Omicron Variant - What you need to know

a microbiology newsletter - december, 2021

The new COVID Omicron Variant

What You Need to Know...

Will it evade the vaccines?
Is it more infectious?
Are the symptoms more severe?
Will it come to America?

Find out...

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Fatalities associated with imported product

Aromatherapy Spray

Found to be Deadly

Melioidosis (also called Whitmore’s Disease) is an infectious and potentially fatal bacterial disease affecting approximately 165,000 individuals worldwide.(1) Symptoms of this disease range from mild fever, chest pain, and cough to more severe symptoms such as ulcers, chronic respiratory illness, and even central nervous system infection.(2, 3) Thankfully, person-to-person spread is extremely rare.(4) Yet, Burkholderia pseudomallei has been an ongoing bioterrorism concern because of its high transmissibility through air, water, and soil.(5)

Melioidosis is often difficult to diagnose, in the United States, because it is not a part of routine diagnostic screening and is commonly confused with tuberculosis. Melioidosis is primarily found in tropical climates such as Southeast Asia where Burkholderia pseudomallei, the microorganism causing this infectious disease, is endemic and commonly found in water and soil.(2) For this reason, most Americans have never had to worry about Melioidosis, however, recently four cases of Melioidosis were reported in Georgia, Kansas, Minnesota, and Texas over a four month time frame. How did the tropical microorganism Burkholderia pseudomallei find its way to the central U.S.?

This was a puzzling question for CDC public health investigators. Approximately, 12 cases of Melioidosis are reported annually in the U.S., almost all exclusively to individuals who recently traveled outside of the country to areas where Burkholderia pseudomallei is endemic.(4) However, this was not the case for the most recent outbreak, as all infected individuals had not travelled internationally. Even more puzzling, the four cases emerged in four separate states among both adults and children who became sick months apart from each other.(6)

In order to help narrow down the culprit, investigators performed whole genome sequencing of the Burkholderia pseudomallei strains found in the infected patients.(7) Sequencing showed that all four strains were highly related, indicating a common source of infection among the individuals. Interestingly, the strains were also found to be highly similar to strains found in Southeast Asia.(7) Since travel was out of the equation, investigators suspected that an imported household product may be the common source of infection.

To investigate, CDC officials surveyed the families for common household products and compiled a list of products ranging from cleaning supplies to garden soil.(8) Additionally, blood samples were collected and some family members were found to have antibodies to Burkolderia pseudomallei, although they did not develop serious symptoms.(8) This may be worrisome as Burhkolderia pseduomallei has shown to have a long latency period, with one such reported case of 29 years.(2)

After months of testing household products, the CDC announced in October 2021 that Burkholderia pseudomallei was identified in a scented room spray from the Georgia patient’s home.(4) The CDC was able to confirm by the genetic fingerprint of the bacteria that the three other cases were also linked to this room spray or at least one of its ingredients.(8) The aromatherapy room spray, “Better Homes & Gardens Lavender & Chamomile Essential Oil Infused Aromatherapy Room Spray with Gemstones,” was sold in over 55 Walmart stores between February and October 2021.(4) Walmart has issued a recall of this product and five other scents in this product line. The CDC is working closely with the manufacturer in India to determine if additional products are at risk.(8) Of the four patients originally infected, two have died and the four-year-old patient from Texas has suffered severe brain damage.(8)

Consumers who still own this product are urged to dispose of it properly by not simply throwing it in the trash or down the sink as this may have detrimental effects on U.S. water and soil.(8, 9) Healthcare providers are being asked to consider Melioidosis for patients who have not travelled outside the U.S. and for those with symptoms similar to tuberculosis and who are not responding to antibiotics.(9)

Culture of B. pseudomallei from any clinical specimen is considered diagnostic for melioidosis. Ideal specimens for culture include blood, urine, throat swab, and, when relevant, respiratory specimens, abscesses, or wound swabs. Serological testing is available at CDC for diagnostic testing but is less sensitive and requires paired sera.

The CDC cautions microbiologists that the MALDI-TOF and Vitek-2 have been noted for misidentifying this dangerous pathogen. Details on how to successfully identify this difficult organism are provided in various articles.(11, 12) Once properly diagnosed, the disease can be successfully treated using ceftazidime, trimethoprim-sulfamethoxazole, meropenem, or amoxicillin/clavulanic acid.(13)

As this case demonstrates, Melioidosis is a severe bacterial disease that can be difficult to diagnose and identify when discovered in non-endemic regions. Further research into how this organism is spread, how this disease can be treated, as well as increased screening for Burkholderia pseudomallei is needed to ensure another outbreak does not occur again.

References: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13

By Allie Malmberg

Technical Support Microbiologist

Hardy Diagnostics

Did you know that Hardy Diagnostics was the first to introduce Chromogenic Media to America in 1996?

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Phraseology

"Raising Cain"

This expression means to make a disturbance or cause a ruckus. It originates from the 1840s in America, but soon crossed the Atlantic and was used by the British authors, Rudyard Kipling and Robert Luis Stevenson. This saying alludes to the wicked biblical Cain, who killed his brother, Abel, out of extreme jealousy for making a more pleasing offering to God.(Genesis 4:5). Also, it's somewhat of a euphemism for "raising hell."

CRISPR technology used to control the fourth biggest infectious disease killer...

Will Releasing Genetically Modified Mosquitos Finally Conquer Malaria?

Self-Destructing Mosquitoes:

A new way to combat malaria and other mosquito vector diseases.

For the first time, scientists have shown that a new kind of genetic engineering, known as a "gene drive," can crash populations of malaria-spreading mosquitoes.

The objective of the study was to alter three species of mosquito most responsible for disease transmission – Anopheles gambiae, A. coluzzii and A. arabiensis. The photo above shows an infected erythrocyte with the characteristic malaria ring form.

Despite years of effort, malaria remains a major health problem. This mosquito-borne parasitic disease infects more than 200 million people every year and kills more than 400,000, many of whom are children.¹ Worldwide,it is the fourth biggest infectious disease killer behind tuberculosis, HIV/AIDS, and hepatitis C.

Dr. Ruth Müeller, PhD, and her colleagues utilized CRISPR to make precise edits to the Anopheles species. CRISPR, shorthanded for CRISPR-Cas9, acts as “molecular scissors” that cut DNA at a specific location when guided by a RNA template. Once snipped, the cell activates a DNA repair mechanism and scientists can use this mechanism to introduce, delete, or mutate a gene of interest.⁷

In this study, the modification consisted of a mutation in a gene known as “doublesex” which female mosquitoes need for normal development.While genetically female, the transformed insects have distorted mouths, resembling their male counterparts; which prevent them from biting and spreading malaria. In addition, the females’ reproductive organs are deformed preventing them from laying eggs.²Essentially, the mutated gene converts female mosquitos into males, thus drastically reducing the population of the mosquitos capable of carrying and transmitting the malaria parasite.

“[This] gene drive is like a ‘selfish gene’…. All the mosquito offspring – have this modification,” Müeller says. “The idea and hope is that they would spread their mutation and eventually sterilize all the females. That would crash – or drastically reduce – local populations of the main species of mosquitoes that spreads malaria”.⁶

To safely test the mosquitoes under more natural conditions, researchers built a special high-security lab in Italy (far away from Africa) designed to keep the mutated mosquitoes from escaping. The researchers then released dozens of the gene-drive mosquitoes into special large cages containing hundreds of wild-type mosquitoes. The gene-driven mosquitoes decimated the natural mosquito populations in less than a year.^{5, 2}

Some researchers are welcoming the advance while others are highly skeptical and say the technology is too dangerous. Dr. Ethan Bier, PhD, noted, “One should never predicate the use of a gene drive…Just like with insecticides, you can expect that the insect will become resistant one way or another. The drive itself [could] create a mutation preventing the drive from going further.”⁴

Dr. Alekos Simoni, PhD, cautiously noted, “Looking at the roles of Anopheles mosquitoes is crucial in terms of the food web, pollination and the general ecosystem. I think there can be a problem for species that are distributed around the world like the mosquito because it is difficult to constrain in the area”.⁴

So what does the future hold for gene drives? Whether gene drives will end up being utilized as a tool to control wild populations or remain a tool to be used in the lab, remains to be seen. It is a complex issue, with valid arguments being made for and against the use of the technology.

by Francisco Pinon

R&D Microbiologist

HARDY DIAGNOSTICS

References: 1, 2, 3, 4, 5, 6, 7

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