SIEMENS

When Alexander Fleming discovered penicillin in 1928, he achieved a medical milestone. The antibiotic gave mankind its first effective weapon for combating bacterial pathogens. Unfortunately, this success did not last. By 1961, the first bacteria resistant to all active ingredients of the penicillin group appeared: methicillin-resistant Staphylococcus aureus (S. aureus), or MRSA for short.
Since then, MRSA has spread rapidly, particularly in hospitals. According to the U.S. Centers for Disease Control and Prevention, MRSA's share of total infections at intensive care units in the U.S. rose from 2 % in 1974 to 64 % in 2004. Of the estimated 292,000 infections caused yearly in hospitals by S. aureus, around 126,000 are due to MRSA, and 19,000 of these are fatal.
Because these bacteria multiply exponentially, effective antibiotics have to be administered as quickly as possible. If it is suspected that a patient is suffering from an infection, for example due to a deterioration of his or her overall condition, hospital staff take a sample, which is then analyzed in a diagnostics lab to determine which antibiotics would be most effective in combatting it, and in what concentration. Traditionally, microbiology labs run a series of biochemical identification procedures along with disk diffusion tests to determine a bacteria's antimicrobic susceptibility profile. These procedures are extremely personnel-intensive, however, which is why new, sometimes fully automatic, processes for identifying primary isolates and determining their antimicrobial susceptibility are so popular.
Siemens' MicroScan Systems combine such methodologies for isolate identification and antimicrobial susceptibility testing on one test panel. The MicroScan Systems use direct growth-based susceptibility testing that allows for the true expression of resistance. The test panels contain multiple "wells" for holding culture media, biochemicals, and antibiotics in various concentrations. Once the panels have been prepared with a previously isolated culture of the organism at a determined concentration, they are placed inside a MicroScan WalkAway instrument for processing. There, the bacterial isolate is incubated with identification substrates and other materials. The system's software interprets the measured bacterial concentrations and analyzes the test to detect any atypical or unknown reactions.
The results are then transferred to the physician to verify if the patient's current therapy is appropriate and, if not, to immediately administer effective antibiotics as determined by the test. "We offer a range of different microtiter plates, including several for use in the rapid identification of the isolate with key antimicrobial results in as little as four and one-half hours," reports Laura Jackson, Global Product Manager at MicroScan. "The susceptibility incubation period can be automatically extended to 16 hours when absolutely accurate resistance information is needed. In this case, the system offers the same degree of precision as manual tests. This degree of accuracy has been proved by direct comparisons of clinical isolates such as S. aureus."
Until 1997, doctors faced with cases of MRSA infection were able to fall back on vancomycin. However, in that year, the first strain of S. aureus with reduced susceptibility to this powerful antibiotic appeared in Tokyo. The MicroScan system is the first fully automatic system to be approved by the FDA that can identify this vancomycin-resistant S. aureus (VRSA).

Breaking Bacterial Resistance. To ensure that mutated pathogens like these can be quickly and reliably recognized and diagnosed, scientists at Siemens Corporate Research (SCR) in Princeton, New Jersey, are now focusing their research on new identification methods that target the bacteria's genetic material and proteins.
Gayle Wittenberg and her colleagues at SCR are working together with the Power and Sensor Systems department of Siemens Corporate Technology (CT) in Erlangen, Germany, to develop such a process. Unlike the MicroScan system, which directly uses a sample to determine what antibiotic concentrations are effective, the SCR approach relies on a rapid method for analyzing the genetic material. Once this has been done, researchers look for an effective antibiotic, using the genetic data stored in a computer. "The advantage of our approach is that we can not only develop rapid tests, providing results in one hour, but we have also developed a framework that will allow us to develop new diagnostic tests rapidly based on the genetic sequence of the pathogen," Wittenberg explains. The system is still in the development stage.
Wittenberg wants to conduct the rapid tests with lab-on-a-chip technology (Pictures of the Future, Fall 2004, Biosensors: http://www.siemens.com/innovation/en/publikationen/publications_pof/pof_fall_2004/sensors_articles/biosensors.htm). With this technology, a drop of saliva or blood, for example, is placed on a mobile examination plate equipped with a microscopic diagnostics lab. Here, the bacteria are automatically opened, and the genetic material is deciphered using the polymerase chain reaction (PCR) method. This method multiplies the DNA in vitro (outside of a living organism). Finally, the individual DNA building blocks are detected using a special biochip. To this end, the individual building blocks are marked with special molecules and measured on the basis of a voltage change. It will take at least another year until the first prototype becomes available.
Because its design will make it so easy to handle and operate, the lab-on-a-chip system is not intended for use in laboratories, but in treatment rooms themselves. The technology will allow doctors and nursing staff to take blood from a patient, analyze it, and receive a result from an associated computer within a few minutes — no external labs required. Besides being suitable for hospitals, the system is also a solution for applications in the food industry, where products have to be tested for microbial contamination. Thanks to the speed of the analysis and the mobile nature of the lab-on-a-chip, the system could also be used to regularly check sterile areas such as operating rooms — or even to provide early warning of epidemics, and defend against bio-terrorism.
Wittenberg and her team are already planning the next step, which will include identifying bacteria not on the basis of their genetic material alone, but also on their proteins. However, they still have to develop the marker molecules that will be needed for this process. Success here would allow faster and simpler identification of bacteria. "Focusing on proteins in addition to genes will help us identify biomarkers linked directly to the mechanisms of drug resistance. These should be less sensitive to the organism's ongoing evolution," explains Wittenberg.