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Infectious Disease | QIAstat-Dx

Identifying a rare bacterial infection in Brazil with the right diagnostic

Differentiating bacterial infections from viral ones not only enhances patient care but also represents a pivotal step in the global fight against antibiotic resistance. A case example involving an atypical respiratory infection in São Paulo, Brazil showcases the importance of using molecular diagnostic tests to provide the right treatment. And quickly.

Maira Marranghello Maluf, M.D., was confronted with a highly complex case. A lethargic elderly woman suffering from a high fever, dehydration and respiratory symptoms had been admitted to the intensive care unit of the Israelita Albert Einstein Hospital in São Paulo, Brazil.

A CT scan of her lungs revealed hallmarks typical of respiratory infection. But was it viral, fungal, bacterial? The patients’ symptoms pointed to many possible culprits. Laboratory cultures from blood and respiratory fluid samples to rule out a bacterial infection turned up negative. Despite the clinical team’s best efforts, she wasn’t getting any better.

The patient’s doctor asked the hospital laboratory to run a molecular diagnostic test on the samples. “Respiratory syndromes have very similar clinical manifestations and it is difficult to make an etiological diagnosis based on clinical symptoms alone,” says Maluf, a clinical pathologist in the laboratory.

Maluf tested the woman’s respiratory sample with the QIAstat-Dx Respiratory SARS-CoV-2 Panel*. What she found was completely unexpected: Legionella pneumophilia, a bacteria.

Based on the result, the clinical team added a different class of antimicrobial to her treatment. The patient recovered, says Maluf “and we were all very happy because it’s not a common diagnosis.” The panel has been “of great benefit to our team.”

Since joining the lab in 2018, Maluf has been at the forefront of adopting molecular diagnostic technology, and frequently works with the QIAstat-Dx respiratory syndromic panel. Her firsthand experience highlights the tangible benefits this test offer to patients. “We can now make diagnoses that were very difficult to do previously.”


Maira Marranghello Maluf
Maira Marranghello Maluf, M.D. is a clinical pathologist in the microbiology department of the clinical laboratory of Hospital Israelita Albert Einstein where she has worked since 2018. She earned her medical degree from the University of Cuiabá in Mato Grosso and Master’s in Clinical Pathology at Federal University of São Paulo, where she also completed her medical residency. 
Respiratory syndromes have very similar clinical manifestations and it is difficult to make an etiological diagnosis based on clinical symptoms alone.
Maira Marranghello Maluf, M.D., Clinical pathologist, Hospital Israelita Albert Einstein

What it means to provide a fast diagnosis

The ability to quickly distinguish between viruses and other pathogens can greatly improve patient outcomes.

If the infection is viral, no specific treatment is required most of time, says Maluf. On the other hand, a bacterial infection usually requires antimicrobial therapy, she adds.

To identify non-viral infections, laboratories without access to molecular diagnostic testing must rely on assays that require growing microbes from a fluid or tissue sample. But some bacteria and fungi are notoriously difficult to culture, while others can’t be cultured in the lab at all. Moreover, results usually take several days to arrive.

For the patient with Legionella pneumophilia, “the panel was essential for diagnosis because the cultures were negative,” says Maluf. In fact, the hospital lab discontinued their Legionella culture kit. “It was rarely requested, required a specific culture medium and had low sensitivity.”

The syndromic QIAstat-Dx Respiratory SARS-CoV-2 Panel detects four subtypes of influenza A, influenza B, four coronavirus subtypes and nine other common respiratory viruses. In addition, it detects Mycoplasma, Bordetella, Chlamydophila and Legionella bacteria too, all of which cause similar symptoms. Results take less than 90 minutes.

“We call it syndromic testing because diseases are grouped by symptoms,” says Martí Juanola, PhD, the QIAGEN Associate Director of Medical Affairs. “The panel is designed to test for more than 20 different pathogens and all of them are potential causes of respiratory disease.”

Legionella bacteria

Legionella bacteria are found naturally in freshwater lakes and streams. When Legionella grow and multiply in a water system, the bacteria can spread to people via inhaled water droplets. Symptoms include cough, shortness of breath, fever, muscle aches and headaches, which overlap with so many other infections that it can be extremely difficult to diagnose the infection correctly. Legionella infection can lead to severe pneumonia. It can also cause a less severe illness that doesn’t affect the lungs, called Pontiac fever, that often resolves without treatment. 

We can now make diagnoses that were very difficult to do previously.
Maira Marranghello Maluf, M.D., Clinical pathologist, Hospital Israelita Albert Einstein

The mission

Another important advantage of the PCR-based QIAGEN respiratory panel, says Maluf, is the ability to access cycle threshold (Ct) values. Ct values represent the number of PCR cycles required to amplify pathogen DNA. Molecular testing of the respiratory tract often detects more than one organism. It can be difficult to distinguish what is just a harmless resident of the person’s microbiome and what is pathogenic, says Maluf.  “Knowing the Ct value can help distinguish between them.”

“With early and effective treatment, it is possible to obtain better clinical outcomes, reduce hospitalization time and consequently reduce costs,” says Maluf. “In addition, it is possible to avoid the indiscriminate use of antimicrobials, which has contributed so much to the increase in bacterial resistance to antimicrobials.” 

The elderly patient serves as testament to the need for more widespread testing; without a quick and accurate diagnosis, the patient could have suffered serious consequences.

“What motivates me is that I know I can help each patient’s journey,” she says. “We can help a lot of people doing the best we can with the resources we have. As a doctor, it’s very satisfying when patients recover. I feel like each one is a mission accomplished.”

Maluf hopes that as technology advances, costs will come down and Brazilian insurance providers will come to realize that quick diagnoses can save healthcare costs in the long-term. She also hopes that advances in technology will slash the time to results even further. Because “quicker results can save even more lives.”

Lab director checking display on instrument

New technologies are constantly being developed to expedite patient care, knowing that faster results can save lives. An example of these innovations is the QIAsphere app, which allows users to get real-time updates on QIAstat-Dx test status and immediate access to epidemiology reports. This provides valuable insights into the prevalent pathogens in the population, which can help clinicians enhance patient care and curb infectious outbreaks.

February 2024