Drug-resistant strains of pneumonia-causing bacteria are becoming
increasingly prevalent and dangerous among the elderly, new research
In a study of 590 adult patients who became infected with pneumococcal
bacteria between January 1991 and April 1994, researchers in Columbus,
Ohio, found that more than half the cases occurred in patients
age 65 or over.
Furthermore, they found that penicillin-resistant pneumococcal
bacteremia doubled among elderly patients over the course of the
study. Cases increased from 5.3 per 100,000 people in 1991 to
10.6 per 100,000 in 1993.
"The incidence of bacteremia cases resistant to penicillin
in the elderly patients increased to where it exceeded the total
incidence of pneumococcal bacteremia in the younger patients,"
said Dr. Joseph F. Plouffe, professor of internal medicine at
Ohio State University and lead author of the study.
"The findings of this study suggest that physicians who treat
the elderly will have to consider drug resistance when deciding
about treatment options. Increased use of pneumococcal vaccines
and recognition of antimicrobial resistance patterns may help
physicians in treating patients with pneumococcal bacteremia."
Plouffe conducted this research with Drs. Robert F. Breiman and
Richard R. Facklam, both from the Centers for Disease Control
and Prevention (CDC). The group's work appeared in the January
16, 1996, special issue of the Journal of the American Medical
Association on global and emerging microbial threats.
For their study, Plouffe and his colleagues identified 590 patients
who were treated for pneumococcal bacteremia at 10 hospitals in
Franklin County, Ohio, between January 1991 and April 1994. For
each patient, the researchers identified the particular strain
of Streptococcus pneumoniae causing the infection, as well
as its susceptibility to antimicrobial drugs. To determine patient
age, gender, and outcome, researchers reviewed the microbiology
logs and patient charts at each hospital.
The study had the following results:
Patients age 65 or over were almost nine times more likely to
suffer from bacteremia as were younger patients. Patients who
were HIV-positive were 42 times more likely than other adults
to develop the condition.
Nearly one-fifth (19%) of the patients in the study died as a
result of bacteremia. The death rate was 11% among patients under
65 years of age, 22% among patients age 65 to 84, and 38% among
patients age 85 and over. "Bacteremia with S pneumoniae
continues to be a severe disease with a significant mortality
rate," said Plouffe.
The specific pneumococcal bacteria strains causing patients' bacteremia
remained relatively unchanged over time. However, several of these
bacterial strains became resistant to antimicrobial drugs over
the course of the study. Specifically, penicillin, ceftazidime,
and trimethoprim-sulfamethozazole appeared to lose some of their
More Vigorous Pneumococcal Vaccine Campaigns Warranted
The bacterial strains identified as penicillin-resistant belonged
to eight general categories or serotypes. These bacterial serotypes
are all included in the currently available pneumococcal vaccine,
Plouffe said. Unfortunately, he said, studies in Franklin County
suggest that fewer than one-fifth (19%) of people at risk for
pneumococcal infection have been immunized against it.
"We believe that more vigorous pneumococcal vaccine campaigns
should be mounted," Plouffe said. "'Administrators of
managed health care plans could be valuable allies by adding pneumococcal
vaccination to routine preventive health strategy."
The hospital stays of patients with penicillin-resistant pneumococcal
infections were, on average, 3.7 days longer than those of patients
whose infections responded to penicillin.
"At current hospital charges of at least $1,000 per day,
it's clear that significant additional expenditures of health
care resources are required to treat bacteremic patients with
these infections," Plouffe said.
Plouffe said the study's findings underscore the need for restraint
in prescribing and using antibiotics. "Excessive antibiotic
use appears to be the driving force behind the spread of drug-resistant
pneumococcal bacteria in communities," he said. "National
educational programs must be aimed at patients and their physicians
to reduce the demand and use of unnecessary antibiotics. Such
efforts may be particularly valuable in communities that have
not yet experienced a dramatic rise in drug-resistant pneumococcal
"Physicians face new challenges with pneumococcal disease,"
he said. "Increased use of pneumococcal vaccine and knowledge
of antimicrobial susceptibility patterns of the pneumococcal bacteria
present in their communities will assist physicians in better
caring for their patients."