Invasive pneumococcal infection in South and West England

Abstract

Variation in the incidence of invasive pneumococcal disease across South and West England, in 1995, was measured through a survey of microbiology laboratories. A 100% response rate was achieved. The incidence by laboratory varied between 5.2 and 20.4 per 100,000 catchment population (P < 0.001). Adjusting for pneumococcal vaccine uptake rate in over 65 year olds, hospital admission rates, blood culture system used and for the age and sex structure of the population, did not account for this variation. When blood culture sampling rates were included in a logistic regression model, the variation between laboratories was much less and of lower statistical significance (P = 0.019). Higher rates of blood culture sampling were associated with a higher incidence of invasive pneumococcal disease. Consistently high sampling should be encouraged because a higher diagnostic rate should result in more selective prescribing of antibiotics, and secondly because improved ascertainment of severe pneumococcal infections is a prerequisite for the evaluation of new pneumococcal conjugate vaccines.

Trends in incidence of pneumococcal disease before introduction of conjugate vaccine: South West England, 1996–2005

“…Although the incidence of IPD increased significantly over the study period, this could be explained by an increase in the rate of blood culture sampling. Similarly, higher rates of blood culture sampling were associated with higher incidence by laboratory catchment population, consistent with findings of Smith et al [17]. The rate of blood culture sampling should therefore be taken into account in any evaluation of the impact of vaccination programmes.…”

Invasive Pneumococcal Infections in Denmark from 1995 to 1999: Epidemiology, Serotypes, and Resistance

“…The reason for the increase of the percentage of CSF isolates during the period from 1996 to 1999 may be at least partially explained by the fact that type 1 was more frequently found in blood than in CSF, and the marked decline in the frequency of type 1 since 1996 is therefore most evident among the blood isolates. Whether the rising number of invasive cases of pneumococcal infection in the 1990s that has been observed in a number of countries, including Denmark, is due to better and more frequently used blood culturing systems has been discussed previously (24,26). Whether the introduction of new automatic blood culturing systems in the late 1990s, some of which we found to disfavor the detection of pneumococci, could explain this observed decrease has also been considered.…”

“…In several countries, there was an increase in the incidence of invasive pneumococcal infection in the late 1990s (5; J. Giesecke and H. Fredlund, Letter, Lancet 349:699, 1997 [Erratum, 349:1106]) and, in some countries, a few types were dominant among the invasive strains (4,10,20). It has previously been discussed whether there was a real increase in the number of invasive cases or whether it was just the result of more sensitive and more frequently used blood culture systems (24,26). In recent years there has been an increase in the frequency of pneumococcal isolates with reduced sensitivity to various antibiotics in many countries, and this is of major concern.…”

Rapid Diagnosis of Bacteremic Pneumococcal Infections in Adults by Using the Binax NOW Streptococcus pneumoniae Urinary Antigen Test: a Prospective, Controlled Clinical Evaluation

“…The sensitivity of blood culture is severely limited by prior administration of antibiotics. Apparent geographical variation in the incidence of invasive infection can be explained in part by variations in blood culture sampling rates (17) and possibly also by hospital referral patterns. These factors undermine studies of vaccine efficacy at a time when new pneumococcal conjugate vaccines are being introduced.…”