient- and sport-specific.

The antibiotic treatment of community-acquired, atypical, and nosocomial pneumonias

Optimal antibiotic regimens and duration of treatment are not universally agreed on for community-acquired or nosocomial pneumonias. Experience suggests that community-acquired pneumonias may be treated for less than 2 weeks with a combination of intravenous and oral antibiotics of appropriate spectrum that penetrate the lung, have a good safety profile, do not foster the development of resistance, and are cost-effective. After initial intravenous therapy, oral switch therapy may be begun as soon as the patient defervesces clinically, which is usually 3 days after admission. Switching to oral therapy does not invariably lead to earlier hospital discharge. There is no "standard of care" for pneumonias, but guidelines for empiric use have existed for decades. The least expensive beta-lactamase stable antibiotic should be used as monotherapy for the empiric treatment of community-acquired pneumonia. Because community-acquired atypical pneumonias are clinically distinct from bacterial pneumonias owing to their extrapulmonary features, clinicians should be able to differentiate atypical pneumonias from bacterial pneumonias, which permits prompt and appropriate treatment. Nosocomial pneumonias remain a difficult diagnostic challenge. Therapeutically the most important principle in treating nosocomial pneumonia is to provide for double-drug coverage against P. aeruginosa. Differentiation of respiratory tract colonization from respiratory tract invasion remains the central key issue in patients with pulmonary infiltrates acquired during hospitalization. Most patients complete their course of intravenous therapy for nosocomial pneumonia leaving little or no time for completion of their therapy by oral antibiotics. Hospital-acquired atypical pneumonias are largely limited to legionnaires' disease, which is a more difficult diagnosis than in the community-acquired setting. Clinicians taking care of patients with pneumonia should employ a simplified therapeutic approach using a single drug for community-acquired infections. The use of additional antibiotics to increase gram-negative coverage is medically unjustified and not cost-effective and is to be discouraged. The most cost-effective strategy for the treatment of community-acquired pneumonias is to switch the patient from an intravenous to an oral antibiotic as soon as the patient clinically defervesces and is able to take oral medications. Antimediator therapies have no role in the treatment of community-acquired or nosocomial pneumonias.

Atypical pneumonias. Clinical and extrapulmonary features of Chlamydia, Mycoplasma, and Legionella infections

Pneumonias caused by atypical organisms usually have extra-pulmonary features. Chlamydial pneumonia often starts with hoarseness and fever, and respiratory tract symptoms may not appear for days. Mycoplasmal pneumonia may manifest with ear pain and a nonproductive cough. Legionnaires' disease presents with high fevers and central nervous system and gastrointestinal abnormalities. Diagnosis of chlamydial infection is accomplished with serologic testing. Patients are unresponsive to erythromycin treatment and should be started on empirical doxycycline (Doryx, Vibramycin) therapy. The presence of cold agglutinins in the appropriate clinical setting permits a presumptive diagnosis of mycoplasmal infection. Clinical diagnosis of Legionella pneumonia may be made in patients with pneumonia who also have relative bradycardia with elevated serum transaminases or hypophosphatemia with gastrointestinal or central nervous system symptoms. Erythromycin is the mainstay of treatment of legionnaires' disease, but treatment failures have been reported. Doxycycline is less expensive, has a better safety profile, and is better tolerated than erythromycin.