Aetiology of community-acquired pneumonia in hospital treated patients

Management of community-acquired pneumonia in immunocompetent adults: updated Swedish guidelines 2017

Based on expert group work, Swedish recommendations for the management of community-acquired pneumonia in adults are here updated. The management of sepsis-induced hypotension is addressed in detail, including monitoring and parenteral therapy. The importance of respiratory support in cases of acute respiratory failure is emphasized. Treatment with high-flow oxygen and non-invasive ventilation is recommended. The use of statins or steroids in general therapy is not found to be fully supported by evidence. In the management of pleural infection, new data show favourable effects of tissue plasminogen activator and deoxyribonuclease installation. Detailed recommendations for the vaccination of risk groups are afforded.

Serological investigation of pneumonia as it presents to the physician's office

PURPOSE

To define the etiology of pneumonia, using a battery of serological tests, among patients presenting to physicians' offices in Cumberland County, Nova Scotia from July 2, 1989 to July 1, 1990.

METHODS

Patients presenting to their physician's office with symptoms suggestive of pneumonia were invited to participate in the study by completing a questionnaire, having a chest radiograph and providing acute and convalescent phase serum samples. These serum samples were tested for antibodies to Mycoplasma pneumoniae, Coxiella burnetii, Legionella pneumophila, adenovirus, and influenza viruses A and B. Some of the samples were tested for antibodies to Chlamydia pneumoniae.

RESULTS

Seventy-five of the inception cohort of 203 patients had a chest radiograph compatible with pneumonia, a completed questionnaire and acute and convalescent phase serum samples. There were 39 females and 36 males with a mean age of 41.7 years. Twenty-six (35%) were admitted to hospital. The mortality rate was 3%. Forty-five per cent had a diagnosis made by serology: M pneumoniae, 22 (29%); influenza A virus, five (7%); C burnetii, L pneumophila, adenovirus, two (3%) each.

CONCLUSIONS

While it is not possible to generalize about these findings because of ascertainment bias, the data suggest that M pneumoniae is a common cause of pneumonia presenting to a physician's office and that mortality is low in this group of patients.

Swedish guidelines on the management of community-acquired pneumonia in immunocompetent adults--Swedish Society of Infectious Diseases 2012

This document presents the 2012 evidence based guidelines of the Swedish Society of Infectious Diseases for the in- hospital management of adult immunocompetent patients with community-acquired pneumonia (CAP). The prognostic score 'CRB-65' is recommended for the initial assessment of all CAP patients, and should be regarded as an aid for decision-making concerning the level of care required, microbiological investigation, and antibiotic treatment. Due to the favourable antibiotic resistance situation in Sweden, an initial narrow-spectrum antibiotic treatment primarily directed at Streptococcus pneumoniae is recommended in most situations. The recommended treatment for patients with severe CAP (CRB-65 score 2) is penicillin G in most situations. In critically ill patients (CRB-65 score 3-4), combination therapy with cefotaxime/macrolide or penicillin G/fluoroquinolone is recommended. A thorough microbiological investigation should be undertaken in all patients, including blood cultures, respiratory tract sampling, and urine antigens, with the addition of extensive sampling for more uncommon respiratory pathogens in the case of severe disease. Recommended measures for the prevention of CAP include vaccination for influenza and pneumococci, as well as smoking cessation.

Guidelines for the management of adult lower respiratory tract infections--full version

This document is an update of Guidelines published in 2005 and now includes scientific publications through to May 2010. It provides evidence-based recommendations for the most common management questions occurring in routine clinical practice in the management of adult patients with LRTI. Topics include management outside hospital, management inside hospital (including community-acquired pneumonia (CAP), acute exacerbations of COPD (AECOPD), acute exacerbations of bronchiectasis) and prevention. Background sections and graded evidence tables are also included. The target audience for the Guideline is thus all those whose routine practice includes the management of adult LRTI.

Diagnostic tests for agents of community-acquired pneumonia

Lower respiratory infections are the major cause of death due to infectious disease in the United States and worldwide. Most forms of community-acquired pneumonia (CAP) are treatable, and there is consensus that the selection of antimicrobial agents is notably simplified if the pathogen is defined. The rich history of CAP studies in the prepenicillin era showed that an etiologic diagnosis was established in >90% of cases, but the 2009 data from Medicare indicate that a probable pathogen is now detected in <10% according to a review of the records of >17,000 patients hospitalized with CAP. This review addresses the issue of the state of the art of microbiological studies of CAP in terms of the realities of current-day practice. Unfortunately, the desire for better data to achieve pathogen-directed treatment clashes with a multitude of harsh realities, including cost, Centers for Medicare and Medicaid Services (CMS) requirements for antibiotics to be administered within 6 h of disease onset, guidelines that discourage any microbiological studies in most cases, belief in empiricism that is well supported by at least 1 prospective study, the decline of microbiological analysis standards in most laboratories, and the devastating impact of the Clinical Laboratory Improvement Amendments (CLIA) regulations that led to the demise of "the house staff laboratory" and the distancing of microbiological analysis from the site of care. Microbiological principles are reviewed, with emphasis on specimen source, pathogenic potential of isolates, concentrations, impact of antecedent antibiotics, and the "Washington criteria" for expectorated sputum. The recommendation is that the high-quality microbiological analysis that is still achieved in some places should be retained but that to advance the field on the basis of the contemporary realities, two goals should be adopted: First is the broad use of antigen tests for Streptococcus pneumoniae and Legionella pneumophila with interpretation by clinical staff under the CLIA waiver for low-complexity tests. The second and more ambitious recommendation is the adoption of molecular techniques, with particular emphasis on nucleic acid detection, which is rapid and sensitive and has already been developed for virtually all recognized pulmonary pathogens. This may be the ultimate solution for many laboratories, and it is likely to have selected use.

Definite, probable, and possible bacterial aetiologies of community-acquired pneumonia at different CRB-65 scores

According to the recommendations of the Swedish Community-Acquired Pneumonia (CAP) guidelines, the selection of empirical antibiotic therapy should be based on the CRB-65 rule. The guidelines recommend empirical therapy directed predominantly against Streptococcus pneumoniae for patients with low CRB-65 scores and broad-spectrum therapy for patients with high CRB-65 scores. In order to study the utility of the recommendations, we analyzed the data from an aetiological study previously performed on 235 hospitalized adult CAP patients at our medical centre. A definite, probable, or possible bacterial aetiology was noted in 194 cases (83%), including 112 cases (48%) with S. pneumoniae aetiology. The following frequencies of definite-probable aetiologies were noted in the patients with CRB-65 score 0-1 (n=155) and CRB-65 score 2-4 (n=80): S. pneumoniae 30% and 35%, Haemophilus influenzae 6.5% and 14% (p=0.063), Mycoplasma pneumoniae 15% and 5.0% (p=0.019), Chlamydophila species 2.6% and 1.2%, Legionella pneumophila 1.9% and 0%, and Staphylococcus aureus 1.3% and 1.2%, respectively. The high frequency of S. pneumoniae in the study supports the recommendations to predominantly cover this bacterium in the empirical therapy of patients with low CRB-65 scores. In the case of treatment failure in these patients, the study indicates that coverage against M. pneumoniae and H. influenzae should be considered.

A community outbreak of Legionnaires’ disease from an industrial cooling tower: Assessment of clinical features and diagnostic procedures

An outbreak of Legionnaires' disease (LD) occurred in Lidköping, Sweden, in August 2004. A cooling tower was identified as the probable source of infection. During the outbreak period an unexpected 3-6-fold increase in pneumonia patients was noted at the local hospital. During 7 weeks LD was diagnosed in 15 patients by urinary antigen and/or sputum culture. Additionally, 15 LD patients were diagnosed later by serology. Patients with LD were generally younger, more healthy, and more often smokers compared to other pneumonia patients. On admittance they had more severe symptoms with high fever and raised CRP levels, and more often hyponatraemia, gastrointestinal and CNS symptoms. A causative agent besides Legionella was found in 2 patients only. A significant titre rise for Mycoplasma and/or Chlamydophila pneumoniae was found in 13 of 29 tested patients with confirmed LD. We conclude that the clinical diagnosis of LD is difficult and that available diagnostic methods detect only a minority of patients in the acute phase. Therefore in severe pneumonia, empirically targeted therapy should be instituted on clinical grounds irrespective of the results of diagnostic tests. The observation of increased antibody levels for M. and C. pneumoniae suggests an unspecific immune reaction and merits further study.

Bacterial Infections

In Osier’s time, bacterial pneumonia was a dreaded event, so important that he borrowed John Bunyan’s characterization of tuberculosis and anointed the pneumococcus, as the prime pathogen, “Captain of the men of death.”1 One hundred years later much has changed, but much remains the same. Pneumonia is now the sixth most common cause of death and the most common lethal infection in the United States. Hospital-acquired pneumonia is now the second most common nosocomial infection.2 It was documented as a complication in 0.6% of patients in a national surveillance study,3 and has been reported in as many as 20% of patients in critical care units.4 Furthermore, it is the leading cause of death among nosocomial infections.5 Leu and colleagues6 were able to associate one third of the mortality in patients with nosocomial pneumonia to the infection itself. The increase in hospital stay, which averaged 7 days, was statistically significant. It has been estimated that nosocomial pneumonia produces costs in excess of $500 million each year in the United States, largely related to the increased length of hospital stay.

Naso- and oropharyngeal potential respiratory pathogens in adults with nonpneumonic lower respiratory tract infection

The objective of this prospective study was to determine positive isolation rates for potential respiratory pathogens (PRPs) in the naso- and oropharynx of adults hospitalized for nonpneumonic lower respiratory tract infection (NPLRTI), compared with patients with community-acquired pneumonia (CAP) and healthy controls. The study population was 315 non-chronic obstructive pulmonary disease adults hospitalized with febrile lower respiratory tract infection (158 NPLRTI and 157 CAP) and 450 control subjects. Each participant was sampled by oropharyngeal swab, nasopharyngeal swab, and nasopharyngeal washings that were tested by conventional bacteriologic methods to identify PRP. At least 1 of the samples was positive for at least 1 of the 3 PRP bacteria in 55 NPLRTI patients (35%) compared with 51 CAP patients (33%) (NS) and 100 controls (22%) (P = 0.003 compared with NPLRTI and P = 0.02 compared with CAP). Samples were positive for Streptococcus pneumoniae in 14 NPLRTI patients (9%) compared with 29 CAP patients (19%) (P = 0.02) and 16 controls (4%) (NPLRTI P = 0.015, CAP P < 0.0001). The corresponding rates for Haemophilus influenzae were 23 (15%), 16 (10%), and 60 (13%) (NS for all 3 comparisons), and for Moraxella catarrhalis, 28 (18%), 25 (16%), and 48 (11%), respectively (NPLRTI versus controls, P = 0.03, NS other comparisons). We conclude that the rate of positive naso/oropharyngeal isolates for at least 1 of the 3 PRP bacteria in NPLRTI patients is similar to the corresponding rates for CAP patients and is higher in both groups than in controls.

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

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

Pneumonia adquirida na comunidade em pacientes tratados ambulatorialmente: aspectos epidemiológicos, clínicos e radiológicos das pneumonias atípicas e não atípicas

Objetivo: Avaliar o percentual etiológico das pneumonias atípicas tratadas ambulatorialmente. Identificar os fatores epidemiológicos, clínicos e radiológicos que permitam diferenciar pneumonia atípica de não atípica. Métodos: Os pacientes foram submetidos a avaliação clínica, radiológica, coleta de escarro para estudo pelo método de Gram e sangue para testes sorológicos, incluindo Legionella pneumophila, Chlamydia sp, Mycoplasma pneumoniae, vírus Influenza A e Influenza B, no primeiro dia e 21 dias após inclusão. As radiografias de tórax foram revistas por três observadores independentes que desconheciam o quadro clínico. Resultados: Avaliados inicialmente 129 pacientes durante 22 meses. A amostra final para estudo comparativo entre os grupos consistiu de 69 pacientes que tinham em média 37 anos, sendo 46 (67%) homens e 23 (33%) mulheres. O diagnóstico etiológico foi definido em 34 (50%) dos pacientes. Chlamydia sp foi o agente atípico mais freqüente, com 11 (16%) casos, seguido por M. pneumoniae com 7 (10%). Influenza A respondeu por 4 (6%) dos casos e Legionella em 4 (6%) pacientes. Infecções mistas foram evidenciadas, com associação de Chlamydia sp e M. pneumoniae em 5 (7%) casos, Chlamydia sp e Influenza B em um caso e M. pneumoniae e Influenza A em outro. A presença de sintomas respiratórios e achados gerais sugestivos de pneumonia atípica foram comparados entre os grupos e não foram observadas diferenças significantes. A avaliação radiológica realizada por três observadores independentes mostrou discordância entre eles para os tipos de pneumonia. O diagnóstico radiográfico de cada observador comparado com o diagnóstico clínico não mostrou associação significante. Conclusões: A pneumonia causada por agente atípico ocorre em 50% dos pacientes com pneumonia adquirida na comunidade em tratamento ambulatorial. Não é possível distinguir pacientes com pneumonia atípica de pneumonia não atípica. A apresentação clínica e a radiológica são similares nos dois grupos.

Pneumococcal disease in Sweden: experiences and current situation

During the last decade, the incidence of invasive pneumococcal disease in Sweden has risen, seemingly due chiefly to an increasing incidence of pneumococcal bacteremia among the elderly. On the other hand, mortality due to invasive disease in Sweden is low, approximately 10% for bacteremic pneumococcal pneumonia. Beta-lactam resistance in Streptococcus pneumoniae is still a relatively minor problem in Sweden, with only 3%-4% of strains demonstrating decreased susceptibility to penicillin. However, local outbreaks of pneumococcal disease with up to 10% resistance have occurred among children, especially in southern Sweden.

Community-acquired pneumonia guidelines--an international comparison: a view from Europe

Following an outline that details the pathogens causing community-acquired pneumonia (CAP) identified in studies from Europe, this article reviews the guidelines for the management of CAP in four European countries--France, Italy, Spain, and the United Kingdom. The method behind the development of each document is described, followed by a comparison of the scope of each document. All four documents provide guidelines for the management of two groups of patients--the severely ill and the nonseverely ill patient. A penicillin or macrolide feature for the nonseverely ill and the combination of a third-generation cephalosporin plus a macrolide for the severely ill patient are described in all four guidelines. Despite their different origins and methods, these four guidelines have more similarities than differences--the latter serving to emphasize some of the areas that require further research in this important condition. An important area for research is the impact that these guidelines have on practice and especially on clinical outcomes.

Severe community-acquired pneumonia

Community-acquired pneumonia (CAP) is likely to be severe in the very elderly, and clinically significant in those with hepatic/ renal insufficiency, cardiopulmonary disease, or, impaired host defenses. Pathogens in mild, moderately severe, and severe CAP are the same. These pathogens determine prognosis, complications, and duration of therapy. Empiric antimicrobial therapy should be based on likely pathogens, not severity of illness which affects the potency but not spectrum of antibiotic selected.

Practical considerations and guidelines for the management of community-acquired pneumonia

Community-acquired pneumonia (CAP) is a common condition which has a significant mortality. The management of a patient with CAP is centred around assessment and correction of gas exchange and fluid balance together with administration of appropriate antibiotics. Up to 10 different pathogens regularly cause CAP, of which Streptococcus pneumoniae is the most important. These different pathogens cannot be distinguished by clinical features or simple laboratory tests. Microbiological tests are slow and insensitive, so empirical therapy is necessary, at least initially. Accurate assessment of illness severity is the most important factor determining initial management, since this assists the decision of whether to admit the patient to hospital in addition to guiding antibiotic choice and route of administration. Two different approaches to severity assessment are outlined. Our antibiotic recommendation for empirical therapy for the patient managed at home and the previously fit patient admitted to hospital is amoxicillin. Amoxicillin/clavulanate plus a macrolide is our choice for the severely ill previously fit patient and a third-generation cephalosporin plus a macrolide is recommended for the severely ill patient with comorbidity. Alternative pathogens and specific treatment regimens are also described. There may be several causes of treatment failure, and in patients who fail to respond to therapy, it is essential to review all the initial clinical and laboratory information, which if necessary must be repeated.

Recurrence of pneumonia in middle-aged and elderly adults after hospital-treated pneumonia: aetiology and predisposing conditions

In order to investigate the predisposing conditions and aetiologic agents in patients with recurrent pneumonia, we prospectively studied 653 immunocompetent patients, 50-85 years of age, who had been treated in hospital for community-acquired pneumonia. After an average patient follow-up period of 32 months, 11 variables were examined for association with the following end points: death, recurrence of pneumonia and recurrence of pneumococcal pneumonia. During the follow-up period there were 171 episodes of pneumonia in 115 of the 653 patients, and 52 deaths (all causes). Multivariate analysis showed that age, male sex, congestive heart failure and presence of other chronic diseases were significantly associated with higher mortality. Age and chronic pulmonary disease were associated with recurrence of pneumonia. The major aetiologic agents were Streptococcus pneumoniae (26%), Haemophilus influenzae (11%) and Moraxella catarrhalis (6%). We conclude that pneumonia recurrences are common in middle-aged and elderly patients after treatment in hospital for community-acquired pneumonia. The recurrence risk is higher in elderly patients, and in those with chronic pulmonary diseases. Given the prominence of H. influenzae and M. catarrhalis found in the present study, these organisms should always be considered when choosing the initial antibiotic in patients with recurrent pneumonia.

Bottle-blowing in hospital-treated patients with community-acquired pneumonia

A study was carried out to determine whether bottle-blowing has any positive effects in patients with pneumonia. In a prospective open study 145 adults with untreated community-acquired pneumonia requiring hospitalization were randomized to early mobilization (group A), to sit up and take 20 deep breaths on 10 occasions daily (group B), or to sit up and to blow bubbles in a bottle containing 10 cm water through a plastic tube 20 times on 10 occasions daily (group C). Peak expiratory flow (PEF), vital capacity (VC), forced expiratory volume in 1 sec (FEV1) and serum concentration of C-reactive protein (CRP) were determined on admission, and on days 4 and 42. Fever duration and hospital stay were recorded. In a subset of 16 patients, single breath diffusion capacity of carbon monoxide was measured on 3 occasions. The patients in group A were hospitalized for a mean of 5.3 days, group B for 4.6 days and group C for 3.9 days. Treatment was a significant factor (p = 0.037) in a Cox regression model, with group C significantly better than group A (p = 0.01). The number of days with fever was 2.3, 1.7 and 1.6 in groups A, B and C respectively. These differences were not significant (p = 0.28). No significant differences were found between the groups regarding CRP, PEF, VC, FEV1, or diffusion capacity. Intensive bottle-blowing shortens the hospital stay in patients with pneumonia. The underlying mechanism is not clear.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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.

Detection of pneumococcal polysaccharide antigens in the urine of patients with bacteraemic and non-bacteraemic pneumococcal pneumonia

Countercurrent-immunoelectrophoresis (CIE) was used to detect pneumococcal capsular polysaccharide and C-polysaccharide (C-Ps) antigens in urine. The neutral capsular polysaccharides of types 7F and 14 were detected by coagglutination. We found pneumococcal polysaccharide in urine with the same frequency in two groups of patients, i.e. a non-bacteraemic pneumonia group (68%) and a group of patients with pneumococcal bacteraemia (66%). C-Ps was detected in the urine of two patients (4%) and, therefore, this test has no value in the diagnosis of pneumococcal infections. Since there is no sensitive, non-invasive, single procedure for the diagnosis of non-bacteraemic pneumococcal pneumonia we conclude that attempts to detect pneumococcal capsular polysaccharide by CIE in combination with coagglutination (types 7F and 14) may be a useful diagnostic supplement in the search for the etiological agent in pneumonia in adults until new, more sensitive diagnostic methods have been developed.

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.

Detection of Streptococcus pneumoniae in sputum samples by PCR

A method for the detection of Streptococcus pneumoniae in sputum samples by PCR has been developed. The assay employs oligonucleotide primers specific for a portion of the autolysin gene lytA of S. pneumoniae. Other closely related streptococci, Haemophilus influenzae, and Moraxella catarrhalis do not give a positive result in the assay. The assay was capable of detecting between 10 and 100 CFU of S. pneumoniae in distilled water and 1.4 x 10(4) CFU/ml in simulated sputum samples. Sputum samples from 33 patients with acute pneumonia were collected and subjected to culture, PCR, and C-polysaccharide antigen detection by enzyme-linked immunosorbent assay (ELISA). A significant isolate of S. pneumoniae was isolated from 14 patients, of which 13 were positive by PCR and C-polysaccharide antigen ELISA. No positive results were obtained for the 19 patients in whom other pathogens or upper respiratory tract floras only were isolated. The sensitivity of the autolysin PCR is 92.8%, the specificity is 100%, the predictive value of a positive result is 100%, and the predictive value of a negative result is 95%. This suggests that autolysin PCR is suitable for the detection of S. pneumoniae in clinical samples.

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.

Detection of pneumococcal capsular antigen in the presence of penicillin in vitro

Eight strains of Streptococcus pneumoniae were tested in vitro for their ability to produce capsular antigen in the presence of penicillin. It was found that, provided 10(6) to 10(7) pneumococci/ml were present, capsular antigen could be detected during the 72 h in which the experiment was conducted, irrespective of whether penicillin was added at 0 h or 8 h, and even when no viable pneumococci remained. When fewer pneumococci were present, capsular antigen could not be detected at any time in the presence of penicillin. Control cultures, without penicillin, yielded detectable capsular antigen only when the threshold value of 10(6)-10(7) pneumococci/ml was reached. It is concluded that the presence of penicillin does not influence the detection of pneumococcal capsular antigen, but demonstration of this antigen is totally dependent on the number of pneumococci present.

Microbial etiology of acute pneumonia in hospitalized patients

The purpose of this study was to determine the microbial etiology of pneumonia by using strict criteria among a group of hospitalized patients. Patients with acute community-acquired or hospital-acquired pneumonia were studied in a systematic and comprehensive manner for bacterial, viral, chlamydial, mycobacterial, and fungal pathogens. A total of 198 patients with 204 episodes of pneumonia were evaluated. Despite 100 percent follow-up of all surviving patients, a specific etiologic agent could be found in only 103 episodes. Among 154 episodes of community-acquired pneumonia, a diagnosis was made in 79; the most common pathogen was from the genus Legionella, followed by various Gram-negative enteric bacteria, Gram-positive cocci, influenza A virus, and Mycoplasma pneumoniae. The etiologic agent was found in 24 of the 50 patients with hospital-acquired pneumonia; no pathogen predominated. We conclude that even when elaborate diagnostic studies are done, including many invasive procedures, the etiology can be determined in only about half of the patients with acute pneumonia. The pathogens of pneumonia in this study are not markedly different between community-acquired and hospital-acquired infection.

Regional differences of Chlamydia pneumoniae as causative agent of pneumonia in Sweden

A retrospective serological study was performed on sera from 1982-83 and 1989 to investigate the incidence of Chlamydia pneumoniae infection in hospital treated patients with pneumonia in Orebro County. Paired sera from 231 patients were available and 3 cases (1.3%) of C. pneumoniae infection were documented by microimmunofluorescence. The results differ from those reported by others implying regional differences of C. pneumoniae as causative agent of pneumonia. The findings from Orebro County do not support any change in current antibiotic policy and we still regard penicillin as the first drug of choice in community-acquired pneumonia.

Severe community-acquired pneumonia. Epidemiology and prognostic factors

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

The scope of lower respiratory tract infection

Lower respiratory tract infections (LRTI) are commonly classified as either bronchitis or pneumonia, and these infections are associated with an extremely high morbidity in the community, as well as a high mortality in those patients that require hospitalisation. Therefore, such infections place a huge burden, both economically and as a user of health services, on the entire health care system. The antibiotic treatment of community-acquired pneumonia caused by gram-negative organisms or staphylococci is controversial, and these organisms may cause one-third of the cases of community-acquired pneumonia. Nosocomial pneumonia is caused even more often by gram-negative bacteria, and as such the development of rational and effective antibiotic therapy to cover these organisms is very important.

The value of routine microbial investigation in community-acquired pneumonia

The way in which microbiological investigations are used in routine clinical practice and the value of such tests in directing antibiotic prescribing, was studied in adults admitted to hospital with a diagnosis of community-acquired pneumonia. One-hundred and twenty-two consecutive patients admitted to one teaching and one district general hospital were studied between April 1988 and March 1989. Blood cultures were performed in 81% of cases, sputum was examined in 45% and complete serological tests were performed in 28%. No causative pathogen was found in 74% of cases and results of microbial tests directed a change in antibiotic therapy in only 8% of cases. Routine microbial investigation of all adults admitted to hospital with community-acquired pneumonia is unhelpful and probably unnecessary. We suggest a strategy for microbial investigation linked to initial illness severity to replace the current haphazard approach.

Community acquired pneumonia: aetiology and prognostic index evaluation

A 10 month prospective study of all adults admitted to Waikato Hospital with community acquired pneumonia was performed to assess aetiology, mortality, hospital stay, and the value of a prognostic index based on that obtained from a British Thoracic Society study. The 92 patients in the survey had a mean age of 56 (range 13-97) years. A microbiological diagnosis was established in 72%; Streptococcus pneumoniae (33%), Mycoplasma pneumoniae (18%), and influenza A virus (8%) were the most common microorganisms. Other causative organisms were Legionella pneumophila (4 cases), Staphylococcus aureus (3), Klebsiella pneumoniae (2), Haemophilus influenzae (2), Nocardia brasiliensis (1), and Acinetobacter calcoaceticus (1). Chlamydia sp, influenza B virus and adenovirus were each found in one case; all were cultured on nasopharygeal aspirates. Aspiration was considered to be the underlying cause in five patients, two with epilepsy and one with pseudobulbar palsy. Five of the six deaths that occurred were in patients over 75 years of age and the other was 69. In four of the six the established causative organisms were Chlamydia sp (1), K pneumoniae (1), and S aureus (2). Patients had a 16 fold increased risk of death if they had two or more of the following on admission: a respiratory rate of 30/minute or more, diastolic blood pressure of 60 mm Hg or less, and either confusion or a plasma urea concentration greater than 7.0 mmol/l.

Legionellosis in patients with HIV infection

During the five-year period 1984-1988 we received 192 specimens from 180 patients infected with the human immunodeficiency virus (HIV) for investigation of Legionella infection. The majority of specimens were bronchoalveolar lavage (BAL) fluids (84%), but tracheal suctions and lung tissue from autopsies were also examined. The diagnostic methods used were a direct immunofluorescence assay (DFA) for the detection of Legionella antigen, and culture on buffered charcoal yeast extract (BCYE-alpha) media. All specimens were also examined for the presence of other bacterial lung pathogens, and all BAL specimens additionally for Pneumocystis carinii and mycobacteria. Legionellosis was not found to be common among HIV-infected patients, as only six specimens (3%) from six patients were found positive by DFA, and no specimens were culture-positive for Legionella species. Dual infection with Legionella and P. carinii occurred in two patients. Clinical data of the six patients are presented, and currently used methods for diagnosing legionellosis are discussed.

Nasopharyngeal culture in the pneumonia diagnosis

The diagnostic value of bacterial cultures from nasopharynx (NPH) was prospectively studied in 261 patients with community-acquired pneumonia requiring hospitalization. NPH culture results were compared with those of other diagnostic methods: Culture from blood and sputum, pneumococcal antigen detection, enzyme immuno assay (EIA) for detection of antibodies against pneumococcal hemolysin and in selected cases bronchoscopy. Pneumococcal pneumonia was diagnosed by these other methods in 121 patients. Streptococcus pneumoniae was detected in NPH in 33 of these patients (27%, or 36% if only cultures obtained before start of antibiotics are considered), but in only four of the other 140 patients. For other species the relevance of NPH culture was uncertain. Because of its simplicity and high specificity NPH culture can be a valuable supplement to other diagnostic methods, particularly when sputum samples are difficult to obtain.