Antibiotic-resistant germs repeatedly spread panic among hospital staff and patients – and frequently cost human lives. The problem is that today’s antibiotics are powerless against these germs, and available treatments are often ineffective. Researchers are therefore looking for new ways of combating the mutant bacteria and fungi.
Do your tonsils hurt whenever you swallow? Are you constantly running to the bathroom, and feel a burning sensation when urinating? To treat these and other inflammatory infections, doctors prescribe a course of broad-spectrum antibiotics and the patient soon feels well again. But there are an increasing number of cases of infection caused by resistant bacteria or fungi that cannot be treated with the usual broad-spectrum antibiotics. This is a particular problem in hospitals. Despite the best efforts by hospital staff to comply with strict rules of hygiene, new outbreaks of infection keep on reoccurring.
One villain is the Acinetobacter bacillus, which upon entering the patient’s body can trigger an infection and cause blood poisoning – this is a potentially life-threatening condition. And then there’s the infamous “hospital germ”, MRSA or methicillin-resistant Staphylococcus aureus. What makes these bacteria so hard to combat is that their resistance is highly variable. Doctors often have to make an educated guess when choosing a suitable antibiotic. Each case requires a new investigation to determine which resistant strain is present, and decide what can be done to eliminate it. For an infected patient, every minute counts. The vital question is: which resistances does the bacterium carry, and which of the many available antibiotics will help?
Tracking down resistances
A number of clinics are working together with the Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB in Stuttgart to track down resistant forms of pathogens. The number of resistances carried by bacteria is immense: some 60 to 80 different forms are known. Often, a single bacterium exhibits two or more resistances, hence the term “multi-resistant pathogens”. “By finding out which resistances a particular bacterium or fungus carries, we can enable doctors to target the treatment of infected patients by administering an antibiotic to which the pathogen is not resistant,” explains Prof. Dr. Steffen Rupp, department head and deputy director at the IGB.
Participating clinics send patient specimens containing resistant bacteria to the researchers at the IGB. The specimens are usually in the form of blood samples, but swabs and secretions are also possible. There are two causes of resistance. One is plasmids, i.e. DNA molecules that do not form part of the original genome and can replicate autonomously in bacterial or fungal cells. The other cause of drug resistance is mutations in the pathogen’s genome. The researchers therefore isolate the plasmids or bacterial DNA from the patient specimens, replicate this genetic material, and identify the sequence of individual building blocks. They then use a special software program to compare this sequence with a library of DNA sequences that code for known forms of drug resistance. In this way they can find out which resistance genes are present. It takes between one and four hours to complete the analysis. Then the doctor can be sure which antibiotic will help the patient.