Pathogens In Community-acquired Pneumonia Research Articles

Levofloxacin in the treatment of community-acquired pneumonia

Levofloxacin is a fluoroquinolone that has a broad spectrum of activity against several causative bacterial pathogens of community-acquired pneumonia (CAP). The efficacy and tolerability of levofloxacin 500 mg once daily for 10 days in patients with CAP are well established. Furthermore, a high-dose (750 mg), short-course (5 days) of once-daily levofloxacin has been approved for use in the USA in the treatment of CAP, acute bacterial sinusitis, acute pyelonephritis and complicated urinary tract infections. Levofloxacin can be used as a monotherapy in patients with CAP, however, levofloxacin combination therapy with anti-pseudomonal β-lactam (or aminoglycoside) should be considered if Pseudomonas aeruginosa is the causative pathogen of the respiratory infection. The high-dose, short-course levofloxacin regimen maximizes its concentration-dependent antibacterial activity, decreases the potential for drug resistance and has better patient compliance. Oral levofloxacin is rapidly absorbed and is bioequivalent to the intravenous formulation and the patients can switch between these formulations, which results in more options with respect to the therapeutic regimens. Furthermore, levofloxacin is generally well tolerated, has good tissue penetration and adequate concentrations can be maintained at the site of infections.

A Comparison of Culture-Positive and Culture-Negative Health-Care-Associated Pneumonia

The aim of this study is to describe the initial antibiotic treatment regimens, severity of illness, and in-hospital mortality among culture-negative (CN) and culture-positive (CP) patients with health-care-associated pneumonia (HCAP). We used a retrospective cohort study, examining adult patients with HCAP from Barnes-Jewish Hospital, a 1,200-bed urban teaching hospital. Eight hundred seventy patients with HCAP were identified over a 3-year period (January 2003 through December 2005) of whom 431 (49.5%) were CP. Among the non-CP patients, 290 (66.1%) had no respiratory cultures obtained, and 149 (33.9%) had no growth or nonpathogenic oral flora identified and were classified as CN. CN patients were more likely to have received an initial antibiotic regimen (ceftriaxone +/- azithromycin or moxifloxacin) targeting community-acquired pneumonia pathogens compared with CP patients (71.8% vs 25.5%, P < .001). Severity of illness as assessed by ICU admission and mechanical ventilation (MV) was statistically lower in CN compared with CP patients (ICU admittance 12.1% vs 48.7%, P < .001; MV: 6.7% vs 44.5%, P < .001). In-hospital mortality and hospital length of stay were also statistically lower for CN patients (mortality: 7.4% vs 24.6%, P < .001; hospital length of stay: 6.7 +/- 7.4 days vs 12.1 +/- 11.7 days, P < .001). In this analysis, patients with CN HCAP had lower severity of illness, hospital mortality, and hospital length of stay compared with CP patients. These data suggest that patients with CN HCAP differ substantially from patients with HCAP with positive microbiologic cultures.

Methicillin-Resistant Staphylococcus aureus in Community-Acquired and Health Care-Associated Pneumonia: Incidence, Diagnosis, and Treatment Options

Pneumonia is one of the leading causes of death in the United States. As health care has expanded into community settings, including outpatient clinics, long-term care facilities, and dialysis centers, a new category of pneumonia—health care-associated pneumonia (HCAP)—has been defined. Bacterial resistance to antibiotics is rising among community-acquired infections, and the emergence of community-associated methicillin-resistant Staphylococcus aureus (MRSA) infections, particularly the severe form of necrotizing pneumonia mediated by USA 300 in young and healthy individuals, warrants attention. Although Streptococcus pneumoniae remains the most prevalent causative pathogen in community-acquired pneumonia (CAP), S aureus infections are increasingly being reported in community settings, especially in patients with HCAP. Recent surveillance of community-dwelling adults with pneumonia admitted to United States hospitals has demonstrated a steady increase in S aureus isolates. Thus, MRSA should be considered in severe pneumonia associated with influenza-like symptoms, particularly when accompanied by hemoptysis or leukopenia. However, MRSA pneumonia also can develop in the absence of preceding influenza-like illness. Effective empiric therapy for pneumonia, whether CAP or HCAP, mandates selection of an agent with coverage against all likely pathogens. Failure to provide adequate initial antimicrobial coverage has been associated with an increased risk of death. The spread of resistant pathogens in the community challenges currently available antimicrobial agents for effective treatment of MRSA-mediated pneumonia. Approval of newer antimicrobials with MRSA activity may provide additional options for the management of pneumonia. This article provides a review of the role of MRSA as a causative pathogen in CAP and HCAP.

Fluoroquinolones in the management of community-acquired pneumonia

Review of the current guidelines for the use of respiratory fluoroquinolones in the management of community-acquired pneumonia (CAP). Data were collected from recent clinical trials on fluoroquinolone therapy in patients with CAP and from updated recommendations of antimicrobial therapy in managing CAP, with a focus on current North American guidelines. Randomised clinical trials of respiratory fluoroquinolones (moxifloxacin, levofloxacin and gemifloxacin) in the treatment of CAP were identified and analysed. The bacteriology of CAP, and susceptibility rates, resistance rates and pharmacokinetic and pharmacodynamic properties of fluoroquinolones against causative pathogens in CAP, and adverse event profiles of these agents were described. Respiratory fluoroquinolones have broad-spectrum antibacterial activities against common causative pathogens in CAP and provide an important treatment option as monotherapy for outpatients with comorbidities and inpatients who are not admitted to the intensive care unit (ICU), including those with risk factors of drug-resistant Streptococcus pneumoniae. For treatment of ICU patients with severe CAP, it is recommended that fluoroquinolones be used in combination with a beta-lactam. Recent studies also demonstrated a more rapid resolution of clinical symptoms with the use of highly potent respiratory fluoroquinolones. Appropriate use of fluoroquinolone agents may shorten the duration of antimicrobial therapy and the length of hospital stay and contribute to the decreased development of resistance in patients with CAP. Adverse event profiles of these agents should be considered to facilitate the selection of an appropriate fluoroquinolone for appropriate CAP patients. The fluoroquinolone class, specifically those with adequate activity against respiratory pathogens, represents an important and convenient treatment option for patients with CAP.

Clinical Evaluation of the Multiplex PCR Assay for the Detection of Bacterial Pathogens in Respiratory Specimens from Patients with Pneumonia

Background: Community-acquired pneumonia (CAP) is a major infectious disease with significant morbidity and mortality worldwide. Streptococcus pneumoniae, Haemophilus influenzae, Mycoplasma pneumoniae, Chlamydophila pneumoniae, Legionella pneumophila, and Bordetella pertussis are common pathogens of CAP; however, the conventional methods used to detect these agents, including culturing, lack sensitivity and are time-consuming. We evaluated a recently developed multiplex PCR assay which can test these agents simultaneously. Methods: One hundred patients with pneumonia and 99 healthy adults were tested using the Seeplex Pneumobacter ACE Detection assay (Seegene, Inc., Seoul, Korea). Culture and urinary antigen tests were also performed. Results: In patients with pneumonia, the positive detection rates of PCR for S. pneumoniae and H. influenzae were 52.0% (52/100) and 30.0% (30/100), respectively, those of M. pneumoniae and L. pneumophila were 2.0% (2/100) and 1.0% (1/100), respectively, and B. pertussis and C. pneumoniae were not detected. In healthy adults, the detection rates of S. pneumoniae and H. influenzae revealed similar results, 53.5% (53/101) and 40.4% (40/101), respectively, and the other four pathogens were not detected. The sensitivity and specificity of PCR for S. pneumoniae in pneumonia patients were 100% (95% confidence interval [CI], 87.9∼100%) and 65.7% (95% CI, 55.2∼76.5%), respectively, according to the urinary antigen test and cultures of the respiratory samples and blood. Conclusion: Differentiating S. pneumoniae and H. influenzae colonization from infection was difficult using the PCR assay. Therefore, the use of this assay is inappropriate for the diagnosis of pneumonia due to these agents, although multiplex PCR assay would be useful for the detection of M. pneumoniae and L. pneumophila. (Korean J Clin Microbiol 2010;13:40-46)

Legionnaires’ disease: do not forget the fluoroquinolones or macrolides.

Atypical community-acquired pneumonia pathogens, such as Legionella, cause systemic infections with pneumonia. As Legionella infection is likely to present as severe pneumonia, it is important to presumptively diagnose Legionnaires’ disease clinically so that coverage against Legionella spp. is included in the initial empiric antimicrobial therapy.We described a case of respiratory failure secondary to Legionnaires’ disease. An extensive review of the literature about the clinical aspects of Legionnaires’ disease is presented.

Study of human metapneumovirus‐associated lower respiratory tract infections in Egyptian adults

There is a deficiency in the data concerning the role of hMPV in lower respiratory tract infections in adults, and until now there has been no data available regarding the prevalence of hMPV in adults in our region. In the present study the association of hMPV with varieties of lower respiratory tract disorders in immunocompetent adult patients, either alone or with bacterial pathogens, has been highlighted. Eighty-eight patients were included in the study. They included 46 males and 42 females with an age range of 38-65 years. Patients presented with lower respiratory tract infections associated with acute exacerbation of asthma (67%), pneumonia (17%), and acute exacerbation of chronic obstructive lung diseases. Sputum and nasopharyngeal samples were obtained from the patients and subjected to a full microbiological study. In addition, detection of hMPV was performed by nested reverse transcriptase polymerase chain reaction. The pathogens isolated were Streptococcus pneumoniae 46.6%, Staphylococci aureus 35.2%, and human metapneumovirus 13.6%. Influenza virus and rhinovirus were each isolated from 4.5% of patients. Human metapneumovirus was associated with S. pneumoniae in 4.5% in studied patients, while in 9.1% it was the only pathogen found in those patients. The commonest clinical condition with significant association with human metapneumovirus was pneumonia. The clinical and laboratory studies demonstrated an association between lower respiratory tract infections in adults and hMPV either as sole pathogen or in association with Streptococcus pneumoniae. It was a common pathogen in community-acquired pneumonia.

Nrc of Streptococcus pneumoniae suppresses capsule expression and enhances anti-phagocytosis

Streptococcus pneumoniae is a major pathogen of community-acquired pneumonia and one of its major virulence factors is pneumolysin, which functions as a cholesterol-dependent cytolytic pore-forming toxin. In this study, we identified the ply-like gene spd0729 in a BLAST search. Unexpectedly, hemolytic and cytotoxic assays showed no significant differences between a Δ spd0729 mutant strain and the wild-type strain, whereas the mutant strain exhibited weaker anti-phagocytic activity in human peripheral blood. In addition, real-time RT-PCR analysis revealed that four capsular biosynthesis genes in the mutant strain had expressions 7- to 432-fold greater than those of the wild type, while an enzyme-linked immunoassay showed a mean 3-fold greater amount of total capsular polysaccharide in the mutant strain. These results suggest that Spd0729 is not a cytolysin, though it plays crucial roles in anti-phagocytosis and regulation of capsule expression. Thus, we named Spd0729 as a negative regulator of capsular polysaccharide synthesis (Nrc).

Important Role for CC Chemokine Ligand 2-Dependent Lung Mononuclear Phagocyte Recruitment to Inhibit Sepsis in Mice Infected with Streptococcus pneumoniae

The monocyte chemoattractant CCL2 is of major importance in inflammatory monocyte recruitment to the lungs in response to bacterial infection. Streptococcus pneumoniae is the most prevalent pathogen in community-acquired pneumonia causing significant morbidity and mortality worldwide. In the current study, we examined the role of CCL2 in lung-protective immunity against two strains of S. pneumoniae exhibiting different virulence profiles. Both wild-type mice and CCL2 knockout (KO) mice became septic within 24 h of infection with serotype 3 S. pneumoniae and died of infection by day 4 after challenge. In contrast, wild-type mice challenged with serotype 19 S. pneumoniae did not become septic or succumb to pneumococcal pneumonia, whereas CCL2 KO mice showed an early bacterial outgrowth in their lungs and sepsis starting by day 2 after infection, finally resulting in approximately 50% decreased survival compared with wild-type mice. This phenotype was not due to impaired lung neutrophil recruitment in the KO mice, but was characterized by a significantly reduced recruitment of lung exudate macrophages and conventional lung dendritic cells, suggesting that these two phagocyte subsets critically regulate protection against septic disease progression in mice. In conclusion, we show here a differential role for CCL2-dependent lung exudate macrophage and conventional dendritic cell recruitment that critically contributes to lung protective immunity against S. pneumoniae.

Atypical bacterial pathogens in community-acquired pneumonia in children: a hospital-based study

A total of 243 children aged one month to five years with World Health Organization defined severe community acquired pneumonia were studied for the presence of atypical bacterial pathogens: 24 were found positive for mycoplasma infection. There was no significant association with any of the clinical, laboratory and radiological variables in children with pneumonia by the atypical pathogen.

Clinico-pathological study of atypical pathogens in community-acquired pneumonia: a prospective study

Atypical respiratory pathogens such as Mycoplasma pneumoniae, Legionella species, and Chlamydia pneumoniae are isolated with increasing frequency from community-acquired pneumonia (CAP). This study highlights the importance of organisms responsible for CAP. One hundred consecutive patients with clinically and radiographically diagnosed CAP were evaluated from October 2005 to October 2006. Sputum, bronchoalveolar lavage, and blood samples were collected for microbiological culture. Determination was performed for specific immunoglobulin M (IgM) for Chlamydia pneumoniae, Mycoplasma pneumoniae, Legionella pneumophila, Coxiella burnettii, adenovirus, and influenza virus. The most common isolated bacteria was Streptococcus pneumoniae (22%) followed by Haemophilus influenzae (18%). Mycoplasma pneumoniae was isolated from 5% and Legionella pneumophila was isolated from 5% of patients. The most common positive serological reaction was for Chlamydia pneumoniae (30%) and Adenovirus (30%). In the study of accuracy of determination of specific IgM for Mycoplasma pneumoniae and Legionella pneumophila compared to culture, the sensitivity was 60% and 80% respectively, specificity was 93.7 %, and 98.9 % respectively, and accuracy was 92 % and 97 % respectively. This study highlights the prominence of mixed bacterial/viral infections in lower respiratory tract infection diagnosis. Our data showed that at least 30% of our patients had concurrent infections. This observation raises two important questions: 1) whether sequential or concurrent viral and bacterial infections have a synergistic impact on the evolution of disease in children; and 2) should diagnostic batteries for any patient with CAP include methods for detecting both the typical and atypical bacterial or viral pathogens.

START Stewardship Tactics for Antimicrobial Resistance Trends

START Stewardship Tactics for Antimicrobial Resistance Trends

The science of selecting antimicrobials for community-acquired pneumonia (CAP).

Among infectious diseases, community-acquired pneumonia (CAP) is the leading cause of death in the United States and is associated with a substantial economic burden to the health care system. Initiating appropriate empiric therapy can be challenging given elevated resistance rates among Streptococcus pneumoniae strains. To present current recommendations for management of CAP with respect to (a) choosing the appropriate site of care, and (b) antimicrobial selection based on bacterial etiology and the prevalence of resistance. Mortality prediction tools, such as the PORT (Pneumonia Outcomes Research Team) Severity Index, CURB-65 (Confusion, Urea concentration, Respiratory rate, Blood pressure, and age>65), or CRB-65 (Confusion, Respiratory rate, Blood pressure, and age>65), can be invaluable in determining which CAP patients require hospitalization. These tools can help reduce overall costs for CAP by limiting hospitalizations of low-risk patients. S. pneumoniae remains the most common causative pathogen for CAP across all disease severities, and elevated rates of resistance to penicillin and macrolides can hinder selection of appropriate antimicrobial therapy. Antimicrobial resistance can impact clinical outcomes, including increasing the risk of treatment failure and breakthrough bacteremia. Current management guidelines recommend monotherapy with a respiratory fluoroquinolone or combination therapy with a beta-lactam and a macrolide (for patients admitted to the general medical ward) or with a beta-lactam and either a respiratory fluoroquinolone or a macrolide (for patients admitted to the intensive care unit [ICU] and who do not have risk factors for methicillin-resistant S. aureus or Pseudomonas). Optimized dosing regimens aim to ensure that pharmacokinetic and pharmacodynamic targets are met to achieve successful clinical outcomes and minimize resistance development. Effective management of patients with CAP requires selection of the proper site of care and appropriate empiric antimicrobial. Given the elevated rates of resistance among S. pneumoniae, local resistance patterns must be considered when choosing empiric therapy.

Severe Q fever community-acquired pneumonia (CAP) mimicking Legionnaires' disease: Clinical significance of cold agglutinins, anti-smooth muscle antibodies and thrombocytosis

Atypical community-acquired pneumonia (CAP) may be caused by zoonotic or nonpulmonary pathogens. However, atypical pathogens are systemic infectious disease accompanied by pneumonia in contrast with typical bacterial pathogens with infection limited to the lungs and absent extrapulmonary findings. Clinically and radiologically, the atypical CAP pathogens that most closely resemble each other are psittacosis, Q fever, and Legionnaires' disease. Psittacosis can usually be readily suspected or eliminated on the basis of a recent psittacine bird contact history. The 2 atypical pneumonias that most closely resemble each other clinically are Q fever and Legionnaires' disease. The epidemiology of Q fever is related to livestock, and sporadic cases are related to contact to parturient cats. In nonendemic areas, Q fever CAP mimics Legionnaires' disease most closely. Both Q fever and Legionella CAP have several clinical and laboratory features in common. However, there are subtle but important differences that allow the astute clinician to differentiate between these 2 disorders on the basis of clinical and nonspecific laboratory findings before definitive diagnostic tests results are reported. We report a case of severe Q fever CAP mimicking Legionnaires' disease in a young adult normal host. Her initial zoonotic contact history was negative, and her clinical presentation suggested Legionnaires' disease as the most likely diagnosis. Against the diagnosis of Legionnaires' disease was the patient's age and occurrence of the disease in spring time. In contrast, Legionnaires' disease is usually an infection of older individuals and occurs in late summer/fall. Although the patient did not have splenomegaly, a common finding in Q fever CAP, she did have mild hepatomegaly. Hepatomegaly is a uncommon in Q fever CAP but is not a feature of Legionnaires' disease. In the absence of a positive zoonotic contact history, the cardinal findings pointing to the diagnosis of Q fever in this case were "multiple round opacities" on chest computed tomography scan and thrombocytosis during her hospitalization. Against the diagnosis of Legionnaires' disease was the absence of hypophosphatemia and highly elevated ferritin levels. In patients with atypical pneumonias in whom the clinical presentation and nonspecific laboratory findings suggest Legionnaires' disease, but in addition have findings not associated with Legionnaires' (eg, hepatomegaly, thrombocytosis), Q fever serology should be ordered. We conclude that Q fever may closely mimic Legionnaires' disease. Severe atypical CAP with "multiple round opacities" on chest x-ray/computed tomography chest scan with elevated anti-smooth muscle antibodies or thrombocytosis should suggest the diagnosis of Q fever and prompt specific testing for Q fever. Rarely, Q fever CAP may be associated with elevated cold agglutinin titers.

Efficacy of Azithromycin in the Treatment of Community-acquired Pneumonia, Including Patients with Macrolide-Resistant Streptococcus pneumoniae Infection

The growing problem of drug resistance among respiratory pathogens in community-acquired pneumonia (CAP), particularly Streptococcus pneumoniae, (S. pneumoniae) has complicated initial empiric therapy of CAP. This study was undertaken to evaluate the efficacy and tolerability of a 3-day course of azithromycin in adults with mild to moderately severe CAP, and to determine whether in vitro macrolide resistance among strains of S. pneumoniae is related to clinical efficacy/failure. An open-label, non-comparative study was undertaken at 3 university-affiliated hospitals in Japan. Patients were eligible if they were 18 years or older and had mild or moderately severe CAP. All patients received azithromycin 500 mg/day for three days, and clinical and microbiological responses were evaluated 1 and 2 weeks after initiating therapy. A total of 78 patients received the study medication, 59 of whom had sufficient data available for efficacy analysis. Overall, a good clinical response with azithromycin was achieved in 49 patients (83.1%) and a microbiological response was achieved in 78.3%. Azithromycin resistance, based on CLSI criteria, was demonstrated in 85.7% (12/14) of S. pneumoniae isolates, and the presence of ermB genes was found in 50.0% (7/14). However, among patients in whom S. pneumoniae was isolated (n=17), a good clinical response was achieved in 76.5% (13/17), and the microbiological response rate was 64.3% (9/14). Furthermore, 6 of 7 patients in whom high-level resistance was documented (MICs >256 microg/mL and carrying ermB genes) exhibited good clinical responses. Azithromycin was well tolerated; adverse events, mainly of a gastrointestinal nature, were recorded in 6 patients (7.7%). Most patients responed well to azithromycin, indicating that azithromycin might be clinically effective for the treatment of CAP with macrolide-resistant S. pneumoniae. However, a larger study is necessary to prove the efficacy against macrolide-resistant S. pneumoniae.

Recombinant human tissue factor pathway inhibitor exerts anticoagulant, anti-inflammatory and antibacterial effects in murine pneumococcal pneumonia

Streptococcus pneumoniae is the most common causative pathogen in community-acquired pneumonia and a major cause of sepsis. Pneumonia elicits a procoagulant state in the lung resulting from activation of coagulation, downregulation of anticoagulant pathways and concurrent inhibition of fibrinolysis. Tissue factor is the main initiator of coagulation. Recombinant human tissue factor pathway inhibitor (rh-TFPI) attenuates sepsis-induced coagulation and has been evaluated in clinical trials involving patients with sepsis and community-acquired pneumonia.

Molecular Diagnostics for Detection of Bacterial and Viral Pathogens in Community‐Acquired Pneumonia

Traditional microbiological methods for detection of respiratory tract pathogens can be slow, are often not sensitive, may not distinguish infection from colonization, and are influenced by previous antibiotic therapy. Molecular diagnostic tests for common and atypical causative pathogens of community-acquired pneumonia have the potential to dramatically increase the diagnostic yield and decrease the time required to render results. Unfortunately, these tests often lack standardization and are not widely available. Consideration should be given to the development and evaluation of companion molecular diagnostic tests for detection of respiratory pathogens in future clinical trials of antimicrobials intended to treat community-acquired pneumonia.

Atypical pneumonias: current clinical concepts focusing on Legionnairesʼ disease

Purpose of reviewThis review provides clinicians with an overview of the clinical features of the atypical pneumonias. Atypical community-acquired pneumonia pathogens cause systemic infections with pneumonia. The key to the clinical diagnosis of atypical pneumonias depends on recognizing the charact

Modulation of the Inflammatory Response toStreptococcus pneumoniaein a Model of Acute Lung Tissue Infection

Streptococcus pneumoniae is the leading pathogen of community-acquired pneumonia and is a main cause of infectious deaths. However, little is known about host-pathogen interaction in human lung tissue. We tested the hypothesis that human alveolar macrophages (AMs) and alveolar epithelial cells (AECs) are important for initiating the host response against S. pneumoniae, and we evaluated the role of Toll-like receptor (TLR) 2, TLR4, and p38 mitogen-activated protein kinase (MAPK) signaling in the inflammatory response after pneumococcal infection. We established a novel model of acute S. pneumoniae infection using vital human lung specimens. In situ hybridization analysis showed that S. pneumoniae DNA was detected in 80 to 90% of AMs and 15 to 30% of AECs after in vitro infection accompanied by increased expression of inflammatory cytokines. Enhanced phosphorylation of p38 MAPK and increased TLR2 and 4 mRNA expression were observed in infected lung tissue. Thirty to fifty percent of AMs and 10 to 20% of AECs showed evidence of apoptosis 24 hours after pneumococcal infection. After macrophage deactivation with Clodronate/liposomes, infected lung tissue exhibited a significantly decreased release of inflammatory mediators. Inhibition of p38 MAPK signaling markedly reduced inflammatory cytokine release from human lungs, whereas TLR2 blockade revealed only minor effects. AMs are central resident immune cells during S. pneumoniae infection and are the main source of early proinflammatory cytokine release. p38 MAPK holds a major role in pathogen-induced pulmonary cytokine release and is a potential molecular target to modulate overwhelming lung inflammation.

Atypical pneumonias: current clinical concepts focusing on Legionnaires' disease

This review provides clinicians with an overview of the clinical features of the atypical pneumonias. Atypical community-acquired pneumonia pathogens cause systemic infections with pneumonia. The key to the clinical diagnosis of atypical pneumonias depends on recognizing the characteristic pattern of extrapulmonary organ involvement different for each pathogen. As Legionella is likely to present as severe pneumonia and does not respond to beta-lactams, it is important to presumptively diagnose Legionnaires' disease clinically so that Legionella coverage is included in empiric therapy. This study reviews the clinical features and nonspecific laboratory markers of atypical pathogens, focusing on Legionnaires' disease. Case reports/outbreaks increase our understanding of Legionnaires' disease transmission. Both Mycoplasma pneumoniae and Chlamydophilia pneumoniae may cause asthma. Antimicrobial therapy of Chlamydophilia pneumoniae/Mycoplasma pneumoniae is important to decrease person-to-person spread and to decrease potential long-term sequelae. Atypical pulmonary pathogens cause systemic infections accompanied by a variety of characteristic extrapulmonary features. Clinically, it is possible to differentiate Legionnaires' disease from the other typical/atypical pneumonias. Rapid clinical diagnosis of atypical pathogens, particularly Legionnaires' disease, is important in selecting effective empiric therapy and prompting definitive laboratory testing.