Cutibacterium avidum: A Potent and Underestimated Pathogen in Prosthetic Hip Joint Infections.

Cutibacterium avidum has recently been reported as a rare cause of prosthetic joint infections (PJIs), contrary to Cutibacterium acnes, which is well established as a cause of PJIs, especially in shoulder arthroplasties. Two specific risk factors for PJI due to C. avidum have been reported: obesity and the skin incision approach. Here, we report four cases of hip PJIs caused by C. avidum admitted over a 30-month period at a single center. Whole-genome sequencing revealed that the four C. avidum strains were all individual strains and did not originate from a common source, such as an outbreak. Antibiotic susceptibility tests showed that the isolates were fully susceptible, and none carried known antibiotic resistance genes. In conclusion, the occurrence of four cases of PJI caused by C. avidum over a limited time at a single center may indicate that this pathogen is underestimated and is either emerging or more common than previously recognized. The patients presented overt signs of infection during surgery, indicating that C. avidum is a virulent pathogen. None of the previously reported risk factors for C. avidum PJI applied to these patients as only one was obese and none were operated on using a direct anterior skin incision approach.

The impact of the ST131 clone on recurrent ESBL-producing E. coli urinary tract infection: a prospective comparative study.

The global emergence of extended-spectrum beta-lactamase-producing Escherichia coli (ESBL-E. coli), mainly causing urinary tract infections (UTI), is of great concern. Almost one third of patients with UTI, develop recurrent UTI (RUTI). We followed 297 patients for one year after their first episode of UTI due to ESBL-E. coli. Our aim was to evaluate the impact of the globally dominant sequence type (ST)131 clone and its clades, on the risk of subsequent recurrences with ESBL-E. coli. Isolates from patients developing RUTI (68/297) were compared with those from patients with sporadic UTI (SUTI, 229/297). No association was found between RUTI and the two most prevalent phylogroups B2 and D, blaCTX-M genes, or resistance profile. Half of the patients with RUTI were infected with ST131 isolates. Clade C2 were in dominance (50/119) among ST131 isolates. They were more common in patients with RUTI than SUTI (28% vs 13%) and multivariate analysis showed an increased odds-ratio (OR = 2.21, p = 0.033) for recurrences in patients infected with these isolates as compared to non-ST131 isolates. Detecting specific biomarkers, as ST131 clade C2, in ESBL-E. coli UTI isolates may aid in prediction of RUTI and improve diagnostics and care of patients with a risk of ESBL-E. coli recurrences.

Mass Spectrometry Proteotyping-Based Detection and Identification of Staphylococcus aureus, Escherichia coli, and Candida albicans in Blood.

Bloodstream infections (BSIs), the presence of microorganisms in blood, are potentially serious conditions that can quickly develop into sepsis and life-threatening situations. When assessing proper treatment, rapid diagnosis is the key; besides clinical judgement performed by attending physicians, supporting microbiological tests typically are performed, often requiring microbial isolation and culturing steps, which increases the time required for confirming positive cases of BSI. The additional waiting time forces physicians to prescribe broad-spectrum antibiotics and empirically based treatments, before determining the precise cause of the disease. Thus, alternative and more rapid cultivation-independent methods are needed to improve clinical diagnostics, supporting prompt and accurate treatment and reducing the development of antibiotic resistance. In this study, a culture-independent workflow for pathogen detection and identification in blood samples was developed, using peptide biomarkers and applying bottom-up proteomics analyses, i.e., so-called "proteotyping". To demonstrate the feasibility of detection of blood infectious pathogens, using proteotyping, Escherichia coli and Staphylococcus aureus were included in the study, as the most prominent bacterial causes of bacteremia and sepsis, as well as Candida albicans, one of the most prominent causes of fungemia. Model systems including spiked negative blood samples, as well as positive blood cultures, without further culturing steps, were investigated. Furthermore, an experiment designed to determine the incubation time needed for correct identification of the infectious pathogens in blood cultures was performed. The results for the spiked negative blood samples showed that proteotyping was 100- to 1,000-fold more sensitive, in comparison with the MALDI-TOF MS-based approach. Furthermore, in the analyses of ten positive blood cultures each of E. coli and S. aureus, both the MALDI-TOF MS-based and proteotyping approaches were successful in the identification of E. coli, although only proteotyping could identify S. aureus correctly in all samples. Compared with the MALDI-TOF MS-based approaches, shotgun proteotyping demonstrated higher sensitivity and accuracy, and required significantly shorter incubation time before detection and identification of the correct pathogen could be accomplished.