Community-acquired pneumonia. A prospective outpatient study

We initiated a prospective study with a group of practitioners to assess the etiology, clinical presentation, and outcome of community-acquired pneumonia in patients diagnosed in the outpatient setting. All patients with signs and symptoms suggestive of pneumonia and an infiltrate on chest X-ray underwent an extensive standard workup and were followed over 4 weeks. Over a 4-year period, 184 patients were eligible, of whom 170 (age range, 15-96 yr; median, 43 yr) were included and analyzed. In 78 (46%), no etiologic agent could be demonstrated. In the remaining 92 patients, 107 etiologic agents were implicated: 43 were due to "pyogenic" bacteria (39 Streptococcus pneumoniae, 3 Haemophilus spp., 1 Streptococcus spp.), 39 were due to "atypical" bacteria (24 Mycoplasma pneumoniae, 9 Chlamydia pneumoniae, 4 Coxiella burnetii, 2 Legionella spp.), and 25 were due to viruses (20 influenza viruses and 5 other respiratory viruses). There were only a few statistically significant clinical differences between the different etiologic categories (higher age and comorbidities in viral or in episodes of undetermined etiology, higher neutrophil counts in "pyogenic" episodes, more frequent bilateral and interstitial infiltrates in viral episodes). There were 2 deaths, both in patients with advanced age (83 and 86 years old), and several comorbidities. Only 14 patients (8.2%) required hospitalization. In 6 patients (3.4%), the pneumonia episode uncovered a local neoplasia. This study shows that most cases of community-acquired pneumonia have a favorable outcome and can be successfully managed in an outpatient setting. Moreover, in the absence of rapid and reliable clinical or laboratory tests to establish a definite etiologic diagnosis at presentation, the spectrum of the etiologic agents suggest that initial antibiotic therapy should cover both S. pneumoniae and atypical bacteria, as well as possible influenza viruses during the epidemic season.     

Community-acquired pneumonia with rhabdomyolysis]

We assessed the frequency and etiology of rhabdomyolysis in patients with community-acquired pneumonia. In 594 patients with community-acquired pneumonia whose serum CPK were measured, 25 patients (2.4%) were found to have rhabdomyolysis. Including 4 patients with mixed infections, the etiologies in 25 patients with community-acquired pneumonia with rhabdomyolysis were as follows: Legionella species, 11 patients (44%); Influenza virus, 6 (24%); Streptococcus pneumoniae, 4 (16%); Chlamydia psittaci, 3 (12%); Mycoplasma pneumoniae, 2 (8%); unknown 3 patients (12%). The rates of rhabdomyolysis for each etiologic category were as follows: Legionella species, 26.8% (11/41); Chlamydia psittaci, 21.4% (3/14); Influenza virus, 9.5% (6/63) ; Streptococcus pneumoniae, 4.7% (4/85);Mycoplasma pneumoniae, 3.1% (2/65). Renal dysfunction with a serum creatinine concentration greater than 1.5 mg/dl occurred in 6 patients (24%). Our experience illustrates that 5 pathogens can cause rhabdomyolysis in patients with community-acquired pneumonia. Legionella species are the most common organisms followed by Influenza virus, Streptococcus pneumoniae, Chlamydia psittaci, Mycoplasma pneumoniae.     

Diagnostic test for etiologic agents of community-acquired pneumonia

Diagnostic tests for the detection of the etiologic agent of pneumonia are neither recommended nor done for most outpatients with CAP (Table 4).Most of these patients have no clear diagnosis but seem to do well with empiric antibiotic treatment, which often costs less than the diagnostic tests. For hospitalized patients, a pre-treatment blood culture and an expectorated sputum gram stain and culture should be done. Testing for Legionella spp is appropriate in hospitalized patients, especially those who are seriously ill.New tests that merit use in selected patients are the urinary antigen assay for S pneumoniae and the PCR test for L pneumophila. Anticipated developments in the near future are PCR tests for detection of C pneumoniae and M pneumoniae.     

The etiology of community-acquired pneumonia at an urban public hospital: influence of human immunodeficiency virus infection and initial severity of illness.

In a prospective study, the etiology of community-acquired pneumonia (CAP) was investigated among consecutive patients admitted to an academic, urban public hospital in Seattle. The study population was uniquely young, was predominantly male, and had high rates of homelessness, cigarette smoking, alcoholism, injection drug use, and human immunodeficiency virus (HIV) infection. Leading causes of CAP among HIV-negative patients were aspiration, followed by Streptococcus pneumoniae, Legionella species, and Mycoplasma pneumoniae. Among HIV-positive patients, Pneumocystis carinii, Mycobacterium tuberculosis, S. pneumoniae, and M. pneumoniae were the most common etiologic agents. Severe CAP was associated with typical bacterial infections and aspiration pneumonia but not Legionella infection among HIV-negative patients and with Pseudomonas aeruginosa infections among HIV-positive patients. These findings emphasize the need to tailor empirical antibiotic therapy according to local patient populations and individual risk factors and highlight the importance of recognizing underlying HIV infection in patients who are hospitalized with CAP.     

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.     

Etiology of community-acquired pneumonia: impact of age, comorbidity, and severity.

The aim of this study was to determine the etiology of community-acquired pneumonia (CAP) and the impact of age, comorbidity, and severity on microbial etiologies of such pneumonia. Overall, 395 consecutive patients with CAP were studied prospectively during a 15-mo period. Regular microbial investigation included examination of sputum, blood culture, and serology. Sampling of pleural fluid, transthoracic puncture, tracheobronchial aspiration, and protected specimen brush (PSB) sampling were performed in selected patients. The microbial etiology was determined in 182 of 395 (46%) cases, and 227 pathogens were detected. The five most frequent pathogens were Streptococcus pneumoniae (65 patients [29%]), Haemophilus influenzae (25 patients [11%]), Influenza virus A and B (23 patients [10%]), Legionella sp. (17 patients [8%]), and Chlamydia pneumoniae (15 patients [7%]). Gram-negative enteric bacilli (GNEB) accounted for 13 cases (6%) and Pseudomonas aeruginosa for 12 cases of pneumonia (5%). Patients aged < 60 yr were at risk for an "atypical" bacterial etiology (odds ratio [OR]: 2.3; 95% confidence interval [CI]: 1.2 to 4.5), especially Mycoplasma pneumoniae (OR: 5.3; 95% CI: 1.7 to 16.8). Comorbid pulmonary, hepatic, and central nervous illnesses, as well as current cigarette smoking and alcohol abuse, were all associated with distinct etiologic patterns. Pneumonia requiring admission to the intensive care unit was independently associated with the pathogens S. pneumoniae (OR: 2.5; 95% CI: 1.3 to 4.7), gram-negative enteric bacilli, and P. aeruginosa (OR: 2.5; 95% CI: 0.99 to 6.5). Clinical and radiographic features of "typical" pneumonia were neither sensitive nor specific for the differentiation of pneumococcal and nonpneumococcal etiologies. These results support a management approach based on the associations between etiology and age, comorbidity, and severity, instead of the traditional syndromic approach to CAP.     

Atypical pathogens in adult patients admitted with community-acquired pneumonia in Korea

This study examined the prevalence of atypical pathogens causing community-acquired pneumonia (CAP) in Korea. We collected sera and clinical data for a period of 1 year for the adult patients consecutively admitted to Chunchon Sacred Heart Hospital with CAP. The diagnosis was made using serologic methods to detect antibodies for Mycoplasma pneumoniae, Chlamydia pneumoniae, Legionella spp., Chlamydia psittaci, and Coxiella burnetii. Among 81 recruited patients, C. pneumoniae (n = 10, 12.3%) was the leading cause of illness, followed by M. pneumoniae (n = 7, 8.6%). One case of C. burnetii pneumonia was detected, but there were no cases of Legionella spp. or C. psittaci. Three cases of C. pneumoniae pneumonia were co-infected with either M. pneumoniae or C. burnetii. There was no significant difference between atypical pneumonia and non-diagnosed pneumonia in terms of clinical manifestations. In conclusion, of the atypical pathogens causing CAP, C. pneumoniae and M. pneumoniae appear to be the important etiologic pathogens in Korea.     

Etiology of community-acquired pneumonia in hospitalized patients in chile: the increasing prevalence of respiratory viruses among classic pathogens

BACKGROUND AND STUDY OBJECTIVES: The range and relative impact of microbial pathogens, particularly viral pathogens, as a cause of community-acquired pneumonia (CAP) in hospitalized adults has not received much attention. The aim of this study was to determine the microbial etiology of CAP in adults and to identify the risk factors for various specific pathogens. METHODS: We prospectively studied 176 patients (mean [+/- SD] age, 65.8 +/- 18.5 years) who had hospitalized for CAP to identify the microbial etiology. For each patient, sputum and blood cultures were obtained as well as serology testing for Mycoplasma pneumoniae and Chlamydophila pneumoniae, urinary antigen testing for Legionella pneumophila and Streptococcus pneumoniae, and a nasopharyngeal swab for seven respiratory viruses. RESULTS: Microbial etiology was determined in 98 patients (55%). S pneumoniae (49 of 98 patients; 50%) and respiratory viruses (32%) were the most frequently isolated pathogen groups. Pneumococcal pneumonia was associated with tobacco smoking of > 10 pack-years (odds ratio [OR], 2.6; 95% confidence interval [CI], 1.2 to 5.4; p = 0.01). Respiratory viruses were isolated more often in fall or winter (28%; p = 0.011), and as an exclusive etiology tended to be isolated in patients >/= 65 years of age (20%; p = 0.07). Viral CAP was associated with antimicrobial therapy prior to hospital admission (OR, 4.5; 95% CI, 1.4 to 14.6). CONCLUSIONS: S pneumoniae remains the most frequent pathogen in adults with CAP and should be covered with empirical antimicrobial treatment. Viruses were the second most common etiologic agent and should be tested for, especially in fall or winter, both in young and elderly patients who are hospitalized with CAP.     

Legionella as a cause of severe pneumonia

Legionella pneumophila has been found to be a common cause of community-acquired pneumonia in patients who required intensive care unit (ICU) admission. In many studies, the clinical manifestations for Legionnaires' disease were more severe and the mortality was higher when compared with pneumonias of other etiology. However, this may be due to delay in diagnosis and suboptimal antibiotic therapy, rather than enhanced virulence of L. pneumophila. A syndromic approach using high fever, diarrhea, mental status changes, hyponatremia, etc., may be useful in suggesting the correct diagnosis in patients with severe pneumonia, but this remains to be validated. The availability of Legionella diagnostic microbiology testing in-house (rather than being sent to an outside reference laboratory) maximizes the ability to correctly diagnose Legionnaires' disease. All patients with community-acquired pneumonia admitted to an ICU should undergo Legionella testing using the urinary antigen and culture on selective media. Moreover, we recommend routine cultures of the hospital water supply once a year (regardless of whether a case of nosocomial Legionnaires' disease has ever been diagnosed). If Legionella is found in the water supply, all patients with nosocomial pneumonia should undergo diagnostic tests for Legionella; empiric anti-Legionella antibiotics should be administered pending definitive diagnosis.     

Community-acquired pneumonia: the clinical dilemma

Community-acquired pneumonia (CAP) is the sixth most common cause of death in the United States. Despite its frequency and mortality, specific etiologic diagnosis remains a major clinical challenge. The organisms most commonly implicated in CAP are Streptococcus pneumoniae, Mycoplasma pneumoniae, Legionella pneumophila, Haemophilus influenzae, Chlamydia pneumoniae (TWAR), and viruses. Clinical and radiographic criteria have proven to be of little value in determining the etiology of CAP. Laboratory studies, including Gram's stain and culture of sputum, have also been shown to be of severely limited value to the clinician faced with the patient with CAP. Antibiotic therapy must, therefore, generally be empiric. Regimens including erythromycin either as a single agent or coupled with an aminoglycoside or cephalosporin appear to be most efficacious.     

Etiology and outcome of community-acquired pneumonia in relation to age and severity in hospitalized adult patients]

The aim of this study was to determine the etiology and outcome of community-acquired pneumonia (CAP) in relation to age and severity in hospitalized patients. Overall, 652 consecutive patients with CAP were studied retrospectively during a 4-year period from 2002. Severity of pneumonia was classified according to the guidelines of the Japanese Respiratory Society (JRS 2005) and American Thoracic Society (ATS 2001). The etiology was identified in 401 of 652 (61.5%) cases. The four most frequent pathogens were Streptococcus pneumoniae (26.2%), influenza virus (12.4%), Mycoplasma pneumoniae (10.9%), and Haemophilus influenzae (5.9%). The most common pathogen in the younger (15-44 years) group and very severe patients (JRS) was Mycoplasma pneumoniae (38.4%) and influenza virus (28.6%), respectively. The three most frequent pathogens in severe CAP patients (ATS) were Streptococcus pneumoniae (29.0%), influenza virus (17.4%), and Legionella species (13.0%). The overall mortality was 6.4%. The mortality of CAP patients among aged 1544, 45-64, 65-74, and 75 years or older was 1.4%, 3.3%, 6.9% and 9.3%, respectively. The mortality of mild, moderate, severe, and very severe patients (RS) was 0%, 4.1%, 15.5%, and 53.6%, respectively. The mortality of non-severe and severe patients (ATS) was 1.8% and 23.9%, respectively. Age and severity had influence on the prevalence of the main microbial pathogens. Streptococcus pneumoniae remained the most important pathogen that needs consideration in initial antibiotic therapy in patients with CAP of all ages and severities. Pathogens identified in patients with severe CAP in Japan were similar to those of Western countries, except for the high incidence of the influenza virus.     

Differences in the etiology of community-acquired pneumonia according to site of care: a population-based study

BACKGROUND: A few population-based studies assessing the etiology of community-acquired pneumonia in both hospitalized and ambulatory patients, with special emphasis on the etiologic role of viral infections, have been reported. The purpose of this study was to assess microbiological differences according to initial site of care in patients with community-acquired pneumonia. METHODS: We studied 496 patients > 14 years of age collected from the study samples of three population-based studies carried out in the same geographical area ("Maresme" region in the Mediterranean coast in Barcelona, Spain) with the same methodology over an 8-year period (1987-1995). RESULTS: Fifty-six percent of patients were hospitalized and 44% were treated at home. Of the 474 patients with etiological evaluation, 195 patients had an identifiable etiology (overall diagnostic yield 41%). Streptococcus pneumoniae was the most common causative organism. Viral infection was diagnosed in 26.5% of hospitalized patients vs. 13.2% of ambulatory patients (P=0.03). Twenty-five percent of the 68 patients with documented etiology treated at home had Chlamydia pneumoniae infection compared with 14.3% of those treated in the hospital. Ten percent of hospitalized patients had pneumonia caused by two pathogens compared with 9.7% of ambulatory patients. The association of viruses and bacteria was the most frequent cause of dual infection (79% inpatients, 67% outpatients). CONCLUSIONS: This study has provided information on etiology of community-acquired pneumonia in hospitalized patients and in patients treated at home. A considerable proportion of patients had viral pneumonia, frequently requiring hospital admission for inpatient care.     

Multicenter study of hospital-acquired pneumonia in non-ICU patients

STUDY OBJECTIVE: To know the incidence, epidemiology, etiology, and outcome of hospital-acquired pneumonia (HAP) in non-ICUs adult patients. SETTING: Twelve Spanish teaching hospitals. INTERVENTIONS: From April 1999 to November 2000, non-ICU HAP was prospectively studied by active, bimonthly 1-week surveillance. Epidemiologic data, etiology, and evolution of pneumonia were recorded. Blood and sputum cultures and Legionella pneumophila and Streptococcus pneumoniae urinary antigen tests were performed. RESULTS: We included 186 patients, with complete data available in 165 patients (70.3% male gender; mean age, 63.7 +/- 16.9 years [ +/- SD]) The mean incidence of HAP was 3 +/- 1.4 cases/1,000 hospital admissions. Most patients (64.2%) were in medical wards, had severe underlying diseases (66.6%), and had a hospital stay > 5 days (76.4%). Blood cultures were performed in 139 patients (84.2%), sputum cultures were performed in 89 patients (53.9%), and urinary antigen detection was performed in 123 patients (74.5%). An etiologic diagnosis was obtained in 60 cases (36.4%), and 31 were definitive. The most frequent etiologies were S pneumoniae (16 cases, 14 definitive), L pneumophila (7 cases, 7 definitive), Aspergillus sp (7 cases, 3 definitive), Pseudomonas aeruginosa (7 cases, 2 definitive), and several Enterobacteriaceae (8 cases, 4 definitive). Clinical complications occurred in 52.1% of the cases, and mortality was 26% (13.9% attributed to pneumonia). CONCLUSIONS: Non-ICU HAP is an important cause of hospital morbidity, observed most frequently in medical wards and elderly patients with severe underlying diseases. In this setting, S pneumoniae and Legionella sp should be considered in addition to other nosocomial pathogens; urinary antigen detection is useful in determining the prevalence of these microorganisms.     

Causes and factors associated with early failure in hospitalized patients with community-acquired pneumonia

BACKGROUND: Early failure is a matter of great concern in the treatment of community-acquired pneumonia. However, information on its causes and risk factors is lacking. METHODS: Observational analysis of a prospective series of 1383 nonimmunosuppressed hospitalized adults with community-acquired pneumonia. Early failure was defined as lack of response or worsening of clinical or radiologic status at 48 to 72 hours requiring changes in antibiotic therapy or invasive procedures. Concordance of antimicrobial therapy was examined for cases with an etiologic diagnosis. RESULTS: At 48 to 72 hours, 238 patients (18%) remained febrile, but most of them responded without further changes in antibiotic therapy. Eighty-one patients (6%) had early failure. The main causes of early failure were progressive pneumonia (n = 54), pleural empyema (n = 18), lack of response (n = 13), and uncontrolled sepsis (n = 9). Independent factors associated with early failure were older age (>65 years) (odds ratio [OR], 0.35), multilobar pneumonia (OR, 1.81), Pneumonia Severity Index score greater than 90 (OR, 2.75), Legionella pneumonia (OR, 2.71), gram-negative pneumonia (OR, 4.34), and discordant antimicrobial therapy (OR, 2.51). Compared with treatment responders, early failures had significantly higher rates of complications (58% vs 24%) and overall mortality (27% vs 4%) (P<.001 for both). CONCLUSIONS: Early failure is infrequent but is associated with high morbidity and mortality rates. Its detection and management require careful clinical assessment. Most cases occur because of inadequate host-pathogen responses. Discordant therapy is a less frequent cause of failure, which may be preventable by rational application of the current antibiotic guidelines.     

Etiology and management of community-acquired pneumonia in Asia

The causative organisms of community-acquired pneumonia, especially in Japan and Korea, are essentially similar to those in Western countries. If there are any differences, these are due to the laboratory tests and criteria used to define pathogenicity. Overall, Streptococcus pneumoniae is the most frequently occurring pathogen and Haemophilus influenzae, Mycoplasma pneumoniae, Chlamydia pneumoniae and viruses follow. Legionella spp. look likely to be low frequency pathogens in Asian countries, but a reason for this might be limitations of the laboratory tests used. A high frequency of Gram-negative bacilli as pathogens of community-acquired pneumonia in some Asian countries may be due to different criteria used to identify disease-causing organisms. A small number of papers about antibiotic resistance have shown no large differences between Asian countries, but considerable differences to Western countries, such as frequency of macrolide-resistant S. pneumoniae. Some Asian countries have their own guidelines for community-acquired pneumonia, but these are written in their own languages.     

Community-acquired pneumonia in children

The clinical findings and etiologic agents of childhood pneumonia vary, dependent upon the age of the child, with major differences seen in neonates, young infants 1 to 3 months of age, older infants or young children 3 months to 5 years of age, and older children or adolescents. Appropriate medical management and antibiotic therapy of children with pneumonia require consideration of these various age-dependent factors. Commonly the bacterial or viral etiologic agent causing community-acquired childhood pneumonia is not identified and thus antibiotic therapy is based on the probability of the most likely causative organisms. The choice of antibiotic for continuation of therapy is based on the clinical response to empiric therapy.     

Polymicrobial infections in patients with Legionella pneumonia]

We assessed the frequency and clinical significance of polymicrobial infections in 31 patients with sporadic community-acquired Legionella pneumonia. Twenty-six patients were men, 5 were women and mean age was 61 years. Eighteen patients were smokers, 6 patients were chronic alcoholics and 23 had underlying diseases. Regarding severity, the illnesses were mild (two patients), moderate (seven patients) and severe (twenty-two patients). In 9 (29%) of the patients, one other etiologic agent for community-acquired pneumonia was identified in addition to the Legionella species. The distribution of one other causal agent was as follows: Mycoplasma pneumoniae, 2 patients; Chlamydia pneumoniae, 2; Chlamydia psittaci, 1; Influenza virus, 1; Streptococcus pneumoniae, 1; Klebsiella pneumoniae, 1; Pseudomonas aeruginosa, 1 patient. Because an antimicrobial agent with activity against Legionella species can also provide coverage for Mycoplasma pneumoniae. Chlamydia pneumoniae, and Chlamydia psittaci, the patients with these coinfections improved without any complications. The patient with influenzavirus coinfection became seriously ill, and the condition was complicated by disseminated intravascular coagulation, renal failure and aspergillus bronchitis. The case of Pseudomonas aeruginosa coinfection was accompanied with a lung abscess and empyema. Our experience illustrates the importance of considering polymicrobial infections in patients with sporadic community-acquired Legionella pneumonia.     

Severe community-acquired pneumonia. Epidemiology and prognostic factors

Over a period of 4 consecutive yr, 92 nonimmunosuppressed patients (21 women and 71 men aged 53 +/- 16 yr, means = SD) with critical acute respiratory failure (PaO2/FiO2, 209 +/- 9 mm Hg) caused by severe community-acquired pneumonia were admitted to the respiratory intensive care unit (RICU) of a general hospital. The most frequent underlying clinical condition was chronic obstructive pulmonary disease (44 patients, 48%). A total of 56 patients (61%) required mechanical ventilation for a mean period of 10.7 +/- 12.5 days, 29 of them (52%) needing PEEP (9.9 +/- 3.8 cm H2O). A group of 23 (25%) patients had criteria of adult respiratory distress syndrome (ARDS). A causal microorganism was identified in 48 patients (52%), the two most frequent etiologies being Streptococcus pneumoniae (14, 15%) and Legionella pneumophila (13, 14%). Pseudomonas aeruginosa (5, 5%) was always associated with bronchiectasis. Mortality due to severe community-acquired pneumonia was 22% (20 patients). According to univariate analysis, mortality was associated with anticipated death within 4 to 5 yr, inadequate antibiotic treatment before RICU admission, mechanical ventilation requirements, use of PEEP, FIO2 greater than 0.6, coexistence of ARDS, radiographic spread of the pneumonia during RICU admission, septic shock, bacteremia, and P. aeruginosa as the cause of the pneumonia. Further, recursive partitioning analysis selected two factors significantly related to the prognosis: the radiographic spread of the pneumonia during RICU admission and the presence of septic shock.(ABSTRACT TRUNCATED AT 250 WORDS)     

Predictive factors of etiologic agents of community-acquired pneumonia presenting at a district general hospital]

Community-acquired pneumonia is one of the major respiratory diseases causing hospital admission in previously healthy patients. Prompt and appropriate antibiotic selection is essential for recovery. The authors tried to determine the distribution of the etiologic agents of community-acquired pneumonias and to analyze predictive factors. Out of 188 cases of community-acquired pneumonia presenting to our hospital, etiologic agents were determined in 106 cases (56%). Twenty-nine cases were due to Streptococcus pneumoniae, 27 cases due to Mycoplasma, 17 cases due to Haemophilus influenzae and 21 cases due to Mycobacterium tuberculosis. M. tuberculosis was the cause in 11% of all cases and the importance of pulmonary tuberculosis must be emphasized as a community-acquired pneumonia. Out of 58 cases under 50 years old, Mycoplasma pneumoniae was the etiologic agent in 23 cases (40%) and S. pneumoniae in 7 cases (12%). Out of 62 cases not less than 70 years old. M. tuberculosis was the most common etiologic agent (15 cases, 24%). S. pneumoniae followed, being causative in 13 cases (21%). M. tuberculosis was the cause in 10 cases out of 31 cases who did not complain of fever at presentation. In 86 cases who did not show leukocytosis on admission, 21 cases were due to Mycoplasma (24%) and 15 cases were due to M. tuberculosis (17%). In particular 17 cases were due to Mycoplasma among 28 cases under 50 years old without leukocytosis (61%), and 11 cases were due to M. tuberculosis in the 27 cases no less than 70 years old without leukocytosis (41%).(ABSTRACT TRUNCATED AT 250 WORDS)     

Clinical analysis of community-acquired pneumonia in the elderly

OBJECTIVE: To evaluate the clinical features, etiology, and outcome of patients over 65 years old hospitalized for community-acquired pneumonia. PATIENTS: Eighty-four patients (50 males, 34 females) hospitalized for community-acquired pneumonia in Kawasaki Medical School Kawasaki Hospital between April 1998 and March 2000. RESULTS: Most of the patients had respiratory symptoms or signs, but over one-third also had atypical symptoms of pneumonia such as dyspnea, consciousness disturbance, and gastrointestinal symptoms. The causative microorganisms were identified in 48% of these patients. Streptococcus pneumoniae (13%), respiratory viruses (13%), Haemophilus influenzae (8%) and Mycobacterium tuberculosis (8%) were frequently identified, but Mycoplasma pneumoniae was less frequently noted in the elderly. Double infection was recognized in 19 % and a combination of some virus and bacteria in 13%. Treatment consisted of the administration of second or third generation cephalosporin antibiotics intravenously, because antibiotics had already been preadministered in 39%. The prognosis was poor (mortality rate 9%) for the elderly with community-acquired pneumonia despite mechanical ventilation in 8%. CONCLUSIONS: Although the range of microorganisms causing community-acquired pneumonia differed slightly from that in previous reports; namely, lower frequency of Chlamydia pneumoniae and Legionella pneumophila, it is suggested that the initial antibiotic treatment should always cover S. pneumoniae and H. influenzae. In addition, since a prevalence of virus infections related to the increase in community-acquired pneumonia in the elderly was found in this study, the routine use of influenza vaccine and pneumococcal vaccines in the elderly is recommended to reduce the high mortality rate.