New and emerging etiologies for community-acquired pneumonia with implications for therapy. A prospective multicenter study of 359 cases

Perspectives in fatal epidemics

This article discusses four epidemics of fatal infectious diseases: a 1993 cluster of deaths among previously healthy persons in the southwestern United States that led to the identification of a new clinical syndrome, hantavirus pulmonary syndrome; the first epidemic of Ebola hemorrhagic fever identified in nearly two decades occurring in 1995 in Zaire, which resulted in 317 cases with a mortality rate of 77%; an outbreak of Legionnaires' disease among cruise ship passengers in 1994; and a 1989 cluster of illnesses among nonhuman primates in Reston, Virginia leading to the identification of a new strain of Ebola virus. In each outbreak, the public health emergency was recognized and reported by alert clinicians, and the control of disease was facilitated through rapid, coordinated responses involving multiple agencies. Such collaboration between clinical and public health entities and among various agencies will be increasingly needed as surveillance and diagnostic capabilities for emerging and reemerging infectious diseases are enhanced around the world.

Oral empiric treatment of community-acquired pneumonia. A multicenter, double-blind, randomized study comparing sparfloxacin with roxithromycin. The Scandinavian Sparfloxacin Study Group

STUDY OBJECTIVE

Comparison of efficacy and safety of sparfloxacin (Spfx) vs roxithromycin (ROXI) for treatment of community-acquired pneumonia (CAP).

DESIGN

Multicenter, double-blind, randomized study.

SETTING

Twenty-three university and community hospitals in Scandinavia.

PATIENTS

Three hundred four adults (> or = 18 years of age) with CAP treated as outpatients (25%) or inpatients (75%).

INTERVENTIONS

Randomization 1:1 to Spfx, 400 mg on day 1, then 200 mg once daily, or ROXI, 150 mg twice daily, 10 to 14 days. Safety and efficacy analyses in intention-to-treat (ITT) and evaluable populations.

RESULTS

Three hundred three of 304 patients were included in the ITT and safety analyses and 260 (86%) were evaluable at the end of follow-up. Streptococcus pneumoniae was the cause of pneumonia in 62 (20%) patients (11 with bacteremia), Chlamydia pneumoniae in 40 (13%), and Mycoplasma pneumoniae in 38 (13%) patients. The success rates for Spfx and ROXI at the end of follow-up were 82% and 72%, respectively, in the ITT population, and 94% and 79%, respectively, in the evaluable population. The odds ratio Spfx/ROXI for success was 4.5 (95% confidence interval, 1.9, 10.8) for the evaluable population. Both drugs were, overall, equally safe. GI symptoms were the most common adverse experiences in both groups. Prolongation of QTc, without clinical symptoms, was seen in 3% of Spfx patients and in 1% of ROXI patients, and photosensitivity, mostly mild to moderate, was seen in 5% of the Spfx group.

CONCLUSIONS

Oral treatment with Spfx was superior to ROXI for the treatment of moderately severe CAP. Spfx was effective for all isolated pathogens, including S pneumoniae, and may be an alternative for empiric treatment of CAP, especially in areas with a high incidence of beta-lactam-resistant pneumococci.

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.

Ambulatory patients with community-acquired pneumonia: the frequency of atypical agents and clinical course

OBJECTIVES

To determine the etiology of community-acquired pneumonia in patients treated in an ambulatory setting, using serological methods, and to compare presenting symptoms, radiographic manifestations, and clinical outcomes of patients with pneumonia of "atypical" and undetermined etiology.

PATIENTS AND METHODS

This prospective cohort study was conducted in emergency room and outpatient facilities of Victoria General Hospital, Halifax, Nova Scotia, and in offices of participating family doctors based in Halifax. One hundred forty-nine adults with acute onset of one or more symptoms or signs suggestive of pneumonia and radiographic evidence of pneumonia who provided informed consent were enrolled. Patients known to be HIV positive or who had been discharged from a hospital within the previous 10 days were ineligible for enrollment. Demographic features and clinical data were collected by direct patient interview and chart review by trained research nurses. Outcome measures included quantitative evaluation of pneumonia-specific symptoms, and responses to the Short Form 36 Health Survey at presentation and at 30 days after presentation. Information was also collected on each patient's health prior to pneumonia, as well as the time until each patient's self-reported return to work and to usual activities. The etiology of pneumonia was determined by testing acute and convalescent serum samples for antibodies to Legionella pneumophila serogroup 1, Mycoplasma pneumoniae, Chlamydia pneumoniae, Chlamydia psittaci, Coxiella burnetii, adenovirus, respiratory syncytia virus, influenza viruses A and B, and parainfluenza viruses 1, 2, 3.

RESULTS

The study population consisted of 149 patients, 54 (36%) of whom were men, with a mean age (+/- SD) of 41 +/- 15 years. An etiological diagnosis was made in 74 (49.7%) patients using serological methods. Etiological agents included M pneumoniae 34 (22.8%); C pneumoniae 16 (10.7%); M pneumoniae and C pneumoniae 5 (3.4%); C burnetii 4 (2.7%); influenza A virus 4 (2.7%); and other agents 6% (7.4%). Three patients (2%) had a conventional bacterial etiology, and 72 patients (48.3%) had pneumonia of undetermined etiology. Patients with pneumonia of known (atypical) and undetermined etiology were similar in terms of age, gender, race, education, employment, and comorbidity. Despite a higher proportion of patients with pneumonia of known etiology reporting sweats, chills, and headache at presentation, the two groups were similar for symptom severity and bother. The patients with pneumonia of undetermined etiology were more likely to have multilobar pneumonia (P < 0.02). Both patients with atypical pneumonia and those with pneumonia of undetermined etiology suffered severe deterioration of physical functioning with a marked but incomplete recovery at 30 days. Those with atypical pneumonia had higher physical functioning and general mental health scores at 30 days.

CONCLUSIONS

Nearly half the cases of ambulatory community-acquired pneumonia are due to "atypical" agents. It is not possible to reliably distinguish patients with atypical pneumonia from those with pneumonia of undetermined etiology by clinical features at baseline. The outcomes in terms of resolution of symptoms, functional status, return to work, and return to usual activities are essentially similar in the two groups.

Limits of the microimmunofluorescence test and advantages of immunoblotting in the diagnosis of chlamydiosis

The Western blot (immunoblot) patterns of 56 serum specimens, all examined previously by the microimmunofluorescence (MIF) test for species-specific Chlamydia antibodies, were analyzed. Predominant specific-antibody activity was directed to the 170-, 155-, 145-, 120-, 115-, 100-, 57-, and 38-kDa proteins of Chlamydia trachomatis and to the 175-, 130-, 110-, 98-, and 30-kDa proteins of Chlamydia pneumoniae. All of these antigens appeared to be species specific. The reactivity with 90-, 80-, 75-, 62- or 60-, and 55-kDa proteins and the major outer membrane protein appeared to be genus specific. Fourteen serum samples which had identical titers of immunoglobulin G as determined by the MIF test were investigated by Western blotting. We found that nine serum samples had anti-C. trachomatis protein profiles and two had anti-C. pneumoniae protein profiles. The double seropositivity observed by MIF corresponded with cross-reactivity to genus-specific antibodies. As for the three remaining serum specimens, we observed identical protein profiles for C. trachomatis and C. pneumoniae, confirming the double seropositivity experienced with the MIF test. Western blotting can differentiate between specific reactions and interfering noise from other, partly cross-reacting chlamydial species.

A prospective randomized study of inpatient iv. antibiotics for community-acquired pneumonia. The optimal duration of therapy

STUDY OBJECTIVE

To compare therapeutic outcome and perform a cost-benefit analysis of inpatients with community-acquired pneumonia (CAP) treated with a shortened course of i.v. antibiotic therapy.

DESIGN

A prospective, randomized, parallel group study with a follow-up period of 28 days.

SETTING

Bronx Veterans Affairs Medical Center (VAMC) and the Castle Point VAMC; university-affiliated VAMC general medical wards from September 1993 to March 1995.

PATIENTS

Seventy-two male veterans and 1 female veteran with 75 episodes of CAP defined by a new infiltrate on chest radiograph and either history or physical findings consistent with pneumonia. Study population was 42%(31) black, 33%(24) white, and 25%(18) Hispanic.

INTERVENTIONS

Patients were randomized (1:1:1) to 1 of 3 treatment groups: group 1 received 2 days of i.v. and 8 days of oral therapy; group 2 received 5 days of i.v. and 5 days of oral therapy; and group 3 received 10 days of i.v. therapy. Antibiotics consisted of cefuroxime, 750 mg every 8 h for the i.v. course, and cefuroxime axetil, 500 mg every 12 h for the oral therapy.

MEASUREMENTS AND RESULTS

No differences were found in the clinical course, cure rates, or resolution of chest radiograph abnormalities among the three groups. A significant difference was found in the length of stay (LOS) among the three groups. The mean +/- SD LOS was 6 +/- 3 days in group 1, 8 +/- 2 days in group 2, and 11 +/- 1 days in group 3. The shortened LOS could potentially save $95.5 million for the Department of Veterans Affairs and $2.9 billion for the US private sector.

CONCLUSIONS

Adult patients hospitalized for CAP who are not severely ill can be successfully treated with an abbreviated (2-day) course of i.v. antibiotics and then switched to oral therapy. A longer course of i.v. therapy prolongs hospital stay and cost, without improving the therapeutic cure rate.

Community acquired pneumonia: aetiology and usefulness of severity criteria on admission

BACKGROUND

Community acquired pneumonia remains an important cause of hospital admission and carries an appreciable mortality. Criteria for the assessment of severity during admission have been developed by the British Thoracic Society (BTS). A study was performed to determine the sensitivity and specificity of a severity rule based on a modification of the BTS prognostic rules applied on admission, to compare severity as assessed by medical staff with the modified rule, and to determine the microbiological cause of community acquired pneumonia in Christchurch.

METHODS

A 12 month study of all adults admitted to Christchurch Hospital with community acquired pneumonia was undertaken. Three hundred and sixteen consecutive patients with suspected community acquired pneumonia were screened for inclusion. Variables obtained from the history, examination, investigations, and initial treatment were examined for association with mortality.

RESULTS

Two hundred and fifty five patients met the inclusion criteria. Their mean age was 58 years (range 18-97). A microbiological diagnosis was made in 181 cases (71%), Streptococcus pneumonia (39%), Mycoplasma pneumoniae (16%), Legionella species (11%), and Haemophilus influenzae (11%) being the most commonly identified organisms. Patients had a 36-fold increased risk of death if any two of the following were present on admission: respiratory rate > or = 30/min, diastolic BP < or = 60 mm Hg, urea > 7 mmol/l, or confusion. The severity rule identified 19 of the 20 patients who died and six of eight patients admitted to the intensive care unit as having life threatening community acquired pneumonia. The sensitivity of the modified rule for predicting death was 0.95 and the specificity 0.71. In 47 cases (21%) the clinical team appeared to underestimate the severity of the illness.

CONCLUSIONS

The organisms responsible for community acquired pneumonia in Christchurch are similar to those reported from other centres except for Legionella species which were more common than in most studies. The modification of the BTS prognostic rules applied as a severity indicator at admission performed well and could be incorporated into management guidelines.

Chlamydia pneumoniae pneumonia in hospitalized patients. Clinical characteristics and diagnostic value of polymerase chain reaction detection in BAL

STUDY OBJECTIVE

To evaluate the incidence and clinical characteristics of Chlamydia pneumoniae infection as detected by polymerase chain reaction (PCR) and culture of BAL in hospitalized patients with pneumonia, HIV-infected persons, and control subjects.

DESIGN

Prospective, comparative clinical study.

SETTING

University hospital medical center.

PATIENTS

Fifty-seven hospitalized patients with acute lower respiratory tract infection (group 1); 47 HIV-positive patients (group 2); 100 patients with noninfectious bronchopulmonary disorders (group 3).

INTERVENTIONS

BAL was performed in all patients at hospital admission for diagnostic purposes. In addition to semiquantitative bacterial and fungal culture, isolation and detection of C pneumoniae were performed by cell culture and PCR of the lavage fluid.

MEASUREMENTS AND RESULTS

C pneumoniae was detected in 16% of group 1, 13% of HIV-positive persons, and 0% of control subjects. The sensitivity of chlamydial culture was much lower as compared with PCR (4 vs 15 cases). In contrast to group 1, in the HIV-positive patients, acute respiratory symptoms were not always present, and in 3 of 6 cases, copathogens were found in the BAL. BAL differential cell counts disclosed a significant lymphocyte elevation mostly due to the CD8 subset (group 1: 15% vs 5%; group II: 18.5% vs 4%; C pneumoniae positive vs negative cases, respectively).

CONCLUSIONS

C pneumoniae is frequently detected in the BAL of hospitalized patients with pneumonia as sole pathogen. PCR detection is highly specific and far more sensitive than cell culture. Asymptomatic carriage seems to be uncommon in immunocompetent patients, but does occur in HIV-positive patients. A lymphocytic alveolitis is frequently found by BAL cytologic study and may represent a T-cell response to chlamydial infection in the lower respiratory tract.

Interobserver reliability of the chest radiograph in community-acquired pneumonia. PORT Investigators

OBJECTIVE

To evaluate the interobserver reliability of pulmonary radiographic findings in patients with community-acquired pneumonia (CAP).

DESIGN

A prospective, multicenter study.

SETTING

Physician offices, medical walk-in clinics, emergency departments, and inpatient wards affiliated with three university hospitals, one community hospital, and one staff model health maintenance organization in three geographic areas.

METHODS

Copies of the initial chest radiograph of patients suspected of having CAP were independently read by two staff radiologists at the coordinating university hospital. Interobserver reliability for the interpretation for radiographic findings was assessed by calculation of agreement rates and the kappa statistic.

PARTICIPANTS

Adults (age > or = 18 years) with symptoms or signs of CAP and a pulmonary radiographic infiltrate documented by a local study site radiologist.

RESULTS

Among the 282 patients whose initial pulmonary radiographs were evaluated, there was agreement between the two staff radiologists on the presence of infiltrate in 79.4% and on the absence of an infiltrate in 6.0% (kappa = 0.37; 95% confidence interval [CI] = 0.22 to 0.52). For the 224 patients with an infiltrate identified by both radiologists, there was further agreement that the infiltrate was unilobar in 41.5% and multilobar in 33.9% (kappa = 0.51; 95% CI = 0.28 to 0.62), pleural effusion was present in 10.7% and absent in 73.2% (kappa = 0.46; 95% CI = 0.33 to 0.50), and the infiltrate was alveolar in 96.3% of patients and interstitial in no patients (kappa = -0.01; 95% CI = -0.03 to 0.00). Among the 210 patients with an alveolar infiltrate, both radiologists classified the infiltrate as lobar in 74.6% and bronchopneumonia in 2.4% (kappa = 0.09; 95% CI = -0.04 to 0.22), and agreed on the presence of air bronchograms in 7.6% and their absence in 52.9% (kappa = 0.01; 95% CI = -0.13 to 0.15).

CONCLUSION

In patients with CAP, two university radiologists identified the presence of infiltrate, multilobar disease, and pleural effusion with fair to good interobserver reliability. However, interobserver reliability for the pattern of infiltrate and the presence of air bronchograms was poor.

Prospective study of epidemiology and prognostic factors in community-acquired pneumonia

Of 342 patients with community-acquired pneumonia, 100 were diagnosed etiologically. In these patients, disease epidemiology, prognostic factors, and influence of antibiotic treatment were analyzed prospectively. Fifty-two patients were treated with a broad-spectrum antibiotic (ceftriaxone), and 48 received a medium-spectrum antibiotic (cefuroxime); some patients in each group also received erythromycin. Streptococcus pneumoniae was the most frequently isolated microorganism (43%), followed by Chlamydia pneumoniae (21%), Haemophilus influenzae (19%), and Mycoplasma pneumoniae (11%). Factors significantly associated with increased mortality were initially critical or poor clinical condition, involvement of two or more lobules, and complications. Prior administration of antibiotics was predictive of penicillin and erythromycin resistance in Streptococcus pneumoniae, but had no effect on the course of the disease. Eight patients died, 89 were cured, and three had recurrences; there was no significant difference in outcome between treatment groups, regardless of whether patients also received erythromycin. Increased knowledge of epidemiological, predictive, and prognostic factors can significantly improve early diagnosis of community-acquired pneumonia and facilitate the choice of appropriate antibiotic treatment, thereby helping to reduce morbidity and mortality.

A new therapeutic option for the treatment of pneumonia

Patients with bacterial pneumonia often are treated empirically with parenteral broad-spectrum antimicrobials intended to cover potential gram-negative and gram-positive pathogens. However, beta-lactamase-mediated resistance has developed to many of these antimicrobials, particularly third-generation cephalosporins, and has led to the development of fourth-generation agents that are relatively beta-lactamase stable. The purpose of these studies was to compare the efficacy and safety of the fourth-generation agent, cefepime, with that of the third-generation agent, ceftazidime, in the treatment of hospitalized patients with moderate-to-severe bacterial pneumonia. A total of 336 (97 evaluable) patients were enrolled in an open-label study, and 99 (23 evaluable) patients were enrolled in a blinded study of patients with lower respiratory tract infections (LRTI) including pneumonia. Patients were randomized to receive either cefepime 1 g every 12 hours or ceftazidime 1 g every 8 hours given as an intravenous infusion over 30 minutes. Efficacy analysis included the evaluable patients while the safety analysis included all patients. The results in the open-label study were as follows: In patients with pneumonia, clinical response was satisfactory in 58 (85%) of 68 patients in the cefepime group and 21 (72%) of 29 patients in the ceftazidime group. Bacteriologic eradication occurred for 75 (93%) of 81 pathogens and 30 (94%) of 32 pathogens isolated from the 68 cefepime-treated patients and 29 ceftazidime-treated patients, respectively. The results in the blinded study were as follows: In patients with pneumonia, clinical response was satisfactory in 12 (80%) of 15 cefepime patients and in 7 (88%) of 8 ceftazidime patients, and the bacteriologic eradication rates were 85% (17/20 pathogens) and 73% (8/11 pathogens) isolated from the 15 cefepime-treated patients and the eight ceftazidime-treated patients, respectively. Among the most frequent adverse events in both groups were nausea, diarrhea, vomiting, and abdominal pain. Similar adverse events were noted in the 99 patients in the blinded study. These studies indicate that the efficacy and safety of cefepime administered at 1 g twice daily is comparable to that of ceftazidime administered at 1 g three times daily for treatment of hospitalized patients with pneumonia caused by susceptible pathogens.

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.

Adult respiratory distress syndrome due to Chlamydia pneumoniae in a young adult

A case of life-threatening Chlamydia TWAR pneumonia complicated by encephalitis in a young, previously healthy adult is described. The patient presented with full blown adult respiratory distress syndrome and required prolonged ventilatory support and rigorous antibiotic and supportive care. He recovered fully without any neurologic sequelae. Chlamydia pneumoniae pneumonia should be included in the differential diagnosis of the severe community acquired pneumonia, because if properly sought and adequately treated, may have an excellent outcome.

Replication of Chlamydia pneumoniae in vitro in human macrophages, endothelial cells, and aortic artery smooth muscle cells

Chlamydia pneumoniae has recently been associated with atherosclerotic lesions in coronary arteries. To investigate the biological basis for the dissemination and proliferation of this organism in such lesions, the in vitro growth of C. pneumoniae was studied in two macrophage cell lines, peripheral blood monocyte-derived macrophages, human bronchoalveolar lavage macrophages, several endothelial cell lines, and aortic smooth muscle cells. Five strains of C. pneumoniae were capable of three passages in human U937 macrophages and in murine RAW 246.7 macrophages. Titers were suppressed in both macrophage types with each passage, as compared with growth titers in HEp-2 cells. Both human bronchoalveolar lavage macrophages and peripheral blood monocyte-derived macrophages were able to inhibit C. pneumoniae after 96 h of growth. Eleven C. pneumoniae strains were capable of replicating in normal human aortic artery-derived endothelial cells, umbilical vein-derived endothelial cells, and pulmonary artery endothelial cells. Infection in human aortic artery smooth muscle cells was also established for 13 strains of C. pneumoniae. The in vitro ability of C. pneumoniae to maintain infections in macrophages, endothelial cells, and aortic smooth muscle cells may provide support for the hypothesis that C. pneumoniae can infect such cells and, when infection is followed by an immune response, may contribute to atheroma formation in vivo. More studies are needed to investigate the complex relationship between lytic infection and persistence and the potential for C. pneumoniae to influence the generation of atheromatous lesions.

Legionella species community-acquired pneumonia. A review of 56 hospitalized adult patients

BACKGROUND

In a prospective study, Legionella species (Lsp) was identified as the causative agent in 56 (16.2%) of 346 adult patients hospitalized over the course of 1 year with community-acquired pneumonia (CAP), in the Soroka Medical Center, Beer-Sheva, Israel.

OBJECTIVE

To characterize patients with Lsp CAP in our study.

METHODS

The diagnosis of infection with Lsp was based on serologic testing of antibodies using the indirect immunofluorescent method.

RESULTS

In 35 (62.5%) of the patients, at least one other etiologic agent for CAP was identified in addition to Lsp. The patient population was relatively young, with relatively low rates of chronic comorbidity, and a broad spectrum of disease severity compared with previously published studies. No single epidemiologic, clinical, laboratory, or radiographic characteristic differentiated between Lsp CAP and other CAP patients in our study. Three patients (5.4%) who were not treated with erythromycin died. However, in contrast, nine patients who were treated with beta-lactam antibiotics recovered completely.

CONCLUSIONS

Lsp is a common cause of CAP in our region, usually as a coinfection with another causative agent. Lsp CAP, which cannot be characterized on the basis of clinical, routine laboratory, or radiographic data, requires specific microbiologic or serologic diagnosis. Treatment with erythromycin appears to be important to reduce mortality from this disease, but in a significant number of patients, the disease may be self-limited.

Levofloxacin in vitro activity against bacteremic isolates of Streptococcus pneumoniae. Franklin County Pneumonia Study Group

Levofloxacin had excellent activity in vitro against bacteremic isolates of Streptococcus pneumoniae with 495 (99.2%) of 499 isolates being susceptible. A total of 38 (97.4%) of 39 isolates with minimal inhibitory concentrations > or = 0.12 micrograms/ml of penicillin were susceptible to levofloxacin. There was excellent correlation between the disk diffusion and broth microdilution methods for determining susceptibility. Resistant isolates belonged to four different serotypes. There was no increase in proportion of isolates of S. pneumoniae resistant between 1991 and 1994.

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.

Chlamydia pneumoniae community-acquired pneumonia: a review of 62 hospitalized adult patients

In a prospective study, Chlamydia pneumoniae was identified as the etiological agent in 62 (17.9%) of 346 adult patients hospitalized over the course of one year for community-acquired pneumonia at the Soroka Medical Center in Beer-Sheva, Israel. The diagnosis of C. pneumoniae infection was based on serological testing of antibodies by the MIF technique. In 43 of these patients (69.4%), at least one other etiological agent, in addition to C. pneumoniae for community-acquired pneumonia was identified. Streptococcus pneumoniae was identified in 34 patients with C. pneumoniae (54.8%), as an additional causative factor in infection. Community-acquired pneumonia patients with C. pneumoniae were significantly older than non-C. pneumoniae patients (p = 0.03), had a higher APACHE II score on admission (p < 0.05), a higher rate of positive blood cultures (p = 0.02), and longer periods of hospitalization (p = 0.022). Seven patients with pure C. pneumoniae infection recovered, despite treatment which is not considered to be specific for C. pneumoniae. It was concluded that C. pneumoniae is a common etiological agent for community-acquired pneumonia in our region, particularly in the elderly, and is characterized by a high rate of concomitant infections with other pulmonary pathogens. No specific clinical or radiological pattern was discerned that could distinguish between C. pneumoniae community-acquired pneumonia and non-C. pneumoniae community-acquired pneumonia.

Variation in plasma lipid and lipoprotein concentrations in community-acquired pneumonia a six-month prospective study

The nature of changes in the lipid profile caused by an acute infection is controversial. The aims of the present study were to study the changes in plasma lipids and lipoproteins in community-acquired pneumonia, to determine whether these changes differ according to the aetiologica/agents, and finally to observe the behaviour of these lipoproteins six months later. Sixty patients, aged between 18 and 87 years, admitted during the period September 1992 and April 1993 with suspected community-acquired pneumonia, were included in the study. Fifty-three of the patients completed the 15-day follow-up investigation, and 37 remained available for study for up to 6 months. On admission and at 15 and 180 days, analyses were carried out for total cholesterol, HDL cholesterol, apolipoproteins A1 and B, triacylglycerols and transaminases. Student's t test for parametric variables was used for statistical analysis, and the Mann-Whitney test for non-parametric variables. The concentrations of total cholesterol (4.2 +/- 1.0 vs 5.5 +/- 1.3 mmol/1), HDL cholesterol (0.9 +/- 0.4 vs 1.2 +/- 0.3 mmol/l), apolipoprotein A1 (0.80 +/- 0.25 vs 1.15 +/- 0.28 g/l) and apolipoprotein B (0.77 +/- 0.28 vs 0.95 +/- 0.28 g/l) showed significantly lower values during the acute infectious process. These analyte concentrations became stable after 15 days with the exception of HDL cholesterol which continued to increase until 6 months (1.2 +/- 0.3 vs 1.3 +/- 0.3 mmol/l, p < 0.01). Patients with non-viral atypical pneumonia showed, on admission, higher triacylglycerol values (1.8 +/- 0.8 vs 1.3 +/- 0.9 mmol/l, p < 0.01) and lower HDL cholesterol values (0.6 +/- 0.3 vs 1.0 +/- 0.4 mmol/l, p < 0.03). Values of aspartate aminotransferase (112 +/- 117 vs 23 +/- 11 U/l, p < 0.001), alanine aminotransferase (127 +/- 141 vs 24 +/- 16 U/l, p < 0.02) and gamma-glutamyl transferase (113 +/- 158 vs 33 +/- 25 U/l, p < 0.03) were higher in the subgroup of non-viral atypical pneumonia. In conclusion, patients with community-acquired pneumonia present a significant decline in total cholesterol, HDL cholesterol and apolipoprotein A1 and B concentrations. Lower concentrations of HDL cholesterol are maintained up 15 days. Patients with non-viral atypical pneumonia present on admission significantly higher triacylglycerol and lower HDL cholesterol values. Those with non-viral atypical pneumonia also present higher transaminase values.

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.

Multiple pathogens in adult patients admitted with community-acquired pneumonia: a one year prospective study of 346 consecutive patients

BACKGROUND

The purpose of this study was to assess the causes of community-acquired pneumonia in adult patients admitted to hospital.

METHODS

A prospective study was performed on 346 consecutive adult patients (54% men) of mean (SD) 49.3 (19.5) years (range 17-94) admitted to a university affiliated regional hospital in southern Israel with community-acquired pneumonia over a period of one year. Convalescent serum samples were obtained from 308 patients (89%). The aetiological diagnosis for community-acquired pneumonia was based on positive blood cultures and/or significant changes in antibody titres to Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, respiratory viruses, Coxiella burnetii, Mycoplasma pneumoniae, Chlamydia pneumoniae, and Legionella sp.

RESULTS

The aetiology of community-acquired pneumonia was identified in 279 patients (80.6%). The distribution of causal agents was as follows: S pneumoniae, 148 patients (42.8%); M pneumoniae, 101 (29.2%); C pneumoniae, 62 (17.9%); Legionella sp, 56 (16.2%); respiratory viruses, 35 (10.1%); C burnetii, 20 (5.8%); H influenzae 19 (5.5%); and other causes, 21 patients (6.0%). In patients above the age of 55 years C pneumoniae was the second most frequent aetiological agent (25.5%). In 133 patients (38.4%) more than one causal agent was found.

CONCLUSIONS

The causal agents for community-acquired pneumonia in Israel are different from those described in other parts of the world. In many of the patients more than one causal agent was found. In all these patients treatment should include a macrolide antibiotic, at least in the first stage of their illness.

Respiratory infections: community-acquired pneumonia and newer microbes

Respiratory infections, especially community-acquired forms of pneumonia (CAP), are challenging for clinicians because (1) a causative microorganism can only be found in about 50% of cases; (2) initial therapy, therefore, must be based on a probable or most likely etiology in the context of the patient's overall medical condition; and (3) new microbes or those considered previously as normal flora or less virulent forms seem responsible for some cases. It is important to be acquainted with new causes of infection which include Legionella species, Chlamydia pneumoniae, diphtheroids in certain instances (Corynebacterium pseudodiphtheriticum), and viruses such as the Hanta strains. Infections with Bordetella pertussis are increasing. However, the ever present and most common cause of CAP, Streptococcus pneumoniae, continues to present problems because of increasing antibiotic resistance, the high case fatality rate when bacteremia accompanies pneumonia, and the inability to give prophylactic immunization to all people with risk factors for this infection.

Community acquired, nursing home acquired and hospital acquired pneumonia: A five-year review of the clinical, bacteriological and radiological characteristics

PURPOSE

To assess the contemporary clinical, bacteriological and radiographic features of hospitalized patients with community acquired (ca), nursing home acquired (na) and hospital acquired pneumonia (ha) and to examine patient outcome.

PATIENTS AND METHODS

All hospital records of patients with pneumonia over a five-year period from April 1987 to March 1992 were reviewed retrospectively. Patients included in the study were all those with a diagnosis of pneumonia as identified by computer records of diagnostic codes at discharge; patients with a specific diagnosis of Pneumocystis carinii pneumonia were excluded. Of 74,435 discharges over the five-year period, 1782 patients met the inclusion criteria.

RESULTS

Charts of 1622 of the total 1782 cases were reviewed. Mean age was 64.4 years with 59.4% men and 40.6% women. Sixty-three per cent were ca, 28.5% were ha and 8.5% were na. A total of 1542 patients (95%) had at least one concomitant medical condition. Chest roentgenogram was abnormal in 97%. Common organisms isolated overall were Haemophilus influenzae (from 204 patients), Staphylococcus aureas (from 152 patients), Streptococcus pneumoniae (from 143 patients ), Escherichia coli (from 113 patients) and Pseudomonas aeruginosa (from 111 patients). H influenzae and S pneumoniae were most common in ca pneumonia, whereas S aureus and Gram-negative organisms were more common in the ha group and Gram-negative agents in the na group. One hundred and four patients developed complications. Fifteen per cent required intensive care unit admission. The average length of hospitalization in the ca and na groups was 17 days and in the ha group, 43 days. At time of discharge 1261 patients (78%) were cured or improved, and 361 patients (22%) died during the admission.

CONCLUSIONS

These results suggest that hospitalization for pneumonia in the 1990s is primarily for elderly patients with significant co-morbidity. Although microbiology appears unchanged compared with earlier reports, the contemporary population is significantly sicker than previous cohorts. This may account for the persistently high morbidity and mortality despite better or newer antibiotics.

Clinical utility of blood cultures in adult patients with community-acquired pneumonia without defined underlying risks

STUDY OBJECTIVE

We retrospectively examined the clinical utility of obtaining routine blood cultures before the administration of antibiotics in certain nonimmunosuppressed patients with community-acquired pneumonia (CAP) admitted to the hospital during 1991.

DESIGN

Retrospective review.

SETTING

Grady Memorial Hospital (a county hospital primarily serving inner-city Atlanta).

PATIENTS OR PARTICIPANTS

Hospital discharge diagnosis listings identified 1,250 adults ( > or = 18 years old) with pneumonia. From this group of patients, we selected patients admitted to the hospital with (1) respiratory symptoms and a lobar infiltrate on chest radiograph that were present at the time of hospital admission, (2) two or more sets of blood cultures obtained within 48 h of hospital admission, and (3) absence of defined risk factors: HIV-related illness, malignancy, recent chemotherapy, steroid therapy, sickle cell disease, nursing home residence, or hospital stays within the past 14 days.

MEASUREMENTS AND RESULTS

Five hundred seventeen patients (mean age, 52 years;: age range, 18 to 103 years) qualified. Of these 517 patients, 25 patients (4.8%) had growth in blood cultures considered contaminants while 34 (6.6%) had blood cultures positive for the following pathogens: 29 Streptococcus pneumoniae, 3 Haemophilus influenzae, and 1 Streptococcus pyogenes, 1 Escherichia coli. Antibiotic therapy was changed for 7 of the 34 patients with positive blood cultures (1.4% of study patients). Antibiotic regimens were altered in 48 additional patients based on sputum culture, poor clinical response, and allergic reactions.

CONCLUSIONS

Few blood cultures were positive for likely infecting organisms in adult patients with CAP without defined underlying risk factors. Furthermore, a total of $34,122 was spent on blood cultures at $66 per patient. In this carefully defined group of patients, blood cultures may have limited clinical utility and questionable cost-effectiveness.

Bacterial pneumonia in persons infected with the human immunodeficiency virus. Pulmonary Complications of HIV Infection Study Group

BACKGROUND

Patients with human immunodeficiency virus (HIV) infection are at increased risk for bacterial pneumonia in addition to opportunistic infection. However, the risk factors for bacterial pneumonia and its incidence in this population are not well defined.

METHODS

In a multicenter, prospective, observational study, we monitored 1130 HIV-positive and 167 HIV-negative participating adults for up to 64 months for pulmonary disease. The HIV-positive group comprised 814 homosexual or bisexual men, 261 injection-drug users, and 55 female partners of HIV-infected men.

RESULTS

There were 237 episodes of bacterial pneumonia among the HIV-positive participants (rate, 5.5 per 100 person-years), as compared with 6 episodes among the HIV-negative participants (rate, 0.9 per 100 person-years; P < 0.001). The rate of bacterial pneumonia increased with decreasing CD4 lymphocyte counts (2.3, 6.8, and 10.8 episodes per 100 person-years in the strata with more than 500, 200 to 500, and fewer than 200 cells per cubic millimeter, respectively; P < or = 0.022 for each comparison). Injection-drug users had a higher rate of bacterial pneumonia than did homosexual or bisexual men or female partners. In the stratum with the fewest CD4 lymphocytes, cigarette smoking was associated with an increased rate of pneumonia. Mortality was almost four times higher among participants with an episode of pneumonia than among the others. Prophylaxis with trimethoprim-sulfamethoxazole was associated with a 67 percent reduction in confirmed episodes of bacterial pneumonia (P = 0.007).

CONCLUSIONS

Bacterial pneumonia is more frequent in HIV-positive persons than in seronegative controls, and the risk is highest among those with CD4 lymphocyte counts below 200 per cubic millimeter and among injection-drug users.

Microparticle agglutination versus antibody-capture enzyme immunoassay for diagnosis of community-acquired Mycoplasma pneumoniae pneumonia

Community-acquired Mycoplasma pneumoniae pneumonia is a common disease which is usually diagnosed by serological methods. The objective of the present study was to understand the diagnostic significance and test characteristics of two different serological tests used to identify current Mycoplasma pneumoniae infection. Three hundred sixty-six patients who suffered from community-acquired pneumonia served as the study population. Six hundred ninety-four (328 paired and 38 unpaired) sera were examined for the presence of antibodies to Mycoplasma pneumoniae with commercial kits based on two serological methods, microparticle agglutination and antibody-capture EIA. Agreement between the two kits was 85.2% when individual sera were compared (kappa = 0.62) and 88.5% when patients were compared (Kappa = 0.69). The positive predictive value and the specificity for the identification of current Mycoplasma pneumoniae infection using a single acute-phase serum were 49.3% and 86.9%, respectively, for the microparticle agglutination method, compared to 91.3% and 97.7% for the antibody-capture EIA method (p < 0.001). The negative predictive value and the sensitivity were 86.3% and 48.1% for the microparticle agglutination, not significantly different from the corresponding values of 86.5% and 61.2% for the antibody-capture EIA. It is concluded that the overall agreement between the two methods tested is good, but not perfect. The methods complement each other in the identification of Mycoplasma pneumoniae as the causative agent in patients with community-acquired pneumonia.

Pneumococcal virulence factors and host immune responses to them

The principal virulence determinant of most encapsulated bacterial pathogens is the possession of an extracellular capsule. This paper discusses biological aspects of the Streptococcus pneumoniae capsule, putative roles played by accessory virulence factors of this pathogen and prospects for improvement of the currently available pneumococcal vaccine. Even though the interruption of genes encoding selected proteins has been shown to attenuate virulence to some degree, the physical removal of the pneumococcal capsule or the interruption of encapsulation genes completely abolishes virulence in mice. The role of the capsule in pathogenesis is not completely clear, however, since it is not known whether this structure is important in colonization, the obligatory first step in the process. In addition, a number of proteins have been implicated as possible accessory virulence factors. These include pneumolysin, two distinct neuraminidases, an IgA1 protease and two surface proteins, pspA and psaA. While interruption of the expression of some of these proteins examined to date has been shown to attenuate virulence, so far it has not proven possible to completely abolish virulence in this fashion. Proteinaceous accessory virulence factors may prove important to the development of second-generation pneumococcal vaccines, however. Pneumococcal and other proteins conjugated to pneumococcal polysaccharides are currently being evaluated as carriers in attempts to improve the immunogenicity of polysaccharide vaccines, primarily in small children.

Aetiology of community-acquired pneumonia: a prospective study among adults requiring admission to hospital

BACKGROUND

The prevalence of microorganisms causing community-acquired pneumonia in patients who required admission to hospital was investigated and the percentage of cases whose aetiology remained unknown due to the study design and logistical problems estimated.

METHODS

Between January 1991 and April 1993 all patients with community-acquired pneumonia admitted to six hospitals were included in the study. Aetiological diagnosis, categorised as definite, probable and possible, was based on the results of routine microbiological and serological tests.

RESULTS

Three hundred and thirty four patients with a median age of 65 (range 17-92) years were enrolled in the study. The diagnosis of community-acquired pneumonia was definite in 108 cases, and probable or possible in 73 and 27 cases, respectively, including dual infections. Streptococcus pneumoniae was the predominant pathogen (27%) followed by viruses and Haemophilus influenzae (both about 8%) and Mycoplasma pneumoniae (6%). Chlamydia spp (3%) and Legionella pneumophila (2%) were less frequently detected. No diagnosis was made in 45% of the cases. With adjustment for anti-microbial therapy before admission and for other logistical considerations, it is estimated that the aetiology could have been ascertained in 65% of the cases.

CONCLUSIONS

Streptococcus pneumoniae is the most frequently detected cause of community-acquired pneumonia. The inability to detect a micro-organism results mainly from the use of routine diagnostic tests and, to a lesser extent, from logistical problems or the use of antibiotics before admission.

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

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

Potable water and nosocomial Legionnaires' disease--check water from all rooms in which patient has stayed

We studied 7 patients with nosocomial Legionnaires' disease to determine the relationship between isolates of Legionella pneumophila recovered from potable water and those recovered from patients. Potable water was cultured from all rooms in which patients had stayed prior to the diagnosis of Legionnaires' disease. The 38 isolates of L. pneumophila (31 environmental, 7 patient) were resolved into 9 distinct patterns by pulse-field gel electrophoresis (PFGE), 3 by plasmid content and 2 each with monoclonal antibodies and conventional agarose gel electrophoresis of small fragments of DNA. Using PFGE it was determined that 4 of the 7 patients were infected with L. pneumophila identical to an isolate recovered from the potable water supply in one of the rooms each had occupied prior to the diagnosis of Legionnaires' disease. Patients had resided in a mean of 3.57 rooms before a diagnosis of nosocomial Legionnaires' disease. We conclude that in the setting of contaminated potable water and nosocomial Legionnaires' disease water from all the rooms which the patient has occupied prior to this diagnosis should be cultured. PFGE of large DNA fragments discriminated best among the isolates of L. pneumophila.

Efficacy and safety of azithromycin versus benzylpenicillin or erythromycin in community-acquired pneumonia

Azithromycin, a recently introduced antibiotic, offers the potential advantages of short-course administration and lower toxicity compared to other macrolides. Approved for the treatment of mild pneumonia, this drug was investigated in a study of patients hospitalized for community-acquired pneumonia. In an open-labelled randomized study, oral azithromycin was compared with intravenous benzylpenicillin in patients suspected to have pneumococcal pneumonia. Azithromycin was also compared with erythromycin, both administered orally, in all other patients. Three hundred thirty-four patients with community-acquired pneumonia were hospitalized, 108 of whom were randomized; 104 could be evaluated. A need for intravenous therapy was the most common reason for exclusion. In the pneumococcal group, 35 patients received azithromycin and 29 benzylpenicillin. The clinical and radiological success rate achieved with azithromycin (83%) was considerably higher than that achieved with benzylpenicillin (66%), though the difference was not significant. In the non-pneumococcal group, 19 patients received azithromycin and 21 erythromycin; no differences in the success rate were found (79% and 76%, respectively). Eight patients on azithromycin had a blood culture positive for Streptococcus pneumoniae; in three of these patients therapy was changed. None of the five patients with pneumococcal bacteraemia who received benzylpenicillin required a change in therapy. It is concluded that oral azithromycin, administered as short-course therapy, is an appropriate antibiotic for treating patients with community-acquired pneumonia. However, it is not yet certain that azithromycin is a good choice for patients with pneumococcal bacteraemia.