In August 2016, doctors at a hospital were informed about an inpatient infected with a carbapenem-resistant Enterobacteriaceae (CRE) – specifically, Klebsiella pneumoniae, which was resistant to all available antibiotics. A local resident in her 70s, the woman had recently returned from an extended visit to India, where she had been hospitalised multiple times in relation to a femur fracture and subsequent osteomyelitis of her right femur and hip. The isolate sent for testing was resistant to 26 antibiotics. A point-prevalence survey conducted among patients admitted to the same unit as the patient did not identify additional CRE.

The case is an extreme example of a growing problem: the battle against bacteria resistant to currently available antibiotics. A successful campaign against this trend will require accurate bacterial identification and susceptibility testing, and appropriate infection control contact precautions to prevent transmission.

The microbiology laboratory is now at the forefront of this battle – a fact that Dr Emilia Cercenado of the Hospital General Universitario Gregorio Marañón in Madrid, Spain, knows all too well.

Accuracy matters

"Accurate information is crucial in the rapid diagnosis of infectious diseases," Cercenado explains. "The rapid detection of the etiologic agent and its resistance pattern is essential for the adequate treatment of the patients."

Cercenado runs a large clinical microbiology lab at of the Hospital General Universitario Gregorio Marañón, covering a large number of patients across the Spanish capital.

"We perform the microbiological diagnosis of infectious diseases – viral, bacterial, fungal, mycobacterial and parasitic – by culturing or detection of DNA using molecular techniques on clinical samples from hospitalised or ambulatory patients," she says. "We also perform serology. We have a laboratory dedicated specifically to the identification of bacteria and antimicrobial susceptibility testing."

Emerging antimicrobial resistance

Cercenado’s laboratory uses the Beckman Coulter MicroScan panels, with the MicroScan WalkAway plus instrument. MicroScan panels provide accurate results on contemporary isolates without reliance on historical resistance patterns and calculated minimum inhibitory concentrations.

The MicroScan system is effective at detecting frequently seen resistance patterns in Dr Cercenado’s laboratory like extended-spectrum beta-lactamases, hyperproducing AmpC beta-lactamases among different Enterobacteriaceae, CRE, multiresistant Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus. Use of the WalkAway system supports the high-volume testing necessary in a large laboratory.

This is doubly important as, in recent years, Cercenado and her colleagues have witnessed an increase in CRE, in addition to an increase in the detection of multiresistant Pseudomonas aeruginosa.

"We have few options for treating infections in patients with these microorganisms, so it is very important to detect and identify the organisms as early as possible; not only for the rapid treatment of the patients, but also to avoid the spread of these organisms," she explains.

All in all, the MicroScan system has proved highly beneficial in detecting resistance, says Cercenado.

"Compared with other systems, the MicroScan has the advantage of allowing the visual inspection of the panels, plus the large number of different panels provided, which are adapted to different types of laboratories," she says.