A newly found bacteria called Peptoniphilus lacydonensis was first identified in 2018 from a patient with long-lasting sinus troubles. It’s a gram-positive bacteria belonging to the Peptoniphilus group, which includes 15 similar species. The epidemiology of P. lacydonensis is not well understood. So far, only one case has been reported.  

An 85-year old man with ethmoidal adenocarcinoma underwent multiple surgeries & antibiotic treatments for sinusitis. The bacterium was identified through culturomics, which combines culture conditions and molecular tools to detect rare pathogenic bacteria. The frequency of P. lacydonensis in different groups and regions is studied well. The frequency of P. lacydonensis in different groups and regions is studied well. 

P.lacydonensis is categorized under Clostridia and Peptoniphilaceae. It is a gram-positive bacterium and grows without oxygen or with little oxygen. This round-shaped bacteria are between 0.5 to 1.0 µm wide. The bacteria clump together in irregular groups or short chains.

P.lacydonensis has a tough outer layer made of peptidoglycan and teichoic acids. Unlike some bacteria, it doesn’t have a capsule, whiplike tails, or spores, which emphasizes its unique physical traits.

Peptoniphilus lacydonensis has a circular chromosome. It has 1,836,433 base pairs, and 28.1% of its bases are G+C. This gram-positive bacteria contains 1,650 protein-coding genes and 54 RNA genes. P. lacydonensis makes short-chain fatty acids like butyrate and propionate from peptone and other protein sources.

Importantly, P. lacydonensis is very similar to other bacteria in the genus Peptoniphilus. Its 16S rRNA gene sequence matches 97.8% with Peptoniphilus harei, the type species. It also matches 95.7% with Peptoniphilus rhinitidis. The type strain, called EL1 or ED1, came from a human nasal swab. This strain has culture collection numbers DSM 100661 and CSUR P2013. Another strain, JCM 17448 or KCTC 5985, was found in chronic rhinosinusitis samples. 

The way Peptoniphilus lacydonensis causes the disease is still unclear. It’s a rare and new pathogen identified. But its traits suggest it could infect people with weak immune systems or illnesses.  

P.lacydonensis might spread from fluids, cuts, or instruments having it. It may exist naturally on the skin, mouth, or gut, infecting when the host’s defenses are weakened.

As an opportunistic pathogen, P. lacydonensis can invade tissues and organs in vulnerable hosts. It may infect the skin, soft tissues, bones, joints, and surgical sites. The bacterium likely makes toxins or enzymes. These damage host cells, causing inflammation, necrosis and abscesses. 

The nose and sinuses have mucous membranes that make it hard for P. lacydonensis to attach and invade. These membranes release lysozyme, IgG, IgA, and other antimicrobial substances to stop infections. The complement system also helps by covering Peptoniphilus lacydonensis with opsonins, so phagocytes can engulf it or by forming membrane attack complexes that cause lysis. 

Cytokines and chemokines are released locally to recruit and activate immune cells like natural killer cells, neutrophils, and dendritic cells to fight the infection. Epithelial cells and phagocytes also produce antimicrobial peptides such as defensins and cathelicidins as a defense. 

Autophagy is another important defense mechanism. During autophagy, epithelial cells and macrophages degrade P. lacydonensis or damaged cell components by forming double-membrane vesicles called autophagosomes. This process plays a key role in the body’s fight against the bacteria. 

Peptoniphilus lacydonensis is a newly discovered bacteria linked to humans. It was first found in a patient with chronic sinus issues and nose cancer. This new bacterium can cause many infections. It can infect the skin, soft tissues, bones, joints, surgery sites, the womb lining, and the bloodstream. 

Infections from Peptoniphilus lacydonensis often cause fever, pain, swelling, redness, pus, drainage, and dead tissue. Doctors should consider this bacterium, especially for long-lasting sinus infections or localized infections in different areas. 

Detecting P. lacydonensis infections combines culture techniques, biochemical testing, and molecular analysis. For cultures, the bacteria grow on a modified PYG medium under anaerobic or microaerophilic conditions at 37°C, forming tiny, pale, circular colonies. 

Biochemical tests using API rID32A strips identify the microbe through positive reactions indicating indole production, tryptophan breakdown, and nitrate reduction. Negative reactions arise for arginine dihydrolase, urease, and various sugar fermentations. 

More precise diagnosis utilizes molecular methods examining the 16S rRNA gene sequence, showing 97.7% similarity to the closely related P. harei species. Additionally, the availability of the bacterium’s complete genome sequence on GenBank enhances accurate identification. 

• Saline nasal sprays or irrigation devices can be used. These flush out the sinuses, reducing inflammation. They may prevent sinus-related infections caused by P. lacydonensis. 

• Good hygiene habits like often cleaning and disinfecting stomach, skin, and mouth areas help stop P. lacydonensis from spreading or colonizing. 

• Staying hydrated and avoiding smoke support a healthy immune system. Drinking plenty of fluids and avoiding smoking which contribute to resistance against infections, including those caused by P. lacydonensis.  

Bloodstream infections due to Peptoniphilus spp.: report of 15 cases – PMC (nih.gov) 

Peptoniphilus lacydonensis sp. nov., a new human-associated species isolated from a patient with chronic refractory sinusitis – PubMed (nih.gov)