Aims:  To compare the bacteriostatic and bactericidal activity of 13 chemotyped essential oils (EO) on 65 bacteria with varying sensitivity to antibiotics. Methods and Results:  Fifty‐five bacterial strains were tested with two methods used for evaluation of antimicrobial activity (CLSI recommendations): the agar dilution method and the time‐killing curve method. EO containing aldehydes (Cinnamomum verum bark and Cymbopogon citratus), phenols (Origanum compactum, Trachyspermum ammi, Thymus satureioides, Eugenia caryophyllus and Cinnamomum verum leaf) showed the highest antimicrobial activity with minimum inhibitory concentration (MIC) <2% (v/v) against all strains except Pseudomonas aeruginosa. Alcohol‐based EO (Melaleuca alternifolia, Cymbopogon martinii and Lavandula angustifolia) exhibited varying degrees of activity depending on Gram status. EO containing 1·8‐cineole and hydrocarbons (Eucalyptus globulus, Melaleuca cajeputii and Citrus sinensis) had MIC90% ≥ 10% (v/v). Against P. aeruginosa, only C. verum bark and O. compactum presented MIC ≤2% (v/v). Cinnamomum verum bark, O. compactum, T. satureioides, C. verum leaf and M. alternifolia were bactericidal against Staphylococcus aureus and Escherichia coli at concentrations ranging from to 0·31% to 10% (v/v) after 1 h of contact. Cinnamomum verum bark and O. compactum were bactericidal against P. aeruginosa within 5 min at concentrations <2% (v/v). Conclusions:  Cinnamomum verum bark had the highest antimicrobial activity, particularly against resistant strains. Significance and Impact of the Study:  Bacteriostatic and bactericidal activity of EO on nosocomial antibiotic‐resistant strains.

The cases of 52 patients with Propionibacterium acnes infection of orthopaedic implants are summarized: 20 patients with definite infection (sepsis, with P. acnes recovered from multiple specimens per patient), 15 with probable infection (sepsis, with P. acnes recovered from one specimen), and 17 with possible infection (signs of prosthetic malfunction or pseudo-osteoarthritis, with P. acnes recovered from one specimen). The patient population consisted of 37 males and 15 females with a mean age of 51.8 years (range 17-88). Besides bone surgery, 21% of these patients had severe coexisting illness. The study population was very heterogeneous and clinical presentation very polymorphic; infections became clinically apparent through sepsis, prosthetic malfunction, or a delay in consolidation. The diagnosis was highly dependent on the quality of the samples taken and the methodology used by the microbiology laboratory to isolate this bacterium. Culture time was long, on average 11.4 days. Treatment involved a combination of antibiotic treatments (67% of cases) and ablation of the material (83% of cases). Although P. acnes is considered to be weakly pathogenic, this bacterium may be responsible for infections in patients with implanted orthopaedic material. Ablation of the arthroplastic or osteosynthetic material is necessary in the majority of cases.

Staphylococcus aureus nasal carriage is a well-defined risk factor of infection with this bacterium. The increased risk of S. aureus infection in nasal carriers is supported by the fact that the strains isolated from both colonization and infection sites are indistinguishable in most of the cases. Persistent nasal carriage seems to be associated with an increased risk of infection and this status could be defined now in clinical routine by using one or two quantitative nasal samples. There is evidence for supporting the detection of nasal carriage of S. aureus in patients undergoing cardiac surgery and in those undergoing hemodialysis in order to implement decolonization measures. More studies are needed to determine which carriers have the highest risk of infection and why decolonization strategies failed to reduce S. aureus infection in some other groups of patients.

Cultures and eubacterial PCR are complementary techniques for bacterial identification in eyes with acute postcataract endophthalmitis. PCR technique was needed for identification of the involved microbial pathogen in 25% of all the cases. Eubacterial PCR is more effective than cultures in detecting bacteria in vitreous samples from patients with previous intravitreous administration of antibiotics.

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These results emphasize the need for applying various infection control measures to prevent colonization of patients with P. aeruginosa, including strategies to limit the potential of sinks from acting as a source or reservoir for this bacterium.

Up to 15% of patients infected by SARS-CoV-2 present severe forms requiring hospitalisation in intensive care units and which are associated with high mortality. The prevalence of bacterial infections in these patients is not well established and more data are needed to guide empiric antibiotic therapy and improve patient outcomes. In this prospective multicenter study, we assessed bacterial co-infections identified in culture from 99 French patients infected by SARS-Cov-2 and hospitalized in intensive care units. We concomitantly evaluated the value of the use of an innovative molecular diagnostic technologies, the BioFire® FilmArray® Pneumonia Panel plus (FA-pneumo) assay, to early identify these co-infections in these patients and the concordance with conventional culture. We showed that a bacterial co-infection was detected in 15% of patients based on conventional culture. S. aureus and H. influenzae were the most prevalent pathogens. The sensitivity of FA-pneumo compared to culture was 100%. Conversely, the specificity varied between 88.4 and 100% according to the pathogen and our results highlighted that 60.5% of bacterial targets reported using this assay were not recovered by culture; 76.9% of discordant results corresponded to bacteria belonging to commensal oral flora and/or reported with ≤ 10 5 copies/mL of bacterial nucleic acids. Based on its excellent sensitivity, the FA-pneumo assay is useful to rule out bacterial co-infections in the context of severe SARS-CoV-2 infection and avoid the inappropriate prescription of antibiotics. However, positive tests should be interpreted carefully taking into consideration DNA bacterial load, all clinical and biological signs.