Community acquired pneumonia: aetiology and prognostic index evaluation

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

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

The role of new quinolones in the treatment of respiratory tract infections

Infections of the respiratory tract are the leading cause of antibacterial prescribing in both hospital and community practice. The microbial aetiology is diverse in both of these settings and differs in the distribution and virulence of the pathogens. Furthermore, in recent years the antibacterial susceptibility of many of the common pathogens has changed significantly. In particular, penicillin resistance has emerged among pneumococci, while beta-lactamase production among Haemophilus influenzae and many Gram-negative bacilli has led to alterations in first-line therapy options. The fluoroquinolone antibacterials have been used in selected respiratory tract infections, but concerns have remained with regard to their efficacy in infections caused by marginally susceptible organisms, and in particular pneumococcal infections. The availability of a number of quinolones with enhanced Gram-positive activity, which includes Streptococcus pneumoniae, is of considerable interest. In vitro data and preliminary clinical experience with sparfloxacin suggest that managing pneumococcal lung disease with this and future agents is a distinct possibility. One caveat must be considered, and that is the potential for more resistant strains of pneumococci emerging, against which even these new quinolones could prove less effective.

A criterion based audit of community-acquired pneumonia

We undertook a prospective audit of patients admitted to a specialist respiratory unit in order to assess: (a) the completeness of the objective assessment of severity of community-acquired pneumonia in patients on admission to hospital, and whether such indices were useful in predicting outcome; (b) the completeness of microbiological testing and whether maximizing the number of specimens sent to the laboratory would increase the frequency of positive microbiological diagnoses and; (c) the influence of the above on clinical management. Forty-eight patients with consolidation on chest X-ray were studied in two audit periods: 1 February 1991 to 1 May 1991 and 2 May 1991 to 16 March 1992. After the first audit period, a rubber stamp with a check list of microbiological investigations was used in the patients' notes. Seven 'markers of severity' of pneumonia, were recorded consistently throughout the study and these were useful in predicting outcome (P < 0.01). In the first audit period sputum culture, blood culture and acute serology were recorded in approximately 50% of patients. Following the introduction of the rubber stamp, the requesting of sputum, blood and urine antigen rose from none in the first audit period to 40-60%. The increase in the number of specimens obtained was not associated with an increase in the proportion of positive microbiological diagnoses. Clinical management was altered in 10 patients because of the microbiological reports and in four patients with negative microbiology (chi2 = 8.19; P < 0.01).

CONCLUSION

The standard of initial assessment was high in this specialist unit, and the presence of two or more 'markers of severity' did help predict outcome. A simple change in work practice resulted in a significant improvement in the thoroughness of microbiological investigations.(ABSTRACT TRUNCATED AT 250 WORDS)

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

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

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

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

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

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

Nocardia species: host-parasite relationships

The nocardiae are bacteria belonging to the aerobic actinomycetes. They are an important part of the normal soil microflora worldwide. The type species, Nocardia asteroides, and N. brasiliensis, N. farcinica, N. otitidiscaviarum, N. nova, and N. transvalensis cause a variety of diseases in both normal and immunocompromised humans and animals. The mechanisms of pathogenesis are complex, not fully understood, and include the capacity to evade or neutralize the myriad microbicidal activities of the host. The relative virulence of N. asteroides correlates with the ability to inhibit phagosome-lysosome fusion in phagocytes; to neutralize phagosomal acidification; to detoxify the microbicidal products of oxidative metabolism; to modify phagocyte function; to grow within phagocytic cells; and to attach to, penetrate, and grow within host cells. Both activated macrophages and immunologically specific T lymphocytes constitute the major mechanisms for host resistance to nocardial infection, whereas B lymphocytes and humoral immunity do not appear to be as important in protecting the host. Thus, the nocardiae are facultative intracellular pathogens that can persist within the host, probably in a cryptic form (L-form), for life. Silent invasion of brain cells by some Nocardia strains can induce neurodegeneration in experimental animals; however, the role of nocardiae in neurodegenerative diseases in humans needs to be investigated.

Nocardia species: host-parasite relationships

The nocardiae are bacteria belonging to the aerobic actinomycetes. They are an important part of the normal soil microflora worldwide. The type species, Nocardia asteroides, and N. brasiliensis, N. farcinica, N. otitidiscaviarum, N. nova, and N. transvalensis cause a variety of diseases in both normal and immunocompromised humans and animals. The mechanisms of pathogenesis are complex, not fully understood, and include the capacity to evade or neutralize the myriad microbicidal activities of the host. The relative virulence of N. asteroides correlates with the ability to inhibit phagosome-lysosome fusion in phagocytes; to neutralize phagosomal acidification; to detoxify the microbicidal products of oxidative metabolism; to modify phagocyte function; to grow within phagocytic cells; and to attach to, penetrate, and grow within host cells. Both activated macrophages and immunologically specific T lymphocytes constitute the major mechanisms for host resistance to nocardial infection, whereas B lymphocytes and humoral immunity do not appear to be as important in protecting the host. Thus, the nocardiae are facultative intracellular pathogens that can persist within the host, probably in a cryptic form (L-form), for life. Silent invasion of brain cells by some Nocardia strains can induce neurodegeneration in experimental animals; however, the role of nocardiae in neurodegenerative diseases in humans needs to be investigated.

Management of community acquired lower respiratory tract infection

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Re-evaluation of pneumonia requiring admission to an intensive care unit: a prospective study

BACKGROUND

Appropriate treatment of severe community and hospital acquired pneumonias requiring admission to a medical intensive care unit depends on knowledge of the likely aetiological agents in any community. Little is known about the pattern and outcome of patients with such pneumonias in Saudi Arabia.

METHODS

In a prospective study 113 patients with pneumonia were investigated in the medical intensive care unit at King Khalid University Hospital, Riyadh, Saudi Arabia between September 1991 and December 1992. The diagnosis was established by microscopy and culture of sputum, blood culture, or serological examination. A standard proforma was used to collect demographic, clinical, and laboratory data.

RESULTS

A microbiological diagnosis was made in 80% of the cases with a single pathogen accounting for 69% of the isolates and multiple pathogens for 11%. Pseudomonas aeruginosa was the most common infecting agent (16%), followed by Streptococcus pneumoniae (12%), Staphylococcus aureus (9%), and Mycobacterium tuberculosis (8%). Pneumonia due to Legionella pneumophilia was diagnosed in three patients and infection due to Mycoplasma pneumoniae in two. These five cases were identified by serological examination. Gram negative rods were the predominant pathogens in both community and hospital acquired pneumonia. The aetiology of pneumonia was not identified in 20% of cases. The overall mortality was 37%. Patients with hospital acquired pneumonia had a higher mortality than those with a community acquired pneumonia. Similarly, a high mortality was found in patients who had a serious underlying disease, abnormal mental state, diastolic blood pressure < 60 mm Hg, blood urea > 7 mmol/l, abnormal liver function tests, serum albumin < 30 g/l, those who required mechanical ventilatory support, and those with APACHE II scores > 20.

CONCLUSIONS

This study highlights two major findings which differ from previous reports on the aetiology of pneumonia. Firstly, Gram negative rods were the predominant pathogens in community acquired pneumonia and secondly, M tuberculosis was an important cause of pneumonia in these patients, indicating that tuberculous pneumonia should be considered in the differential diagnosis of pneumonia in Saudi Arabia.

Quality of published reports of the prognosis of community-acquired pneumonia

OBJECTIVE

To systematically assess the quality of published reports of the prognosis of community-acquired pneumonia using a formal quality assessment instrument.

DESIGN

Retrospective review of studies published during 1966-1991. ARTICLES: 108 articles related to the prognosis of community-acquired pneumonia retrieved by a computerized search.

INTERVENTION

All articles, blinded to author(s), journal title, year of publication, and study institution(s), were independently reviewed by two investigators using a ten-item quality assessment instrument designed to evaluate: 1) identification of the inception cohort (4 items), 2) description of referral patterns (1 item), 3) subject follow-up (2 items), and 4) statistical methods (3 items). Adherence to each of the ten individual quality items and an overall quality score were calculated for all articles and across three time periods.

MAIN RESULTS

Among all 108 articles that underwent quality assessment, 30 were published from 1966 to 1979, 61 from 1980 through 1989, and 17 from 1990 through 1991. The mean total quality score of all articles was 0.55 (range 0.22-0.90). There was a significant trend toward improvement in total quality scores over the three time periods (0.50 to 0.56 to 0.65; p < 0.001). However, several systematic errors in the study design or reporting of these studies were discovered throughout time: only 3.7% provided comparative information about nonenrolled patients, 28.7% determined whether the study institution was a referral center, 36.1% specified inclusion or exclusion criteria, and 45.5% used appropriate statistical analyses to adjust for more than one prognostic factor.

CONCLUSIONS

Despite improvement in overall quality of published articles, systematic errors exist in the design and reporting of studies related to the prognosis of community-acquired pneumonia. The quality assessment tool employed in this study could be used to guide the development of high-quality outcomes research in the future.

Factors of importance for the long term prognosis after hospital treated pneumonia

BACKGROUND

Elderly patients admitted to hospital for community acquired pneumonia have a high risk of recurrence of pneumonia and of death during the years after discharge. In this study potential factors of importance for the long term prognosis after hospital treated pneumonia were retrospectively investigated.

METHODS

A total of 241 patients (103 men) with a mean age of 60 (range 18-102) years discharged from hospital after treatment for community acquired pneumonia were studied. After an average follow up period of 31 months, 18 independent variables present during hospital treatment of the initial pneumonia were examined for association with the following end points: recurrence of pneumonia, death from any cause, and death from pneumonia.

RESULTS

Age adjusted analysis showed that systemic treatment with corticosteroids correlated significantly with recurrence of pneumonia and with death. The presence of low serum albumin levels on admission or colonisation of the respiratory tract with Gram negative enteric bacteria seemed to be important negative prognostic factors for the outcome during pneumonia recurrences after discharge.

CONCLUSIONS

Patients who are admitted to hospital with pneumonia are at risk of subsequent pneumonia and death after discharge. This risk seems to be even higher in patients who are treated with corticosteroids systemically, who have a low serum albumin level on admission, or who become colonised in the respiratory tract with Gram negative enteric bacteria during their hospital stay.

Treatment of Legionnaires' disease. Current recommendations

Legionnaires' disease is a relatively common cause of community-acquired pneumonia and of some outbreaks of hospital-acquired pneumonia. Moreover, Legionella pneumophila is frequently involved in the aetiology of the subset of pneumonias that is characterised by severe clinical course and high mortality. No sure clinical, radiographical or analytical features are useful in differentiating Legionella infection from other aetiologies of pneumonia. On the basis of these data, a rational initial therapeutic approach to community-acquired pneumonia, as well as to nosocomial pneumonia in certain circumstances, has to include an antimicrobial agent that is clinically effective against Legionella spp. Clinical studies have provided evidence that erythromycin is the first-line treatment. An intravenous dosage of 1g every 6 hours as initial therapy will be effective in most cases. Parenteral treatment may be switched to oral administration only after clinical response is observed. In vitro susceptibilities and preliminary experimental and clinical results suggest that clarithromycin will most likely become the preferred treatment once an intravenous preparation is available worldwide. However, orally administered clarithromycin at the dosage of 500 mg every 12 hours may be recommended in those developing countries in which health systems cannot afford the costs of intravenous therapy. In the case of clinically severe illness or in seriously immunosuppressed hosts with confirmed legionellosis, a combined therapeutic approach is warranted. Rifampicin 600 mg every 12 hours intravenously or orally has to be added to the usual dosage of erythromycin. Other alternative therapies, but with less distinct clinical efficacy, that can be combined with erythromycin are doxycycline 100 mg every 12 hours intravenously or orally, and intravenous ciprofloxacin 200 mg every 6 hours.

Pneumonia mortality reduction and quality improvement in a community hospital

Rather than explain adverse results on the basis of flawed data, a physician-directed quality improvement program was initiated to improve the delivery of care to patients admitted to Forbes Health System (Monroeville, Penn) with community-acquired pneumonia. Following the introduction of standardized physician orders and modification and elimination of inefficient processes of care, the mortality rate for this infection decreased from 10.2% to 6.8%. This initial exposure to the quality improvement process led to the participation of the medical staff in other related clinical and support service initiatives. In addition, Forbes and its clinical partners are now better positioned to respond to increasing government, managed care, and consumer inquiries relating to cost and quality outcomes. Finally, this positive experience facilitated the organization's transition from inspection-based quality assessment to quality improvement activities, which should assist in efforts to meet or exceed new accreditation standards.

Quinolones in the treatment of lower respiratory tract infections in adult patients

The potential role of quinolones is discussed on the basis of data obtained during the past 2 years from epidemiological studies, in vitro investigations, animal experiments and clinical trials. Although the newest compounds exhibit good activity against Streptococcus pneumoniae and intracellular pathogens in animal models, the role of quinolones as first line therapy in community-acquired pneumonia is still debatable and may be modified according to clinical presentation and the rate of resistance of pneumococci to beta-lactams and macrolides. Cost-utility and cost-benefit studies are required to delineate precisely the role of quinolones in the treatment of acute exacerbations of chronic bronchitis. In addition, promising results indicating a possible future for the clinical use of quinolones in the therapy of mycobacterial infections have been obtained.