DOME home
Search Dome
A publication for all the members of the Johns Hopkins Medicine family Volume information

National Medical Laboratory Week: April 24–30


A Culture All Its Own
The Micro Lab works behind the scenes to banish bugs and keep patients safe

The detective work of Lisa Maragakis, left, and Karen Carroll led to the banishment of a drug-resistant organism.
In September 2003, staff in the Medical Microbiology Laboratory detected a particularly resistant strain of a common bacteria in samples taken from five patients. Oddly, these patients all had different primary diagnoses, and they were located in various units throughout the hospital. How could each have become infected with the same unusual organism? It was a mystery that needed to be solved, and quickly, too. For if this hardy organism were to become established in the hospital, it would be extremely difficult to eradicate.

Few places play more of a central role in keeping patients safe from harm than the Medical Microbiology Laboratory at Hopkins Hospital. Here, invisible to most, amid a warren of labs in the basement of Meyer, staff work round the clock to provide results on 460,000 patient specimens a year, including samples from JH Bayview and Howard County General Hospital. The Micro Lab develops, conducts and interprets tests for patients with viral, bacterial, fungal and parasitic infections as well as for those prone to infections, such as cancer and AIDS patients.

Medical Microbiology, a division of the Department of Pathology, consists of seven subsections, among them a virology laboratory, which detects and identifies viruses like influenza and plays a key role in understanding each flu season, and a bacteriology laboratory, which grows and identifies bacteria and tests them for resistance to antibiotics. The molecular epidemiology section helps to detect and track outbreaks of pathogenic bacteria like the drug-resistant organism recovered from the five patients.

Acinetobacter (pronounced “as-in-EE-toe-back-ter”) is a group of bacteria with a particular fondness for moist, humid environments. It is not very virulent, but it can cause disease in debilitated patients given the right circumstances. The strain detected in the five patients, known as Acinetobacter baumannii, is resistant to most drugs and can survive on environmental surfaces for months, making spread difficult to prevent and control.

In a warren of labs in the basement of Meyer, Medical Microbiology staff work round the clock to provide results on 460,000 patient specimens a year.

On detecting the cluster, the Microbiology Lab notified Hospital Epidemiology and Infection Control. Soon, Lisa Maragakis was on the case. “We started by going to the patients and reviewing their medical charts, looking for a common denominator,” says Maragakis, who is one of three faculty with appointments in both Infection Control and Infectious Diseases. The patients did not share the typical risk factors such as mechanical ventilation, long hospital stays and ICU care. They did, however, have wounds. Most had received a therapy called pulsatile lavage, a fairly common, water-based, high-pressure irrigation treatment very helpful for those with hard-to-heal wounds. All of them, as molecular tests in the Micro Lab would prove, had the exact same strain of the bacteria.

The Micro Lab also processed samples from the surfaces in the wound treatment room and found the identical strain of A. baumannii. This finding suggested that the bacteria had been dispersed into the environment and pointed to pulsatile lavage as the likely culprit.

A wider net, involving additional departments, was cast. “We closed the treatment area and soon began using additional infection control precautions such as impervious gowns, booties and goggles,” says Nancy Ciesla, a physical therapy supervisor in Physical Medicine and Rehabilitation. To assure a completely safe environment for patients, Facilities and Engineering reconstructed the wound treatment rooms in such a way that they could be easily cleaned and completely disinfected between patients.

“All this led to a termination of the outbreak and prevented this organism from becoming established in this institution,” says Karen Carroll, director of Medical Microbiology, of the work, which was published in the Journal of the American Medical Association in December. Ciesla and other wound care therapists presented two abstracts at their national meeting in February and are working with vendors to get updated product information to physical therapy schools and others. “This is a huge success story, a true multidisciplinary patient safety initiative with microbiologists at the core,” says Carroll.

For the future, Carroll plans to continue the division’s emphasis on patient safety. Reducing mislabeled or unlabeled samples is a top priority. When such samples arrive, lab staff posts incident reports on the new electronic Patient Safety Net, where they are routed to the offending departments.

“Improving the quality of specimens could definitely impact test results,” says Carroll, who urges physicians to go to the Pathology Web site ( for guidelines on collecting good samples.

Acinetobacter, in hand.
The Micro Lab will also aim to speed the process of detecting and identifying organisms. It is building on its menu of molecular tests, which are generally faster, more sensitive and cost-effective than culture-based tests. The lab recently completed an FDA clinical trial on a new chromogenic media that will enable it to more quickly identify MRSA, short for methicillin-resistant staphylococcus aureus, a “superbug” now well established in hospitals everywhere. “This test has made it possible to get results at least 24 hours faster than conventional methods,” says Carroll. “Patients will be placed in isolation faster and theoretically, we can then prevent spread.”

Although MRSA is typically acquired in hospitals, in the mid-1990s it started turning up in the community, particularly among high school wrestlers and other young, otherwise healthy athletes in whom it caused serious skin infections. Last winter, a handful of previously healthy patients were hospitalized at Hopkins Hospital and Bayview with severe pneumonia caused by MRSA.

In the Micro Lab, Mian Cai, an expert in molecular testing, was able to develop a special polymerase chain reaction (PCR) test that identified the particular toxin in the MRSA strain. The Micro Lab became one of the first clinical labs in the country to do this assay and is now receiving requests for it from throughout Maryland and beyond.

An ongoing priority in the Micro Lab is preparing for the next big bug. That, says Carroll, will likely be avian influenza, a disease that has infected poultry in Asia. So far, there has not been sustained human-to-human transmission, but Carroll and other experts say it is only a matter of time. “We are going to have to be able to identify this in a timely fashion and make sure we have the tools to do it.”

With all the Micro Lab’s expertise, special capabilities and services, there is no reason to think that things will turn out otherwise.

—Anne Bennett Swingle



Johns Hopkins Medicine

About DOME | Archive
© 2005 The Johns Hopkins University
and Johns Hopkins Health System