Molecular Typing in Public Health Laboratories: From an Academic Indulgence to an Infection Control Imperative / 예방의학회지

Using three Austrian case studies, the variegated applications of molecular typing in today's public health laboratories are discussed to help illustrate preventive management strategies relying on DNA subtyping. DNA macrorestriction analysis by pulsed field gel electrophoresis has become the gold standard for subtyping of food borne pathogens like listeria, salmonella, campylobacter and Bacillus cereus. Using a Salmonella Mbandaka outbreak from the year 2010 as example, it is shown how the comparison of patterns from human isolates, food isolates, animal isolates and feed isolates can allow to identify and confirm a source of disease. An epidemiological connection between the simultaneous occurrence of tuberculosis in cattle and deer with cases of human tuberculosis due to Mycobacterium caprae in 2010 was excluded using mycobacterial interspersed repetitive units variable-number tandem repeats subtyping. Also in 2010, multilocus sequence typing with nonselective housekeeping genes, the so-called sequence based typing protocol, was used to elucidate connections between an environmental source (a hospital drinking water system) and a case of legionellosis. During the last decades, molecular typing has evolved to become a routine tool in the daily work of public health laboratories. The challenge is now no longer to simply type microorganisms, but to type them in a way that allows for data exchange between public health laboratories all over the world.

2010 Austrian Salmonella enteritidis PT4 outbreak associated with a laying hen holding previously involved in an S. enteritidisPT4 cluster: Pitfalls of regulatory responses in risk management

We report on an outbreak caused by Salmonella enteritidis phage type 4 [PT4] among 143 participants at a soccer camp in Austria in August 2010. The outbreak affected 34 persons, including 24 epidemiologically related cases and 10 laboratory-confirmed cases. Food-specific cohort analyses revealed spaetzle [homemade noodles] [relative risks [RR]: 2.68; 95% CI: 1.13-6.45], hamburger [RR: 2.70; 95% CI: 1.13-6.45] and potato salad [RR: 2.91; 95% CI: 1.69-5.02] as the most biologically plausible infection sources. Eggs used as ingredients were considered to be the vehicle of infection for the outbreak strain. The sole egg producer supplying the hotel that housed the soccer camp participants with table eggs operated two flocks. One flock had been epidemiologically and microbiologically related to a previous S. Enteritidis PT4 outbreak affecting the same Austrian province in the four months preceding the August outbreak. We hypothesize that eggs from this flock, already condemned for industrial use only, were falsely declared table eggs and sold among eggs from the non-banned flock causing the subsequent outbreak. In Austria, the illegal distribution of eggs designated for industrial use [i.e., false declaration of these eggs as table eggs] has been previously documented. Our findings underscore the potential of proper epidemiological outbreak investigation to identify the pitfalls of regulatory responses in risk management