Clostridium ramosum rapidly identified by MALDI-TOF MS. A rare gram-variable agent of bacteraemia

Co-Colonization of Non-difficile Clostridial Species in Antibiotic-Associated Diarrhea Caused by Clostridioides difficile

Background/Objectives: Antibiotic-associated diarrhea (AAD) is a public health problem that develops in the hospital setting. The most common causative agent of AAD is Clostridioides difficile infection (CDI), although other non-difficile Clostridia (NDC) might also be present. NDC include members of the RIC group such as Clostridium ramosum [T. ramosa], Clostridium innocuum and Clostridium clostridioforme [E. clostridioformis]. The co-colonization of NDC and CDI in patients with AAD has not been fully analyzed. Methods: We compared clinical and laboratory data of patients with C. difficile infection (CDI) plus NDC against patients with only CDI. This study was a retrospective, case-control study. Hospitalized confirmed CDI cases were analyzed. CDI detection was performed using a 2-step diagnostic algorithm, including glutamate dehydrogenase (GDH) with toxin A/toxin B assays and molecular detection of the tpi gene. Stool samples were cultured and colonies morphologically compatible with any Clostridia were identified with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Fisher's exact test and odds ratio (OR) were calculated to determine the degree of correlation between the variables and the study groups. Results: In the CDI + NDC group (n = 7), positive culture was observed for C. ramosum [T. ramosa] (n = 3), C. innocuum (n = 3), and C. butyricum (n = 1). According to our results, CDI + NDC patients received more days of antibiotic therapy, took more days to reduce diarrhea, had a significant increase in the number of days to suppress diarrhea, and previous hospitalizations were more frequently reported. Conclusions: In conclusion, the positive culture of NDC species such as C. innocuum or C. ramosum in patients with AAD caused by CDI correlates with treatment extension and/or failure.

Aspiration Pneumonia Leading to Clostridium ramosum Bacteremia in a Neutropenic Patient: Case Report and Management Strategy

BACKGROUND Clostridium ramosum is an anaerobic, spore-producing, gram-positive rod, enteric pathogen that is difficult to identify and is rarely pathogenic. We present a case of Clostridium ramosum bacteremia secondary to aspiration pneumonia in a 65-year-old immunocompromised man on chemotherapy for follicular lymphoma. CASE REPORT We report the case of a 65-year-old man, on active chemotherapy for follicular lymphoma, presenting with a fever of 38.3°C, nonproductive cough, fatigue, and confusion. Physical examination was unremarkable except for +2 lower-extremity pitting edema. CT abdomen pelvis showed left lower-lung consolidation and CT chest angiogram showed that the consolidation was concerning for infarct verses abscess and segmental/subsegmental pulmonary emboli despite anticoagulation use. Blood cultures later grew Clostridium ramosum, which was successfully treated with IV piperacillin-tazobactam. Subsequent outpatient imaging demonstrated resolution of the lung consolidation. CONCLUSIONS Our case highlights the rare diagnosis of Clostridium ramosum bacteremia secondary to aspiration pneumonia in an immunocompromised patient and our approach to management. We highlight the difficulties in identification of Clostridium ramosum, rare pathogenicity, risk factors, and potential sources.

Antimicrobial Evaluation of Two Polycyclic Polyprenylated Acylphloroglucinol Compounds: PPAP23 and PPAP53

Polycyclic polyprenylated acylphloroglucinols (PPAPs) comprise a large group of compounds of mostly plant origin. The best-known compound is hyperforin from St. John's wort with its antidepressant, antitumor and antimicrobial properties. The chemical synthesis of PPAP variants allows the generation of compounds with improved activity and compatibility. Here, we studied the antimicrobial activity of two synthetic PPAP-derivatives, the water-insoluble PPAP23 and the water-soluble sodium salt PPAP53. In vitro, both compounds exhibited good activity against methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecium. Both compounds had no adverse effects on Galleria mellonella wax moth larvae. However, they were unable to protect the larvae from infection with S. aureus because components of the larval coelom neutralized the antimicrobial activity; a similar effect was also seen with serum albumin. In silico docking studies with PPAP53 revealed that it binds to the F1 pocket of human serum albumin with a binding energy of -7.5 kcal/mol. In an infection model of septic arthritis, PPAP23 decreased the formation of abscesses and S. aureus load in kidneys; in a mouse skin abscess model, topical treatment with PPAP53 reduced S. aureus counts. Both PPAPs were active against anaerobic Gram-positive gut bacteria such as neurotransmitter-producing Clostridium, Enterococcus or Ruminococcus species. Based on these results, we foresee possible applications in the decolonization of pathogens.

Clostridium ramosum Bacteremia in an Immunocompetent Patient with SARS-CoV-2 Infection: A Case Report

We report a case of Clostridium ramosum bacteremia in a 73-year-old patient with SARS-CoV-2 infection and right lower abdominal tenderness in China. The microbiological features and genomic epidemiological characteristics of C. ramosum worldwide were investigated to identify the possible sources of infection. Whole-genome sequencing of C. ramosum WD-I2 was performed using an Illumina NovaSeq 6000 platform. Phylogenetic analysis of C. ramosum WD-I2 and other publicly available C. ramosum isolates was performed and visualized using the interactive Tree of Life (iTOL) web server. The resistome of C. ramosum WD-I2 consists of two antimicrobial resistance genes (tetM and ermB), which explains the antimicrobial resistance trait to tetracycline and macrolides. Phylogenetic analysis showed that the strain closest to our isolated strain WD-I2 was SUG1069, recovered from a pig feces sample from Canada, which differed by 589 SNPs. To our knowledge, this is the first report of C. ramosum bacteremia in China. Our findings highlight the potential risk of invasive C. ramosum infections during the COVID-19 pandemic.

Bacterial pathogens in pediatric appendicitis: a comprehensive retrospective study

Background

Appendicitis is a frequent condition, with peak incidences in the second decade of life. Its pathogenesis is under debate, but bacterial infections are crucial, and antibiotic treatment remains essential. Rare bacteria are accused of causing complications, and various calculated antibiotics are propagated, yet there is no comprehensive microbiological analysis of pediatric appendicitis. Here we review different pre-analytic pathways, identify rare and common bacterial pathogens and their antibiotic resistances, correlate clinical courses, and evaluate standard calculated antibiotics in a large pediatric cohort.

Method

We reviewed 579 patient records and microbiological results of intraoperative swabs in standard Amies agar media or fluid samples after appendectomies for appendicitis between May 2011 and April 2019. Bacteria were cultured and identified via VITEK 2 or MALDI-TOF MS. Minimal inhibitory concentrations were reevaluated according to EUCAST 2022. Results were correlated to clinical courses.

Results

Of 579 analyzed patients, in 372 patients we got 1330 bacterial growths with resistograms. 1259 times, bacteria could be identified to species level. 102 different bacteria could be cultivated. 49% of catarrhal and 52% of phlegmonous appendices resulted in bacterial growth. In gangrenous appendicitis, only 38% remained sterile, while this number reduced to 4% after perforation. Many fluid samples remained sterile even when unsterile swabs had been taken simultaneously. 40 common enteral genera were responsible for 76.5% of bacterial identifications in 96.8% of patients. However, 69 rare bacteria were found in 187 patients without specifically elevated risk for complications.

Conclusion

Amies agar gel swabs performed superior to fluid samples and should be a standard in appendectomies. Even catarrhal appendices were only sterile in 51%, which is interesting in view of a possible viral cause. According to our resistograms, the best in vitro antibiotic was imipenem with 88.4% susceptible strains, followed by piperacillin-tazobactam, cefuroxime with metronidazole, and ampicillin-sulbactam to which only 21.6% of bacteria were susceptible. Bacterial growths and higher resistances correlate to an elevated risk of complications. Rare bacteria are found in many patients, but there is no specific consequence regarding antibiotic susceptibility, clinical course, or complications. Prospective, comprehensive studies are needed to further elicit pediatric appendicitis microbiology and antibiotic treatment.

Clostridium ramosum Bacteremia With Mesenteric Ischemia Secondary to Superior and Inferior Mesenteric Arteries Occlusion

Clostridium ramosum, despite being a common enteric bacterium, is not commonly identified as the cause of pathologic infections in humans. It was first identified by Veillion and Zuber in 1898 from a patient with pulmonary gangrene and appendicitis. After performing an extensive literature search of major databases, only a few cases of pathologic C. ramosum infection were found in the medical literature. In this piece of work, we add to existing research by presenting a case report of an 83-year-old female who presented with abdominal pain, fever, and shortness of breath, requiring ICU admission due to mesenteric ischemia and C. ramosum bacteremia.

Clostridium ramosum bacteremia: A case series at a general acute care hospital

Clostridium ramosum infections have been rarely reported, probably due to underestimating in clinical practice. Seven patients with bacteremia from gastrointestinal sources and skin and soft tissue were recognized between 2009 and 2020. Most of them were older and in compromised status, and they had risk factors including cancer, diabetes, liver cirrhosis, gangrene, and pressure ulcers. The source of infections was considered bacterial translocation from the gastrointestine and the skin and soft tissue infections. All patients were treated with antimicrobials, and two received surgical interventions. Four patients died secondary to sepsis due to C. ramosum. The bacteremia of C. ramosum should be appropriately evaluated and treated, especially in compromised hosts.