Diagnosis Of Pneumococcal Pneumonia Research Articles

Prospective study of the usefulness of sputum Gram stain in the initial approach to community-acquired pneumonia requiring hospitalization.

From February 1995 through May 1997, we prospectively studied 533 patients with community-acquired pneumonia requiring hospitalization in order to assess the current usefulness of sputum Gram stain in guiding the etiologic diagnosis and initial antibiotic therapy when applied routinely. Sputum samples of good quality were obtained in 210 (39%) patients, 175 of whom showed a predominant morphotype. Sensitivity and specificity of Gram stain for the diagnosis of pneumococcal pneumonia were 57% and 97%, respectively; the corresponding values for Haemophilus influenzae pneumonia were 82% and 99%. Patients with a predominant morphotype were more frequently treated with monotherapy than were patients without a demonstrative sputum sample (89% vs. 75%; P<.001). Analysis of our data shows that a good-quality sputum sample can be obtained from a substantial number of patients with community-acquired pneumonia. Gram stain was highly specific for the diagnosis of pneumococcal and H. influenzae pneumonia and may be useful in guiding pathogen-oriented antimicrobial therapy.

Diagnosis of pneumococcal pneumonia by polymerase chain reaction (PCR) in whole blood: a prospective clinical study

BACKGROUNDStreptococcus pneumoniae is the leading cause of community acquired pneumonia; however, only a small proportion of cases can be detected by conventional methods. The ability of the polymerase chain reaction...

Validation of Immune-Complex Enzyme Immunoassays for Diagnosis of Pneumococcal Pneumonia among Adults in Kenya

The efficacy of pneumococcal vaccines in protecting against pneumococcal pneumonia can feasibly be measured only with a diagnostic technique that has a high specificity (0.98 to 1.00) and a sensitivity greatly exceeding that of blood cultures (>0.2 to 0.3). In this context immune-complex enzyme immunoassays (EIAs) offer a novel, convenient diagnostic method, and we have investigated three such assays with appropriate study populations in Kenya. Sera from 129 Kenyan adults with pneumococcal pneumonia and 97 ill controls from the same clinics, but without pneumococcal disease syndromes, were assayed with immune-complex EIAs for pneumolysin, C-polysaccharide, and mixed capsular polysaccharides (Pneumovax II). At an optical density (OD) threshold yielding a specificity of 0.95, the sensitivities (95% confidence intervals) of the assays were 0.22 (0.15 to 0.30), 0.26 (0.19 to 0.34), and 0.22 (0.15 to 0.29), respectively. For pneumolysin immune complexes, human immunodeficiency virus (HIV)-positive patients had a higher mean OD than HIV-negative patients (639 versus 321; P < 0.0001), but stratification by HIV infection status did not alter the performance of this test. Combining the results of all three EIAs did not enhance the diagnostic performances of the individual assays. In Kenyan adults the sensitivities of the immune-complex EIAs could exceed that of blood cultures only at levels of specificity that were insufficient for the performance of vaccine efficacy studies.

Comparative evaluation of new and old methods for the diagnosis of pneumococcal pneumonia

The 53 kDa protein pneumolysin (PLY) is the main virulence factor of Streptococcus pneumoniae, a leading cause of invasive pneumococcal diseases. PLY forms pores in cholesterol-containing membranes, thereby interfering with the function of cells. Bone destruction is a serious matter in chronic inflammatory diseases such as septic arthritis and osteomyelitis. S. pneumoniae is increasingly being recognized as a common cause of septic arthritis, but its pathogenesis is poorly defined.We examined the effect of PLY on osteoblast differentiation and its mechanisms of action. The effect of PLY on osteoblast differentiation was evaluated by qRT-PCR, ALP activity assay, flow cytometric analysis, and Western blotting. We also examined the role of PLY-induced autophagy in osteoblast differentiation using RNA interference analysis.PLY inhibited osteoblast differentiation by decreasing the expression of osteoblast marker genes such as Runx2 and OCN, along with ALP activity. ROS production was increased by PLY during osteoblast differentiation. PLY induced autophagy through ROS-mediated regulation of AMPK and mTOR, which downregulated the expression of Sp1 and subsequent inhibition of differentiation. Treatment with autophagy inhibitors or Atg5 siRNA alleviated the PLY-induced inhibition of differentiation.The results suggest that PLY inhibits osteoblast differentiation by downregulation of Sp1 accompanied by induction of autophagy through ROS-mediated regulation of the AMPK/mTOR pathway.This study proposes a molecular mechanism for inhibition of osteoblast differentiation in response to PLY.

Diagnosis of pneumococcal pneumonia in epidemiological studies: evaluation in Kenyan adults of a serotype-specific urine latex agglutination assay.

A serotype-specific tube latex agglutination assay for 10 pneumococcal serotypes was evaluated with use of urine samples from 72 Kenyan adults with pneumonia whose blood or lung aspirate cultures were positive for Streptococcus pneumoniae, 203 patients with pneumonia whose cultures were negative for S. pneumoniae, and 101 afebrile controls. Detection thresholds for purified capsular polysaccharide in normal urine ranged from 0.33 to 10 ng/mL. The sensitivity of the assay for the 10 pneumococcal serotypes was 0.57 (95% confidence interval, 0.44-0.70) and was unaffected by human immunodeficiency virus seropositivity, prior antibiotic use, and bacteremic or nonbacteremic status but varied significantly by serotype. Of the pneumococci obtained by culture, 81% were of serotypes (1, 4, 5, 6, 7, 9, 12, 14, 19, and 22) that were included in the antigen assay. Strong simultaneous agglutinations against two different serotypes were found in urine samples from two patients. The specificity of the assay was 0.98 (lower 95% confidence limit, 0.95). Subjective reading of agglutination results introduced variation in specificity that may be inapparent if not formally measured. The assay extended the diagnostic yield in pneumococcal pneumonia by a factor of 2.2 (from 54 diagnoses established by blood culture to 119 established by both methods) and may therefore prove useful in reducing the sample size of epidemiological studies of pneumococcal pneumonia in adults.

Pneumococcal Pneumonia.

Pneumococcal pneumonia accounts for about one-sixth to two-thirds of all cases of community-acquired pneumonia. Its high frequency of occurrence worldwide and the high number of deaths associated with it--especially with bacteremic (invasive) disease--mark its importance. Invasive disease is associated with case-fatality rates of 15% to 25% among elderly adults. Penicillin-resistant Streptococcus pneumoniae (PRSP) first appeared in the 1970s, and its increased incidence in the late 1980s signaled its emerging importance. In individual patients in whom PRSP infection is suspected, the clinician must follow guidelines for empiric antibiotic therapy for community-acquired pneumonia until microbiological test results are known. When a diagnosis of pneumococcal pneumonia is established, the clinician should change to a regimen that targets the pneumococcus. Adults at highest risk for death from pneumococcal pneumonia include immunocompetent persons with underlying chronic diseases, immunocompromised persons, elderly persons, and unvaccinated residents of nursing homes and other chronic care facilities. Safe and effective, polyvalent polysaccharide pneumococcal vaccine should be used in persons 2 years of age and older who are at increased risk for serious pneumococcal pneumonia and in all persons 65 years of age and older.

Pneumococcal pneumonia diagnosis by demonstration of pneumolysin antibodies in precipitated immune complexes: a study in 350 Philippine children with acute lower respiratory infection.

In searching for suitable methods for aetiological diagnosis of pneumococcal disease we determined capsular polysaccharide, C-polysaccharide and pneumolysin antibodies bound in immune complexes (IC) in Filipino children. Sera were obtained from 150 healthy infants (all under 12 months old) and from 350 paediatric patients (mean age 18 months) hospitalized with severe pneumonia. The findings in healthy children were not associated with age, sex or pneumococcal carrier status; 3-7% exceeded the cut-off limits for positivity in different antibody assays. By contrast, 97 (51%) of the 190 patients with a complete 3-sample series exceeded the cut-off limit for IC-bound pneumolysin-IgG in at least 1 of the serum samples studied. Positivity rates for IC-bound pneumolysin-IgG in the admission day, in-patient and convalescent sample of the 350 patients were 25%, 25% and 34%. Pneumolysin-IgM, capsular polysaccharide and C-polysaccharide antibodies in the IC were positive in only 4-6% of the patients' samples. IC-bound pneumolysin-IgG antibody assay seem to be a useful method for species-specific diagnosis of pneumococcal infections.

Benzathine penicillin for unilateral lobar or segmental infiltrates presumptively caused by Streptococcus pneumoniae in children 2-12 years old

A randomized controlled study was carried out to assess the efficacy of a single dose of benzathine penicillin for treating children 2-12 years old with presumed S. pneumoniae pneumonia. One-hundred-and-seventy-six children screened at self-referral pediatric emergency services in Belo Horizonte, Brazil, were randomized to only one injection of benzathine penicillin (n = 93, case-group) or a 7-day procaine penicillin regimen (n = 83, control-group), upon diagnosis of pneumococcal pneumonia based on clinical and radiological characteristics. Follow-up was carried out on the second day after treatment and around the 7th and/or 14th day after treatment allocation. No statistical significant difference was found for sociodemographic, clinical, laboratory or radiographic characteristics among the two groups. Evident or total radiographic clearing was demonstrated for 92.3 and 95.1 per cent of the benzathine penicillin and procaine penicillin groups, respectively (P = 0.54). Benzathine penicillin may be considered an alternative to classic regimens for treating pneumonia due to sensitive strains of S. pneumoniae among children 2-12 years old. Other benefits are its lower cost, better compliance and low rates of adverse reactions.

Adult Bacteremic Pneumococcal Pneumonia in a Community Teaching Hospital, 1992-1996n

To review the clinical and laboratory findings of 108 adult patients with bacteremic pneumococcal pneumonia admitted to a community hospital and to determine the value of sputum Gram stains and cultures in the diagnosis of pneumococcal pneumonia in this setting. Using the laboratory logbooks to identify adult inpatients with pneumococcal bacteremia from January 1, 1992, to June 30, 1996, were reviewed medical records. We found 108 patients. There was an apparent increase in prevalence from 1995 to 1996 compared with 1992 to 1994. Patients included 44 men and 64 women. Ages ranged from 20 to 95 years (median, 70 years). The fatality rate was 24.1% and increased with advancing age (no patient younger than 45 years died, and 36.8% of patients aged 85-95 years died). Cigarette smoking, cardiovascular disease, chronic obstructive lung disease, malignant disease, and diabetes mellitus were major underlying conditions. Fever, dyspnea, and cough were the most common presenting symptoms. Sputum Gram stain was useful in the diagnosis when moderate to abundant Gram-positive diplococci were seen. Sputum culture was less useful. Factors associated with higher fatality rate were being 65 years of age or older, APACHE II (Acute Physiologic and Chronic Health Evaluation II) score greater than 15, intensive care unit admission, low or normal leukocyte count, thrombocytopenia, renal dysfunction, diffused infiltrates on chest radiography, bilateral pneumonia, and sputum culture positive for Streptococcus pneumoniae. We found a recent increase in the prevalence of bacteremic pneumococcal pneumonia in adults. Gram stain of sputum is useful, but sputum culture is less sensitive in the diagnosis of pneumococcal pneumonia. The fatality rate remains high. More effort should be made at prevention using pneumococcal immunization.

Rapid detection of pneumococcal antigen in lung aspirates: comparison with culture and PCR technique

Detection of pneumococcal antigen has been used to increase the rate of diagnosis of pneumococcal pneumonia. The present study was designed to determine the value of rapid detection of pneumococcal antigen in samples obtained by transthoracic needle aspiration (TNA) from patients with community-acquired pneumonia (CAP) in a comparative analysis with culture and polymerase chain reaction (PCR). Pneumococcal antigen was detected by latex agglutination. One hundred and ten consecutive patients diagnosed with CAP underwent TNA. Patients were grouped, according to PCR, culture and serological results, into pneumococcal pneumonia ( n = 18), other known aetiology ( n = 67) and unknown aetiology ( n = 25). In patients with pneumococcal pneumonia, antigen was detected in 17 (94·4%) cases. Antigen was detected in one and nine patients with pneumonia of other known or unknown aetiologies, respectively, yielding a specificity of 89·1%. In conclusion, detection of pneumococcal antigen on samples obtained by TNA from patients with CAP provides a sensitive and specific diagnosis of Streptococcus pneumoniae infection. Furthermore, its rapid results would reduce the dependence on empirical treatments.

Evaluation of polymerase chain reaction for diagnosis of pneumococcal pneumonia.

To test the ability of the polymerase chain reaction (PCR) to detect Streptococcus pneumoniae in blood, we generated two sets of nested primers. The first defined 559-bp and 649-bp regions of the pneumolysin gene, and the second defined 445-bp and 553-bp regions of the autolysin gene. These nucleotide segments were detected in DNAs from isolates of all 20 pneumococcal serotypes tested, but they were not detected when used to test DNAs from 41 isolates of nonpneumococcal bacteria and fungi. The sensitivity was evaluated by using purified pneumococcal DNA. We were able to detect 10 fg of S. pneumoniae DNA, or 4.3 genome equivalents. Blood samples were obtained from 16 patients with culture-proven pneumococcal bacteremia and were subjected to PCR analysis. Of eight buffy coat fractions tested, six showed reactivity in the PCR with the pneumolysin primers, and five of the eight produced the expected products when tested with the autolysin primers (sensitivities, 75 and 63%, respectively). Of the eight whole-blood specimens tested, only three produced the expected products with either set of primers. Additionally, we tested 14 samples from patients with bacteremia that were culture positive for nonpneumococcal bacterial species, and 13 were negative (specificity, 93%). This combination of sensitivity and specificity may make detection of S. pneumoniae in blood by PCR in comparison with that by blood culture a very promising alternative for a means of definitive diagnosis.

Antigen detection in oropharyngeal secretions for rapid diagnosis of pneumococcal pneumonia.

To determine the value of detection of antigen in the oropharynx in the diagnosis of pneumococcal pneumonia, oropharyngeal secretions were cultured for the presence of Streptococcus pneumoniae and tested for the presence of pneumococcal antigen. Sputum (if available) collected on the same day was also investigated for the presence of antigen. Detection of pneumococcal antigen was found to be directly related to the severity of pneumococcal carriership or infection (p < 0.0001) and was not related to culture results. Patients with pneumococcal pneumonia had the highest antigen detection rate (38%), followed by patients with pneumonia of unknown etiology (32%) and patients with an acute lower respiratory tract infection due to Streptococcus pneumoniae (20%). Pneumococcal carriers had a detection rate of only 9%. Antigen could be detected in only one patient of the control groups. Although antigen detection in sputum was superior to that in oropharyngeal secretions, concordant results were obtained in 8 (40%) and 6 (36%) patients with pneumococcal pneumonia and pneumonia of unknown etiology respectively. The results strongly suggest that pneumococcal carriage seldom leads to a detectable level of antigen, and that antigen detection in the oropharynx appears to be of additive value in the diagnosis of pneumococcal pneumonia.

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

Detection of pneumococcal antigen may help to increase the rate of diagnosis of pneumococcal pneumonia. This study was designed to determine the value of rapid detection of pneumococcal antigen in pleural fluid from patients with community acquired pneumonia. Thoracentesis was performed in patients suspected of having empyema and in patients with pneumonia of unknown aetiology. Pneumococcal capsular antigen was detected by latex agglutination and this method was compared with Gram staining and culture, specimens of pleural fluid being examined in parallel by the three methods. Pleural fluid was radiographically identified in 63 of 135 patients with community acquired pneumonia. In nine of 45 patients with pneumococcal pneumonia and pleural fluid pneumococci were identified by Gram stain in two and by culture in one specimen of pleural fluid, whereas antigen was detected in eight of these specimens. In 12 of 33 patients with pneumonia of other known aetiology only one pleural fluid specimen was antigen positive, providing a specificity of 92% for this test. Pleural fluid obtained from 12 of 58 patients with pneumonia of unknown aetiology yielded detectable antigen in seven cases. Detection of pneumococcal antigen by latex agglutination in pleural fluid may yield important and rapid information in patients with community acquired pneumonia.

Pneumococcal Antigen Persistence in Sputum from Patients with Community-Acquired Pneumonia

The purpose of this study was to establish the diagnostic value of pneumococcal capsular antigen by comparing this with the results of Gram stain and culture in representative and nonrepresentative sputa during follow-up in patients with community-acquired pneumonia. Antigen was detected by a latex particle agglutination test. At the time of hospital admission, antigen was detected in 17 representative sputum specimens from 30 patients with pneumococcal pneumonia, which was comparable to the results of Gram stain and culture. In five additional patients, antigen was demonstrated in nonrepresentative specimens. During follow-up under antibiotic treatment, this number increased by six: three patients with representative and three patients with nonrepresentative sputum, respectively. Two of the 22 patients with pneumonia of other known cause had an antigen-positive sputum on admission and in another two patients, sputum antigen was detected during follow-up. Ten of 34 patients with pneumonia of unknown cause had detectable antigen in representative or nonrepresentative sputum on admission. During follow-up, antigen was detected in sputa of an additional seven patients. There was no difference in duration of antigen persistence between patients with pneumococcal pneumonia and pneumonia of unknown cause. It was observed that the first antigen-positive sputum specimen was always detected within the first five days of the hospital stay. We conclude that antigen detection in both representative and nonrepresentative sputum specimens at the time of hospital admission and during follow-up is of additional value for the diagnosis of pneumococcal pneumonia. It markedly increases the number of patients with pneumococcal pneumonia detected, who would otherwise be considered to have pneumonia of unknown cause. However, antigen-positive results should be interpreted carefully, especially in those pneumonia patients with chronic bronchitis, because detectable antigen may be caused by pneumococcal carriership of the lower respiratory tract.

Diagnosis of Pneumonia by Cultures, Bacterial and Viral Antigen Detection Tests, and Serology with Special Reference to Antibodies against Pneumococcal Antigens

In a prospective study of the etiology of pneumonia 196 adult patients were included. One of the following criteria was required for diagnosis of pneumococcal pneumonia: isolation of pneumococci from blood; isolation from transtracheal aspirate; isolation from sputum or nasopharynx or detection of capsular antigen in sputum in combination with a significant increase in antibodies against at least one pneumococcal antigen (type-specific capsular polysaccharide, C-polysaccharide, pneumolysin); or increase in antibodies against two pneumococcal antigens. Pneumococcal pneumonia was diagnosed in 63 patients (32%). Other diagnoses were nonencapsulated Haemophilus influenzae isolated from transtracheal aspirates, 9; Mycoplasma pneumoniae diagnosed by serology, 17; Chlamydia psittaci, 6; and viral infections, 42. Twenty-two patients (11%) had evidence of infection with more than one agent. The pathogen could not be determined in 70 (36%). Many patients were given antibiotics before admittance to the study, and in some cases a convalescent serum sample was not available.

Detection of Capsular Polysaccharide in Serum for the Diagnosis of Pneumococcal Pneumonia: Clinical and Experimental Evaluation

To improve diagnostic options for pneumococcal pneumonia, an ELISA system was developed that can detect less than or equal to 6 ng/ml capsular polysaccharide in serum. The test was limited to 39 serotypes causing greater than 95% of pneumococcal infections. In clinical evaluation the test identified 14 of 15 cases (missing one serotype not included). No false-positive reaction occurred. However, the duration and level of antigenemia were variable (greater than or equal to 500-2.5 ng/ml) and seemed not to depend solely on the severity of infection. Therefore, the question of whether the extent of antigenemia was determined by a serotype-dependent variation in the elimination rates of polysaccharides was investigated. Clearance rates for 12 serotypes varied in rabbits and rats by a factor of greater than 250. This remarkable variability appeared to affect the extent of clinical antigenemia. Thus, only very sensitive systems can detect circulating antigen from rapidly cleared polysaccharide serotypes. Furthermore, the question arises whether slow polysaccharide clearance contributes to the virulence of some pneumococcal serotypes.

Demonstration of pneumolysin antibodies in circulating immune complexes—a new diagnostic method for pneumococcal pneumonia

We isolated immune complexes (IC) from the sera obtained from 129 adult patients with community-acquired pneumonia and from 120 healthy controls and measured antibodies to pneumococcal pneumolysin in dissociated complexes. None of the healthy controls had demonstrable pneumolysin-specific IC in their sera irrespective of whether they had high or low serum antibody titers to pneumolysin. By contrast, 62 (48%) of pneumonia patients had pneumolysin-IC in one or more of serum specimens. All 11 patients with positive blood culture for pneumococcus and 86% of those in whom pneumococcal involvement was suggested by culture or antigen detection in sputum or who showed serum antibody response to pneumolysin had pneumolysin antibodies in circulating IC. In addition, pneumolysin-IC were detected in 17 patients without other evidence of pneumococcal infection. The lack of pneumolysin-IC in healthy controls and their presence in patients with pneumococcal pneumonia suggest that the demonstration pneumolysin-IC is a sensitive, reliable method for the diagnosis of pneumococcal pneumonia.

Pneumolysin, produced in Bacillus subtilis as antigen in enzyme immunoassay for etiological diagnosis of pneumococcal pneumonia

We have expressed the pneumolysin gene in Bacillus subtilis and produced pneumolysin in this strain (Bac-Ply). To compare the performance of the Bac-Ply preparation to the authentic pneumolysin isolated from Streptococcus pneumoniae (Pnc-Ply) we used both of them as antigens in EIA to measure antibodies in 53 single and 105 paired serum specimens of healthy adults and in 112 hospitalized elderly patients with pneumonia. In the healthy controls the antibody levels decreased with increasing age in both Pnc-Ply and Bac-Ply assays and the titer rise seen between the paired sera was greater than two-fold at most. The correlation of titers obtained with the two antigens was highly significant. Antibody response to Bac-Ply and Pnc-Ply were demonstrated in 24 (22%) and 25 (23%) of 112 pneumonia patients respectively. Among these patients six had Pnc positive blood culture and nine had pneumococcus in purulent sputum. Bac-Ply EIA compared to Pnc-Ply EIA showed a sensitivity of 91% ( 21 23 ) and a specificity 96% ( 106 110 ). We conclude that Pnc-Ply can be replaced by Bac-Ply as antigen in EIA to measure antibodies to pneumolysin.

Measurement of antibody responses to pneumolysin-A promising method for the presumptive aetiological diagnosis of pneumococcal pneumonia

An enzymeimmunoassay (EIA) for measuring antibodies to pneumococcal pneumolysin has been developed. The method was used to study the possible pneumococcal aetiology of pneumonia in 159 mostly elderly patients admitted to hospital because of a positive chest X-ray. The results obtained with the assay were compared to those obtained by other diagnostic methods, namely blood culture, detection of pneumococcal antigen in urine and demonstration of an antibody response to pneumococcal C-polysaccharide and capsular polysaccharides. Antibody response to pneumolysin was found in 32 of 39 (82%) patients with pneumococcal pneumonia aetiologically diagnosed presumptively by other methods. In addition, the EIA for pneumolysin antibodies was positive in 31 patients without evidence of pneumococcal aetiology by other methods. The clinical and laboratory investigations of these patients supported the presumption of bacterial infection. We conclude that the EIA we have developed for measuring pneumolysin antibodies is a promising, sensitive method for the presumptive aetiological diagnosis of pneumococcal pneumonia. The assay is simple to perform because only one antigen is needed and measurement of IgG antibodies alone seems to be enough for aetiological diagnosis.

Rapid detection of pneumococcal antigens in sputa in patients with community-acquired pneumonia by coagglutination

This paper introduces the clinical use of coagglutination as a method for the rapid detection of pneumococcal antigens in patients with community-acquired pneumonia and compares it with the sputum Gram stain and culture methods. Among 105 patients, 50 (48%) were diagnosed as having pneumococcal pneumonia by at least one of the three methods. Of 95 sputa tested, 44 (46%) were found to be positive by the coagulation test, 26 (27%) by Gram staining and only 16 (17%) by the bacterial culture method. The rate of detection of pneumococcal antigens was thus greater with coagulation than with either of the other two methods. The differences were very significant (both P less than 0.01). Our study indicates that the advantages of coagglutination over the traditional bacteriological methods are its speed, sensitivity, convenience and also its relative independence of antibiotic therapy. It thus provides a new dimension in the aetiological diagnosis of pneumococcal pneumonia.