Comparative features of pneumococcal, mycoplasmal, and Legionnaires' disease pneumonias

The efficacy of high-dose penicillin G for pneumococcal pneumonia diagnosed based on initial comprehensive assessment at admission: an observational study

Objectives

High-dose penicillin therapy is effective in approximately 90% of pneumococcal pneumonia cases diagnosed based on urinary pneumococcal antigen tests or Gram staining at admission. The efficacy of high-dose penicillin therapy for pneumococcal pneumonia diagnosed based on an initial comprehensive assessment comprising a syndromic approach, Gram staining of sputum and urinary pneumococcal antigen testing was investigated.

Results

Seventy adult patients diagnosed with pneumococcal pneumonia based on an initial comprehensive assessment and treated with high-dose penicillin G at admission were included. The median patient age was 76.5 years, and 37.1% of the patients were women. The urinary pneumococcal antigen test was positive in 67.1% of all patients, and Gram staining of sputum showed that gram-positive cocci were dominant in 58.6% of the patients. The primary outcome was treatment success based on vital signs until day 6. Treatment with high-dose penicillin G was effective in 87.1% of the patients (95% CI 79.1–95.2%), and the proportion of patients who received other antibiotics because of treatment failure with penicillin G was only 5.7%. The efficacy of high-dose penicillin G treatment for pneumococcal pneumonia diagnosed based on a comprehensive assessment at admission may be comparable to that in previous reports.

Electronic supplementary material

The online version of this article (10.1186/s13104-018-3510-7) contains supplementary material, which is available to authorized users.

Legionella pneumonia cases over a five-year period: a descriptive, retrospective study of outcomes in a UK district hospital

As the recent outbreaks in Edinburgh and Camarthen, UK, have shown, Legionella pneumonia (LP) remains a significant public health problem, which is not only confined to those who have travelled abroad. In both outbreaks and sporadic cases, diagnosis can go unrecognised. We reviewed the demographics, comorbidities, diagnosis, treatment and clinical outcome of LP cases over five years in a district general hospital in northwest England. Over half of LP cases were UK acquired and 'classic' clinical features were common. Clinical criteria for diagnosing LP were confirmed, but few sputum samples were sent to reference laboratories, limiting further essential epidemiological mapping of UK cases. Following current UK community-acquired pneumonia guidance would have missed nearly one quarter of LP cases in our series, potentially leading to further morbidity and mortality.

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.

Swedish guidelines for the management of community-acquired pneumonia in immunocompetent adults

This document presents the evidence-based guidelines of the Swedish Society of Infectious Diseases for the management of adult immunocompetent patients with community-acquired pneumonia (CAP), who are assessed at hospital. The prognostic score 'CURB-65' is recommended for all CAP patients in the emergency room. The score provides an assessment tool for the decision regarding outpatient treatment or level of hospital supervision, the choice of microbiological investigations, and empirical antibiotic treatment. In patients with non-severe CAP (CURB-65 score 0-2) we recommend initial narrow-spectrum antibiotic treatment, orally or intravenously, primarily directed at Streptococcus pneumoniae. In those with CURB-65 score 3, penicillin G or a cephalosporin intravenously is recommended. For CURB-65 score 0-3 atypical pathogens should be covered only when they are suspected on clinical or epidemiological grounds. In patients with CURB-65 score 4-5 intravenous combination therapy with either cephalosporin/macrolide or penicillin G/fluoroquinolone is recommended. Efforts should be made to identify the CAP aetiology in order to support the ongoing antibiotic treatment or to suggest treatment alterations. Recommended measures for prevention of CAP include influenza -- and pneumococcal -- vaccination to risk groups and efforts for smoking cessation.

Reliability of radiographic findings and the relation to etiologic agents in community-acquired pneumonia

In a clinical setting the chest radiograph is the reference standard in establishing the diagnosis of community-acquired pneumonia (CAP). This study aimed to assess interobserver reliability (IR) of radiographic findings and the relationship to different causative pathogens in CAP. Chest radiographs of 192 patients with pneumonia, obtained from a database, were reviewed by 2 radiologists and 1 respiratory physician without specific clinical information. Main pattern of infiltrate, extent of pneumonia, presence of pleural fluid, thickened bronchial walls, lymphadenopathy and air bronchogram were scored. Also, the involved lobes were identified. Sputum cultures, blood cultures and serological tests were performed to identify the causative pathogen. IR was poor (kappa <0.4) for determining the main pattern of infiltrate and presence of air bronchogram, lymphadenopathy and thickening of bronchial walls. IR was fair to good (kappa 0.4-0.7) or even excellent (kappa>0.7) for determining the presence of pleural effusion, the extent of pneumonia and for identifying the lobes involved. Mycoplasma pneumoniae was associated more often with patchy alveolar opacities than Streptococcus pneumoniae (P=0.05). Chlamydia spp. were associated with unilobar involvement (86%), especially when compared to M. Pneumoniae (P=0.03) and S. pneumoniae (P=0.004). In conclusion, simple features such as presence of pleural fluid, the extent of pneumonia and identifying the involved lobes show fair to excellent IR. Other features such as main pattern of infiltrate are difficult to assess and show poor IR. Hardly any relation between different pathogens and radiological features was found. Therefore, chest radiographs are of limited value in predicting the causative pathogen, but are of good use to determine the extent of pneumonia and to detect complications such as parapneumonic effusion.

The pattern and significance of abnormal liver function tests in community-acquired pneumonia

BACKGROUND: The pattern of liver function tests (LFTs) in community-acquired pneumonia has not been investigated in detail. Although abnormal tests are thought to be more frequent in patients with atypical pneumonia, the prognostic value of LFTs have not been clearly established. METHODS: We assessed 96 consecutive patients admitted to one hospital with a chest infection over a period of 6 weeks. The infection was classified as bronchitis or lobar pneumonia on clinical and radiological criteria. The site and severity of the infection were assessed and correlated with LFTs and standard British Thoracic Society prognostic criteria. Mortality and length of stay in survivors were used as major outcome measures. RESULTS: There were 17 deaths (18%) overall and patients with abnormal LFTs were significantly more likely to die than those with normal tests (25% vs. 5%; p=0.026). Length of stay was significantly longer in survivors with abnormal liver function than in those with normal tests (9.7 vs. 5.8 days; p=0.006). A low albumin was the most useful predictor of poor outcome and carried a relative risk of dying of 1.8, comparable to the predictive value of tachypnoea. ALT was increased threefold in those succumbing to their disease, but alkaline phosphatase levels were not predictive of outcome and an increase in gamma GT appeared to be protective. CONCLUSIONS: Abnormal LFTs are common in community-acquired pneumonia and are of prognostic value. Patients with a low albumin or raised ALT are significantly more likely to die from their disease or to stay in hospital for a prolonged period. However, other LFTs are of less value in predicting prognosis.

Clinical diagnosis of Legionella pneumonia revisited: evaluation of the Community-Based Pneumonia Incidence Study Group scoring system

This prospective case-control study sought to identify differences in presentation between Legionella pneumonia (LP) diagnosed by urinary antigen and bacteremic pneumococcal pneumonia (PP), with the aim of assessing the ability of physicians to recognize such differences at admission and validating the Community-Based Pneumonia Incidence Study (CBPIS) Group scoring system for LP diagnosis. Significant differences in presentation were found: male sex, previous receipt of beta-lactam therapy, and temperature >39 degrees C were positively associated with LP; purulent sputum, pleuritic chest pain, and previous upper respiratory tract infection were negatively associated with LP. Physicians considered Legionella to be the most likely diagnosis in 52 (64%) of 81 LP cases and in 8 (6%) of 136 PP cases. Initial administration of a macrolide and rifampin and requests for urinary antigen testing for Legionella at admission were significantly more frequent among patients with LP. Overall, the CBPIS score did not differentiate reliably between LP and PP. Although certain presenting clinical features may allow recognition of LP, it is difficult to express them in a reliable scoring system.

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.

Nonresolving or slowly resolving pneumonia

Given the variability in rate of radiographic resolution, it remains controversial to decide when to initiate an invasive diagnostic work-up for nonresolving or slowly resolving pulmonary infiltrates. In immunocompetent patients who present with classical features of CAP (i.e., fever, chills, productive cough, new pulmonary infiltrate), clinical response to therapy is the most important determinant for further diagnostic studies. Within the first few days, persistence or even progression of infiltrates on chest radiographs is not unusual. Defervescence, diminished symptoms, and resolution of leukocytosis strongly support a response to antibiotic therapy, even when chest radiographic abnormalities persist. In this context, observation alone is reasonable, and invasive procedures can be deferred. Serial radiographs and clinical examinations dictate subsequent evaluation. In contrast, when clinical improvement has not occurred and chest radiographs are unchanged or worse, a more aggressive approach is warranted. In this setting, we advise fiberoptic bronchoscopy with BAL and appropriate cultures for bacteria, legionella, fungi, and mycobacteria. When endobronchial anatomy is normal and there is no purulence to suggest infection, TBBs should be done to exclude noninfectious causes (discussed earlier) or infections attributable to mycobacteria or fungi. An aggressive approach is also warranted in patients who are clinically stable or improving when the rate of radiographic resolution is delayed. As discussed earlier, what constitutes excessive delay is controversial, and depends upon the acuity of illness, specific pathogen, extent of involvement (i.e., lobar versus multilobar), comorbidities, and diverse host factors. Stable infiltrates even 2 to 4 weeks after institution of antibiotic therapy does not mandate intervention provided patients are improving clinically. Invasive techniques can also be deferred when unequivocal, albeit incomplete, radiographic resolution can be demonstrated. Lack of at least partial radiographic resolution by 6 weeks, even in asymptomatic patients, however, deserves consideration of alternative causes (e.g., endobronchial obstructing lesions, or noninfectious causes). Fiberoptic bronchoscopy with BAL and TBBs has minimal morbidity and is the preferred initial invasive procedure for detecting endobronchial lesions or substantiating noninfectious causes. The yield of bronchoscopy depends on demographics, radiographic features, and pre-test likelihood. In the absence of specific risk factors, the incidence of obstructing lesions (e.g., bronchogenic carcinomas, bronchial adenomas, obstructive foreign body) is low. Bronchogenic carcinoma is rare in nonsmoking, young (< 50 years) patients but is a legitimate consideration in older patients with a history of tobacco abuse. Non-neoplastic causes (e.g., pulmonary vasculitis, hypersensitivity pneumonia, etc.) should be considered when specific features are present (e.g., hematuria, appropriate epidemiologic exposures). Ancillary serologic tests or biopsies of extrapulmonary sites are invaluable in some cases. In rare instances, surgical (open or VATS) biopsy is necessary to diagnose refractory or non-resolving "pneumonias."

'Atypical pneumonia'. Why this term may be better left unsaid

I have attempted to mount an argument to rid the medical literature of the term "atypical pneumonia." It really adds nothing to diagnostic and therapeutic decisions in patients with respiratory infections caused by various organisms.

The role of atypical pathogens: Mycoplasma pneumoniae, Chlamydia pneumoniae, and Legionella pneumophila in respiratory infection

Infections caused by M. pneumoniae, C. pneumoniae, and Legionella spp. are important causes of community-acquired pneumonia (CAP). In the past decade, considerable new information has come to light concerning these organisms. Despite this, debate continues concerning the syndromic approach to CAP and the scientific merit of lumping these pathogens together. Because the etiologic diagnosis of these pathogens is established only in a minority of cases, the true prevalence tends to be underestimated. In clinical practice, these pathogens are often empirically treated. More rapid and cost-effective diagnostic techniques are needed so that the clinical course of patients with these infections can be better characterized.

Comparative study of the clinical presentation of Legionella pneumonia and other community-acquired pneumonias

The aim of this study was to compare the clinical, biological, and radiologic features of presentation in the emergency ward of community-acquired pneumonia (CAP) by Legionella pneumophila (LP) and other community-acquired bacterial pneumonias to help in early diagnosis of CAP by LP. Three hundred ninety-two patients with CAP were studied prospectively in the emergency department of a 600-bed university hospital. Univariate and multivariate analyses were performed to compare epidemiologic and demographic data and clinical, analytical, and radiologic features of presentation in 48 patients with CAP by LP and 125 patients with CAP by other bacterial etiology (68 by Streptococcus pneumoniae, 41 by Chlamydia pneumoniae, 5 by Mycoplasma pneumoniae, 4 by Coxiella burnetii, 3 by Pseudomonas aeruginosa, 2 by Haemophilus influenzae, and 2 by Nocardia species. Univariate analysis showed that CAP by LP was more frequent in middle-aged, male healthy (but alcohol drinking) patients than CAP by other etiology. Moreover, the lack of response to previous beta-lactamic drugs, headache, diarrhea, severe hyponatremia, and elevation in serum creatine kinase (CK) levels on presentation were more frequent in CAP by LP, while cough, expectoration, and thoracic pain were more frequent in CAP by other bacterial etiology. However, multivariate analysis only confirmed these differences with respect to lack of underlying disease, diarrhea, and elevation in the CK level. We conclude that detailed analysis of features of presentation of CAP allows suspicion of Legionnaire's disease in the emergency department. The initiation of antibiotic treatment, including a macrolide, and the performance of rapid diagnostic techniques are mandatory in these cases.

A predictive model for the treatment approach to community-acquired pneumonia in patients needing ICU admission

OBJECTIVE

To create a predictive model for the treatment approach to community-acquired pneumonia (CAP) in patients needing Intensive Care Unit (ICU) admission.

DESIGN

Multicenter prospective study.

SETTING

Twenty-six Spanish ICUs.

PATIENTS

One hundred seven patients with CAP, all of them with accurate etiological diagnosis, divided in three groups according to their etiology in typical (bacterial pneumonia), Legionella and other atypical (Mycoplasma, Chlamydia spp. and virus). For the multivariate analysis we grouped Legionella and other atypical etiologies in the same category.

METHODS

We recorded 34 variables including clinical characteristics, risk factors and radiographic pattern. We used a multivariate logistic regression analysis to find out a predictive model.

RESULTS

We have the complete data in 70 patients. Four variables: APACHE II, (categorized as a dummy variable) serum sodium and phosphorus and "length of symptoms" gave an accurate predictive model (c = 0.856). From the model we created a score that predicts typical pneumonia with a sensitivity of 90.2% and specificity 72.4%.

CONCLUSION

Our model is an attempt to help in the treatment approach to CAP in ICU patients based on a predictive model of basic clinical and laboratory information. Further studies, including larger numbers of patients, should validate and investigate the utility of this model in different clinical settings.

Diagnosis and treatment of bacterial pneumonia in Korea

Even with advancements in knowledge the problem of pneumonia will not be eliminated. It should be understood who is at risk, why such people develop pneumonia, what causes the pneumonia, and respiratory infection should be managed and prevented. The relative frequency of the isolation of various etiologic agents that cause bacterial pneumonia differ according to age group, geography, socio-economic status, underlying disease, time of year, and possible concomitant viral illnesses. Prompt identification of the causative agent is vital in the management of pneumonia. The present status of elucidating the etiologic agent is far from complete and recently, newer techniques using DNA probes and polymerase chain reactions were used for the identification of microbial pathogens. The timely use of appropriate systemic antibacterial therapy eradicates the pathogens. Considering the alterations of the etiologic agents of bacterial pneumonia and antibiotic susceptibilities, attention should be directed to the usage of antimicrobial agents in order to maximize the efficacy and the therapeutic implications.

Early recognition of Streptococcus pneumoniae in patients with community-acquired pneumonia

The objective of this study was to assess the predictive value of signs, symptoms, and rapidly available laboratory parameters for pneumococci in community-acquired pneumonia (CAP). A prospective study on patients with CAP who were admitted to hospital was conducted. Clinical and laboratory data were collected according to a protocol. Two hundred sixty-eight patients aged 18 years or older, not living in a nursing home or not admitted to hospital within one week of this admission, with a new infiltrate on the chest radiograph consistent with pneumonia were included. According to microbiological and serological tests, patients were allocated to one of two aetiological groups, Streptococcus pneumoniae or "other pathogens". Seventy-three variables were examined for a correlation with one of the aetiological categories by means of univariate and multivariate analysis. The resulting discriminant function was considered a clinical test for which posttest probabilities for pneumococcal pneumonia were calculated. Streptococcus pneumoniae was demonstrated in 79 patients and other pathogens in 83; no pathogens were detectable in 106 patients. The variables "cardiovascular disease", "acute onset", "pleuritic pain", "gram-positive bacteria in the sputum Gram stain", and "leucocyte count" correctly predicted the cause of CAP in 80% of all cases in both groups. Depending on the prevalence of Streptococcus pneumoniae, posttest probabilities for pneumococcal pneumonia were up to 90%. It is concluded that data on history, together with the result of the Gram stain of sputum and the leucocyte count, can help to distinguish Streptococcus pneumoniae from other pathogens causing CAP.

Clinical picture of community-acquired Chlamydia pneumoniae pneumonia requiring hospital treatment: a comparison between chlamydial and pneumococcal pneumonia

BACKGROUND

The importance of Chlamydia pneumoniae as a cause of pneumonia has remained controversial. The clinical picture of C pneumoniae and Streptococcus pneumoniae in patients admitted to hospital with community-acquired pneumonia was compared during a C pneumoniae epidemic in Finland.

METHODS

Group I consisted of 24 patients in whom serological testing and bacterial culture indicated an association with C pneumoniae only, group II comprised nine patients with both C pneumoniae and S pneumoniae, and group III consisted of 13 patients with S pneumoniae only.

RESULTS

The patients with C pneumoniae suffered from headache more frequently than the other patients (group I, 46%; group II, 11%; and group III, 15%) and had received antimicrobial treatment more often before admission to hospital (group I, 54%; groups II and III, 0%). The patients with C pneumoniae produced few good sputum samples and had suffered from respiratory symptoms longer than those with S pneumoniae (group I, 10 days; groups II and III, 4 days). C reactive protein values on admission were lowest in group I and highest in group II. The antimicrobial treatment provided in hospital covered C pneumoniae in 36% of cases in group I and 0% in group II, while S pneumoniae was covered in all patients. C pneumoniae and S pneumoniae together were associated with more severe disease and a longer stay in hospital.

CONCLUSIONS

Pneumonia caused by C pneumoniae was milder but clinically resembled that caused by S pneumoniae, and required hospital treatment even among young patients. Mixed infections were common and should be taken into account when planning antimicrobial treatment for community-acquired pneumonia. Further studies with more patients are needed to evaluate the severity of C pneumoniae pneumonia.

Severe community-acquired pneumococcal pneumonia. The French Study Group of Community-Acquired Pneumonia in ICU

Streptococcus pneumoniae is the most frequent pathogen of severe community-acquired pneumonia (CAP) necessitating hospitalization. The main objective of this multicentre prospective study was to determine the value of clinical, biological, and radiological features for predicting pneumococcal etiology and to define prognostic factors. Streptococcus pneumoniae was isolated in 43/132 patients (33%) with CAP requiring ICU treatment. The mean age of the patients with pneumococcal pneumonia was 55 +/- 17 (SD) yrs and 34 were male. On admission, 14 patients with pneumococcal pneumonia were in shock, 24 were mentally confused, and 27 required mechanical ventilation during their hospitalization. Among the clinical, biological, and radiological features, fever > 39 degrees C, pleuritic chest pain, lobar distribution or alveolar consolidation, and an increase in immature granulocytes > or = 5% of WBC were more frequent in pneumococcal pneumonia than in other etiologies. Mortality was 35%. Fatal outcome was significantly related to the presence of impaired alertness, septic shock, mechanical ventilation, acute renal failure, and bacteremic pneumonia.

Pneumonia in the elderly. Special diagnostic and therapeutic considerations

Clinical and radiologic signs and symptoms of gram-negative infections are often muted or obscured by a concurrent disease, and therefore, are not reliable for predicting the infecting organisms. Thus, initial therapy is nearly always empiric and based on the clinician's judgment that a patient's pneumonia is likely to be caused by particular pathogens. The choice of an appropriate regimen requires careful consideration of the extent and severity of coexisting illness and debilitation, the severity of the pneumonia, and the level of care required.

Severe community-acquired pneumonia. Etiology, epidemiology, and prognosis factors. French Study Group for Community-Acquired Pneumonia in the Intensive Care Unit

A prospective study of 132 patients with severe community-acquired pneumonia (CAP) treated in the ICU was carried out to determine the causative agents, the value of the clinical, biological, and radiologic features in predicting the etiology, and to define prognostic factors. The study group included 98 men and 34 women (mean age: 58 +/- 18 years). The most frequent underlying condition was COPD (51 patients, 39 percent). On admission, 35 patients were in shock, 71 were mentally confused, and 81 (61 percent) required mechanical ventilation during their hospitalization. The clinical, laboratory, and radiologic parameters were of little value for predicting the etiology in patients with severe CAP. An etiologic diagnosis was made in 95 (72 percent) patients. The most frequent pathogens were Streptococcus pneumoniae (43 cases [45 percent]), Gram-negative bacilli (14 cases [15 percent]), and Haemophilus influenzae (14 cases [15 percent]) Mortality was 24 percent. It was significantly associated with a age more than 60 years, septic shock, impairment of alertness, mechanical ventilation requirement, bacteremic pneumonia, and S pneumoniae or Enterobacteriaceae as the causes of the pneumonia. Recommendations for antibiotic chemotherapy in patients with severe CAP admitted to the ICU are included.

Quality of published reports of the prognosis of community-acquired pneumonia

OBJECTIVE

To systematically assess the quality of published reports of the prognosis of community-acquired pneumonia using a formal quality assessment instrument.

DESIGN

Retrospective review of studies published during 1966-1991. ARTICLES: 108 articles related to the prognosis of community-acquired pneumonia retrieved by a computerized search.

INTERVENTION

All articles, blinded to author(s), journal title, year of publication, and study institution(s), were independently reviewed by two investigators using a ten-item quality assessment instrument designed to evaluate: 1) identification of the inception cohort (4 items), 2) description of referral patterns (1 item), 3) subject follow-up (2 items), and 4) statistical methods (3 items). Adherence to each of the ten individual quality items and an overall quality score were calculated for all articles and across three time periods.

MAIN RESULTS

Among all 108 articles that underwent quality assessment, 30 were published from 1966 to 1979, 61 from 1980 through 1989, and 17 from 1990 through 1991. The mean total quality score of all articles was 0.55 (range 0.22-0.90). There was a significant trend toward improvement in total quality scores over the three time periods (0.50 to 0.56 to 0.65; p < 0.001). However, several systematic errors in the study design or reporting of these studies were discovered throughout time: only 3.7% provided comparative information about nonenrolled patients, 28.7% determined whether the study institution was a referral center, 36.1% specified inclusion or exclusion criteria, and 45.5% used appropriate statistical analyses to adjust for more than one prognostic factor.

CONCLUSIONS

Despite improvement in overall quality of published articles, systematic errors exist in the design and reporting of studies related to the prognosis of community-acquired pneumonia. The quality assessment tool employed in this study could be used to guide the development of high-quality outcomes research in the future.

Etiology of community-acquired pneumonia. Evaluation by transtracheal aspiration, blood culture, or serology

In a 5-year period, 254 patients with community-acquired pneumonia were attended to. Transtracheal aspiration (TTA) could be performed on 119 patients, blood cultures were performed on 201 patients, and 74 patients underwent serologic examinations. By use of these procedures, an etiologic diagnosis was established in 93 cases. Streptococcus pneumoniae was the most common pathogen as it was found in 35 cases. Eleven of these 35 patients (31.4 percent) had pneumococcemia, and the mortality in this group was 27.3 percent. None of the patients with pneumococcal pneumonia and negative blood culture died. Haemophilus influenzae was the only isolated pathogen from transtracheal aspirated sputum in 16 cases and accounted for 17.5 percent of pneumonias in previous healthy individuals under 50 years of age. Mycoplasma pneumonia infections, Legionella pneumophila infections, and Chlamydia infections were found in ten, eight, and three cases, respectively. The overall agreement between microscopy and culture of respiratory secretions obtained by TTA was 58.8 percent, and microscopy can be a guide when choosing the initial antibiotic treatment. No statistically significant difference in the rate of isolating bacteria among patients treated with antibiotics prior to TTA and patients not previously treated with antibiotics was seen. When contraindications were respected, we found TTA to be a safe procedure.

Atypical pneumonias: therapeutic possibilities

The atypical pneumonia syndrome is characterized by systemic complaints rather than respiratory symptoms. The causative pathogens include Mycoplasma, Chlamydia, Legionella and respiratory viruses (influenza, adenovirus, respiratory syncytial virus). The reported incidence of disease caused by these pathogens in community-acquired pneumonias varies from study to study. As most of these pathogens are intracellular, the antibiotics used in the treatment of atypical pneumonia are those able to penetrate into cells. Empirical antimicrobial therapy consists of macrolides (erythromycin or some of the newer agents such as roxithromycin, azithromycin or clarithromycin) or tetracyclines (e.g. doxycycline). In cases of severe legionellosis and in immunocompromised and critically-ill patients, the macrolides are sometimes given in combination with rifampicin. Promising alternatives are some of the newer fluoroquinolones (e.g. ofloxacin, pefloxacin) in the treatment of legionellosis.

Rapid detection of pneumococcal antigen in pleural fluid of patients with community acquired pneumonia

BACKGROUND

Detection of pneumococcal antigen may help to increase the rate of diagnosis of pneumococcal pneumonia. This study was designed to determine the value of rapid detection of pneumococcal antigen in pleural fluid from patients with community acquired pneumonia.

METHODS

Thoracentesis was performed in patients suspected of having empyema and in patients with pneumonia of unknown aetiology. Pneumococcal capsular antigen was detected by latex agglutination and this method was compared with Gram staining and culture, specimens of pleural fluid being examined in parallel by the three methods.

RESULTS

Pleural fluid was radiographically identified in 63 of 135 patients with community acquired pneumonia. In nine of 45 patients with pneumococcal pneumonia and pleural fluid pneumococci were identified by Gram stain in two and by culture in one specimen of pleural fluid, whereas antigen was detected in eight of these specimens. In 12 of 33 patients with pneumonia of other known aetiology only one pleural fluid specimen was antigen positive, providing a specificity of 92% for this test. Pleural fluid obtained from 12 of 58 patients with pneumonia of unknown aetiology yielded detectable antigen in seven cases.

CONCLUSIONS

Detection of pneumococcal antigen by latex agglutination in pleural fluid may yield important and rapid information in patients with community acquired pneumonia.

Changes in crackle characteristics during the clinical course of pneumonia

Recorded crackling lung sounds of 11 patients with pneumonia were studied with phonopneumography, FFT spectrography and time-expanded waveform display. The sounds were recorded on average six days after the onset of pneumonia and the recording was repeated two to four days later. In the first recording the crackles were coarse and midinspiratory. The patients with unilateral pneumonia had a significant difference in the upper frequency limit of inspiratory sound of the FFT spectrum between the healthy and diseased lung (p less than 0.01). In the second recording, the beginning of crackling had shifted later (p less than 0.01) and the end point of crackling also became later (p less than 0.05). The largest deflection width of the individual crackles became shorter (p less than 0.05). The results indicate that the pneumonic crackles vary markedly during the clinical course of pneumonia. The duration of the individual crackles became shorter and the timing of the crackles shifted toward the end of inspiration.

Legionella pneumophila lipopolysaccharide activates the classical complement pathway

Legionella pneumophila is a gram-negative bacterium capable of entering and growing in alveolar macrophages and monocytes. Complement and complement receptors are important in the uptake of L. pneumophila by human mononuclear phagocytes. The surface molecules of L. pneumophila that activate the complement system are unknown. To identify these factors, we investigated the effects of L. pneumophila lipopolysaccharide (LPS) on the classical and alternative complement pathways of normal human serum by functional hemolytic assays. Although incubation of LPS in normal human serum at 37 degrees C resulted in the activation of both pathways, complement activation proceeded primarily through the classical pathway. Activation of the classical pathway by LPS was dependent on natural antibodies of the immunoglobulin M class that were present in various quantities in sera from different normal individuals but were absent in an immunoglobulin-deficient serum obtained from an agammaglobulinemic patient. Additional studies using sheep erythrocytes coated with LPS suggested that the antibodies recognized antigenic sites in the carbohydrate portion of LPS. The ability of LPS to interact with the complement system suggests a role for LPS in the uptake of L. pneumophila by mononuclear phagocytes.

Legionella pneumophila. A cause of severe community-acquired pneumonia

In a prospective study of community-acquired pneumonias, 30 patients were diagnosed with Legionnaires' disease in 15 months. Clinical, laboratory and radiologic features of these patients are reviewed and compared with those who have pneumococcal pneumonia. Alcoholism, history of smoking, previous antimicrobial therapy, gastrointestinal and neurologic manifestations, elevations of serum transaminases, alkaline phosphatase and creatinine levels were more frequent in pneumonia due to Legionella pneumophila than in pneumococcal pneumonia. The presence of respiratory failure and radiologic progression were common findings that suggested L pneumophila as the etiologic agent of a community-acquired pneumonia. Development of respiratory failure was associated with involvement of several lobes and isolation of L pneumophila in any specimen. In 21 of 30 patients with Legionnaires' disease, L pneumophila was isolated from respiratory specimens. Overall mortality was 10 percent, but it increased to 27 percent in patients not treated with erythromycin initially.

Rapid aetiological diagnosis of pneumonia based on routine laboratory features

The values of some basic laboratory features on admission to hospital were recorded and compared in 418 adult patients with community-acquired pneumonia, namely erythrocyte sedimentation rate, C-reactive protein, white blood cell (WBC) count, serum lactate dehydrogenase (S-LD), serum alanine-aminotransferase, and serum sodium. Discriminant analysis was performed to obtain an aetiological diagnosis. WBC value of greater than 15 x 10(9)/l strongly indicated a bacterial and, especially a pneumococcal aetiology, whereas increased S-LD could imply a mycoplasmal infection. For patients less than 50 years of age the equation C2 = -1.788 + 0.204 x WBC-0.0909 X S-LD was constructed, in which C2 greater than 0 indicated a pneumococcal aetiology. This function correctly classified 31/33 (93.9%) patients with a mycoplasmal and 20/31 (64.5%) patients with a pneumococcal infection. Patients with viral, Haemophilus influenzae or chlamydial infection could not be discriminated from each other. The age of the patient, WBC and possibly S-LD on admission are easily accessible parameters and these results could therefore be of value in daily clinical practice in hospitals.