Observations regarding historical accounts of pneumococcal diseases due to serotypes 1 and 3

Abstract

Observations regarding historical accounts of pneumococcal diseases due to serotypes 1 and 3 aBstract Surveillance of the serotypes causing invasive pneumococcal diseases in the UK has indicated increasing incidence of serotype 1-and serotype 3-related disease in recent years. The introduction of a pneumococcal conjugate vaccine to the paediatric vaccination schedule in 2006, which did not cover these serotypes, has been regarded as a contributing factor. Serotypes 1 and 3 were perhaps the most extensively studied pneumococcal serotypes in the early twentieth century when pneumococcal serotyping began. Such historical observations are pertinent to our understanding of contemporary disease manifestations for these serotypes as many parallels can be seen between their behaviour in the early twentieth century and the early twenty-first century. There are many relevant lessons to be learned from these pre-antibiotic era descriptions and the observations of our predecessors. 18,19 S. mucosus (renamed Pneumococcus mucosus) was described in 1917 as 'larger, rounder, and less lanceolate than other types of pneumococcus' and possessing 'a large distinct capsule '. 20 It grew on blood agar with colonies which were 'moist, mucoid, and confluent' and became known as the Type III pneumococcus. 20 This phenotypic description matches that which would be seen for contemporary serotype 3 isolates ( Figure 1). There is potential for misclassification when only the phenotypic appearances are used to classify serotype 3 as mucoid colonies can be observed in some other pneumococcal serotypes, albeit uncommonly. 21 It was not until 1934 that Type III could be distinguished serologically from phenotypically similar Type VIII. 22 So only after 1934 can it be concluded that the Type III pneumococcus is equivalent to the contemporary serotype 3 pneumococcus.In the absence of antibiotics and with growing success in the treatment of lobar pneumonia using type-specific horse or rabbit sera, 23 serotyping of disease-related isolates of pneumococci became important in order to use the correct antisera as therapy. Lobar pneumonia was a reportable illness and in the 1920s the prevalence of, and mortality associated with, the different serotypes of pneumococci responsible for lobar pneumonia and other invasive disease manifestations began to be documented in Britain. This continued throughout the 1930s.The discovery of sulphonamide and penicillin antibiotics (which no longer required a knowledge of serotype to determine appropriate treatment) resulted in a decline in interest in pneumococcal serotyping from the 1940s until the 1980s when it again became important to determine the composition of local pneumococcal populations as polysaccharide vaccines were being introduced. By this time (likely due to the success of its pharmacological treatment), lobar pneumonia was no longer a notifiable condition. Consequently serological surveillance switched to documenting instances of pneumococcal bacteraemia and meningitis to record IPD cases. This m...

What is Different About Serotype 1 Pneumococci?

“…Three studies have reported the relative incidence of serotype 1 disease over many decades (Boston City Hospital, USA [36], Danish national statistics [32], and more limited data from Glasgow, UK [37]). All demonstrated a marked reduction in the incidence of serotype 1 bacteremia around 1940-1955.…”

Serotype 1 pneumococcus: epidemiology, genomics, and disease mechanisms

“…Pneumococcal S1 was among the first serotypes discovered in the early 20 th century [13] and ranks among the most common serotypes associated with IPD globally -particularly in Sub-Saharan Africa (SSA), South America and Asia [14] -where it is widely associated with outbreaks (Table 1). Although bacteraemia, pneumonia, and meningitis are the main IPD caused by pneumococcal S1, it is also widely recovered in patients with empyema [15].…”