A UCLA microbiology lab used whole-genome sequencing to trace a carbapenem-resistant Pseudomonas outbreak to a single ICU sink, revealing how biofilm and plumbing can silently harbor superbugs.
A routine culture from an ICU patient at UCLA Health sparked an investigation that ultimately uncovered a silent, domestic outbreak of a highly resistant strain of Pseudomonas aeruginosa. The discovery was led by the Molecular Microbiology and Pathogen Genomics Laboratory and highlights the critical role clinical laboratories play in outbreak detection, antimicrobial resistance surveillance, and environmental tracking.
The initial isolate appeared typical: P. aeruginosa, a common hospital-associated pathogen. But further analysis revealed something more troubling, the presence of NDM-1 (New Delhi metallo-β-lactamase), an enzyme that breaks down carbapenems and other powerful beta-lactam antibiotics, rendering them ineffective.
“This was the first time we’d ever seen an NDM-1-producing Pseudomonas strain in our hospital—and in a patient with no international travel,” said Shangxin Yang, PhD, director of UCLA Health’s Molecular Microbiology and Pathogen Genomics Laboratory.
Shangxin Yang, PhD, director of UCLA Health’s Molecular Microbiology and Pathogen Genomics Laboratory noted, “While NDM-1 is prevalent in Asia, Europe and the Middle East, it remains rare in the United States. That’s when we knew this wasn’t imported. This was something domestic—and very concerning.” (Photo credit: UCLA)
Sporadic Cases, Elusive Source
Over the next 18 months, seven additional patients were identified with the same rare resistance pattern. The cases were sporadic—spread across time and units—and did not follow conventional outbreak patterns, complicating source identification.
In collaboration with UCLA Health’s infection prevention team, the lab launched a detailed investigation. Routine epidemiologic methods failed to identify commonalities between the cases. Shared equipment, staffing patterns, and care protocols were ruled out. With limited leads, the microbiology team turned to whole-genome sequencing (WGS).
Whole-Genome Sequencing Connects the Dots
WGS became the turning point. By sequencing all eight patient isolates and comparing them to environmental samples, Yang’s lab determined that seven of the eight clinical isolates and two environmental strains shared an almost identical genomic profile. Only one isolate, from a patient previously treated in Iran, was genetically distinct.
“Whole-genome sequencing gave us the clarity we needed,” said Yang. “It allowed us to move from hypothesis to high-resolution confirmation—pinpointing the genetic relatedness of these organisms with certainty.”
The team had uncovered a clonal outbreak of NDM-1-producing P. aeruginosa, likely stemming from a single environmental reservoir.
Unexpected Reservoir: An ICU Sink
During a third round of environmental testing, the lab isolated the same NDM-1-producing strain from a contaminated sink drain and P-trap in one ICU room. Notably, two of the eight patients had been admitted to that room more than a year apart.
The persistence of the organism was attributed to biofilm formation in the sink plumbing. Pseudomonas is known for forming robust biofilms that adhere to moist surfaces and resist standard disinfection methods.
“This wasn’t just about surface contamination,” said Yang. “This was a deeply embedded reservoir that conventional cleaning protocols couldn’t touch.”
Lab-Driven Response and Mitigation
Once the lab identified the environmental source, targeted interventions were put in place:
Weekly disinfection of ICU sinks using Virasept, a biofilm-effective agent
Plumbing replacement, including P-trap components known to harbor persistent biofilms
Engineering modifications to faucet angles to reduce splash-back and droplet spread
Expanded environmental surveillance to monitor other sinks for colonization
The lab continued to monitor the situation post-intervention, and no further cases of NDM-1-producing P. aeruginosa have been identified since the changes were implemented.
Lessons Learned
This case reinforces the value of whole-genome sequencing in resolving complex outbreaks, linking patient isolates to an environmental source that traditional methods missed. It highlights the need to include plumbing and other biofilm-prone areas in environmental sampling. Most importantly, it shows how microbiology labs through genomic, phenotypic, and molecular tools can lead outbreak investigations, especially when paired with strong cross-department collaboration.
“This is a clear example of the power of the clinical lab when genomic tools and environmental surveillance are used strategically,” said Yang. “Without WGS, this would have remained an unsolved mystery.”
The World Health Organization has released updated Target Product Profiles to guide manufacturers in developing faster, more affordable, and accurate tuberculosis screening tools.
Since 2014, the World Health Organization (WHO) has regularly published Target Product Profiles (TPP) for tuberculosis (TB) screening tests. Aimed at manufacturers of TB tests and equipment, they are akin to a wish list for addressing global TB screening needs. The WHO recently published updated TPPs.
The WHO indicates that in 2023, a total of 1.25 million deaths occurred from TB globally. In that year, about 10.8 million people were estimated to have TB, with official diagnoses of about 8.2 million and another 2.6 million believed to have gone undetected. Of the 10.8 million, 1.3 million were children.
TB is an airborne infectious disease caused by the bacterium Mycobacterium tuberculosis. Primarily affecting the lungs, it can impact the entire body. It is typically diagnosed via tuberculin skin tests, blood tests, chest X-rays, and sputum analysis.
TB has recently been moved to the top of the list—over COVID-19—as the leading cause of death in the world from a single infectious agent. TB is also the top killer of people with HIV. About two out of five TB deaths are related to antibiotic-resistant strains of TB.
The WHO stated in the TPPs that, “If TB screening is to be implemented at the levels needed to significantly reduce the global TB burden, there is an urgent need for new tools for TB screening that can be readily and rapidly deployed and brought to scale.”
Tereza Kasaeva, MD, PhD, Director of the WHO Department for HIV, noted “The new WHO TPPs will inform manufacturers about the features that these new tests should have if they are to address the needs of the TB community and achieve the ambitious global commitments for TB detection and reduction of TB incidence and deaths.”
There have been many recent advancements, including mobile and portable digital radiographic equipment, as well as artificial intelligence (AI) in computer-aided detection software. Yet, the WHO notes, there are still challenges to scaling technology to close “the case detection gap.” Some of those challenges include availability, low cost, and high accuracy.
The TPP defined three distinct types of screening tools:
High-sensitivity, high-specificity screening test using a single screening step before referral for diagnostic testing or ruling out TB.
High-sensitivity screening as part of a two-step screening process before referral for diagnostic testing.
A moderate-sensitivity screening test with high specificity that can be used in settings that have limited access to health systems and can’t be reached via existing screening technology.
Current screening methods have accuracy limitations and difficulty in screening asymptomatic TB. The WHO TPPs noted that, “CXR (chest X-ray) can be used to screen most populations and has the best demonstrated sensitivity of available screening tools. CAD software for automated interpretation of CXR imaging can be used along CXR for screening all adults aged 15 years and older.”
The WHO also recommends rapid molecular diagnostic tests for screening all adults, and C-reactive protein (CRP) to screen adults living with HIV.
The latest TPP emphasizes effective community-based screening on a larger scale in settings with lower TB prevalence. This is a challenge to TB assay developers, especially in finding cost-effective methods with high accuracy. Ideally, they would have a small per-test cost and very little or no equipment or capital investments. If they do require centralized equipment for processing, they should have low per-test costs and implementation requirements.
For each category of testing, the TPP sets pricing goals. For high-accuracy one-step tests, the minimum is ≤ US$3; for high-sensitivity two-step tests, the minimum is ≤ US$2 with an optimal of ≤ US$1; and for a high-specificity test, the minimum is ≤ US$2.
The TPP states, “Ideally, a new test should be priced according to the cost of goods and estimated volumes, and should include a reasonable profit margin. Ensuring access to tests while maintaining business interests can be achieved through fair pricing, which requires transparency about the cost of goods and estimated volumes, and a reasonable profit margin.”
The expert panel that created the TPP understands the challenges, noting that “manufacturers may have to consider trade-offs, whereby a novel test has some clear advantages that may offset other downsides.”
Ultimately, the WHO states that the TPPs were issued to “guide and encourage product development for new screening tools in these settings.”
Findings could lead to new therapies and clinical laboratory biomarkers for detecting and defeating antibiotic-resistant bacteria
Once again, new research shows that human gut bacteria (microbiota) may be useful in fighting antibiotic-resistant bacterial infections. The study findings could provide new therapeutics and clinical laboratory biomarkers for diagnosing and treating severe gastrointestinal disorders.
Antibiotic-resistant bacterial infections often appear in patients with chronic intestinal conditions and in those with long-term antibiotic use. Enterobacteriaceae is a large family of gram-negative bacteria that includes more than 30 genera and over 100 species.
“Despite two decades of microbiome research, we are just beginning to understand how to define health-promoting features of the gut microbiome,” said Marie-Madlen Pust, PhD, a computational postdoctoral researcher at the Broad Institute and co-first author of the paper, in the news release.
“Part of the challenge is that each person’s microbiome is unique. This collaborative effort allowed us to functionally characterize the different mechanisms of action these bacteria use to reduce pathogen load and gut inflammation,” she added.
The researchers identified a way to treat patients infected by antibiotic-resistant strains of bacteria that does not involve antibiotics. Should further research validate these early findings, this could be a viable approach to treating patients with this condition.
“Microbiome studies can often consist of analyzing collections of genetic sequences, without understanding what each gene does or why certain microbes are beneficial,” said Ramnik Xavier, MD (above), director of Broad Institute’s immunology program, co-director of the infectious disease and microbiome program, and co-senior author on the study, in a news release. “Trying to uncover that function is the next frontier, and this is a nice first step towards figuring out how microbial metabolites influence health and inflammation.” Clinical laboratories that test for intestinal conditions caused by antibiotic resistance will want to follow the Broad Institute’s research. (Photo copyright: Broad Institute.)
Suppressing Growth of Antibiotic-resistant Bacteria
To perform their research, the scientists isolated about 40 strains of bacteria from the stools of five healthy fecal donors. They then used those stool samples in fecal microbiota transplants to treat mice that had been infected with either Escherichia coli (E. coli) or Klebsiella, both forms of Enterobacteriaceae. The scientists tested different combinations of the 40 strains and identified 18 that suppressed the growth of Enterobacteriaceae.
“Antibiotic-resistant Enterobacteriaceae such as E. coli and Klebsiella bacteria are common in hospitals, where they can proliferate in the gut of patients and cause dangerous systemic infections that are difficult to treat. Some research suggests that Enterobacteriaceae also perpetuates inflammation in the intestine and infection by other microbes,” the Broad Institute news release notes.
The researchers discovered that Klebsiella changed the gene expression in carbohydrate uptake and metabolism in the Klebsiella-infected mice that were treated with the 18 beneficial strains. The gene expression included the downregulating of gluconate kinase and transporter genes, which revealed there is increased competition among gut bacteria for nutrients.
When combined, these 18 strains alleviated inflammation in the guts of the treated mice by depriving the harmful gut bacteria of carbohydrates. This non-antibiotic approach also prevented harmful bacteria from colonizing in the gut.
“In partnership with the Broad’s Metabolomics Platform, led by senior director and study co-author Clary Clish, PhD, they analyzed samples from pediatric patients with ulcerative colitis, looking for the presence of alternate gluconate pathway genes of gut microbes and fecal gluconate levels. They found higher levels of gluconate linked to more gluconate-consuming Enterobacteriaceae in samples from pediatric patients with ongoing inflammation, indicated by high levels of the protein calprotectin,” the study authors wrote in Nature.
“Together, the findings suggest that Enterobacteriaceae processes gluconate as a key nutrient and contributes to inflammation in patients. But when a gut microbiome includes the 18 helpful strains, they likely compete with Enterobacteriaceae for gluconate and other nutrient sources, limiting the proliferation of the harmful bacteria,” the scientists concluded.
Promising New Bacterial Therapies
This research could ultimately lead to the development of fecal microbiota transplants for individuals to eradicate antibiotic-resistant bacteria in a more objective and specific manner, with fewer side effects than current treatments.
“Harnessing these activities in the form of live bacterial therapies may represent a promising solution to combat the growing threat of proinflammatory, antimicrobial-resistant Enterobacteriaceae infection,” the scientists wrote in Nature.
According to the news release, they plan to continue research to “uncover the identity and function of unknown metabolites that contribute to gut health and inflammation.” The team hopes to discover how different bacteria compete with each other, and to develop microbial therapeutics that improve gut microbiome and curb bacterial infections.
More studies are needed to prove the efficacy of this type of fecal bacterial treatment. However, this research demonstrates how using nano processes enabled by new technologies to identify the actual work of proteins, RNA, and DNA in the body cheaply, faster, and with greater precision, will open doors to both therapeutic and diagnostic clinical laboratory biomarkers.
New technology could enable genetic scientists to identify antibiotic resistant genes and help physicians choose better treatments for genetic diseases
Genomic scientists at the Icahn School of Medicine at Mount Sinai Medical Center in New York City have developed what they call a “smart tweezer” that enables researchers to isolate a single bacterium from a patient’s microbiome in preparation for genetic sequencing. Though primarily intended for research purposes, the new technology could someday be used by clinical laboratories and microbiologists to help physicians diagnose chronic disease and choose appropriate genetic therapies.
The researchers designed their new technology—called mEnrich-seq—to improve the effectiveness of research into the complex communities of microorganisms that reside in the microbiomes within the human body. The discovery “ushers in a new era of precision in microbiome research,” according to a Mount Sinai Hospital press release.
“Imagine you’re a scientist who needs to study one particular type of bacteria in a complex environment. It’s like trying to find a needle in a large haystack,” said the study’s senior author Gang Fang, PhD (above), Professor of Genetics and Genomic Sciences at Icahn School of Medicine at Mount Sinai Medical Center, in a press release. “mEnrich-seq essentially gives researchers a ‘smart tweezer’ to pick up the needle they’re interested in,” he added. Might smart tweezers one day be used to help physicians and clinical laboratories diagnose and treat genetic diseases? (Photo copyright: Icahn School of Medicine.)
Addressing a Technology Gap in Genetic Research
Any imbalance or decrease in the variety of the body’s microorganisms can lead to an increased risk of illness and disease.
In researching the microbiome, many scientists “focus on studying specific types of bacteria within a sample, rather than looking at each type of bacteria present,” the press release states. The limitation of this method is that a specific bacterium is just one part of a complicated environment that includes other bacteria, viruses, fungi and host cells, each with their own unique DNA.
“mEnrich-seq effectively distinguishes bacteria of interest from the vast background by exploiting the ‘secret codes’ written on bacterial DNA that bacteria use naturally to differentiate among each other as part of their native immune systems,” the press release notes. “This new strategy addresses a critical technology gap, as previously researchers would need to isolate specific bacterial strains from a given sample using culture media that selectively grow the specific bacterium—a time-consuming process that works for some bacteria, but not others. mEnrich-seq, in contrast, can directly recover the genome(s) of bacteria of interest from the microbiome sample without culturing.”
Isolating Hard to Culture Bacteria
To conduct their study, the Icahn researchers used mEnrich-seq to analyze urine samples taken from three patients with urinary tract infections (UTIs) to reconstruct Escherichia coli (E. Coli) genomes. They discovered their “smart tweezer” covered more than 99.97% of the genomes across all samples. This facilitated a comprehensive examination of antibiotic-resistant genes in each genome. They found mEnrich-seq had better sensitivity than standard study methods of the urine microbiome.
They also used mEnrich-seq to selectively examine the genomes of Akkermansia muciniphila (A. muciniphila), a bacterium that colonizes the intestinal tract and has been shown to have benefits for obesity and Type 2 diabetes as well as a response to cancer immunotherapies.
“Akkermansia is very hard to culture,” Fang told GenomeWeb. “It would take weeks for you to culture it, and you need special equipment, special expertise. It’s very tedious.”
mEnrich-seq was able to quickly segregate it from more than 99.7% of A. muciniphila genomes in the samples.
Combatting Antibiotic Resistance Worldwide
According to the press release, mEnrich-seq could potentially be beneficial to future microbiome research due to:
Cost-Effectiveness: It offers a more economical approach to microbiome research, particularly beneficial in large-scale studies where resources may be limited.
Broad Applicability: The method can focus on a wide range of bacteria, making it a versatile tool for both research and clinical applications.
Medical Breakthroughs: By enabling more targeted research, mEnrich-seq could accelerate the development of new diagnostic tools and treatments.
“One of the most exciting aspects of mEnrich-seq is its potential to uncover previously missed details, like antibiotic resistance genes that traditional sequencing methods couldn’t detect due to a lack of sensitivity,” Fang said in the news release. “This could be a significant step forward in combating the global issue of antibiotic resistance.”
More research and clinical trials are needed before mEnrich-seq can be used in the medical field. The Icahn researchers plan to refine their novel genetic tool to improve its efficiency and broaden its range of applications. They also intend to collaborate with physicians and other healthcare professionals to validate how it could be used in clinical environments.
Should all this come to pass, hospital infection control teams, clinical laboratories, and microbiology labs would welcome a technology that would improve their ability to detect details—such as antibiotic resistant genes—that enable a faster and more accurate diagnosis of a patient’s infection. In turn, that could contribute to better patient outcomes.
Phages are miniscule, tripod-looking viruses that are genetically programmed to locate, attack, and eradicate a specific kind of pathogen. These microscopic creatures have saved lives and are being touted as a potential solution to superbugs, which are strains of bacteria, viruses, parasites, and fungi that are resistant to most antibiotics and other treatments utilized to counteract infections.
“These multi-drug-resistant superbugs can cause chronic infections in individuals for months to years to sometimes decades,” Dwayne Roach, PhD, Assistant Professor of Bacteriophages, Infectious Disease, and Immunology at SDSU told CNN. “It’s ridiculous just how virulent some of these bacteria get over time.”
Labs across the country are conducting research on phages in eradicating superbugs. Roach’s lab is currently probing the body’s immune response to phages and developing purification techniques to prepare phage samples for intravenous use in patients.
“There are a lot of approaches right now that are happening in parallel,” said Dwayne Roach, PhD (above), Assistant Professor of Bacteriophages, Infectious Disease, and Immunology at San Diego State University (SDSU), in a CNN interview. “Do we engineer phages? Do we make a phage cocktail, and then how big is the cocktail? Is it two phages or 12 phages? Should phages be inhaled, applied topically, or injected intravenously? There’s a lot of work underway on exactly how to best do this.” Clinical laboratories that test for bacterial infections may play a key role in diagnosis and treatment involving bacteriophages. (Photo copyright: San Diego State University.)
Building Libraries of Phages
When certain a bacterial species or its genotypes needs to be annihilated, a collection of phages can be created to attack it via methods that enter and weaken the bacterial cell. The bacteria will attempt to counter the intrusion by employing evasive actions, such as shedding outer skins to eliminate the docking ports utilized by the phages. These maneuvers can cause the bacteria to lose their antibiotic resistance, making them vulnerable to destruction.
Some research labs are developing libraries of phages, accumulating strains found in nature in prime breeding grounds for bacteria to locate the correct phage for a particular infection. Other labs, however, are speeding up the process by producing phages in the lab.
“Rather than just sourcing new phages from the environment, we have a bioreactor that in real time creates billions upon billions of phages,” Anthony Maresso, PhD, Associate Professor at Baylor College of Medicine in Houston told CNN. “Most of those phages won’t be active against the drug-resistant bacteria, but at some point, there will be a rare variant that has been trained, so to speak, to attack the resistant bacteria, and we’ll add that to our arsenal. It’s a next-generation approach on phage libraries.”
For the Baylor study, 12 patients were treated with phages customized to each individual’s unique bacterial profile. The antibiotic-resistant bacteria were exterminated in five of the patients, while several others showed improvement.
Clinical trials are currently being executed to test the effectiveness of phages against a variety of chronic health conditions, including:
Using a phage cocktail could be used to treat a superbug outbreak in real time, while preventing a patient from a future infection of the same superbug.
“The issue is that when patients have infections with these drug-resistant bacteria, they can still carry that organism in or on their bodies even after treatment,” Maroya Walters, PhD, epidemiologist at the federal Centers for Disease Control and Prevention (CDC) told CNN.
“They don’t show any signs or symptoms of illness, but they can get infections again, and they can also transmit the bacteria to other people,” she added.
The colorized transmission electron micrograph above shows numerous phages attached to a bacterial cell wall. Phages are known for their unique structures, which resemble a cross between NASA’s Apollo lunar lander and an arthropod. (Caption and photo copyright: Berkeley Lab.)
More Studies are Needed
According to CDC data, more than 2.8 million antimicrobial-resistant (AMR) infections occur annually in the United States. More than 35,000 people in the country will die as a result of these infections.
In addition, AMR infections are a huge global threat, associated with nearly five million deaths worldwide in 2019. Resistant infections can be extremely difficult and sometimes impossible to treat.
More research is needed before phages can be used clinically to treat superbugs. But if phages prove to be useful in fighting antibiotic-resistant bacteria, microbiologists and their clinical laboratories may soon have new tools to help protect patients from these deadly pathogens.
