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

[Pneumococcal bacteremia in patients aged over 65 years. A study of 161 cases]

BACKGROUND

Here we present the results from a prospective analysis of pneumococcal bacteremia in patients older than 65 years, highlighting its differences with regard to patients aged from 15 to 64 years.

PATIENTS AND METHOD

We performed a prospective follow-up study (1988-1999) of patients older than 14 years whohad blood cultures positive for Streptococcus pneumoniae(S. pneumoniae). S. pneumoniae was identified using standard techniques. The antimicrobial sensitivity was analysed using the broth midrodilution technique and the serotype was studied in a reference laboratory. Statistical analyses were performed by means of the SPSS program, version 9.0.

RESULTS

161 out of 321 bacteremias occurred in 154 patients older than 65 years (86 males). Most frequent underlying diseases were chronic obstructive pulmonary disease (COPD), diabetes and neoplasia. Most patients had pneumonia, 29.7% with ilfiltrates involving at least two lung lobes. 9.4% of bacteremias were nosocomial. Among patients older than 65 years, 32.5% of strains were resistant to penicillin, compared to 21.7% in patients younger than 65 years(p = 0.034). Mortality in patients over 65 years was higher than in younger patients (25.3% vs 11.5%; p = 0.002) and mortality predictive factors in a multivariate analysis were age, nosocomial bacteremia and multi-lobe involvement (in patients with pneumonia).

CONCLUSIONS

There is a high incidence of pneumococcal bacteremia in patients over 65 years of age. These patients have a higher rate of resistance to penicillin and a higher mortality rate than younger patients. Mortality predictive factors are age, nosocomial bacteremia and multi-lobe involvement.

Estudo de casos hospitalizados por pneumonia comunitária no período de um ano

Introdução: Apesar dos avanços obtidos nos métodos propedêuticos, cerca de 50% dos casos de pneumonia adquirida na comunidade não têm sua etiologia esclarecida, inclusive os hospitalizados. Apesar disso, a terapêutica adequada proporciona baixas taxas de mortalidade na maioria dos casos. Objetivos: Descrever a epidemiologia, formas de apresentação, o rendimento dos testes diagnósticos, a permanência hospitalar, a morbidade e mortalidade de 42 pacientes consecutivos, internados para tratamento de PAC. Métodos: Foram incluídos pacientes com quadro clínico compatível com PAC, opacidade radiológica pulmonar recente e com dois itens entre febre, tosse produtiva e leucocitose. A solicitação de exames complementares obedeceu à necessidade de cada caso. Resultados: Dos 42 pacientes, com idade de 64,7 ± 16,8 anos, 27 (64,3%) masculinos, 27 (64%) apresentavam co-morbidades. Dezessete (40,5%) estavam em uso de antibióticos à admissão. Pneumonia grave ocorreu em oito casos (19%); não houve diferença quanto à gravidade (p = 0,57) e permanência hospitalar (p = 0,25) entre os grupos > de 60 ou <= de 60 anos. A permanência hospitalar média foi de 14,3 ± 7,6 dias. Diagnóstico etiológico definitivo foi obtido em três casos: Legionella sp em dois, S. aureus em um caso. Em 31 (74%), manteve-se o antibiótico inicial; em 11 (26%) houve troca, seis (54,5%) devido à má resposta clínica e cinco (45,5%) devido ao resultado microbiológico. Hemoculturas foram feitas em 16 casos (38%), positivas em apenas um (6,3%). Nove amostras de escarro (9/22, 41%) foram validadas. Ocorreu um óbito (2,4%), por pneumonia grave, em um paciente com neoplasia. Conclusões: O diagnóstico etiológico em PAC, mesmo em internados, é obtido em uma minoria de casos, contribuindo para isso o uso concorrente de antibióticos. A terapêutica empírica adequada proporciona baixas taxas de mortalidade. Os testes diagnósticos devem ser empregados de maneira individualizada.

Community-acquired pneumonia in patients requiring hospitalization

OBJECTIVE

This study aimed to investigate the microbial aetiology of community-acquired pneumonia (CAP) in patients requiring hospitalization.

METHODOLOGY

A prospective study of consecutive non-immunocompromised patients aged 12 years and above admitted with CAP from August 1997 to May 1999 was undertaken.

RESULTS

Of 127 patients hospitalized for CAP, an aetiological diagnosis was achieved in 53 cases (41.7%). Klebsiella pneumoniae was the most frequently isolated pathogen and caused 10.2% of all the cases, followed by Streptococcus pneumoniae (5.5%), Haemophilus influenzae (5.5%), Mycoplasma pneumoniae (3.9%) and Pseudomonas aeruginosa (3.9%). Gram-negative bacilli were significantly more frequently identified in patients aged 60 years or older and in patients with comorbid illnesses. Twelve of 13 patients who died from CAP had other comorbid illnesses compared to 63 of 114 patients who survived (P = 0.014). Three of eight bacteraemic patients died compared with 10 of 119 non-bacteraemic patients (P = 0.035).

CONCLUSIONS

The microbiology of CAP in patients requiring hospitalization in Malaysia appears to be different from that in Western countries. Gram-negative bacilli were more frequently isolated in older patients and in those with comorbidity. Mortality from CAP is more likely in patients with comorbidity and in those who are bacteraemic.

Usefulness of betalactam therapy for community-acquired pneumonia in the era of drug-resistant Streptococcus pneumoniae: a randomized study of amoxicillin-clavulanate and ceftriaxone

Empirical antibiotic therapy of community-acquired pneumonia (CAP) has been complicated by the worldwide emergence of penicillin resistance among Streptococcus pneumoniae. The impact of this resistance on the outcome of patients hospitalized for CAP, empirically treated with betalactams, has not been evaluated in a randomized study. We conducted a prospective, randomized trial to assess the efficacy of amoxicillin-clavulanate (2 g/200 mg/8 hr) and ceftriaxone (1 g/24 hr) in a cohort of patients hospitalized for moderate-to-severe CAP. Three-hundred seventy-eight patients were randomized to receive amoxicillin-clavulanate (184 patients) or ceftriaxone (194 patients). Efficacy was assessed on Day 2, after completion of therapy and at long term follow-up. There were no significant differences in outcomes between treatment groups, both in intention-to-treat and per-protocol analysis. Overall mortality was 10.3% for amoxicillin-clavulanate and 8.8% for ceftriaxone (NS). There were 116 evaluable patients with proven pneumococcal pneumonia. Rates of high-level penicillin resistance (MIC of penicillin > or = 2 microg/mL) were similar in the two groups (8.2 and 10.2%). Clinical efficacy at the end of therapy was 90.6% for amoxicillin-clavulanate and 88.9% for ceftriaxone (95% C.I. of the difference: -9.3 to +12.7%). No differences in outcomes were attributable to differences in penicillin susceptibility of pneumococcal strains. Sequential i.v./oral amoxicillin-clavulanate and parenteral ceftriaxone were equally safe and effective for the empirical treatment of acute bacterial pneumonia, including penicillin and cephalosporin-resistant pneumococcal pneumonia. The use of appropriate betalactams in patients with penumococcal pneumonia and in the overall CAP population, is reliable at the current level of resistance.

Etiology, reasons for hospitalization, risk classes, and outcomes of community-acquired pneumonia in patients hospitalized on the basis of conventional admission criteria

We performed an observational analysis of prospectively collected data on 533 nonseverely immunosuppressed adult patients who were hospitalized for community-acquired pneumonia on the basis of conventional admission criteria. For this population, we correlated etiology, reasons for admission, and outcomes using the Pneumonia Severity Index (PSI), to identify major discrepancies between the PSI risk class and the conventional criteria for deciding the site of care. PSI classes and corresponding mortality rates were as follows: class I, 51 patients (0%); class II, 62 (2%); class III, 117 (3%); class IV, 198 (10%); and class V, 105 (29%). We identified significant discrepancies between both methods. Overall, 230 patients (40%) who were hospitalized according to conventional criteria were assigned to low-risk classes. Of these 230 patients, 137 (60%) needed supplementary oxygen or had pleural complications; for the remaining patients, there were no irrefutable reasons for admission. This latter group deserves prospective evaluation in randomized studies that compare ambulatory and in-hospital management.

Efficacy and safety of gemifloxacin 320 mg once-daily for 7 days in the treatment of adult lower respiratory tract infections

An open-label, non-comparative study assessed the clinical and bacteriological efficacy of gemifloxacin (320 mg, once-daily for 7 days) in lower respiratory tract infections (LRTI). Patients with acute exacerbation of chronic bronchitis (AECB, n=261) or community-acquired pneumonia (CAP, n=216) were enrolled into the study. Clinical success rates at follow-up (days 21-28) in the intent-to-treat (ITT) population were high, 83.1% in AECB patients (95% CI: 77.9, 87.4) and 82.9% in CAP patients (95% CI: 77.0, 87.5). High bacteriological success rates were achieved (bacteriological ITT population), 91.2% (52/57) in AECB patients (95% CI: 80.0, 96.7) and 77.9% (60/77) in CAP patients (95% CI: 66.8, 86.3). Gemifloxacin was well tolerated with a low incidence of adverse events. Gemifloxacin treatment resulted in high clinical and bacteriological success rates and is a well-tolerated therapy for the treatment of LRTIs.

Clinical policy for the management and risk stratification of community-acquired pneumonia in adults in the emergency department

This clinical policy represents an approach that emphasizes key clinical information to determine the severity of CAP. By using this approach, a determination of whether the patient can be treated as an outpatient or inpatient may be made. Recommendations about the utility of ancillary studies and the use of antibiotics are also given. As more of the questions are answered through controlled studies, an evidence-based approach to this problem will become increasingly important in improving the outcome of patients with CAP.

New directions in antiinfective therapy for community-acquired pneumonia in the emergency department

The emergency department is becoming an increasingly important setting for the management of community-acquired pneumonia (CAP). This trend reflects the shortened hospital stays and decreased mortality among elderly hospitalized patients resulting from rapid administration of antimicrobials. In addition, decisions about the site of care (inpatient vs outpatient) and antimicrobial therapy frequently are made in the emergency department. Recent research and subsequent clinical guidelines may help with these decisions. For example, recently issued guidelines, such as those of the Infectious Diseases Society of America and the American Thoracic Society, suggest that selection of antimicrobials for CAP (which is typically empiric) should be based on the potential pathogens and likelihood of antimicrobial resistance. Macrolides and tetracyclines are recommended in younger patients with mild-to-moderate disease. Patients with more severe disease and those at risk for drug-resistant pathogens should be treated with broad-spectrum therapy, such as a newer fluoroquinolone or a cephalosporin plus a macrolide. When hospitalization is required, early switch from intravenous to oral therapy, followed by early discharge, can be a highly successful strategy. Antimicrobials that are available in both intravenous and oral formulations, such as the newer fluoroquinolones (e.g., levofloxacin and gatifloxacin), can simplify switch therapy For outpatients, an initial long-acting parenteral dose of azithromycin, ceftriaxone, or levofloxacin followed by oral therapy is an effective protocol. In addition, use of a prediction rule to identify low-risk patients with CAP may help guide decisions about the need for hospital admission.

Diagnosis and management of respiratory tract infections for the primary care physician

Respiratory tract infections cause nearly half of deaths owing to infectious disease in the United States. This article has discussed the management of several common respiratory tract infections, with an emphasis on appropriate diagnosis and use of antimicrobial agents. Understanding the cause of various respiratory tract infections enables primary care physicians to avoid unnecessary antibiotic use, decreasing adverse effects owing to medications and preventing the rise in antimicrobial resistance.

Incidence and determinants of bacterial infections in HIV-positive patients receiving anti-Pneumocystis carinii/Toxoplasma gondii primary prophylaxis within a randomized clinical trial

We assessed the incidence and determinants of bacteremia, pneumonia, and sinusitis/otitis in HIV-positive people receiving cotrimoxazole (CTX) or dapsone-pyrimethamine (DP) for primary prophylaxis of Pneumocystis carinii pneumonia (PCP) and toxoplasmic encephalitis (TE) within a randomized clinical trial. In total, 244 patients were randomized: 122 were assigned to CTX and 122 to DP. In the cohort, 22 bacteremia, 63 pneumonia, and 39 sinusitis/otitis cases were observed. Incidence rates of bacteremia, pneumonia, and sinusitis/otitis as well as the 2-year probability of remaining free from any bacterial infection were not significantly different between the two groups. At multivariate analysis, the risks of developing bacteremia and pneumonia were found to be independently increased by the use of a central venous catheter (hazard ratio [HR], 4.48; p <.05 and HR, 4.13; p <.01, respectively) and by hospitalization (HR, 28.82; p <.05 and HR, 10.15; p <.05, respectively). In conclusion, CTX at the dosage employed for primary PCP/TE prophylaxis does not seem to protect against bacterial infections more than second-line DP.

Microbial etiology of community-acquired pneumonia in the adult population of 4 municipalities in eastern Finland

To determine the etiology of community-acquired pneumonia in the adult population of a defined area, specific antibody responses in paired serum samples, levels of circulating pneumococcal immune complexes in serum samples, and pneumococcal antigen in urine were measured. Samples (304 paired serum samples and 300 acute urine samples) were obtained from 345 patients > or =15 years old with community-acquired, radiologically confirmed pneumonia, which comprised all cases in the population of 4 municipalities in eastern Finland during 1 year. Specific infecting organisms were identified in 183 patients (including 49 with mixed infection), as follows: Streptococcus pneumoniae, 125 patients; Haemophilus influenzae, 12; Moraxella catarrhalis, 8; chlamydiae, 37 (of which, Chlamydia pneumoniae, 30); Mycoplasma pneumoniae, 30; and virus species, 27. The proportion of patients with pneumococcal infections increased and of those with Mycoplasma infections decreased with age, but for each age group, the etiologic profile was similar among inpatients and among outpatients. S. pneumoniae was the most important etiologic agent. The annual incidence of pneumococcal pneumonia per 1000 inhabitants aged > or =60 years was 8.0.

Approach to the problem of pneumonia in long-term care facilities

The incidence of pneumonia among patients in long-term care facilities is approximately 1/1000 patient-days. Evidence indicates that the majority can be managed without transfer to a hospital. Immunization with pneumococcal and influenza vaccines is appropriate for all residents.

Community-acquired pneumonia. A prospective outpatient study

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

Nonspecificity of assaying for IgG antibody to pneumolysin in circulating immune complexes as a means to diagnose pneumococcal pneumonia

Detection of immunoglobulin G (IgG) antibody to pneumolysin (PLY) in precipitated circulating immune complexes (CICs) has been used to diagnose pneumococcal pneumonia. With care to include appropriate controls, we precipitated and dissociated CICs and then assayed for IgG antibody to PLY. We detected IgG antibody to PLY in CICs that were precipitated from serum samples that were obtained at the time of admission to the hospital from 5 (23%) of 22 healthy adults, 7 (44%) of 16 subjects with stable chronic obstructive pulmonary disease, 10 (63%) of 16 subjects colonized with Streptococcus pneumoniae, and 9 (60%) of 15 patients with nonbacteremic pneumococcal pneumonia. Of the 16 patients with bacteremic pneumococcal pneumonia, 4 (25%) had IgG antibody to PLY at the time of admission, and 8 (50%) had IgG antibody to PLY in convalescence. Levels of IgG antibody in CICs closely correlated with serum levels of IgG antibody to PLY, implicating precipitation of free serum antibody in tests with false-positive results. Detection of IgG antibody to PLY in precipitated CICs is not a reliable method for diagnosing pneumococcal pneumonia.

Susceptibilities of Haemophilus influenzae and Moraxella catarrhalis to ABT-773 compared to their susceptibilities to 11 other agents

The activity of the ketolide ABT-773 against Haemophilus and Moraxella was compared to those of 11 other agents. Against 210 Haemophilus influenzae strains (39.0% beta-lactamase positive), microbroth dilution tests showed that azithromycin and ABT-773 had the lowest MICs (0.5 to 4.0 and 1.0 to 8.0 microg/ml, respectively), followed by clarithromycin and roxithromycin (4.0 to >32.0 microg/ml). Of the beta-lactams, ceftriaxone had the lowest MICs (</=0.004 to 0.016 microg/ml), followed by cefixime and cefpodoxime (0.008 to 0.125 and </=0.125 to 0.25 microg/ml, respectively), amoxicillin-clavulanate (0.125 to 4.0 microg/ml), and cefuroxime (0. 25 to 8.0 microg/ml). Amoxicillin was only active against beta-lactamase-negative strains, and cefprozil had the highest MICs of all oral cephalosporins tested (0.5 to >32.0 microg/ml). Against 50 Moraxella catarrhalis strains, all of the compounds except amoxicillin and cefprozil were active. Time-kill studies against 10 H. influenzae strains showed that ABT-773, at two times the MIC, was bactericidal against 9 of 10 strains, with 99% killing of all strains at the MIC after 24 h; at 12 h, ABT-773 gave 90% killing of all strains at two times the MIC. At 3 and 6 h, killing by ABT-773 was slower, with 99.9% killing of four strains at two times the MIC after 6 h. Similar results were found for azithromycin, with slightly slower killing by erythromycin, clarithromycin, and roxithromycin, especially at earlier times. beta-Lactams were bactericidal against 8 to 10 strains at two times the MIC after 24 h, with slower killing at earlier time periods. Most compounds gave good killing of five M. catarrhalis strains, with beta-lactams killing more rapidly than other drugs. ABT-773 and azithromycin gave the longest postantibiotic effects (PAEs) of the ketolide-macrolide-azalide group tested (4.4 to >8.0 h), followed by clarithromycin, erythromycin, and roxithromycin. beta-Lactam PAEs were similar and shorter than those of the ketolide-macrolide-azalide group for all strains tested.

Community-acquired pneumonia. Diagnostic and therapeutic approach

Optimal empiric therapy of CAP is with appropriate monotherapy (e.g., doxycycline, levofloxacin). Combination therapy is problematic because of potential side effects and high cost. Empiric coverage should have a high degree of activity against both typical and atypical pathogens. The antibiotic selected should have an excellent side-effect profile and be relatively inexpensive. Clinicians should be selective in their choice of antibiotic for CAP and choose an antimicrobial that has little or no resistance potential, is relatively inexpensive, and permits i.v.-to-PO switch monotherapy.

Legionella and community-acquired pneumonia: a review of current diagnostic tests from a clinician's viewpoint

Many physicians are unaware of the limitations of the available tests for diagnosing infections with Legionella organisms. Geographic differences in the importance of nonpneumophila Legionella species as pathogens are underrecognized, in part because available diagnostic tests are biased toward the detection of pneumophila serogroup 1. Routine laboratory practices reduce the likelihood of culturing Legionella species from clinical isolates. Failure of seroconversion is common, particularly with nonpneumophila species; even when seroconversion occurs, it may take much longer than 4 weeks. Urinary antigen testing has insufficient sensitivity to affect clinical management in most regions of the United States, as it can reliably detect only L. pneumophila serogroup 1 infections. Polymerase chain reaction-based techniques offer hope of providing highly sensitive, rapid diagnostic tests for all Legionella species, but limitations in the current tests will make validating them difficult.

Legionnaires' disease in a newly constructed long-term care facility

OBJECTIVES

To determine whether a newly-constructed long-term care facility would become colonized with Legionella and whether Legionnaires' disease would occur in residents of this new facility.

DESIGN

Prospective environmental surveillance of the hospital's water distribution system for the presence of Legionella pneumophila during construction. Utilization of diagnostic tests for Legionnaires' disease in cases of nosocomial pneumonia.

SETTING

The Pittsburgh VA Health Care System, Aspinwall Division, a two-building 400-bed complex.

PARTICIPANTS

Six patients who acquired Legionnaires' disease while in the facility.

INTERVENTION

Installation of copper-silver ionization systems.

MEASUREMENTS

Isolation of L. pneumophila from potable water and the occurrence of Legionnaires' disease.

RESULTS

L. pneumophila serogroup 1 was recovered from the water distribution system within 1 month of operation; 74% (61/82) of distal sites were positive during construction. In the first 2 years of occupancy, six cases of legionellosis were diagnosed. Both clinical isolates of L. pneumophila were identical to environmental isolates by pulsed field gel electrophoresis (PFGE). Copper-silver ionization systems were installed to control Legionella in the water system.

CONCLUSIONS

We conclude that long-term care residents are at risk for acquiring nosocomial Legionnaires' disease in the presence of a colonized water system, even in a newly constructed building.

Community-acquired pneumonia: etiology, epidemiology, and outcome at a teaching hospital in Argentina

OBJECTIVE

To survey the etiology and epidemiology of community-acquired pneumonia (CAP) in relation to age, comorbidity, and severity and to investigate prognostic factors.

DESIGN

Prospective epidemiologic study, single center.

SETTING

University hospital at Buenos Aires, Argentina.

PATIENTS

Outpatients and inpatients fulfilling clinical criteria of CAP.

INTERVENTIONS

Systematic laboratory evaluation for determining the etiology, and clinical evaluation stratifying patients into mild, moderate, and severe CAP (groups 1 to 3), a clinical rule used for hospitalization.

RESULTS

During a 12-month period, 343 patients (mean age, 64.4 years; range, 18 to 102 years) were evaluated. We found 167 microorganisms in 144 cases (yield, 42%). Streptococcus pneumoniae, the most common pathogen, was isolated in 35 cases (24%). Mycoplasma pneumoniae, present in 19 (13%), was second in frequency in group 1; Haemophilus influenzae, present in 17 cases (12%), was second in group 2; and Chlamydia pneumoniae, present in 12 cases (8%), was second in group 3. Etiology could not be determined on the basis of clinical presentation; identifying the etiology had no impact on mortality. Some findings were associated with specific causative organisms and outcome. A significantly lower number of nonsurvivors received adequate therapy (50% vs 77%).

CONCLUSIONS

Age, comorbidities, alcohol abuse, and smoking were related with distinct etiologies. PaO(2) to fraction of inspired oxygen ratio < 250, aerobic Gram-negative pathogen, chronic renal failure, Glasgow score < 15, malignant neoplasm, and aspirative pneumonia were associated with mortality by multivariate analysis. Local microbiologic data could be of help in tailoring therapeutic guidelines to the microbiologic reality at different settings. The stratification schema and the clinical rule used for hospitalization were useful.

Streptococcus pneumoniae serotype 4 outbreak in a home for the aged: report and review of recent outbreaks

OBJECTIVE

To describe a pneumonia outbreak caused by Streptococcus pneumoniae among residents of a home for the aged and to review contemporary pneumococcal outbreaks.

DESIGN

Epidemiological investigation.

METHODS

S pneumoniae isolates were serotyped and analyzed by pulsed-field gel electrophoresis. Paired sera were tested for antibodies to pneumococcal surface adhesin A protein (PsaA, a 37-kDa cell-wall protein). Pneumococcal outbreaks reported in the last decade in English were reviewed.

RESULTS

Pneumonia developed in 18 of 200 residents. In 11 (61%), a pneumococcal etiology was demonstrated. S pneumoniae, serotype 4, was isolated from the blood cultures of 3 patients; all isolates were indistinguishable by pulsed-field gel electrophoresis. Pneumococcal involvement was established in 2 by sputum culture and latex agglutination of parapneumonic fluid and in 6 others by a twofold rise in optical density of serum antibody reactive to PsaA. Pneumococcal immunization had not previously been received by any patient; mortality was 22%. No additional cases were noted following administration of pneumococcal vaccine and antibiotic prophylaxis with penicillin or erythromycin. Twenty-six outbreaks of invasive pneumococcal disease since 1990 were reviewed. Twelve occurred in the United States, and serotypes 23F, 14, and 4 accounted for 8 (67%) of 12 outbreaks. All confirmed serotypes in US outbreaks are included in the 23-valent vaccine. More than one half of pneumococcal outbreaks worldwide involved elderly persons in hospitals or long-term-care facilities.

CONCLUSIONS

A pneumococcal pneumonia outbreak occurred among unvaccinated residents of a residential facility for the aged. Institutionalized elderly persons are at risk of outbreaks of pneumococcal disease and should be vaccinated.

Potential importance of Legionella species as etiologies in community acquired pneumonia (CAP)

Large percentages of patients with community acquired pneumonia (CAP) do not have a defined etiology. Between 1992-1993, 99 acute and convalescent sera were collected from patients with CAP of unknown etiology. The sera were tested using an indirect immunofluorescence antibody assay (IFA) against the following antigens: Legionella pneumophila, serogroups 3,5,6 and 7 and L. longbeachae, L. anisa, L. bozemanii and Legionella-Like Amoebal Pathogens (LLAP). A four-fold rise in titer to at least one of the antigens tested, was seen in 14% of patients; 8% to L. bozemanii, 4% to L. anisa, 2% to S. lyticum, 2% to LLAP 10 and 1% each to LLAP 1, 6 and 9. Two patients reacted to several antigens. These results indicate that other species of legionella may be important in the etiology of CAP. L. bozemanii was the organism identified in the majority of these infections. Better diagnostic studies i.e. cultures, serologies and urinary antigen testing, which recognize legionella isolates other than L. pneumophila serogroup 1 need to be developed.

Risk factors for community-acquired pneumonia diagnosed upon hospital admission. British Thoracic Society Pneumonia Study Group

A case-control study of risk factors for community-acquired pneumonia in adults admitted to hospital is reported. Cases were surviving patients (n = 178) admitted to 14 hospitals in England. Controls were individuals (n = 385) randomly selected from the electoral registers of the areas served by the hospitals. The two groups were compared with regard to risk factors for pneumonia using a standardized postal questionnaire. Independent risk factors associated with cases in log-linear regression analysis were age, heart disease (as indicated by congestive heart failure and/or digitalis treatment), lifetime smoking history, chronic airway disease (chronic bronchitis and/or asthma), occupational dust exposure, pneumonia as a child, single marital status and unemployment. Corticosteroid and bronchodilator therapy were also independent risk factors in the log-linear regression analysis, but may reflect the severity of underlying lung disease for which these drugs were prescribed. These data suggest that cigarette smoking is the major avoidable risk factor for acute pneumonia in adults.

The incidence of Legionella pneumophila: a prospective study in a tertiary care hospital in India

The prevalence of Legionella pneumophila causing community-acquired pneumonia (CAP) in patients who were admitted to hospital was investigated. Between April 1997 and December 1998, 60 patients admitted to the All India Institute of Medical Sciences with CAP, were included in the study. Aetiological diagnosis was based on the results of routine microbiological blood culture for bacteria and serological test by enzyme linked immunosorbent assay (ELISA) for L. pneumophila serogroup 1-7. Eight (13%) patients had a conventional bacterial aetiology and nine (15%) had serological evidence of recent infection with L. pneumophila. Legionella pneumophila may be an important cause of CAP in adults in developing countries. Empiric antimicrobial treatment should include a combination of agents to cover both atypical agents and bacterial pathogens.

Community-acquired pneumonia in the elderly

Pneumonia in the elderly is a common and serious problem with a clinical presentation that can differ from that in younger patients. Older patients with pneumonia complain of significantly fewer symptoms than do younger patients, and delirium commonly occurs. Indeed, delirium may be the only manifestation of pneumonia in this group of patients. Alcoholism, asthma, immunosuppression, and age >70 years are risk factors for community-acquired pneumonia in the elderly. Among nursing home residents, the following are risk factors for pneumonia: advanced age, male sex, difficulty in swallowing, inability to take oral medications, profound disability, bedridden state, and urinary incontinence. Streptococcus pneumoniae is the most common cause of pneumonia among the elderly. Aspiration pneumonia is underdiagnosed in this group of patients, and tuberculosis always should be considered. In this population an etiologic diagnosis is rarely available when antimicrobial therapy must be instituted. Use of the guidelines for treatment of pneumonia issued by the Infectious Diseases Society of America, with modification for treatment in the nursing home setting, is recommended.

Breakthrough pneumococcal bacteremia in patients being treated with azithromycin and clarithromycin

Streptococcus pneumoniae strains have exhibited decreasing susceptibility to penicillins and macrolides during the past several years. We reviewed the medical charts of all patients with pneumococcal bacteremia who were admitted to a university hospital over a period of 1 year, to identify failures of outpatient therapy. Of 41 patients admitted with pneumococcal bacteremia, 4 had previously taken either azithromycin or clarithromycin for 3-5 days. All 4 had pneumococcal strains that exhibited low-level resistance to macrolide antibiotics. Among pneumococci, low-level resistance to macrolides can lead to clinical failure, and resistance to macrolides should be considered during the selection of empiric therapy for patients with presumed pneumococcal infections.

Summary of Canadian guidelines for the initial management of community-acquired pneumonia: an evidence-based update by the Canadian Infectious Disease Society and the Canadian Thoracic Society

Community-acquired pneumonia (CAP) is a serious illness with a significant impact on individual patients and society as a whole. Over the past several years, there have been significant advances in the knowledge and understanding of the etiology of the disease, and an appreciation of problems such as mixed infections and increasing antimicrobial resistance. The development of additional fluoroquinolone agents with enhanced activity against Streptococcus pneumoniae has been important as well.It was decided that the time had come to update and modify the previous CAP guidelines, which were published in 1993. The current guidelines represent a joint effort by the Canadian Infectious Diseases Society and the Canadian Thoracic Society, and they address the etiology, diagnosis and initial management of CAP. The diagnostic section is based on the site of care, and the treatment section is organized according to whether one is dealing with outpatients, inpatients or nursing home patients.

Clinical presentation, processes and outcomes of care for patients with pneumococcal pneumonia

OBJECTIVE

To describe the presentation, resolution of symptoms, processes of care, and outcomes of pneumococcal pneumonia, and to compare features of the bacteremic and nonbacteremic forms of this illness.

DESIGN

A prospective cohort study.

SETTING

Five medical institutions in 3 geographic locations.

PARTICIPANTS

Inpatients and outpatients with community-acquired pneumonia (CAP).

MEASUREMENTS

Sociodemographic characteristics, respiratory and nonrespiratory symptoms, and physical examination findings were obtained from interviews or chart review. Severity of illness was assessed using a validated prediction rule for short-term mortality in CAP. Pneumococcal pneumonia was categorized as bacteremic; nonbacteremic, pure etiology; or nonbacteremic, mixed etiology.

MAIN RESULTS

One hundred fifty-eight (6.9%) of 2,287 patients (944 outpatients, 1,343 inpatients) with CAP had pneumococcal pneumonia. Sixty-five (41%) of the 158 with pneumococcal pneumonia were bacteremic; 74 (47%) were nonbacteremic with S. pneumoniae as sole pathogen; and 19 (12%) were nonbacteremic with S. pneumoniae as one of multiple pathogens. The pneumococcal bacteremia rate for outpatients was 2.6% and for inpatients it was 6.6%. Cough, dyspnea, and pleuritic pain were common respiratory symptoms. Hemoptysis occurred in 16% to 22% of the patients. A large number of nonrespiratory symptoms were noted. Bacteremic patients were less likely than nonbacteremic patients to have sputum production and myalgias (60% vs 82% and 33% vs 57%, respectively; P <.01 for both), more likely to have elevated blood urea nitrogen and serum creatinine levels, and more likely to receive penicillin therapy. Half of bacteremic patients were in the low risk category for short-term mortality (groups I to III), similar to the nonbacteremic patients. None of the 32 bacteremic patients in risk groups I to III died, while 7 of 23 (30%) in risk group V died. Intensive care unit admissions and pneumonia-related mortality were similar between bacteremic and nonbacteremic groups, although 46% of the bacteremic group had respiratory failure compared with 32% and 37% for the other groups. The nonbacteremic pure etiology patients returned to household activities faster than bacteremic patients. Symptoms frequently persisted at 30 days: cough (50%); dyspnea (53%); sputum production (48%); pleuritic pain (13%); and fatigue (63%).

CONCLUSIONS

There were few differences in the presentation of bacteremic and nonbacteremic pneumococcal pneumonia. About half of bacteremic pneumococcal pneumonia patients were at low risk for mortality. Symptom resolution frequently was slow.

Prevalence of lower respiratory tract infections in hospitalized patients in the United Kingdom and Eire--results from the Second National Prevalence Survey

During 1993 and 1994, the Hospital Infection Society conducted its Second National Prevalence Survey of infections in patients in British hospitals. The prevalence rates for hospital-acquired (HA) and community-acquired (CA), lower respiratory tract infections (LRTIs) were 2.4% and 6.1%, respectively; this shows an increase over that reported in the First National Prevalence Study. The prevalence rate of HA infections for ventilated patients was 18.6%. The prevalence was greater in males, odds ratio (OR, 95% CI) for HA-LRTIs (1.4, 1.1-1.6) and CA-LRTIs (1.2, 1.1-1.3) than in females. In the case of both HA-LRTIs and CA-LRTIs, there was an increase in prevalence in patients with age >75 years, (HA-LRTIs 1.7, 1.3-2.2; CA-LRTIs 1.7, 1.0-2.7). Results of multivariable logistic regression analysis showed an increased risk of HA-LRTIs in patients who had a nasogastric tube (3.6, 2.3-3.6), were ventilated (2.3, 1.6-3.2), trauma patients (2.2, 1.5-3.0), chronic obstructive airway disease (COAD), (1.9, 1.5-2.3), a tracheostomy (1.9, 1.3-2.7), prior blood transfusion (1.5, 1.2-1.8), smokers (1.4, 1.1-1.6) or on systemic corticosteroid therapy (OR 1.3, 1.1-1.6). Community-acquired LRTIs were positively associated with cystic fibrosis (33.7, 19.1-59.3), HIV (9.8, 6.5-14.8), COAD (4.8, 3.8-4.8), systemic corticosteroid therapy (2.5, 2.2-2.8), tracheostomy (1.8, 1.1-2.9), males (1.2, 1.1-1.3) and smoking (1.2, 1.1-1.4).

Importance of atypical pathogens of community-acquired pneumonia

The atypical clinical presentation of patients with community-acquired pneumonia (CAP) was first recognized and reported by astute clinicians 50 years ago. The cause of pneumonia in this group eventually was shown to be Mycoplasma pneumoniae. More recently, Chlamydia pneumoniae also has been recognized as a cause of CAP. Legionella has been lumped together with M. pneumoniae and C. pneumoniae because of its antimicrobial susceptibility pattern. This group of organisms is susceptible to the macrolides, tetracycline, and the newer fluoroquinolones. However, Legionnaires' disease frequently presents a more acute clinical picture than either mycoplasmal or chlamydial infections. Recent data suggest that in the Medicare population hospitalized with pneumonia, morbidity and mortality can be decreased if initial therapy includes coverage for atypical pathogens (i.e., macrolides or fluoroquinolones). Unfortunately, few studies use culture methodology for atypical pathogens. Future studies of the efficacy of macrolide or fluoroquinolone therapy for CAP should include aggressive diagnostic studies for M. pneumoniae, C. pneumoniae, and Legionella species.

Community-acquired pneumonia in the elderly: a practical guide to treatment

The incidence of community-acquired pneumonia (CAP), an infectious disease, sharply increases among the elderly and the main risk factor for CAP in this age group is chronic comorbidity. The use of the term CAP in the elderly population should be reserved for pneumonia acquired outside of the nursing home setting, since nursing home-acquired pneumonia differs from CAP in terms of its aetiology and clinical manifestations. The main aetiology for CAP is Streptococcus pneumoniae, but atypical pathogens also play an important role as causative agents. The clinical presentations of CAP in the elderly can be different from those in younger patients, and therefore it is important to be aware of and familiar with these differences to avoid unnecessary delays in reaching the correct diagnosis. Imaging is essential to diagnose CAP and to assess its severity. Clinical and laboratory indices can be used to identify elderly patients with CAP who are at low risk for mortality and who can be treated as outpatients. The decision not to hospitalise elderly patients with CAP is contingent on a good clinical condition and the existence of home support systems. The aetiology of CAP cannot be determined on the basis of clinical manifestations, imaging or routine laboratory test results, and the initial antibiotic therapy for elderly patients with CAP should be empirical, based on accepted guidelines. In the light of developments in recent years, elderly patients with CAP, except those who are severely ill, can be treated empirically with once-daily antibiotic monotherapy in the initial phase, using a third-generation fluoroquinolone preparation, such as sparfloxacin, levofloxacin or moxifloxacin, or a new macrolide such as clarithromycin, azithromycin or dirithromycin. In addition to antibiotic therapy, it is critically important to identify and treat the physiological disturbances that accompany CAP as well as decompensation of chronic comorbid conditions. As soon as the patient's condition permits, oral antibiotic therapy should replace intravenous therapy and early discharge from the hospital should be considered. Since influenza and pneumococcus immunisation can reduce morbidity and mortality from CAP, it is important to implement regular immunisation programmes in the primary care setting.

Effect of macrolides as part of initial empiric therapy on medical outcomes for hospitalized patients with community-acquired pneumonia

OBJECTIVE

The goal of this study was to compare the outcomes of hospitalized patients receiving a nonpseudomonal third-generation cephalosporin with or without a macrolide for the treatment of community-acquired pneumonia (CAP).

BACKGROUND

The initial treatment of CAP is usually based on empirically selected antibiotic therapy. The need for coverage of atypical pathogens in hospitalized patients is widely debated, and regional variations may exist.

METHODS

All patients admitted to a community hospital or to a university hospital for 1 year who were aged > or =18 years and had a principal discharge diagnosis of pneumonia with no organism specified according to the International Classification of Diseases, Ninth Revision, Clinical Modification were evaluated. Each patient's medical chart was reviewed by a clinical pharmacist at each facility. The following information was collected for each patient using a standardized form: demographic characteristics, coexisting illnesses, length of hospital and intensive care unit stays, antibiotic regimens, length of parenteral and oral therapy, laboratory and radiographic findings (ie, blood urea nitrogen, glucose, hematocrit, sodium, PO2, pH, and pleural effusion), physical examination results, and mortality. Patients treated with a nonpseudomonal third-generation cephalosporin with or without a macrolide were included in this analysis. Categoric variables were compared using the chi-square test or the Fisher exact test, and continuous variables were compared using the Mann-Whitney U test. A P value < 0.05 was considered statistically significant.

RESULTS

A total of 213 patients met the entry criteria and were treated with a nonpseudomonal third-generation cephalosporin with (116 patients) or without (97 patients) a macrolide. The mean (+/- SD) age of the patients was 62.2+/-19.6 years; 47% were male. The most common comorbid conditions were chronic obstructive pulmonary disease, diabetes mellitus, congestive heart failure, and cerebrovascular accident (CVA). Of the 116 patients who received a macrolide, the majority (66%) received erythromycin. Other macrolides used were clarithromycin (19%) and oral azithromycin (15%). There were no statistical differences between patients who did and did not receive a macrolide in terms of comorbid illnesses, length of hospital stay (5.2+/-2.8 vs 5.2+/-3.4 days, respectively), length of intravenous antibiotic therapy (4.4+/-2.5 vs 4.1+/-2.3 days, respectively), or mortality (0.9% vs 3.1%, respectively; P = 0.333). The only difference between the groups was in age. Those patients who received a macrolide were significantly younger than those who received only a nonpseudomonal third-generation cephalosporin (57.4+/-19.2 years vs 67.9+/-18.5 years; P < 0.001). However, when age and severity of illness were taken into account, no difference existed between the patients who received a nonpseudomonal third-generation cephalosporin alone or in combination with a macrolide.

CONCLUSIONS

We concluded that the addition of a macrolide to a nonpseudomonal third-generation cephalosporin as initial therapy for the treatment of CAP may not be necessary. A randomized, prospective clinical trial comparing a nonpseudomonal third-generation cephalosporin alone and in combination with a macrolide is warranted.

Clinical efficacy of intravenous followed by oral azithromycin monotherapy in hospitalized patients with community-acquired pneumonia. The Azithromycin Intravenous Clinical Trials Group

The purpose of this study was to evaluate intravenous (i.v.) azithromycin followed by oral azithromycin as a monotherapeutic regimen for community-acquired pneumonia (CAP). Two trials of i.v. azithromycin used as initial monotherapy in hospitalized CAP patients are summarized. Clinical efficacy is reported from an open-label randomized trial of azithromycin compared to cefuroxime with or without erythromycin. Bacteriologic and clinical efficacy results are also presented from a noncomparative trial of i.v. azithromycin that was designed to give additional clinical experience with a larger number of pathogens. Azithromycin was administered to 414 patients: 202 and 212 in the comparative and noncomparative trials, respectively. The comparator regimen was used as treatment for 201 patients; 105 were treated with cefuroxime alone and 96 were given cefuroxime plus erythromycin. In the comparative trial, clinical outcome data were available for 268 evaluable patients with confirmed CAP at the 10- to 14-day visit, with 106 (77%) of the azithromycin patients cured or improved and 97 (74%) of the comparator patients cured or improved. Mean i.v. treatment duration and mean total treatment duration (i.v. and oral) for the clinically evaluable patients were significantly (P < 0.05) shorter for the azithromycin group (3.6 days for the i.v. group and 8.6 days for the i.v. and oral group) than for the evaluable patients given cefuroxime plus erythromycin (4.0 days for the i.v. group and 10.3 days for the i.v. and oral group). The present comparative study demonstrates that initial therapy with i.v. azithromycin for hospitalized patients with CAP is associated with fewer side effects and is equal in efficacy to a 1993 American Thoracic Society-suggested regimen of cefuroxime plus erythromycin when the erythromycin is deemed necessary by clinicians.

Antimicrobial treatment failures in patients with community-acquired pneumonia: causes and prognostic implications

The aim of the study was to determine the causes and prognostic implications of antimicrobial treatment failures in patients with nonresponding and progressive life-threatening, community-acquired pneumonia. Forty-nine patients hospitalized with a presumptive diagnosis of community-acquired pneumonia during a 16-mo period, failure to respond to antimicrobial treatment, and documented repeated microbial investigation >/= 72 h after initiation of in-hospital antimicrobial treatment were recorded. A definite etiology of treatment failure could be established in 32 of 49 (65%) patients, and nine additional patients (18%) had a probable etiology. Treatment failures were mainly infectious in origin and included primary, persistent, and nosocomial infections (n = 10 [19%], 13 [24%], and 11 [20%] of causes, respectively). Definite but not probable persistent infections were mostly due to microbial resistance to the administered initial empiric antimicrobial treatment. Nosocomial infections were particularly frequent in patients with progressive pneumonia. Definite persistent infections and nosocomial infections had the highest associated mortality rates (75 and 88%, respectively). Nosocomial pneumonia was the only cause of treatment failure independently associated with death in multivariate analysis (RR, 16.7; 95% CI, 1.4 to 194.9; p = 0.03). We conclude that the detection of microbial resistance and the diagnosis of nosocomial pneumonia are the two major challenges in hospitalized patients with community-acquired pneumonia who do not respond to initial antimicrobial treatment. In order to establish these potentially life-threatening etiologies, a regular microbial reinvestigation seems mandatory for all patients presenting with antimicrobial treatment failures.

Anaerobic Infections of the Lung

Although the landmark investigational period for anaerobic pathogens occurred more than 20 years ago, pleuropulmonary infections caused by these pathogens remain an important cause of morbidity and mortality. Despite heightened awareness of pathogenicity and new diagnostic methods, the actual incidence of anaerobes in pulmonary infections--especially those occurring in hospitalized patients--remains controversial. Further complicating the management of these infections is the changing antimicrobial susceptibility of oral anaerobes, which has mandated the abandonment of penicillin monotherapy in seriously ill patients. This article reviews the pathogenesis of anaerobic pulmonary infections, their clinical presentations, and current management issues.

Management of patients with community-acquired pneumonia in a primary care hospital: a critical evaluation

The aim of the study was to evaluate routine management of patients with community-acquired pneumonia (CAP) with regard to severity patterns, diagnostic approaches and results, as well as initial empiric antimicrobial treatment and its impact on outcome. Two hundred and thirty-two consecutive patients with CAP admitted to a primary care hospital were studied prospectively. Patients were classified according to Fine's severity score. Severe pneumonia was defined as admission at the ICU. Diagnostic approaches and initial antimicrobial treatment were judged according to the guidelines of the European Respiratory Society (ERS). Fifty-five patients (24%) had mild, 156 (67%) moderate, and 21 (9%) severe CAP. At least one microbial examination was performed in 124 patients (54%). There was no association between microbial investigation and severity of CAP. Inadequate initial antimicrobial treatment was significantly more frequent in severe (18/21, 86%), than in mild (5/55, 9%) and moderate CAP (39/156, 25%, P < 0.0001). Conversely, antimicrobial overtreatment occurred significantly more often in mild (30/55, 55%) and moderate (77/156, 49%) than in severe CAP (0/21, 0%, P < 0.0001). Inadequate initial antimicrobial treatment was more frequent in non-responders [18/62 (29%) vs. 31/170, (18%), RR 1.6 95% CI 0.9-2.6, P = 0.07] and was associated with a longer duration of hospitalization (17 +/- 11 vs. 14 +/- 8 days, P = 0.03). Mortality was not affected by inadequate initial antimicrobial treatment [5/62 (8%) vs. 10/170 (6%), RR 1.4 95% CI 0.5-3.9, P=0.55]. Principal conceptual weaknesses which might be subject to intervention were (1) the hospitalization of patients with mild pneumonia at low risk of mortality; (2) the lack of association between microbial investigation and severity of CAP; (3) antimicrobial overtreatment of patients with non-severe CAP; and (4) inadequate antimicrobial treatment with increased number of primary treatment failures and duration of hospitalization.

Risk factors for community-acquired pneumonia diagnosed by general practitioners in the community

The purpose of this study was to identify risk factors for pneumonia diagnosed in the community by general practitioners, using a case control study in 29 general practices in Nottingham, U.K. Patients with radiographically confirmed pneumonia were compared with adults randomly selected from electoral registers corresponding to the catchment areas of the general practices taking part in the study. Sixty-six cases and 489 controls participated. Significant risk factors in univariate analysis included age, chronic obstructive pulmonary disease, congestive heart failure and lifetime consumption of cigarettes. Multiple logistic regression analysis of these four variables showed that age [adjusted odds ratio = 2.69 (for 30 year increment), 95%CI = 1.66-4.35] and chronic obstructive pulmonary disease (adjusted odds ratio= 1.99, 95%CI = 1.15-3.45) were independent risk factors. Only age and chronic obstructive pulmonary disease were independent risk factors for pneumonia in this study. Since cigarette smoking is the major cause of chronic obstructive pulmonary disease, these data suggest that cigarette smoking is the main avoidable risk factor for community-acquired pneumonia in adults.