Anaerobic bacteria, particularly Clostridium (C.) species (spp.), play a crucial role in the human intestinal biota, significantly influencing host physiology and health [1,2]. The utilization of ribosomal 16S rRNA gene sequencing as a novel standard for bacterial classification and identification has led to the analysis of numerous Clostridium spp., resulting in the discovery and classification of new spp [2].

In 2001, C. hathewayi was isolated from human feces and was named in tribute to Charles L. Hatheway's contributions to the C. botulinum group [3]. Despite typically being anaerobic gram-positive bacilli, C. hathewayi, akin to C. clostridioforme, often exhibits a gram-negative and endpointed morphology [2,4]. In 2014, Hungatella effluvii, an obligately anaerobic gram-positive, rod-shaped bacterium, was isolated from an effluent treatment plant [4]. This discovery led to the establishment of the Hungatella (H.) genus, and C. hathewayi was subsequently renamed H. hathewayi due to its close relationship with H. effluvii [4].

While generally considered nonpathogenic components of the human gut microbiome [5], human infections caused by H. hathewayi or H. effluvii have been reported, with ten documented cases to date [1,2,[6], [7], [8], [9], [10], [11], [12], [13]]. Here, we highlight a patient's hospitalization due to hyperosmolar hyperglycemic state (HHS) with septic shock, associated with H. hathewayi bacteremia stemming from acute appendicitis. Notably, the presence of the bacterium in the bloodstream preceded the appearance of clinical and radiographic signs indicative of acute appendicitis. Furthermore, a thorough literature review has been conducted to compare this case with all reported human infections involving both Hungatella spp.