The use of the above-described 10 descriptors to characterize surveillance systems may be illustrated by attempting to apply each of them to two existing large surveillance programs, those supported by the PAHO in the Western Hemisphere and the EARSS program in Europe, which is now becoming the European Antimicrobial Surveillance Network (EARS-Net) at the European Center for Disease Prevention and Control (ECDC).
Both systems are publicly supported, by the PAHO and the European Union.
The laboratory type providing the data for both programs is patient care laboratories.
Report inclusion differs. The EARSS files isolates of seven bacterial species (S. pneumoniae
, S. aureus
, E. coli
, Enterococcus faecium
, Enterococcus faecalis
, K. pneumoniae
, and Pseudomonas aeruginosa
) only from blood and cerebrospinal fluid (CSF) cultures from survey laboratories in each of its participating countries (1
). PAHO surveillance more comprehensively files all bacterial isolates tested for resistance from all specimen types from its participating laboratories.
Microbial typing to discriminate phenotypes includes the serotyping of enteric pathogens in the PAHO program (104
). Both programs use resistance phenotypes to summarize the prevalence of resistance to antimicrobials in the types of microbes which they survey but not routinely to detect occasional unusual strains. Some EARSS investigators now use molecular spa
typing to trace MRSA clones (113
Levels of surveillance include local, national, and regional surveillance for each program. The more comprehensive surveillance of all bacteria tested for resistance from all specimens tested in the laboratories of the PAHO program, however, makes more data available for local hospital or multicenter infection control programs than does the more selective filing of only blood and cerebrospinal fluid isolates of seven microbial species by the EARSS program.
Levels of surveillance analysis differ in that each country in the PAHO program now analyzes its own data, and the PAHO collates their summaries centrally, while the EARSS analyzes files for all isolates both nationally and centrally for the whole program (1
). Both programs post their results on websites.
The types of analyses appear to be similar in that each analysis appears to use mostly the %RIS to overview the prevalence of resistance of each tested species to each tested antimicrobial to make comparisons between countries and over time.
The integration of analyses differs by the above-noted accomplishment of the EARSS in correlating the prevalence of antimicrobial resistance in participating countries with national data on antimicrobial usage by patients in the same countries to show a correlation between the two that appears to have then influenced usage widely in the region (75
Automation of analyses seems not to be used much by either program, nor does either program now approach real-time data management. Country data are required quarterly by the EARSS and yearly by the PAHO, which would allow multinational infection control and surveillance to be only retrospective now. Those PAHO-participating centers that do now file all their resistance test results by computer daily or nearly daily can now use those files for real-time local infection control and could utilize automation for it. The limited subset (seven species from blood and CSF specimens only) of its isolates that participating centers report to the EARSS program for its multicountry-level surveillance, however, omits the majority of the isolates that their local infection control programs would need to monitor.
Participation has grown steadily in both programs over the approximate decade of their existence, to a recent total of more than 300 centers in the PAHO program and 1,578 centers in the EARSS, due to the continuing efforts of both program managers and medical center participants. Each program, however, still surveys only a minority of the laboratories in its participating countries.
Summary of PAHO and EARSS Program Comparisons
The comparisons between these two multinational surveillance programs show differences for a number of the listed descriptors. For report inclusion, for example, the PAHO files isolates of all species and specimen types, while the EARSS files only blood and CSF isolates of seven species. For levels of surveillance analysis the EARSS analyzes isolate-level data in country and centrally, while the PAHO collates centrally only summaries of country-level analyses. These differences may reflect differences in original intent. The EARSS may have sought more to overview variances and their causes among national levels of antimicrobial resistance, and the PAHO may have sought more to support its local management.
These differences, however, are mostly in the completeness of descriptor categories. As programs become more complete for a descriptor, e.g., by the EARSS including more of each laboratory's reports and the PAHO analyzing isolate-level data centrally, as are likely, they become more capable and similar. Such growing comparability would empower them to collaborate, benchmark trends and details across their regions, and more fully exemplify the potential of global microbial surveillance.