Hemophilus species in the pharynx. Comparison of sampling sites

The prevalence of potential pathogenic bacteria in nasopharyngeal samples from individuals with a respiratory tract infection and a sore throat--implications for the diagnosis of pharyngotonsillitis

BACKGROUND

Treatment failure in patients with pharyngotonsillitis after a traditional course of penicillin V is a common finding. Several factors have been proposed to explain the failure rate, but the presence of aetiological agents other than group A beta-haemolytic streptococci has attracted little attention.

OBJECTIVES

The aim of the present study was to investigate if a nasopharyngeal sample could suggest the aetiology of a sore throat in patients with a respiratory tract infection.

METHODS

The prevalence of potentially pathogenic bacteria (Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis) in nasopharyngeal samples from 618 healthy individuals was compared with that from 108 patients with a respiratory tract infection and a sore throat.

RESULTS

The prevalence of H.influenzae was higher in patients with a sore throat than in healthy individuals of the same age. For the adult patients with a sore throat, the prevalence was 27.5% compared with 2.7% for the healthy carriers (P < 10(-7)). The corresponding figures for schoolchildren were 31.3% versus 6.1% (P = 0.004) and for pre-school children 37.8% versus 13.2% (P = 0.0003).

CONCLUSIONS

If H.influenzae is found in a nasopharyngeal sample from a patient with a respiratory tract infection and a sore throat, it might be the aetiological agent.

The prevalence of potentially pathogenic bacteria in nasopharyngeal samples from individuals with a long-standing cough-clinical value of a nasopharyngeal sample

BACKGROUND

A long-standing cough is a common cause for visits to a GP. If the patient also has a respiratory tract infection, one of the concerns of the doctor is to decide if the cough is caused by an underlying bacterial infection.

OBJECTIVES

Our aim was to investigate whether a nasopharyngeal sample, obtained in routine medical practice, could yield information about the aetiology of a long-standing cough in patients with a respiratory tract infection.

METHODS

The prevalence of potentially pathogenic bacteria (Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis) in nasopharyngeal swab samples from 618 healthy individuals was compared with that from 236 patients with a respiratory tract infection and long-standing cough (>9 days) of the same age in a defined geographical area.

RESULTS

The proportion of cultures with potentially pathogenic bacteria decreased with age and was 44% among healthy individuals of pre-school age, 13% in schoolchildren and 6% in adults. The corresponding figures for patients with a long-standing cough were 83, 35 and 36%, respectively. All types of potentially pathogenic bacteria were found more frequently in pre-school children and in adults with a long-standing cough compared with healthy individuals of the same age.

CONCLUSIONS

In patients with a respiratory tract infection and a long-standing cough, where a bacterial infection is suspected on clinical grounds, a nasopharyngeal culture could yield information about the aetiology. If M.catarrhalis is found in pre-school children, or if H.influenzae is found in adults, they are likely to be the aetiological agent.

The prevalence of potential pathogenic bacteria in nasopharyngeal samples from healthy children and adults

OBJECTIVE

To elucidate the prevalence of potential pathogenic bacteria in nasopharyngeal samples from healthy individuals, and the influence on the carrier rate of age, season of the year, and type of child day care.

DESIGN

Nasopharyngeal swab samples obtained in routine medical care from individuals with no sign of infection were studied in 159 pre-school children aged below 7 years, 198 schoolchildren aged 7-15 years, and 261 adults (.16 years).

RESULTS

The prevalence of pathogenic bacteria in healthy individuals decreased with age. The overall isolation frequencies for pre-schoolchildren, schoolchildren, and adults, respectively, were: Moraxella catarrhalis (27%, 4% and 2%); Streptococcus pneumoniae (19%, 6% and 0.8%); Haemophilus influenzae (13%, 6% and 3%). The prevalence of S. pneumoniae in children 7-15 years was higher during the summer than in the winter. We could not confirm any variation in the carrier rate due to the type of child day care.

CONCLUSION

Potentially pathogenic bacteria are often present in nasopharyngeal samples taken from healthy pre-school children, but rarely from people > or = 16 years of age. This means that the use of nasopharyngeal samples to discriminate between bacterial and viral respiratory tract infection needs to be evaluated further in patients < 16 years. The importance of the seasonal variation in the prevalence of potential pathogenic bacteria in the nasopharynx needs further study.