Detection of drug resistant bacteria

Antibiotic resistance is a growing problem in hospitals, and the phenomenon is already responsible for increased disease burden globally. Both the importance and urgency of this issue have recently been pointed out by a report of the World Health Organization (published on April 30th 2015), stating that "...this serious threat is no longer a prediction for the future, it is happening right now in every region of the world...without urgent, coordinated action by many stakeholders, the world is headed for a post-antibiotic era, in which common infections and minor injuries which have been treatable for decades can once again kill".

Extended Spectrum Beta-lactamases (ESBLs) have emerged as the fundamental mechanism of resistance in Gram-negative bacteria. Delay in appropriate therapy for infections with ESBL producers not only prolongs hospital stay,  but is also associated with increased mortality. The key to preventing/controlling the spread of infection by ESBLs is to ensure an effective method to identify infected individuals so as to limit transmission from the infected individuals/carriers.

The available strategies for resistance detection present various difficulties:

- they are generally expensive and thus used  to  test pre-screened infected individuals rather than to perform mass-screenings upon admission to hospital;

- it takes 24 hours to acquire a resistance profile, since 12-24 hours are required for the growth of pure bacteria cultures obtained from patients;

- expert personnel is needed;

- delay in releasing an antibiogram report causes high patient risk and high costs for prolonged hospitalization, negative social impact, and high economic burden.

Therefore, rapid detection of bacterial resistance in order to prescribe appropriate antibiotic therapy is urgently needed.

The 'Multianalyte automatic system for the detection of drug resistant bacteria-OPTObacteria' project ( aims to develop an automatic laboratory detector (ALD) device that can provide a drug-resistance report in a shorter time compared with standard methods from patient sample collection. This will be achieved by using recently developed fibre-optic technology.

The ALD is based on a new technology (optoelectronic device) in which the appropriate ligand–probe is anchored onto an optoelectronic surface and which specifically recognizes (and bind or fish out) proteins and biomolecules that are biomarkers of the resistant infections.

To this aim, project members have focused on 5 beta-lactamases most relevant for severity and social impact i.e. CTX-M-15, KPC-2, VIM-1, NDM-1, AmpC, OXA-24, belonging to class A, B , C and D, and whose presence in clinical samples is a common indicator of antibiotic resistance. Then, reflection-type nano-scale fibre-optic label-free biosensors, able to detect at least two of the selected beta-lactamases in small concentrations within a short time from sample reception, have been designed and developed. Prototypes of the transducer have been produced and successfully tested.