Community-acquired bacteraemic pneumococcal pneumonia in adults: effect of diminished penicillin susceptibility on clinical outcome

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Abstract

Pneumococcal pneumonia remains a common disease with a high mortality rate. Between 1995 and 2000, we prospectively analyzed 95 consecutive adult cases of community-acquired bacteraemic pneumococcal pneumonia treated in a single centre. The incidence of pneumococcal resistance to penicillin increased from 19 to 50% during the study period. Multivariate analysis showed that only age and recent hospitalization were independently associated with fatal outcome. The proportion of penicillin-resistant strains was slightly but not significantly higher among patients who died before the fourth hospital day than among those who died later. Patients who died before D4 were more likely to have a recent history of hospitalization, cancer and/or chemotherapy. It thus appears that infection by a resistant pneumococcal strain is not in itself a gravity factor in this setting, but that their acquisition is associated with pejorative clinical features.

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Background

Pneumococcal pneumonia remains a common infection, with a yearly frequency of 1–2 cases per 1000 inhabitants overall, and up to 10 cases per 1000 elderly subjects. Mortality reaches 10–15% among hospitalized patients and 20% in patients over 65 years.1 Reported mortality rates range from two to 30% among hospitalized patients with pneumococcal pneumonia.2 Streptococcus pneumoniae has rapidly developed resistance to penicillin in recent years. First isolated in Australia and New-Guinea in the

Patients and methods

The study took place at Amiens University Hospital (France). From January 1995 to December 2000, cases of S. pneumoniae-positive blood culture were prospectively recorded. S. pneumoniae was identified by standard laboratory techniques and screened for penicillin resistance by the oxacillin disk diffusion method (5 μg/disk). If the oxacillin inhibition zone diameter exceeded 25 mm, the isolate was also tested for susceptibility to erythromycin, doxycycline, pristinamycin, cotrimoxazole and

Patient characteristics

From January 1995 to December 2000, 95 adults with community-acquired pneumonia and S. pneumoniae blood culture-positivity were enrolled in the study. Their baseline characteristic are shown in Table 1. Three-quarters of patients were older than 65 years. Thirty-two patients (34%) had recently spent time in hospital (<6 months previously) and 15% lived in institutions. Thirty-one patients (33%) had a recent history of one or more respiratory disorders. One-quarter of patients had underlying

Discussion

In this study of 95 consecutive cases of community-acquired bacteraemic pneumococcal pneumonia treated in a single centre over a 6-year period, no link was found between mortality and penicillin resistance in vitro. Penicillin resistance was associated with resistance to other antibiotics, implying that S. pneumoniae must now therefore considered as a true multidrug-resistant organism, in the same way as Staphylococcus aureus.

Our results are in keeping with many previous studies of adult

Conclusion

This prospective single-centre study showed no correlation between PRSP pneumonia and fatal outcome. Penicillin resistance increased neither the duration nor the cost of hospitalization. An increasing prevalence of macrolide resistance was also found, suggesting that these drugs should be used with care when pneumococcal infection is suspected. During the 6-year study period, mortality due to pneumococcal pneumonia remained at high, stable level. This frequent community-acquired infection is a

Acknowledgements

We are indebted to Willy Rozenbaum, Gilles Pialoux and David Young for their critical review of this manuscript. The experiments comply with the current laws of the country in which they were performed.

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