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

The aetiology of severe community-acquired pneumonia and its impact on initial, empiric, antimicrobial chemotherapy

Of 259 patients admitted to an intensive care unit with severe acute community-acquired pneumonia, 173 had primary infections and 86 had secondary infections. The commonest organism isolated in each group was Streptococcus pneumoniae (51.3 and 36.6% of known isolates in each group respectively). Klebsiella pneumoniae was the next most common isolate (31.9 and 29.3% respectively). A variety of other Gram-negative organisms and Staphylococcus aureus accounted for most of the remaining pathogens. Based on retrospective analysis of data, there appeared to be no difference in the alcohol consumption of patients with infection due to S. pneumoniae and K. pneumoniae. The overall mortality rate for the primary infections was 47.4%, with 68.4% of these infections due to K. pneumoniae and 33.9% due to the pneumococcus (P < 0.002). Among the secondary infections, the overall mortality rate was 40.8% (not significantly different to that of primary infections) with 45.5% due to K. pneumoniae and 23.1% due to the pneumococcus (not significantly different on statistical analysis, probably due to low patient numbers). Our investigation confirms that severe community-acquired pneumonia due to K. pneumoniae is extremely common, even in patients without obvious risk factors for Gram-negative colonization. This organism is contributing to the high mortality rate seen in our intensive care unit among patients with pneumonia, and our empiric therapy for such cases routinely includes a combination of agents active against this organism (e.g. a cephalosporin and an aminoglycoside).

Diagnostic and prognostic value of interleukin-6 and C-reactive protein in community-acquired pneumonia

The diagnostic and prognostic value of admission serum levels of interleukin-6 (IL-6) and C-reactive protein (CRP) was investigated in 203 hospital-treated patients with community-acquired pneumonia (CAP). In serum samples obtained during the first 24 h after admission, IL-6 was detectable in 198 patients (98%), with a median value of 50 ng/l. Ten % of the patients had IL-6 values of 1000 ng/l. A clear positive correlation between IL-6 and CRP was found (r = 0.29, p < 0.0001). Patients with high IL-6 or CRP levels had longer duration of fever, longer hospital stay, and had less often recovered clinically or radiographically on follow-up weeks after discharge. A high IL-6, but not a high CRP, also seemed to be associated with a higher mortality. Bacteremic pneumococcal pneumonia had the highest levels of IL-6 (mean 2852 and median 420 ng/l) and CRP (mean 292 and median 285 mg/l). High IL-6 values were also seen in patients with non-bacteremic pneumococcal pneumonia, while all patients with pneumonia due to other bacterial, or viral, aetiology had IL-6 levels of < or = 300 ng/l. In conclusion, IL-6 and CRP are promising diagnostic and prognostic tools in the management of CAP. Further studies are needed to establish the usefulness of repeated measurements early in the hospital course of the disease.

Effects of two antibiotic regimens on course and persistence of experimental Chlamydia pneumoniae TWAR pneumonitis

We studied the effects of two antibiotic regimens on the course of Chlamydia pneumoniae infection in the lungs of Swiss Webster mice. After intranasal challenge with isolates AR-388 (1.3 x 10(7) inclusion-forming units per mouse) and AR-39 (1.5 x 10(6) inclusion-forming units per mouse), groups of animals were treated with either doxycycline (10 mg/kg of body weight once a day for 3 days), azithromycin (10 mg/kg [single dose]), or saline. Responses were assessed by the isolation of organisms in cell culture, detection of TWAR DNA in lung tissues by PCR, and lung histology. Both regimens were effective in clearing infections induced by AR-388 (P = 0.02 and 0.007 for doxycycline and azithromycin, respectively) compared with controls. TWAR DNA was detected in 77 and 25% of culture-negative lungs 2 weeks after treatment of AR-388 and AR-39 infections, respectively. Histological changes showed interstitial pneumonitis and were similar over time for all groups. Single-dose azithromycin produced drug levels in lung tissues above the MICs for the test strains for a period three times longer than that of single-dose doxycycline. We concluded that short-term antibiotic regimens were successful for the treatment of experimental TWAR pneumonitis in mice. TWAR DNA was frequently recovered from lung tissues after apparently successful treatment.

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.

Azithromycin for treatment of community acquired pneumonia caused by Legionella pneumophila: a retrospective study

A clinical, retrospective and non-comparative study was undertaken to assess the clinical efficacy and tolerability of azithromycin in the treatment of community-acquired pneumonia caused by Legionella pneumophila. A total of 16 patients with a serologically confirmed diagnosis of Legionnaires' diseases were included. Azithromycin was administered orally at a total dose of 1.5 g for either 3 or 5 days. All patients were no side-effects requiring discontinuation of the treatment. Further increase of abnormal baseline liver function was recorded in 2 patients and in 1 patient mild, transient eosinophilia. Equal clinical efficacy and tolerability were observed with the 3- and 5-day dosage regimen. These results indicate that azithromycin given at a standard dose of 1.5 g is effective and well tolerated in the treatment of Legionnaires' disease.

A five-year study of severe community-acquired pneumonia with emphasis on prognosis in patients admitted to an intensive care unit

OBJECTIVES

To characterize the epidemiology and to determine the prognosis factors in severe community-acquired pneumonia among patients admitted to an intensive care unit.

DESIGN

Retrospective clinical study.

SETTING

Intensive Care and Infectious Diseases Unit of a municipal general hospital of Lille University Medical School.

PATIENTS

299 consecutive patients exhibiting severe community-acquired pneumonia.

MEASUREMENTS AND RESULTS

On admission to ICU, 149 patients required mechanical ventilation for acute respiratory failure and 44 exhibited septic shock. Pulmonary involvement was bilateral in 71 patients. There were 260 organisms isolated from 197 patients (65.9%), the most frequent being Streptococcus pneumoniae (n = 80), Staphylococcus spp. (n = 57) and Gram-negative bacilli (n = 81). Overall mortality was 28.5% (85 patients). According to univariate analysis, mortality was associated with age over 60 years, anticipated death within 5 years, immunosuppression, shock, mechanical ventilation, bilateral pulmonary involvement, bacteremia, neutrophil count < 3500/mm3, total serum protein level < 45 g/l, serum creatinine > 15 mg/l, non-aspiration pneumonia, ineffective initial therapy and complications. Multivariate analysis selected only 5 factors significantly associated with prognosis: anticipated death within 5 years, shock, bacteremia, non-pneumonia-related complications and ineffective initial therapy.

CONCLUSION

The effectiveness of the initial therapy appears to be the most significant prognosis factor and, as the one and only related to the initial medical intervention, suggests a need for permanent optimization of our antimicrobial strategies.

Pneumococcal parotitis and cervical lymph node abscesses in an HIV-infected patient

The case of a 33-year-old patient with rapid onset of bilateral parotid gland and lymph node abscesses is described. The patient was positive for human immunodeficiency virus 1 and presented with a history of interstitial lymphocytic pneumonia and pneumococcal meningitis prior to admission. The patient received cotrimoxazole as primary prophylaxis against Pneumocystis carinii pneumonia. Fine needle aspiration from the abscesses yielded Streptococcus pneumoniae. Penicillin G treatment in combination with surgical drainage of the lesions led to healing with minimal residual lymph node enlargement. No relapse was noted until 12 months after presentation.

Pneumonia in a nursing home

The authors studied nursing home residents serologically to determine whether atypical organisms were causes of radiologic pneumonia. The study was conducted at the Wisconsin Veterans Home, a facility with on-site microbiology and x-ray. Over one year, serologic examinations for Legionella, Mycoplasma, and Chlamydia were conducted for the residents who had pneumonia. Cultures and mortality were reviewed. Fifty-six episodes were studied (mean resident age 78 years). There was no fourfold titer change. Seventeen quality sputum specimens revealed Streptococcus pneumoniae (5), normal flora (4), Hemophilus influenzae (4), Moraxella catarrhalis (3), Staphylococcus aureus (1), and beta-hemolytic Streptococcus, not group A (1). The two-month mortality was 21%. This study did not result in serologic confirmation of atypical organisms' causing pneumonia. Antibiotic choice should be based on coverage of prevalent organisms, including Hemophilus influenzae, Moraxella, and Staphylococcus, as well as clinical features.

Bronchoscopic diagnosis of pneumonia

Lower respiratory tract infections are characterized by significant morbidity and mortality but also by a relative inability to establish a specific etiologic agent on clinical grounds alone. With the recognized shortcomings of expectorated or aspirated secretions toward establishing an etiologic diagnosis, clinicians have increasingly used bronchoscopy to obtain diagnostic samples. A variety of specimen types may be obtained, including bronchial washes or brushes, protected specimen brushings, bronchoalveolar lavage, and transbronchial biopsies. Bronchoscopy has been applied in three primary clinical settings, including the immunocompromised host, especially human immunodeficiency virus-infected and organ transplant patients; ventilator-associated pneumonia; and severe, nonresolving community- or hospital-acquired pneumonia in nonventilated patients. In each clinical setting, and for each specimen type, specific laboratory protocols are required to provide maximal information. These protocols should provide for the use of a variety of rapid microscopic and quantitative culture techniques and the use of a variety of specific stains and selective culture to detect unusual organism groups.

Incidence of lower respiratory tract infections caused by Mycoplasma, Chlamydia and Legionella: an Italian Multicenter Survey

A collaborative retrospective study based on serologic diagnosis was conducted to assess the etiological role sustained by privileged pathogens in Italy. The results obtained indicate the Mycoplasma, Chlamydia and Legionella are important etiologic agents of lower respiratory tract infections in Italy since they account for about 31% of the cases taken into consideration in this survey. We found a high incidence of M. pneumoniae (12.3%), C. pneumoniae (10.5%) and L. pneumophila (8.3%). These results are in line with similar figures reported in the recent literature. While the data gathered in our survey do not allow us to clarify the nature of the agents involved in the etiology of the majority (70%) of the respiratory infections occurring in Italy, it seems safe to assume that after Streptococcus pneumoniae and Haemophilus influenzae, the privileged pathogens represent the most common cause of lower respiratory tract infections.

Respiratory infection with Chlamydia pneumoniae in middle-aged and older adult outpatients

This study was undertaken to characterize the epidemiology and clinical presentation of infection with Chlamydia pneumoniae in a population composed primarily of middle-aged and older adults. Pharyngeal swabs and acute and convalescent phase sera were obtained from outpatients presenting with signs and symptoms of an acute respiratory infection. Sera were examined using the micro-immunofluorescence (MIF) test to detect antibody to Chlamydia pneumoniae and complement fixation tests to detect Mycoplasma pneumoniae, influenza A virus, influenza B virus, respiratory syncytial virus and adenovirus. Pharyngeal swab specimens were cultured for Chlamydia pneumoniae and tested for Chlamydia pneumoniae by the polymerase chain reaction (PCR). A total of 743 patients with a mean age of 40.5 +/- 16.1 years were enrolled in the study. Twenty-one patients were serologically positive for acute Chlamydia pneumoniae infection in the MIF test. PCR was positive in 15 of the 20 serologically positive patients tested. Acute Chlamydia pneumoniae infection was identified in 3% (2/76) of subjects with pneumonia, 5% (12/247) of those with bronchitis, 5% (3/61) of those with sinusitis only and 2% (2/103) of those with pharyngitis only. Of the 21 patients with Chlamydia pneumoniae infection, seven (mean age of 33 years) had an antibody pattern suggesting a primary infection while 14 (mean age of 54 years) had a reinfection pattern. Patients with reinfection had milder disease than those with primary infection. PCR testing in the current study confirms the previously proposed serologic criteria of acute Chlamydia pneumoniae infection.

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.

Overview of community-acquired pneumonia. Prognosis and clinical features

Despite the introduction of newer antibiotics, vaccinations, and better supportive care, CAP remains a common, frequently fatal disease. Age and coexisting illness influence which infectious agents are most likely to cause infection. Severity of illness and clinical features are influenced by various host factors and by the virulence of the infectious agent. Mortality and morbidity are reduced by the rapid institution of appropriate antimicrobial therapy. Because of the limitations of presently available diagnostic tests, many patients are begun on empiric regimens, and in up to half of these individuals, a cause is not identified. Although there are a number of potential pathogens, it is possible to identify likely pathogens based on easily identifiable clinical factors (age, presence of coexisting disease, severity of illness at presentation, and the need for hospitalization). Using this approach, CAP in immunocompetent adults may be divided into four categories. Once empiric therapy has been initiated, therapy should be continued for at least 72 hours unless clinical deterioration is noted. Within 4 days, fever and leukocytosis should return to baseline, but abnormal physical findings (i.e., crackles) require longer to resolve, especially with coexisting illness, and chest radiographic findings are the last to return to baseline and are especially delayed if the patient is bacteremic or has structural lung disease. Not all patients respond to initial empiric therapy. Reasons for this include antimicrobial resistance, the presence of nonbacterial pathogens (respiratory viruses), unusual bacterial pathogens, noninfectious causes that may mimic CAP, infectious complications (i.e., empyema), and pneumonia occurring in patients with unrecognized severe immunosuppression. Failure to improve after 72 hours and development of deterioration are indications for repeat diagnostic workup and consideration of alternative diagnoses. More invasive diagnostic tests are appropriate in severely ill patients and in those whose condition is deteriorating rapidly.

New aspects of old pathogens of pneumonia

Changes in the microorganism or in the host have resulted in exciting new aspects of several old pathogens of pneumonia. Penicillin-resistant Streptococcus pneumoniae, methicillin-resistant Staphylococcus aureus, and "toxic strep" are examples of changes in the microorganisms. Host changes have resulted in Mycoplasma pneumoniae now emerging as a cause of pneumonia in the elderly.

Prevention of community-acquired pneumonia

Preventive measures against CAP are important yet underused. Cost-effective preventive measures against CAP include influenza and pneumococcal vaccines, especially in patients over the age of 65 and other high-risk groups. There are now two antiviral agents, amantadine and rimantadine, that can be used both for prophylaxis and for therapy of influenza A virus infections to decrease the morbidity and mortality of this major predisposer of CAP. Because of fewer side effects, rimantadine should be considered the drug of choice. In selected cases (chronic bronchitis, bronchiectasis, and asplenic patients with poor vaccine response), the early use of antibiotics or prolonged use during winter months may decrease the incidence of lower respiratory infections. Use of monthly gamma globulin infusions in total or selective gamma globulin IgG-deficient patients may be beneficial in reducing the incidence of CAP in selected populations.

Pneumococcal antigen detection in bronchoalveolar lavage fluid from patients with pneumonia

BACKGROUND

Pneumococcal pneumonia can be diagnosed by the detection of capsular antigen in sputum, serum, pleural fluid, or urine using countercurrent immunoelectrophoresis and latex agglutination. In addition, quantitative cultures of bronchoalveolar lavage (BAL) fluid are also reliable for establishing the aetiology of pneumonia. This study investigated the value of rapid detection of pneumococcal antigen in BAL fluid from patients with pneumonia.

METHODS

Pneumococcal antigen was detected by countercurrent immunoelectrophoresis and latex agglutination. Patients were grouped according to BAL quantitative culture results into pneumococcal pneumonia (n = 24), other known aetiology (n = 18), and unknown aetiology (n = 17). Thirteen patients with interstitial lung disease and without pneumonia served as a control group.

RESULTS

In patients with pneumococcal pneumonia, antigen was detected by countercurrent immunoelectrophoresis in 50% and by latex agglutination in 54% of cases. In patients with pneumonia of unknown aetiology pneumococcal antigen was detected by latex agglutination in 53% of cases. Antigen was not detected in patients with pneumonia of other known aetiology or in control patients, yielding a specificity of 100%.

CONCLUSIONS

In patients with pneumococcal pneumonia requiring fibreoptic bronchoscopy detection of pneumococcal antigen in BAL fluid may rapidly and accurately confirm the aetiology. Furthermore, in nearly half the cases of pneumonia of unknown aetiology antigen can be detected, suggesting that Streptococcus pneumoniae is a major causative agent in such patients.

Host defenses against respiratory infection

The respiratory tract is protected from infection by its formidable mechanical and cellular defenses, supplemented when necessary by inflammatory and immune responses. Impairments in these defenses develop as a result of underlying disease and therapeutic interventions. Specific defects in host defenses often predispose to infection with particular etiologic agents. New opportunities for the therapeutic augmentation of defenses are emerging that may be particularly helpful in the care of immunocompromised patients.

Penicillin G/ofloxacin versus erythromycin/amoxicillin-clavulanate in the treatment of severe community-acquired pneumonia

In a prospective, randomized, multicenter trial, the efficacy of penicillin plus ofloxacin was compared to that of amoxicillin-clavulanate plus erythromycin in the treatment of community-acquired pneumonia. One hundred seventeen hospitalized patients presenting with severe community-acquired pneumonia received either penicillin 3 x 10(6) U/6 h plus ofloxacin 200 mg twice daily (group A) or amoxicillin-clavulanate 1 g/6 h plus erythromycin 1 g/8 h (group B). Initial assessment included clinical examination, determination of simplified acute physiology score (SAPS), chest X-ray and evaluation of microbiological data obtained from blood, sputum and/or bronchoscopy. Follow-up was documented at 72 h and at 30 days. Both groups were comparable for age, sex, SAPS, chest X-ray, hypoxemia and microbiological data. The causative pathogen was identified in 54 cases (53%), Streptococcus pneumoniae being most frequent isolate (54.7%). All organisms cultured were susceptible to at least one of the antibiotics of each combination of the protocol, with the exception of two strains of Pseudomonas aeruginosa. A favorable outcome was observed in 76% of the patients, equally distributed between the two groups. After completion of therapy there were 12 clinical failures in each group (20.5%). Six patients in each group (10.3%) died of infection. Tolerance was similar for both regimens, apart from an increased rate of superficial thrombophlebitis in patients receiving intravenous erythromycin. The combination of penicillin with ofloxacin is as effective and as safe as a previously recommended regimen combining amoxicillin-clavulanate and erythromycin in treating patients with community-acquired pneumonia.

Pneumonia and carcinoma of the lung

In a prospective study of 1269 patients with community-acquired pneumonia, 25 (1.97%) were found to have carcinoma of the lung. In 23 cases, the diagnosis was confirmed histologically. For nine of the 23 patients, this episode of pneumonia was the initial manifestation of carcinoma of the lung. The diagnosis of carcinoma was first suggested by the radiologist as the result of a chest radiograph in five of the nine cases. One patient with bronchoalveolar cell carcinoma presented with rapidly progressive diffuse airspace disease. The diagnosis in this case was made by means of open lung biopsy. Two of the 25 patients (8%) had pneumonia caused by Coxiella burnetii, a rate that was 2.4 times higher than that for the other patients with pneumonia. We conclude that pneumonia is uncommonly the presenting manifestation of carcinoma of the lung but is usually evident before the patient leaves hospital. The rate of pneumonia caused by C. burnetii among patients with carcinoma of the lung seems to be higher than that among patients who have pneumonia without carcinoma of the lung.

Effect of immunosuppressive therapy on the clinical presentation of legionellosis

To determine whether the clinical course of legionellosis in patients treated with immunosuppressive agents differs from that seen in other patient groups, data on 52 Finnish patients with legionellosis confirmed by culture or by the direct immunofluorescent antibody test was reviewed. Of these patients 44% were immunosuppressed, 23% had other underlying diseases and 33% had no predisposing conditions. Among those without predisposing conditions, only Legionella pneumophila serogroup 1 was observed, whereas among the immunosuppressed patients, serogroup 6 dominated. Legionellosis was nosocomial in 73% of the immunosuppressed patients and in 33% of the patients with other underlying diseases but was travel-associated in 76% of those without predisposing factors. The case fatality rate (37%) was high but was not associated with preceding immunosuppression. These results indicate that although the serogroups and the sources of legionellosis differ in immunosuppressed patients compared with other groups, the clinical presentation is not more severe.

Review of piperacillin/tazobactam in the treatment of bacteremic infections and summary of clinical efficacy

One method of resistance to beta-lactam antimicrobials involves production of beta-lactamases, enzymes that render the beta-lactam ineffective. Beta-lactamase inhibitors have been combined with beta-lactam antibiotics to combat beta-lactamase producing organisms. One such agent, piperacillin/tazobactam, has been shown to be safe and effective therapy for infections usually treated with a combination of antibiotics such as polymicrobial and nosocomial infection, and has been used for empiric therapy in cases of serious infection. A survey of the literature shows that piperacillin/tazobactam is a safe and efficacious therapy for bacteremia as well as soft tissue, intra-abdominal, and lower respiratory tract infections. When combined with an aminoglycoside, it is also useful in the treatment of severe nosocomial respiratory infections.

Piperacillin/tazobactam in the treatment of polymicrobial infections

Polymicrobial infections are characterized by the presence of micro-organisms from more than one group of bacteria. Empirical treatment of polymicrobial infections requires an agent active against both anaerobic and aerobic/facultative bacteria. An aminoglycoside used in combination with an anti-anaerobe agent is commonly used to treat polymicrobial infections. However, aminoglycoside nephrotoxicity and treatment failures raise questions about the use of such regimens. Among non-aminoglycoside treatment regimens such as penicillin and cephalosporins, effectiveness has been compromised by bacteria producing extended spectrum beta-lactamases. Cefoxitin shows satisfactory results for treatment of intra-abdominal infections. Other studies have shown good results with imipenem, cefotetan and piperacillin used as single agents. Piperacillin/tazobactam, a new combination broad-spectrum antibiotic and potent beta-lactamase inhibitor, can be used for the treatment of infections caused by piperacillin-sensitive micro-organisms as well as beta-lactamase-producing, piperacillin-resistant organisms. This broad-spectrum activity is appropriate for infections traditionally treated empirically by double or triple antibiotic therapy.

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.

Identification of low-risk hospitalized patients with pneumonia. Implications for early conversion to oral antimicrobial therapy

PURPOSE

Few available data exist to define either the medically necessary duration of parenteral antimicrobial therapy or length of stay for hospitalized patients with pneumonia. Therefore, we investigated the potential safety and effectiveness of a practice guideline recommending early conversion of low-risk patients with pneumonia from parenteral to oral antimicrobial therapy and early hospital discharge.

PATIENTS AND METHODS

The practice guideline was studied retrospectively in 503 hospitalized patients with pneumonia at a teaching community hospital.

RESULTS

Thirty-three percent of patients with pneumonia were classified as at low risk for complications and potentially suitable for early conversion to oral antimicrobial therapy according to the guideline. Were the guideline to have been used to guide patient discharge decisions, 619 additional bed-days would have been made available to accommodate incoming patients. A consensus among physician reviewers led to the judgment that quality of care would not have worsened for 98.2 percent of low-risk patients had they been switched to oral antimicrobial therapy on the third hospital day, nor would quality of care have been worsened for 93.4 percent of low-risk patients had they been discharged on the fourth hospital day.

CONCLUSION

The practice guideline that we studied has the potential to safely reduce the duration of parenteral antimicrobial therapy and length of hospital stay for selected low-risk patients with pneumonia. The guideline should be studied in a prospective clinical trial.

Randomized comparative trial with ampicillin/sulbactam versus cefamandole in the therapy of community acquired pneumonia

In a randomized prospective study ampicillin/sulbactam and cefamandole were compared in the therapy of patients hospitalized with community acquired pneumonia. Patients receiving ampicillin/sulbactam (n = 37) and cefamandole (n = 38) were similar with respect to age (mean age 70 vs. 76 years respectively), clinical characteristics, severity of illness and underlying disease. Pathogens isolated from patients in the cefamandole and ampicillin/sulbactam group, respectively, were Streptococcus pneumoniae (7 vs. 7 patients), Haemophilus parainfluenzae (7 vs. 6 patients), Haemophilus influenzae (5 vs. 5 patients), Staphylococcus aureus (5 vs. 4 patients), Escherichia coli (4 vs. 4 patients), Klebsiella pneumoniae (3 vs. 3 patients), Enterobacter spp. (2 vs. 3 patients), Moraxella catarrhalis (1 vs. 2 patients), and organisms of the oral flora (4 vs. 3 patients). The rate of resistance to penicillin was 80%, to clindamycin 76%, to erythromycin 45%, to ampicillin 43%, and to cefazolin 18%. Overall successful treatment rates of 81% for cefamandole and 97% for ampicillin/sulbactam (p = 0.05) were observed. Both cefamandole and ampicillin/sulbactam were shown to be effective agents for therapy of community acquired pneumonia; however ampicillin/sulbactam demonstrated superior overall clinical efficacy.

Diagnostic utility of PCR-enzyme immunoassay, culture, and serology for detection of Chlamydia pneumoniae in symptomatic and asymptomatic patients

To assess the utility of PCR-enzyme immunoassay (EIA) for diagnosis of acute infection with Chlamydia pneumoniae, we compared tissue culture, PCR-EIA, direct fluorescent-antibody (DFA) stain, and serology in studies with 56 patients with respiratory symptoms and 80 asymptomatic persons. Thirty-five patients were positive by either culture or PCR-EIA, and 101 were negative by both assays. Thirty specimens from symptomatic patients and one from an asymptomatic patient were culture positive; 23 of these were also PCR-EIA positive. Of the eight culture-positive, PCR-EIA-negative specimens, five were DFA negative and three were DFA positive. Four additional specimens were culture negative and PCR-EIA positive; of these, three were DFA positive and one was DFA negative. When we used culture- and/or DFA-positive results as a reference or "gold standard," the sensitivity and specificity of PCR were 76.5 and 99.0%, respectively. When we used PCR- and/or DFA-positive results as the reference, the sensitivity of culture was 87.5%. On the basis of single acute serum specimens, only 8 of these 35 patients had diagnostic antibody titers. Of the asymptomatic patients, 75% had immunoglobulin G or immunoglobulin M antibody to C. pneumoniae; 15 (18.8%) of these had antibody levels considered to be diagnostic of acute infection. This multicenter study indicates that culture and/or PCR-EIA is more reliable for prompt diagnosis of C. pneumoniae infection than single-point serology alone.

Management of community acquired lower respiratory tract infection

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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.

Lack of evidence of Chlamydia pneumoniae infection in infants with acute lower respiratory tract disease

In order to determine whether there is serologic evidence of Chlamydia pneumoniae infection in young infants with acute lower respiratory tract infection, serum samples from 86 subjects aged less than 6 months were assayed for IgG and IgM antibodies to Chlamydia pneumoniae using a microimmunofluorescence method. Infants hospitalized in Toronto, Canada, were enrolled between 15 March 1991 and 15 March 1992. No patient had infection determined by the serologic results. IgG antibody was detected at low concentrations in 32 patients, with an inverse relationship between titer and chronological age. In our setting, Chlamydia pneumoniae does not appear to be an important lower respiratory pathogen in young infants.

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.

Efficacy and safety of clarithromycin compared to cefixime as outpatient treatment of lower respiratory tract infections

BACKGROUND

Clarithromycin is a new acid-stable, 14-membered macrolide active against many of the organisms responsible for lower respiratory tract infections. It has been administered to over 5,000 patients worldwide and has been shown to be a safe and effective treatment for acute bacterial exacerbations of chronic bronchitis and bacterial pneumonia when given twice daily (250 to 500 mg). Cefixime is an amino-thiazolyl cephalosporin with an extended spectrum of antibacterial activity inhibiting beta-lactamase-producing respiratory pathogens. It has a long half-life, allowing once-daily administration.

METHODS

This randomized, double-blind multicenter study compared clarithromycin and cefixime as treatment for patients with community-acquired lower respiratory tract infections (n = 213). Patients had bacterial pneumonia (clarithromycin, 19 percent; cefixime, 21 percent) or acute bacterial exacerbation of chronic bronchitis or asthmatic bronchitis (clarithromycin, 81 percent; cefixime, 79 percent). Patients received 500 mg of clarithromycin twice daily (n = 103) or 400 mg of cefixime once daily (n = 110) for 7 to 14 days.

RESULTS

Clinical cure or improvement occurred in 86 percent of the clarithromycin-treated patients and 88 percent of the cefixime-treated patients. When only patients with identified infections with Haemophilus influenzae, Moraxella catarrhalis, or Streptococcus pneumoniae were considered, clinical success rates were 97 percent for clarithromycin and 96 percent for cefixime; the rate of bacteriologic eradication was 91 percent for clarithromycin and 90 percent for cefixime. Adverse events occurred in 29 percent of the clarithromycin-treated patients and 23 percent of the cefixime-treated patients.

CONCLUSIONS

This study demonstrates that clarithromycin and cefixime are effective treatments for pneumonia and acute bacterial exacerbations of bronchitis of mild to moderate severity caused by the most common infecting organisms.

Fluoroquinolones in bronchopulmonary infections

In recent years, Streptococcus pneumoniae and Haemophilus influenzae, two of the most common pathogens causing bronchopulmonary infections, have developed resistance towards beta-lactam antibiotics in many areas of the globe. In some countries, resistance rates are so high that treatment with penicillin can not be recommended as the therapy of choice. Unfortunately, many S. pneumoniae strains resistant to penicillins are also resistant to co-trimoxazole and erythromycin, and even to the novel macrolides. Present fluoroquinolones may have to be used in such resistant cases. The fluoroquinolones possess a superior activity against H. influenzae and other pathogens causing bronchitis and pneumonia. Fluoroquinolones have a favourable pharmacokinetic profile including penetration into sputum, bronchial fluid, alveolar lining fluid and alveolar macrophages, and therapeutic concentrations and ratios are superior to those of the beta-lactams. Fluoroquinolones have been shown to produce better results than the comparative agents in bronchitis and, in cystic fibrosis, they achieve a definite clinical amelioration in paediatric patients without substantial additional toxicity. Their use in legionnaires' disease has not been confirmed and their place in the treatment of community-acquired pneimonias - particularly those caused by Mycoplasma pneumoniae and Chlamydia trachomatis and the TWAR agent - deserves further investigation.

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.

Evaluation of serological methods in the diagnosis of Chlamydia pneumoniae pneumonia during an epidemic in Finland

A complement fixation (CF) test, a micro-immunofluorescence (micro-IF) test and an enzyme immunoassay (EIA) using Re-lipopolysaccharide as antigen were compared in the diagnosis of chlamydial infection in 136 mainly elderly patients hospitalized with community-acquired pneumonia during a Chlamydia pneumoniae epidemic in Finland in 1986-1987. Chlamydial pneumonia was diagnosed in 58 (42.6%) of the 136 pneumonia patients; 44 (75.9%) of them could be shown by micro-IF to be caused by Chlamydia pneumoniae, three by Chlamydia psittaci and four by Chlamydia spp. Only 5 (11.4%) of 44 patients with Chlamydia pneumoniae pneumonia were IgM-positive, indicating that the majority of cases were reinfections. In this population of mainly elderly patients the CF test was insensitive, being positive in only 6 (10.3%) of 58 cases of chlamydial pneumonia. The EIA detected 72.4% of cases and micro-IF 87.9% of cases (including infections with Chlamydia pneumoniae, Chlamydia psittaci and Chlamydia spp.). In the EIA 77% of positive cases were positive in serum samples taken a week apart, whereas the corresponding figure for micro-IF was 50%. In micro-IF the measurement of IgA antibody levels is recommended and IgM-positive sera should be retested after removal of IgG antibody to avoid false-positive findings due to presence of rheumatoid factor. The collection of a third serum sample, for instance one month after onset, is also recommended, since half of the patients showed a diagnostic response in the micro-IF only in the sera taken one month apart.

High rate of erythromycin and clarithromycin resistance among Streptococcus pneumoniae isolates from blood cultures from Providence, R.I

Four (5%) of 81 recent isolates of Streptococcus pneumoniae from the blood of adult patients but no isolates from pediatric patients (n = 51) were resistant (MIC, > or = 1 microgram/ml) to erythromycin. The MICs of clarithromycin were slightly lower than those of erythromycin, but there was complete cross-resistance. Routine testing and surveillance are needed to determine whether erythromycin resistance among S. pneumoniae isolates is increasing throughout the United States.

Incidence of community-acquired pneumonia caused by Chlamydia pneumoniae in Italian patients

The incidence of Chlamydia pneumoniae as a cause of community-acquired pneumonia was evaluated in a one-year prospective study in 108 patients with community-acquired pneumonia. The bacteriological diagnosis was based on culture of sputum or bronchial aspirate and examination of acute and convalescent phase sera for Mycoplasma pneumoniae, Legionella pneumophila and Chlamydia pneumoniae. A definitive microbiological diagnosis was obtained in 58 (54%) patients. Chlamydia pneumoniae was the causative agent in 14 patients (13%) on the basis of positive serological tests; in 10 of the 14 patients Chlamydia pneumoniae was also detected by means of an indirect immunofluorescence test using pharyngeal swab specimens. In conclusion, Chlamydia pneumoniae seems to be a common etiological agent of community-acquired pneumonia, as increasingly reported in the last six to seven years.

Outpatient parenteral antibiotic therapy. Management of serious infections. Part II: Amenable infections and models for delivery. Pneumonia and chronic lung disease

The need for medical support is the determining factor when selecting patients with acute pneumonia for outpatient therapy. Patients are often too old or too sick for early discharge, but a large subgroup can continue parenteral therapy as outpatients. Other pneumonia patients, as well as patients with infectious flares of chronic lung disease, can be treated with outpatient therapy alone.

A seroepidemiologic study of Chlamydia pneumoniae in Rhode Island. Evidence of serologic cross-reactivity

OBJECTIVE

Although Chlamydia pneumoniae is considered a common cause of pneumonia worldwide, the evidence is mainly serologic. Therefore, we examined whether the currently used chlamydial microimmunofluorescence (MIF) antibody test is specific for C pneumoniae infection.

DESIGN AND SETTING

Secondary analysis of data from a cohort study of sarcoidosis among the graduates of ten consecutive apprenticeship classes of firefighters and police officers.

PARTICIPANTS

One hundred forty-seven young adult men.

MEASUREMENTS

Immunoglobulin G and M antibodies to C pneumoniae, 15 serovars of C trachomatis, and 2 strains of C psittaci as measured by MIF.

RESULTS

Evidence of previous C pneumoniae and C trachomatis infection (IgG > or = 1:16 yet < 1:512) was present in 108 (73 percent) and 59 (40 percent) subjects, respectively. Serologic evidence of recent C pneumoniae and C trachomatis infection (IgM > or = 1:16 or IgG > or = 1:512) was present in 19 (13 percent) and 14 (10 percent) subjects, respectively. Chlamydia pneumoniae and C trachomatis IgM titers were highly correlated (r = 0.80; 95 percent CI, 0.73 to 0.85) while C pneumoniae and C trachomatis IgG titers were fairly correlated (r = 0.44; 95 percent CI, 0.30 to 0.56).

CONCLUSIONS

The C pneumoniae seroprevalence of 86 percent is the highest yet reported. The correlations between C pneumoniae and C trachomatis antibody titers suggest that chlamydial MIF may be less specific than is generally appreciated. Moreover, the observed 13 percent seroprevalence of recent C pneumoniae infection in a healthy working population challenges the serologically based belief that this agent accounts for 6 to 10 percent of community-acquired pneumonia. A more objective, more specific test is needed in the serodiagnosis of C pneumoniae infection.

Bacterial pneumonia. S pneumoniae and H influenzae are the villains

Bacterial pneumonia isn't what it used to be. The most common causes, Streptococcus pneumoniae and Haemophilus influenzae, are developing strains that are resistant to powerful antibiotics: How do you choose a therapeutic agent? New organisms are being discovered to be culprits in this disease: How do you keep track of them? New drugs are being developed every day: How does that help if initial treatment is almost always empirical? Dr Wisinger identifies the problems and offers advice.