The etiology of community-acquired pneumonia in Australia: why penicillin plus doxycycline or a macrolide is the most appropriate therapy

Therapy for pneumococcal bacteremia: monotherapy or combination therapy?

PURPOSE OF REVIEW

The issue of whether the outcome of bacteremic pneumococcal infections is improved with the use of combination antibiotic therapy versus monotherapy is still not resolved. This review highlights recent studies that have addressed this issue.

RECENT FINDINGS

Some studies have indicated benefit of combination antibiotic therapy in severely ill patients with community-acquired pneumonia of all-cause. Conversely, in less severely ill hospitalized patients, fluoroquinolone monotherapy was as effective as fluoroquinolone combination regimens and a propensity analysis failed to show benefit of beta-lactam/macrolide combination over beta-lactam monotherapy. Studies across the world have shown a more favorable outcome in patients with community-acquired pneumonia treated with guideline-compliant therapy, mostly beta-lactam/macrolide combination regimens. The only recent study of patients with bacteremic pneumococcal pneumonia failed, however, to show benefit of combination therapy. A large number of investigations have yielded observations that address possible mechanisms by which combination therapy may have benefit, investigating issues such as cover for atypical pathogens, attenuation of pneumococcal virulence factors, and anti-inflammatory activity of the macrolide group of antibiotics.

SUMMARY

Despite a number of recent studies, the definitive decision regarding the need for combination antibiotic therapy for the effective management of bacteremic pneumococcal infections has not yet been formally resolved.

Respiratory infections unique to Asia

Asia is a highly heterogeneous region with vastly different cultures, social constitutions and populations affected by a wide spectrum of respiratory diseases caused by tropical pathogens. Asian patients with community‐acquired pneumonia differ from their Western counterparts in microbiological aetiology, in particular the prominence of Gram‐negative organisms, Mycobacterium tuberculosis, Burkholderia pseudomallei and Staphylococcus aureus. In addition, the differences in socioeconomic and health‐care infrastructures limit the usefulness of Western management guidelines for pneumonia in Asia. The importance of emerging infectious diseases such as severe acute respiratory syndrome and avian influenza infection remain as close concerns for practising respirologists in Asia. Specific infections such as melioidosis, dengue haemorrhagic fever, scrub typhus, leptospirosis, salmonellosis, penicilliosis marneffei, malaria, amoebiasis, paragonimiasis, strongyloidiasis, gnathostomiasis, trinchinellosis, schistosomiasis and echinococcosis occur commonly in Asia and manifest with a prominent respiratory component. Pulmonary eosinophilia, endemic in parts of Asia, could occur with a wide range of tropical infections. Tropical eosinophilia is believed to be a hyper‐sensitivity reaction to degenerating microfilariae trapped in the lungs.

This article attempts to address the key respiratory issues in these respiratory infections unique to Asia and highlight the important diagnostic and management issues faced by practising respirologists.

Delayed administration of antibiotics and mortality in patients with community-acquired pneumonia

STUDY OBJECTIVE

Previous studies have demonstrated a crude association between the time to first antibiotic dose and mortality in patients with community-acquired pneumonia. We hypothesize that time to first antibiotic dose may affect mortality, particularly for patients at high risk of death, that is, patients hypoxic on presentation, patients in Pneumonia Severity Index class IV or V, and patients older than 65 years at our institution.

METHODS

We reviewed data from a prospectively collected database of patients with community-acquired pneumonia, excluding patients who had received antibiotics before presentation and palliative patients not receiving antibiotics. We examined time to first antibiotic dose in patients who died or had prolonged length of stay (all patients) and in specific subgroups regarded as high risk (age >65 years, Pneumonia Severity Index class IV or V, presence of hypoxia or hypotension).

RESULTS

In 501 patients, the median time to first antibiotic dose was 2.7 hours, with 91% of patients receiving antibiotics within 8 hours. Time to first antibiotic dose was not positively associated with mortality or prolonged length of stay in any of the subgroups examined. We found evidence that patients with severe pneumonia received antibiotics earlier than other patients.

CONCLUSION

Most patients at this institution already receive timely antibiotic therapy. This finding may be due to either a true lack of association, in that minor delays in antibiotic administration, where antibiotics are generally administered within 8 hours, do not affect mortality. Additionally, there may be confounding by severity, such that patients at highest risk of death received antibiotics earlier.

SMART-COP: a tool for predicting the need for intensive respiratory or vasopressor support in community-acquired pneumonia

BACKGROUND

Existing severity assessment tools, such as the pneumonia severity index (PSI) and CURB-65 (tool based on confusion, urea level, respiratory rate, blood pressure, and age >or=65 years), predict 30-day mortality in community-acquired pneumonia (CAP) and have limited ability to predict which patients will require intensive respiratory or vasopressor support (IRVS).

METHODS

The Australian CAP Study (ACAPS) was a prospective study of 882 episodes in which each patient had a detailed assessment of severity features, etiology, and treatment outcomes. Multivariate logistic regression was performed to identify features at initial assessment that were associated with receipt of IRVS. These results were converted into a simple points-based severity tool that was validated in 5 external databases, totaling 7464 patients.

RESULTS

In ACAPS, 10.3% of patients received IRVS, and the 30-day mortality rate was 5.7%. The features statistically significantly associated with receipt of IRVS were low systolic blood pressure (2 points), multilobar chest radiography involvement (1 point), low albumin level (1 point), high respiratory rate (1 point), tachycardia (1 point), confusion (1 point), poor oxygenation (2 points), and low arterial pH (2 points): SMART-COP. A SMART-COP score of >or=3 points identified 92% of patients who received IRVS, including 84% of patients who did not need immediate admission to the intensive care unit. Accuracy was also high in the 5 validation databases. Sensitivities of PSI and CURB-65 for identifying the need for IRVS were 74% and 39%, respectively.

CONCLUSIONS

SMART-COP is a simple, practical clinical tool for accurately predicting the need for IRVS that is likely to assist clinicians in determining CAP severity.