Comparison of the in vitro activities of delafloxacin and comparators against Staphylococcus epidermidis clinical strains involved in osteoarticular infections: a CRIOGO multicentre retrospective study.

OBJECTIVES: Staphylococcus epidermidis bone and joint infections (BJIs) on material are often difficult to treat. The activity of delafloxacin has not yet been studied on S. epidermidis in this context. The aim of this study was to assess its in vitro activity compared with other fluoroquinolones, against a large collection of S. epidermidis clinical strains. METHODS: We selected 538 S. epidermidis strains isolated between January 2015 and February 2023 from six French teaching hospitals. One hundred and fifty-two strains were ofloxacin susceptible and 386 were ofloxacin resistant. Identifications were performed by MS and MICs were determined using gradient concentration strips for ofloxacin, levofloxacin, moxifloxacin and delafloxacin. RESULTS: Ofloxacin-susceptible strains were susceptible to all fluoroquinolones. Resistant strains had higher MICs of all fluoroquinolones. Strains resistant to ofloxacin (89.1%) still showed susceptibility to delafloxacin when using the Staphylococcus aureus 2021 CA-SFM/EUCAST threshold of 0.25 mg/L. In contrast, only 3.9% of the ofloxacin-resistant strains remained susceptible to delafloxacin with the 0.016 mg/L S. aureus breakpoint according to CA-SFM/EUCAST guidelines in 2022. The MIC50 was 0.094 mg/L and the MIC90 was 0.38 mg/L. CONCLUSIONS: We showed low delafloxacin MICs for ofloxacin-susceptible S. epidermidis strains and a double population for ofloxacin-resistant strains. Despite the absence of breakpoints for S. epidermidis, delafloxacin may be an option for the treatment of complex BJI, including strains with MICs of ≤0.094 mg/L, leading to 64% susceptibility. This study underlines the importance for determining specific S. epidermidis delafloxacin breakpoints for the management of BJI on material.

Cutibacterium namnetense osteosynthetic cervical spine infections: experience with two cases.

We report two uncommon cases of osteosynthetic cervical spine infection. Clinical patient features, microbiological strain characteristics, diagnostic methods, and treatment were analyzed. Both patients were male, and one had risk factors for surgical site infection. During surgery, perioperative samples were positive yielding an anaerobic microorganism identified as Cutibacterium namnetense by MALDI-TOF MS and confirmed by 16S rRNA/gyrB genes sequencing. All isolates were fully susceptible. C. namnetense osteosynthetic cervical spine infections are rare. Both cases were early surgical site infections. Bruker MALDI-TOF MS appears to be an excellent tool for rapid and accurate identification. Amoxicillin seems to be an option for the treatment.

Development and evaluation of automated synovial fluid total cell count on an Iris iQ® 200 for identifying patients at risk of septic arthritis.

Septic arthritis is a diagnostic emergency. The white blood cell (WBC) count, in synovial fluid (SF), can guide the diagnosis. From November 2021 to November 2022, we included 350 SF. The WBC count was performed with the Iris iQ® 200 compared with the manual method. Automated and manual counts displayed good correlation. However, a Bland Altman plot demonstrates a higher percentage difference at higher WBC counts. The use of Iris iQ® 200 for SF analysis enables a rapid and accurate assessment for WBC count. Its implementation would advantageously replace the long and tedious optical analysis in daily routine.

Systematic screening for digestive carriage of extended-spectrum ß-lactamase-producing Enterobacterales (E-ESBL) at hospital readmission among patients with past history of E-ESBL colonization or infection.

BACKGROUND: Extended-spectrum ß-lactamase-producing Enterobacterales (E-ESBL) are commensal multidrug-resistant (MDR) bacteria of the digestive tract whose prevalence has risen sharply worldwide and in Europe over the past two decades. AIM: To assess digestive carriage at hospital readmission of a large cohort of 2509 patients with E-ESBL carriage over a five-year survey; 833 (33%) patients were readmitted at least once. METHODS: A retrospective, single-centre survey conducted at a tertiary care hospital in France. FINDINGS: Among patients with several hospital readmissions (range: 2-13), the proportion of patients still E-ESBL-colonized at hospital readmission, detected by systematic screening for E-ESBL colonization, was >80% within an 18-month period after prior hospitalization with the first E-ESBL isolation. CONCLUSION: There is a need to reconsider the continuation of systematic screening for E-ESBL colonization because of a high rate of patients still colonized at hospital readmission over a long period of time.

Bartonella quintana infective endocarditis in a homeless man with unexpected positive blood culture.

Bartonella species represent important causative agents of blood culture-negative infective endocarditis (IE). Their diagnosis represents a challenge for microbiologists and often relies on serological and molecular tools. However, even if the sensitivity of blood culture remains low, it should not be definitely ruled out. Indeed, we report the unusual case of a 22 year-old Guinean homeless man diagnosed with an IE due to Bartonella quintana. Unexpectedly, conventional blood cultures were positive after 13 days of incubation. Subculture was obtained on blood and chocolate agar, after 15 days of incubation in a 5 % CO2 atmosphere. Bacterial identification was obtained up to the species level using molecular tools (16S rRNA gene amplification and sequencing). A literature review of B. quintana blood culture-positive IE was conducted and revealed eighteen similar reported cases on a 25-year period. This case illustrates that, despite low sensitivity, Bartonella IE may be diagnosed thanks to prolonged blood culture.

Assessment of the Performance of the Aptima Bacterial Vaginosis Assay Over a 3-Month Period in a French Hospital.

Bacterial vaginosis (BV) is the most common cause of abnormal vaginal discharge. BV represents a dysbiosis with the acquisition of a diverse community of anaerobic bacteria and a reduction in lactobacilli burden. Our objective was to evaluate the Aptima BV assay kit for the diagnosis of BV. From May to August 2019, we enrolled outpatients and inpatients, including nonpregnant women above 18 with vaginosis symptoms, consulting at Nantes University hospital. The Aptima BV assay measures the loads of Gardnerella vaginalis, Atopobium vaginae, and Lactobacillus species in relation to overall bacterial load. The Aptima BV assay was compared to Nugent scoring (NS). A total of 456 women were enrolled, and 347 patients met the inclusion criteria with data available for the analysis. NS was used to classify the samples and 144 (41.5%) samples were classified as normal (NS = 0-3), 45 (13%) as BV (NS = 7-10), 38 (11%) presented an intermediate vaginal microbiota (3 < NS < 7), 79 (22.7%) had various bacteria (excluding vaginal flora), 29 (8.3%) had insufficient bacterial density, and 12 (3.5%) had a predominance of yeasts. The Aptima BV kit displayed a sensitivity of 91.1% and specificity of 94.4% with a positive predictive value (PPV) of 83.7% and a negative predictive (NPV) value of 97.1%. The results of this monocentric retrospective study show that Aptima BV kit has a good diagnostic correlation compared to standard of care for dysbiotic diagnosis cases. IMPORTANCE The possibility exists of the involvement of a new molecular test in the routine algorithm of bacterial vaginosis diagnosis in microbiology laboratories. This manuscript reports on our experience, and we propose an organization combining Nugent scoring and molecular testing, especially for intermediate Nugent scores.

Accuracy of gradient diffusion method for susceptibility testing of dalbavancin and comparators.

OBJECTIVES: This multicenter study aimed to assess the performances of gradient diffusion (GD) method in comparison to broth microdilution (BMD) method for susceptibility testing of dalbavancin, daptomycin, vancomycin, and teicoplanin. METHODS: Minimum Inhibitory Concentrations (MICs) were retrospectively determined concomitantly by BMD and GD methods, for 93 staphylococci and enterococci isolated from clinical samples. BMD was considered as the gold standard. Essential (EA) and categorical agreements (CA) were calculated. Discordant categorical results were categorized as major (ME) and very major errors (VME). RESULTS: EA and CA were 95.7% and 96.8%, 82.8% and 100%, 97.8% and 96.8%, and 94.6% and 95.7% for dalbavancin, daptomycin, vancomycin, and teicoplanin respectively. Concerning dalbavancin, 3 ME without any VME were observed and discrepancies were low (≤ to 2 two-fold dilutions) between both methods. VME were noted in 1 and 3 cases for vancomycin and teicoplanin, respectively, and resulted from 1 two-fold dilution discrepancy in each case. EA was lower for daptomycin. When they were discrepant, BMD MICs were systematically higher than GD ones. Nevertheless, no categorical discrepancy was noted. CONCLUSIONS: GD appears as an acceptable and convenient alternative for dalbavancin, vancomycin, and teicoplanin MICs determination. Our study also emphasizes how achieving accurate daptomycin MICs remains challenging.

Enterobacter cloacae complex outbreak in a neonatal intensive care unit: multifaceted investigations and preventive measures are needed.

We report the investigation to control an Enterobacter cloacae complex outbreak in a neonatal intensive care unit from November 2020 to February 2021. Pulsed-field gel electrophoresis showed that five of eight cases were infected with a clonal strain. Breast pumps, shared among mothers in the unit, could have contributed to the spread of the clonal spread.

Low prevalence of Cutibacterium acnes in prostatic tissue biopsies in a French hospital.

We evaluated the Cutibacterium acnes prevalence in prostatic biopsies and characterized the strains at a molecular level. 18 out of 36 biopsies (50%) were sterile after seven days in culture. C. acnes was observed in only two biopsies. Its prevalence was low (5.6%). Finally, the molecular characterization revealed diverse clusters including phylotypes IA1, IB and II.

Misidentification of Cutibacterium namnetense as Cutibacterium acnes among clinical isolates by MALDI-TOF VitekMS: usefulness of gyrB sequencing and new player in bone infections.

The taxonomy modification of Propionibacterium sp. with the description of new species, especially Cutibacterium namnetense, raises the question of species distribution in routine clinical samples. We performed a retrospective study during 3 years before the implementation of MALDI-TOF. Two hundred sixty-nine isolates were included in the study. MALDI-TOF identification, 16S rRNA, and new developed gyrB partial sequencings were performed. The most representative species was C. acnes in 88% of the cases, regardless of the origin of the clinical sample. Eventually, we identified three C. namnetense strains, representing a 1.1% prevalence over the period of time, including two bone infections. MALDI-TOF databases should be regularly updated to incorporate new species. gyrB sequencing constitutes a both easy and relevant method to identify Cutibacterium sp. especially C. namnetense, a new player in bone infections.

Catheter-related bloodstream infection due to Tsukamurella pulmonis identified by MALDI-TOF spectrometry, 16S rRNA gene sequencing, and secA1 gene sequencing in an immunocompromised child: a case report and literature review.

Tsukamurella species are Gram-positive bacilli related to aerobic Actinomyces. Originally reported from the environment, Tsukamurella species have also been described in human infections, especially in bacteremia. A literature review analysis revealed that Tsukamurella spp. are often initially considered as contaminant microorganisms, especially due to bacterial identification issues. Here, we report a catheter-related bloodstream infection in an immunocompromised child caused by Tsukamurella pulmonis. Matrix-Assisted Laser Desorption/Ionization-Time Of Flight (MALDI-TOF) mass spectrometry allowed rapid genus-level identification and contributed to better patient care. However, accurate species-level identification required 16S rRNA gene sequencing and secA1 gene sequencing. Considering the increased number of Tsukamurella infections, the implementation of new Tsukamurella species in MALDI-TOF databases is required to be more discriminant.

Propionibacterium/Cutibacterium species-related positive samples, identification, clinical and resistance features: a 10-year survey in a French hospital.

A 10-year retrospective study of Propionibacterium/Cutibacterium-positive samples gathered from hospitalized patients was conducted at Nantes University hospital. A total of 2728 Propionibacterium/Cutibacterium-positive samples analyzed between 2007 and 2016 were included. Due to the implementation of MALDI-TOF identification in 2013, most non-Cutibacterium acnes isolates were identified a second time using this technology. Over that period, Cutibacterium acnes remained the most predominant species accounting for 91.5% (2497/2728) of the isolates, followed by Cutibacterium avidum (4.2%, 115/2728) and Cutibacterium granulosum (2.4%, 64/2728). Regarding the origin of samples, the orthopaedic department was the main Cutibacterium sample provider representing 51.9% (1415/2728) of all samples followed by the dermatology department (11.5%, 315/2728). Samples were recovered from various tissue locations: 31.5% (858/2728) from surgery-related samples such as shoulder, spine or hip replacement devices and 19.1% (520/2728) from skin samples. MALDI-TOF method revealed misidentification before 2013. Cutibacterium avidum was falsely identified as C. granulosum (n = 33). Consequently, MALDI-TOF technology using up-to-date databases should be preferred to biochemical identification in order to avoid biased species identification. Regarding antibiotic resistance, 14.7% (20/136) of C. acnes was resistant to erythromycin. 4.1% (41/1005) of C. acnes strains, 17.9% (12/67) of C. avidum strains and 3.6% (1/28) of C. granulosum strains were found resistant to clindamycin.

Risk factors for Cutibacterium acnes spinal implant-associated infection: a case-case-control study.

OBJECTIVES: The aim was to determine the characteristics of patients who developed Cutibacterium acnes spinal implant-associated infection (SIAI) and the associated risk factors. METHODS: We conducted two parallel case-control studies comparing 59 patients with SIAI caused by C. acnes (cases 1) and 93 patients with SIAI caused by other microorganisms (cases 2) diagnosed during 2010-2015 with 302 controls who underwent spinal instrumentation without subsequent infection. RESULTS: Late-onset infections (median time to diagnosis, 843 days versus 23 days; p < 0.001) were more common in cases 1 than in cases 2. However, 20/59 (34%) of cases 1 occurred within the first 3 months after the index surgery. In addition, cases 1 were less likely to have fever (27%, 16/59 versus 58%, 54/93; p 0.001) or wound inflammation (39%, 23/59 versus 72%, 67/93; p < 0.001). Moreover, 24/59 (40%) of cases 1 presented with polymicrobial infections, and staphylococcal pathogens accounted for 22/24 (92%) of the co-infections. By comparing and contrasting the two multivariate risk models (cases 1 versus controls and cases 2 versus controls), the following factors associated with C. acnes SIAI development were identified: age <54 years (adjusted odds ratio (aOR) 2.43, 95% confidence interval (CI) 1.09-5.58, p 0.03), a body mass index <22 kg/m2 (aOR 2.47, 95% CI 1.17-5.29, p 0.02), and thoracic instrumentation (aOR 16.1, 95% CI 7.57-37.0, p < 0.001). CONCLUSIONS: Future therapeutic and prophylactic studies on C. acnes SIAI should focus on young, thin patients who undergo spinal instrumentation procedures involving the thoracic spine.

Acne fulminans and Cutibacterium acnes phylotypes.

BACKGROUND: Acne fulminans (AF) is a rare and severe form of inflammatory acne. It is characterized by a sudden worsening of acne with appearance of ulceronecrotic lesions, which can be associated with systemic signs. Its pathophysiology and the best therapeutic strategy are only partially known. OBJECTIVE: Our main objectives were to describe the clinical and biological profile of AF patients and to determine whether there was a difference in Cutibacterium acnes phylotype in AF compared to acne vulgaris. The secondary objective was to assess the efficacy of different therapies. METHODS: A retrospective observational study was conducted in all patients followed for AF in our department between 2008 and 2018. Bacteriological samples were taken from each patient to analyse C. acnes phylotype distribution. The therapeutic response was assessed using the ECLA and GEA scales. RESULTS: Fifteen patients with a median age of 15 years were included (12 men, 80%). A family history of acne was found in 86.7% of patients. Nine patients (60%) had isotretinoin-induced AF. Only one patient (6.7%) showed systemic signs. The bacteriological culture was positive for C. acnes in 80% of patients. The predominant phylotype was IA1 in 60% of patients, corresponding to the predominant phylotype in acne vulgaris. Only 33.3% of patients were in remission after a first-line treatment with systemic corticosteroids, alone or in combination. Seven patients were treated with biotherapy, including five successfully with secukinumab. CONCLUSION: Our results suggest that there is no specific C. acnes phylotype associated with AF, raising the hypothesis that acute inflammation associated with AF may be more related to an abnormal cutaneous innate immunity activation. The use of preventive strategies, the impact of combined treatments and an assessment of the role of biotherapies, especially anti-IL-17, in AF treatment remain to be more investigated.

PK/PD targets of amikacin and gentamicin in ICU patients.

OBJECTIVES: We aimed to evaluate the probability to achieve PK-PD targets in patients with sepsis hospitalized in the intensive care unit (ICU) after a single dose of 30mg/kg of amikacin or 8mg/kg of gentamicin. PATIENTS AND METHODS: This single-center prospective study included 138 ICU patients with severe sepsis or septic shock with an indication for intravenous amikacin (N=89) or gentamicin (N=49). Maximum concentration (Cmax) was measured 30 minutes after infusion completion. PK/PD objectives were respectively Cmax≥60mg/L and ≥30mg/L for amikacin and gentamicin for empirical therapy, and a Cmax/MIC ratio≥8, as per French guidelines. RESULTS: The median Simplified Acute Physiology Score II was 43 and ICU case fatality rate was 34.8%. A causative bacterial agent was identified in 94 patients (68.1%). Three pathogens had acquired aminoglycoside resistance and 15 were naturally resistant. The targeted Cmax for the first dose was achieved in 53 patients (59.6%) receiving amikacin, and one (2.2%) patient receiving gentamicin. Cmax/MIC ratio≥8 was obtained in all patients infected with susceptible pathogens (N=72). Factors associated with Cmax≥60mg/L of amikacin in multivariate analysis were dose per kg of adapted body weight (OR=1.39, P<0.001) and renal clearance estimated with CKD-EPI formula (OR=0.98, P=0.003). CONCLUSIONS: Despite high doses, amikacin and gentamicin first Cmax remain dramatically low in ICU patients. However, an adequate Cmax/MIC ratio was reached in all patients.

Cutibacterium acnes phylotypes diversity loss: a trigger for skin inflammatory process.

BACKGROUND: Acne has long been understood as a multifactorial chronic inflammatory disease of the pilosebaceous follicle, where Cutibacterium acnes (subdivided into six main phylotypes) is a crucial factor. In parallel, the loss of microbial diversity among the skin commensal communities has recently been shown as often accompanied by inflammatory skin disorders. OBJECTIVE: This study investigated the association of C. acnes phylotype diversity loss and the impact on Innate Immune System (IIS) activation. METHODS: The IIS response of skin after incubation with phylotypes IA1, II or III individually and with the combination of IA1 + II + III phylotypes, was studied in an in vitro skin explant system. The inflammatory response was monitored by immunohistochemistry and ELISA assays, targeting a selection of Innate Immune Markers (IIMs) (IL-6, IL-8, IL-10, IL-17, TGF-ß). RESULTS: IIMs were significantly upregulated in skin when being incubated with phylotype IA1 alone compared with the combination IA1 + II + III. In parallel, ELISA assays confirmed these results in supernatants for IL-17, IL-8 and IL-10. CONCLUSION: We identify the loss of C. acnes phylotype diversity as a trigger for IIS activation, leading to cutaneous inflammation. These innovative data underline the possibility to set up new approaches to treat acne. Indeed, maintaining the balance between the different phylotypes of C. acnes may be an interesting target for the development of drugs.