Antibiotics in the clinical pipeline in October 2019 - The Journal of Antibiotics

'Serious Lung Infection' Linked To Cruise Ship Hot Tubs, CDC Finds

Hot tubs aboard a cruise ship have been linked to outbreaks of a bacterial disease, the U.S. Centers for Disease Control and Prevention (CDC) announced.

Between November 2022 and April 2024, eight cases of Legionnaires' disease were reported on a single cruise ship, "cruise ship A."

The outbreak on cruise ship A is the largest cruise-associated outbreak of Legionnaires' disease since 2008. A CDC investigation found that the hot tubs on the ships were the likely source of the infection.

Four more cases of the disease were reported on a second cruise ship (cruise ship B) between January and June 2024. Hot tubs were also found to be the cause.

"Epidemiologic, environmental, and laboratory evidence suggests that private balcony hot tubs were the likely source of exposure in two outbreaks of Legionnaires disease among cruise ship passengers," the CDC said in the report.

"These devices are subject to less stringent operating requirements than are public hot tubs, and operating protocols were insufficient to prevent Legionella growth."

Stock image of a woman in a hot tub (main) and a legionnaire's disease test (inset). Outbreaks of the disease on cruise ships have been linked to hot tubs. Stock image of a woman in a hot tub (main) and a legionnaire's disease test (inset). Outbreaks of the disease on cruise ships have been linked to hot tubs. ISTOCK / GETTY IMAGES PLUS

Legionnaires' disease is a severe form of pneumonia caused by Legionella bacteria, usually the species often Legionella pneumophila. Legionella bacteria thrive in warm water between 77 and 113 degrees Fahrenheit, which makes hot tubs a prime environment for their growth.

"It gets into the human body through inhaled water droplets, usually from hot tubs, air humidifiers, or air conditioning that contain the bacteria. Of note, it cannot be passed from person to person," Conor Meehan, an associate professor of microbial bioinformatics at Nottingham Trent University, told Newsweek.

Legionnaires' disease gets its name from an outbreak in 1976 at an American Legion convention in Philadelphia. Shortly after the event, many attendees began falling ill with a mysterious type of pneumonia, and scientists identified a previously unknown bacterium as the cause. The bacteria were named Legionella pneumophila.

This disease mainly affects the lungs, causing symptoms like cough, fever, muscle aches and shortness of breath. Sometimes, it can lead to other complications, especially in people with weakened immune systems, older adults, smokers or those with chronic respiratory conditions.

"Patients with the infection are often hospitalized and given oxygen and antibiotic therapy," Primrose Freestone, a senior lecturer in clinical microbiology at the University of Leicester, told Newsweek. "In terms of mortality, Legionella causes a serious lung infection, and while most survive Legionnaires disease, even after treatment with antibiotics, up to 10 percent of those infected die. With no treatment, up to 30 percent of patients infected with Legionella pneumoniae can die."

Six infected patients on cruise ship A and four on cruise ship B were hospitalized, but thankfully, none died, according to the CDC report.

Hot tubs with too low chlorine levels may allow bacteria to survive and multiply. Additionally, bacteria can form biofilms (thin layers of microorganisms) on pipes and surfaces, which makes them harder to eliminate, even with disinfection efforts. When the hot tub releases fine sprays or mists, the bacteria can be carried into the air and breathed in by people in the tubs.

"Cruise ship hot tubs are counted as private hot tubs and not public, so they are not subjected to the same rigor of testing by the state. If not properly maintained, cleaned and heated, they can become infected with Legionella pneumophilia. Combining this with the often more at-risk population in cruise ships—this can lead to more cases," Meehan said.

People on cruise ships are often older than the general population and, therefore, more vulnerable to infections like Legionnaire's disease.

"Morbidity and mortality statistics indicate that older people are more susceptible to serious infection and complications often because they have existing co-morbidities (health conditions), which mean they are more likely to be immunocompromised. It's a bit like with COVID," Anne Clayson, a Population Health program director at the University of Manchester, told Newsweek.

These two outbreaks highlight the importance of hot tub cleanliness, particularly private hot tubs.

"According to current CDC requirements, private hot tubs are not required to have automated continuous disinfectant dosing and monitoring or pH monitoring, as is standard for public hot tubs. To meet CDC requirements, private hot tubs must only be shock-chlorinated, drained, and refilled weekly or between occupancies, whichever is sooner," the CDC report said.

"Although the cruise lines adhered to current CDC requirements for operating and maintaining private hot tubs on ships A and B, these measures were insufficient to prevent Legionella growth."

Do you have a tip on a science story that Newsweek should be covering? Do you have a question about Legionnaire's disease? Let us know via science@newsweek.Com.

Side Effects Of Arikayce: What You Need To Know

ALLERGIC REACTION

For some people, Arikayce can cause an allergic reaction. Symptoms of allergic reaction can be mild to serious.

Mild allergic reaction symptoms may include:

Symptoms of a serious allergic reaction may include:

Inflammation in the lungs from an allergic reaction to Arikayce was a rare side effect that happened in the drug's studies.

Symptoms of lung inflammation may include:

What might help

If you have mild symptoms of an allergic reaction, such as a mild rash, call your doctor right away. They may suggest a treatment to manage your symptoms and can determine whether you should continue Arikayce treatment.

If you have symptoms of a severe allergic reaction, such as swelling or difficulty breathing, call 911 or your local emergency number right away. These symptoms could be life threatening and require immediate medical care.

If your doctor confirms you've had a serious allergic reaction to Arikayce, they may have you switch to a different treatment.

Zinc Deficiency Promotes Acinetobacter Lung Infection, Study Finds

Dietary zinc deficiency promotes lung infection by Acinetobacter baumannii bacteria -- a leading cause of ventilator-associated pneumonia, according to a new study published Nov. 15 in the journal Nature Microbiology.

A Vanderbilt University Medical Center-led team of researchers discovered an unexpected link between the pro-inflammatory cytokine interleukin-13 (IL-13) and A. Baumannii lung infection, and they demonstrated that blocking IL-13 prevented infection-associated death in an animal model.

The findings suggest that anti-IL-13 antibodies, which are FDA-approved for use in humans, may protect against bacterial pneumonia in patients with zinc deficiency.

"To our knowledge, this is the first study showing that neutralization of IL-13 could prevent mortality from a bacterial infection," said Eric Skaar, PhD, MPH, the Ernest W. Goodpasture Professor of Pathology and director of the Vanderbilt Institute for Infection, Immunology and Inflammation. "This discovery points to the possibility of using anti-IL-13 therapy in patients with zinc deficiency and A. Baumannii pneumonia as part of a personalized therapy approach."

Nearly 20% of the world's population is at risk for zinc deficiency, which can impair immune function and is a major risk factor for pneumonia. The World Health Organization considers zinc deficiency a leading contributor to disease and death.

Patients at risk for zinc deficiency, particularly critically ill and elderly patients, are also at risk for A. Baumannii infection. Patients in health care settings have the highest risk for infection, especially those who are on ventilators, have devices such as catheters, are in intensive care units, or have prolonged hospital stays. A. Baumannii is becoming increasingly resistant to antimicrobial treatments, making it a critical public health threat, Skaar said.

To explore whether and how dietary zinc deficiency contributes to A. Baumannii pathogenesis, the researchers established a mouse model of dietary zinc deficiency and acute A. Baumannii pneumonia. Lauren Palmer, PhD, a former postdoctoral fellow at VUMC who is now assistant professor of Microbiology and Immunology at the University of Illinois, Chicago, led the studies.

The researchers found that zinc-deficient mice had increased A. Baumannii bacterial burden in the lungs, spread of bacteria to the spleen, and higher mortality compared to mice with adequate dietary zinc consumption. They showed that the zinc-deficient mice produce more IL-13 during infection and that administration of IL-13 to mice with sufficient zinc promoted spread of A. Baumannii to the spleen. Anti-IL-13 antibody treatment protected zinc-deficient mice from A. Baumannii-induced death.

The findings add to a growing set of studies showing that certain nutrient deficiencies are associated with IL-13 production and a "type 2" immune response.

"IL-13 may be an important risk factor for health care-associated and opportunistic lung infections, further supporting exploration of IL-13 as a target for treatment," Skaar noted.

FDA-approved anti-IL-13 antibodies (lebrikizumab and tralokinumab) have been extensively investigated as potential therapies for uncontrolled severe asthma. Although they were not found to be effective for that indication, the clinical trials demonstrated their safety.

Palmer is the first and co-corresponding author with Skaar of the Nature Microbiology report. Other authors are Zachery Lonergan, PhD, Dziedzom Bansah, Xiaomei Ren, PhD, Lillian Juttukonda, MD, PhD, Christopher Pinelli, DVM, PhD, and Kelli Boyd, DVM, PhD. The research was supported in part by the National Institutes of Health (grants R01AI101171, R01AI017829, F31AI136255, T32HL094296, F32AI122516, K99HL143441, R00HL143441, P30DK058404).

---