Lab-on-a-chip could speed up treatment of drug-resistant pneumonia

November 14, 2006

The emergency treatment of drug-resistant infections with targeted antibiotics is often delayed by the need to identify bacterial strains by growing them in culture first. At this week's AVS 53rd International Symposium & Exhibition in San Francisco, Michael Lochhead, a bioengineer at the Denver biotechnology company Accelr8, described a new lab-on-a-chip that can identify single bacterial cells for the most common cases of drug-resistant pneumonia, cutting down the wait from days to hours. The technology could also help in the development of new drugs.

The constant bombardment by antibiotics and disinfectants has bred strains of super-bugs that only respond to very specific drugs. These super-bugs often lurk in hospitals, where patients with weakened immune systems can pick up obstinate, life-threatening infections such as pneumonia. "When you get pneumonia in the hospital, you're much more likely to get a resistant strain," Lochhead said. "It's an emerging public-health disaster."

The most acute cases are admitted into intensive care units, where doctors have just days, if not hours, to save the patients' lives, Lochhead said. But reliably identifying the bacterial strain that's causing the infection traditionally requires growing the bugs in culture first, a procedure that can take two to three days. Meanwhile, doctors often have no other option than to start stopgap treatments with broad-spectrum antibiotics.

The Accelr8 technology is a "microfluidic" lab-on-a-chip designed to manipulate and analyze bacteria without growing them first. Samples are first washed out of the patient's lungs with saline solution in a procedure called bronchoalveolar lavage. The organisms are then separated, suspended in a specially designed fluid, and pumped into the chip.

Inside the chip, the bacteria flow into several different compartments -- eight in the current version of the chip -- and are made to stick to a bacteria-friendly surface using an electric current. Antibodies then flow in. The antibodies bind specifically to certain strains of bacteria, and mark them with fluorescent dyes of different colors. The dyes color-code cells from known strains. A microscope monitors the viable cells -- those that are still reproducing -- and the rate at which they duplicate helps to identify their species.

In the next step, different antibiotics are pumped into the chambers. If the cells in a chamber stop reproducing, that indicates that a certain drug is likely to be effective at fighting the infection. The death of the bugs is confirmed by checking with a special dye.

Once the bacteria-carrying fluid is injected into the chip, the entire procedure is automatic-- including the counting of fluorescent-marked cells, which is done by a computer -- and takes less than eight hours.

One of the most difficult steps was to design a surface that would be hospitable to the bacteria but that would at the same time keep the antibodies and antibiotics from sticking to it, Lochhead said. While Accelr8 is working on finding a "universal" material that will allow virtually all pathogenic bacteria to stick to it, the company has so far focused on nine bacterial species that cause most of the cases of drug-resistant pneumonia, including Staphylococcus aureus (staph), Pseudomonas aeruginosa, Klebsiella pneumoniae, and Escherichia coli (E. coli). "If we can characterize the nine panel organisms, we'll cover 80 to 90 percent of hospital-acquired pneumonia cases," Lochhead said.

The company also hopes to apply the technology not just to identifying known strains but also to testing the efficacy of new drugs, or of existing drugs on unknown strains. "Even if you don't know the identity of an organism, if you know which drug works, it's still useful," Lochhead says.

Accelr8, a former software company that refashioned itself into a biotechnology company, plans to place development instruments in collaborating clinical laboratories within a year.

Paper: "Microfluidic Devices That Capture Bacteria for Growth and Kill Analysis," Tuesday, November 14, 2006, 9:40am, Room 2001, AVS 53rd International Symposium & Exhibition, San Francisco, CA, abstract at www.avssymposium.org/paper.asp?abstractID=199

Source: American Institute of Physics

Related Stories

Recommended for you

Hibernating ground squirrels provide clues to new stroke treatments

November 17, 2017
In the fight against brain damage caused by stroke, researchers have turned to an unlikely source of inspiration: hibernating ground squirrels.

Age and gut bacteria contribute to multiple sclerosis disease progression

November 17, 2017
Researchers at Rutgers Robert Wood Johnson Medical School published a study suggesting that gut bacteria at young age can contribute to multiple sclerosis (MS) disease onset and progression.

Molecular guardian defends cells, organs against excess cholesterol

November 16, 2017
A team of researchers at the Harvard T. H. Chan School of Public Health has illuminated a critical player in cholesterol metabolism that acts as a molecular guardian in cells to help maintain cholesterol levels within a safe, ...

Prototype ear plug sensor could improve monitoring of vital signs

November 16, 2017
Scientists have developed a sensor that fits in the ear, with the aim of monitoring the heart, brain and lungs functions for health and fitness.

Ancient enzyme could boost power of liquid biopsies to detect and profile cancers

November 16, 2017
Scientists are developing a set of medical tests called liquid biopsies that can rapidly detect the presence of cancers, infectious diseases and other conditions from only a small blood sample. Researchers at The University ...

FDA to crack down on risky stem cell offerings

November 16, 2017
U.S. health authorities announced plans Thursday to crack down on doctors pushing stem cell procedures that pose the gravest risks to patients amid an effort to police a burgeoning medical field that previously has received ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.