Shewanella species are rod-shaped gram-negative bacteria that live in saprophytic environments and are members of the family Vibrionaceae. It is often found in nonhuman sources and is rarely thought to be dangerous to people. Shewanella spp. are found all over the world, and their native habitats include soil and water. At first, they were thought to be saprophytes or colonizers, that thrived on dead or dying tissue.
The gram-negative bacillus Shewanella Putrefaciens is non-fermentative and motile. The species is a member of the genus Shewanella, which was established in honor of James Shewan, a microbiologist who made exceptional contributions to the study of marine microorganisms. Shewanella Putrefaciens is recognized as a significant seafood-spoiling bacterium.
Shewanella Putrefaciens Identification
Shewanella Putrefaciens can attach to surfaces like other Gram-negative bacteria. It can make thick biofilms on surfaces when it grows in places with a lot of nutrients. It is possible to differentiate it from other bacteria based on its Gram morphology, its inability to ferment lactose, its positive oxidase reaction, and its preference for growing at 42 degrees Celsius. Shewanella spp. is identified as the oxidase-positive, non-fermenter gram-negative bacillus that produced H2S gas in TSI slant because it is the only non-fermenter that creates hydrogen sulfide gas in TSI agar.
Shewanella putrefaciens is a significant proteinaceous food-spoiling bacterium, especially for marine chilled fish, due to its capacity to develop at low temperatures and create amines and volatile sulfides. The creature has a significant role in the environment and is presumably involved in the geosphere’s metal turnover.
Shewanella putrefaciens is found everywhere and rarely causes human disease. Shewanella can be extracted from water, natural gas, petroleum, dairy, meat, and fish.
Shewanella Putrefaciens Infection
The only non fermentative gram-negative rod that makes hydrogen sulfide is Shewanella Putrefaciens. Temperature and salinity of seawater are correlated with Shewanella Putrefaciens infections. This means that Shewanella infections happen in warm areas or temperate climates with warm summers.
Hepatobiliary illness, chronic leg ulcer, lack of attention to personal hygiene, peripheral vascular disease, and low socioeconomic position are key risk factors for S. Putrefaciens infection. These bacteria typically hide out in dead tissue or skin that has been stripped of its protective barrier, providing the perfect environment for an opportunistic infection to flourish. Infected leg ulcers, cellulitis, abscess formation, and wound infection are all clinical symptoms of soft tissue infections.
S. putrefaciens infections typically manifest on the skin or in the soft tissues around areas of damaged skin (trauma, cut, ulcer, otitis media). Primary bacteremia with a fulminant course can also occur in immunocompromised persons. S. Putrefaciens doesn’t usually cause infections in the lower respiratory system.
Shewanella Putrefaciens Gram Staining
Shewanella is a gram-negative rod that can range in length from short to long and be filamentous on Gram stain. It grows easily and produces small to medium-sized colonies with a brown-to-tan or yellow-orange soluble pigment that discolors the medium greenish. Colonies may possess a mucoid consistency and a fishy odor. Shewanella, the only non-fermenter that makes hydrogen sulfide on triple sugar iron agar, is oxidase positive and relatively easy to identify in the lab.
Shewanella Putrefaciens Treatment
Infections caused by Shewanella are capable of affecting multiple organs. Surgical therapy/drainage and antibiotics are effective treatments for most Shewanella infections. The most effective medicines include meropenem, gentamicin, and third-generation cephalosporins, however, two of the isolates are resistant to several drugs. Aminoglycosides, carbapenems, erythromycin, and quinolones are effective against Shewanella putrefaciens, however, penicillin is ineffective.
The initial empirical treatment for sepsis is piperacillin-tazobactam. The results of in vitro testing for isolates’ antimicrobial susceptibility are typically used to guide targeted treatment. Patients generally receive β-lactams, aminoglycosides, and quinolones, which work well.