Invasive Serotype Research Articles

Pneumococcal Vaccine Trials in Papua New Guinea: Relationships Between Epidemiology of Pneumococcal Infection and Efficacy of Vaccine

Field trials in Papua New Guinea have shown that pneumococcal capsular polysaccharide vaccine protects children less than 2 years of age from death due to acute lower respiratory infections (ALRI). The vaccine appears to reduce mortality by preventing bacteremia. Evidence suggests that highly invasive "adult" pneumococcal serotypes are comparatively more important as a cause of ALRI in developing countries where ALRI-related mortality is higher than in North America. Capsular polysaccharide vaccines are more likely to be immunogenic for these serotypes than for the "pediatric" serotypes. The evaluation of pneumococcal vaccines in areas where mortality is high should have the highest priority. For such trials investigators should, at minimum, define epidemiologic circumstances in terms of (1) the invasive serotypes of pneumococci, (2) the protective levels of antibody, (3) the antibody response to vaccination, and (4) the general immune status of the population.

Septicemic Colibacillosis and Failure of Passive Transfer of Colostral Immunoglobulin in Calves

Septicemic colibacillosis is a highly fatal disease that occurs in calves less than 2 weeks of age. The disease occurs when a calf that fails to absorb protective levels of immunoglobulin from colostrum is exposed to an invasive serotype of E. coli. Management to ensure good passive transfer of colostral immunoglobulin will prevent this disease and reduce calf mortality caused by other infectious diseases as well.

Association between raw milk and human Salmonella dublin infection.

Between 1971 and 1975 the mean annual incidence of human Salmonella dublin infection in California increased more than five-fold. Investigation of the increase showed an association with exposure to raw milk in 44 out of 113 cases. Of these 44 patients, 35 had used certified raw milk from a single dairy. Faecal swabs confirmed S dublin infection in the dairy herd and the milk, and so a pasteurisation order was issued. S dublin appears to be an unusually invasive and life-threatening salmonella serotype: 65% of isolations were obtained from non-faecal specimens (mainly blood cultures), 89 patients (80%) were admitted to hospital and 22 patients died. Almost three-quarters of the patients were aged 20 or over, and half had serious underlying diseases, particularly leukaemias and lymphomas. Five patients presented with infected vascular lesions that included aneurysms with abscesses and infections of previous arterial graft sites. The public's increasing desire for a "health food" such as raw milk should be tempered with an appreciation of its attendant risk to health.

PNEUMONIA IN NEW GUINEA: II. PNEUMOCOCCAL SEROTYPES AND THE POSSIBLE UTILITY OF POLYVALENT VACCINES OF CAPSULAR POLYSACCHARIDES

Isolates of Pneumococcus obtained from sputum samples and blood cultures of 276 adult patients suffering from pneumonia were typed by the Quellung reaction using the 46 Danish antisera of Lund. All isolates were typable. Types 1, 3, 5, 7, 8, 19 and 46 accounted for 57% of 244 sputum isolates and 68% of 50 blood culture isolates. Type 1 bacteremia was present in five of the six patients who died. The serotypes obtained fom patients with multisegmental and unisegmental pneumonia tended to differ from those isolated from patients with bronchopneumonia and those who had clinical signs suggesting alveolar infection, but from whom a clear chest X-ray film was obtained. Available evidence suggests that the number of highly invasive pneumococcal serotypes Is quite small, and that vaccination of high-risk populations with capsular antigens of these serotypes may offer an important preventive approach.

Experimental Production of LethalEscherichia coliBacteremia of Pelvic Origin

To reproduce the syndrome of overwhelming Escherichia coli bacteremia and shock after pelvic instrumentation, a model was developed by feeding E. coli via drinking water to coliform-free rabbits, injecting nitrogen mustard intravenously, and inserting a temperature probe into the rectum. The temperature probe was inserted to mimic pelvic instrumentation of patients and to detect fever. Rabbits fed invasive serotypes of E. coli all suffered overwhelming bacteremia with high fever and fatal vascular collapse secondary to invasion of pelvic veins as the granulocyte count approached zero. In the absence of granulocytopenia, the rectal temperature probe produced an intensive inflammation with numerous polymorphonuclears and bacteremia did not develop. In the absence of rectal probing, granulocytopenic rabbits developed high fever without bacteremia. This model resembles human bacteremic shock with respect to the endogenous source of the bacteria, the high frequency of bacteremia due to E. coli and other enteric bacilli, the importance of pelvic instrumentation, and the associated immune disturbances such as granulocytopenia.