The probing of live bacteria via the incorporation of fluorescent D-amino acids (FDAAs) during peptidoglycan synthesis has been shown to be practical for visualizing both gram-positive and gram-negative bacterial species. This study demonstrates the reliability and applications of FDAA labelling for the fluorescent imaging of an obligate anaerobe.
Paeniclostridium sordellii is responsible for severe infections in horses, cattle, and sheep, however, conventional vaccines exhibit limitations in production and immunogenicity. This study assessed the immunogenicity of a recombinant bacterin composed of a chimera (rQTcsHL) that combines segments from the lethal (TcsL) and hemorrhagic (TcsH) toxins in mice and sheep. Both immunized animal groups exhibited elevated levels of IgG, with the mice demonstrating moderate protection (<50 %) against lethal challenges, comparable to that of the conventional vaccine. Further molecular optimization is essential to enhance its efficacy.
Clostridioides (Clostridium) difficile (C. difficile) infection (CDI), often severe when producing toxin A, toxin B, and CDT, can cause life-threatening fulminant infections, especially in vulnerable patients. This case report discusses a 39-year-old woman with no medical history who developed severe CDI after antibiotic treatment, leading to fatal hypovolemic shock. A rare C. difficile PCR-ribotype 153 strain which is positive for toxin A, toxin B, and CDT was identified. This case emphasizes the need for early CDI diagnosis, cautious antibiotic use, and prompt treatment to prevent severe outcomes like shock and multiorgan failure.
Objectives: To describe Clostridioides difficile infection (CDI) rates and testing practices, at three tertiary/quaternary hospitals in South Africa (SA) for the period 2017 to 2020.
Methods: A retrospective laboratory record review of all C. difficile testing at the Charlotte Maxeke Johannesburg Academic Hospital (CMJAH), Tygerberg Hospital (TBH) and Inkosi Albert Luthuli Central Academic Hospital (IALCH) was performed. Clinical records of patients with rCDI were reviewed to determine recurrent CDI (rCDI) rates.
Results: The median primary CDI rates per 10 000 patient-days (PD) were 5.3 at CMJAH, 1.8 at TBH, and 0.3 at IALCH. In 2020, all hospitals reported an increase in primary CDI rates compared to 2019. The median testing rates per 10 000 PD were 39 at CMJAH, 14 at TBH, and 4 at IALCH. The median age of patients with primary CDI was 33 years (IQR: 22-45 years). The rCDI rates ranged from 2 to 5 per 100 incident episodes.
Conclusion: Significant variations in CDI and testing rates were observed across the three hospitals. An increase in CDI rates was noted at all centres during the 2020 SARS-CoV-2 outbreak. Advanced age was not prevalent in the cohort, and rCDI rates were relatively low. These findings highlight the need for systematic surveillance of healthcare-onset CDI across SA hospitals.
Introduction: Fusobacterium necrophorum is a rare but significant cause of septic arthritis, typically following oropharyngeal infections in adolescents. This anaerobic pathogen, commonly associated with Lemierre's syndrome, can lead to joint infections, posing risks for severe morbidity if diagnosis and treatment are delayed. Awareness and timely intervention are essential for preventing long-term joint damage.
Case report: We report the case of a 19-year-old woman who developed high fever and acute right hip pain one week after a sore throat. Imaging revealed septic arthritis, with F. necrophorum identified in both blood and synovial fluid cultures. She received intravenous piperacillin/tazobactam, followed by outpatient parenteral therapy through an elastomeric pump, achieving full recovery. This case adds to the 42 cases documented in our literature review, reinforcing the need for prompt antimicrobial therapy.
Conclusion: Fusobacterium-induced septic arthritis, though uncommon, should be considered in young patients presenting with joint infections post-pharyngitis. Early diagnosis and targeted antimicrobial therapy, particularly with β-lactamase inhibitors, are critical for effective management and preventing joint sequelae.
Objectives: To improve the identification of anaerobic bacteria, the identity of clinical isolates which could not be identified using MALDI-TOF MS was assessed using whole genome sequencing (WGS) and in-house made main spectral profiles (MSPs) were created. Four novel Anaerococcus species, each represented by at least two isolates, were encountered.
Methods: The novelty of the isolates was confirmed by comparing the 16S rRNA gene sequences and the WGS with their closest relatives. Phylogenetic and phylogenomic relationships were determined using MEGA X and DSMZ TYGS. Biochemical features were determined and the clustering of the created MSPs was calculated. Possible clinical relevance was assessed.
Results: The novelty of the four different species was confirmed by the ANI value, and phylogenetic/phylogenomic clustering. Three of these species shared the same biochemical features, while one showed a different pattern. Only this latter species can be differentiated from other Anaerococcus spp. Remarkebly, six of the ten isolates were obtained from a positive blood culture, of which in five cases the bacterium was the only species encountered.
Conclusions: We propose to name these novel species: Anaerococcus kampingiae (ENR0874T = DSM 117234T, CCUG 77487T (accession numbers PP192775/JBGMEF000000000)), Anaerococcus groningensis (ENR1011T = DSM 117232T, CCUG 77488T (accession numbers PP192777/JBGMEG000000000)), Anaerococcus martiniensis (ENR0831T = DSM 117233T, CCUG 77486T (accession numbers PP192776/JBGMEI000000000)), and Anaerococcus cruorum (ENR1039T = DSM 117235T, CCUG 77489T (accession numbers PP192778/JBGMEH000000000)).
Introduction: The presence of Clostridioides difficile in water, soil, fertilizers, and animal feces suggests the potential existence of C. difficile in foods that come into contact with these sources or become contaminated through indirect means.
Material & method: A total of 431 samples, consisting of spinach and carrots and raw milk and cheese obtained from cows, goats, buffalo, and sheep, were examined for the presence of C. difficile. Isolates were identified by real-time PCR, ribotyped, and their toxin profiles were determined. Antibiotic susceptibility to vancomycin, clindamycin, and metronidazole was evaluated using the E-test.
Results: C. difficile was detected in 3.27 % (4/122) of spinach, 1.85 % (2/108) of carrots, and 2.19 % (2/91) of milk samples. No C. difficile was detected in the cheeses (n = 110). All isolates were obtained from different fields/farms. Only one isolate (from spinach) carried the tcdA and tcdB toxin genes. Six different PCR ribotypes were detected, with two (001, 060) being identified. All isolates were sensitive to vancomycin, clindamycin, and metronidazole.
Conclusion: The prevalence of C. difficile in spinach, carrot, and milk samples from selected regions was low, and nontoxigenic strains were prevalent. Despite the low prevalence, the detection of C. difficile in these foods highlights the potential risk of foodborne transmission of this pathogen and underscores the need for monitoring and control strategies to ensure food safety.
Objective: Strains of carbapenem-resistant Bacteroides fragilis have frequently emerged in recent years. In China, data on the genotypic and phenotypic characteristics of these antimicrobial-resistant anaerobic bacteria are scarce. Thus, the aim of this study was to characterize clinical isolates of carbapenem-resistant B. fragilis collected from a tertiary hospital in China using whole genome sequencing (WGS), phenotypic susceptibility tests, and a biofilm formation assay.
Methods: We analyzed 49 B. fragilis strains with different antimicrobial resistance profiles. Antimicrobial susceptibility was determined using the agar dilution method and biofilm formation using a crystal violet assay. Genomic characteristics were analyzed using WGS, and the transcription level of cfiA, which is responsible for carbapenem resistance, was determined using quantitative reverse transcription polymerase chain reaction (PCR). Carbapenem-sensitive isolates were used as controls.
Results: All 49 B. fragilis isolates were biofilm producers and the percentage of carbapenem-resistant isolates was 42.86 % (21/49). The percentage of carbapenem-resistant isolates with medium-to-strong biofilm production ability was significantly lower than that of carbapenem-sensitive isolates (19.1 % vs. 88.9 %, p < 0.01). None of the carbapenem-resistant B. fragilis isolates carried bft. In contrast, 53.6 % (15/28) of the carbapenem-sensitive isolates carried bft, and all of them were fpn(+). All carbapenem-resistant isolates (21/21, 100 %) harbored cfiA and its upstream insertion sequence (IS) element. Three isolates (BF058, BF059, and BF060) carried the IS613 element, which was not immediately adjacent upstream to cfiA but was separated by a 1000-kb sequence encoding vatD. The quantitative PCR assay results revealed the elevated expression of cfiA mRNA among carbapenem-resistant isolates, although the relative expression levels varied greatly among isolates. However, a significant correlation between the relative expression level of cfiA mRNA and phenotypic carbapenem resistance was observed.
Conclusions: Carbapenem-resistant B. fragilis isolates carried a low frequency of virulence-related genes and showed weaker biofilm formation ability compared with carbapenem-sensitive B. fragilis isolates. CfiA was the dominant mediator of carbapenem resistance in B. fragilis. This study was the first to identify the structural plasticity of the cfiA-IS element, emphasizing the diverse and complex evolution of carbapenem resistance in B. fragilis, which warrants further investigation.
Introduction: Anaerobic digestion integrates waste treatment, energy generation, and nutrient recycling, producing methane mainly through acetoclastic (AM) and hydrogenotrophic methanogenesis (HM). Methanogenic pathway management can improve biogas productivity and quality. The balance between pathways is influenced by environmental and physicochemical conditions, with conflicting results on the effect of different factors often reported. This systematic review aims to clarify the influence of various parameters on methanogenic pathways in anaerobic digesters.
Methods: Literature search was conducted in the Web of Science and Scopus databases. The effects of different parameters on the predominant methanogenic pathway were evaluated using Kruskal-Wallis tests and Spearman's rank correlation.
Results: Thermophilic temperatures and high free ammonia nitrogen concentrations (>300 mg L-1) increase HM, with a strong combined effect of these variables. Conversely, under moderate temperature and ammonia concentrations, the primary feedstock influences the methanogenic pathway, with algae biomass, pig manure, and food industry wastewater showing the lowest contribution of hydrogenotrophic methanogens. pH effect varied with temperature, with acidic and alkaline pH favoring HM in mesophilic and thermophilic digesters, respectively. Furthermore, higher levels of volatile fatty acids (>2000 mg L-1), carbohydrates (>10 g/L) and lipids (>10 g/L) also appeared to favor HM over AM, while most metals - especially Cr, Se and W - promoted AM.
Conclusion: This study emphasizes the role of various factors in methanogenic pathway selection, highlighting the impact of previously overlooked parameters, such as inorganic elements and organic matter composition. These insights are essential for understanding the methanogenic pathway balance and optimizing biogas processes.
Objectives: Clostridioides difficile infection is a serious healthcare-associated infection linked to antimicrobial use. The severity of the disease can be associated with hypervirulent ribotypes such as RT027. The study aimed to investigate the molecular epidemiology and genomic characteristics of C. difficile isolates from private and public healthcare settings in South Africa.
Methods: One hundred clinical stool specimens were cultured on cycloserine-cefoxitin-fructose agar. Conventional multiplex polymerase chain reaction (M-PCR) assays were conducted for isolate identification and detection of toxin genes. Genomic characteristics of the isolates were determined using whole genome sequencing (WGS) and data was analysed using pubMLST, EnteroBase, Pathogenwatch and CARD.
Results: One hundred clinically presumptive C. difficile positive stool specimens were collected, of which 62 % (62/100) were confirmed as C. difficile by M-PCR assay. Among the 62 identified C. difficile isolates, 97 % (60/62) were toxigenic, with the most dominant toxin profile being A + B + CDT + according to the M-PCR assay. The results showed that 93 % (40/43) of the WGS analysed C. difficile strains clustered into clades 1 to 5. These 40 strains were categorized into 16 sequence types (STs), with ST1 (clade 2) being the most prevalent, representing 45 % (18/40), this strain is an RT027-associated strain previously epidemic hypervirulent strain. One major cluster (n = 18) comprising ST1 strains was identified in Gauteng Province and all the isolates associated with this cluster showed the same resistome (antimicrobial resistance genes and mutations: CDD-1, aac (6')-Ie-aph (2″)-Ia, PnimBG and Thr82Ile). The study also identified one strain as ST11, this strain is well known for its zoonotic potential, and two strains were identified as ST37 known as an epidemic strain. Strains from public healthcare settings exhibited genetic similarity, while those from private settings showed greater genetic diversity.
Conclusion: The study reported, for the first time, hypervirulent strains ST1 in Africa and ST11 in South Africa, with a minimum spanning tree indicating an ongoing ST1 outbreak.
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