Metagenomic sequencing of the skin microbiota of the scalp predicting the risk of surgical site infections following surgery of traumatic brain injury in sub-Saharan Africa.

BACKGROUND: Surgical site infections (SSI) are a significant concern following traumatic brain injury (TBI) surgery and often stem from the skin's microbiota near the surgical site, allowing bacteria to penetrate deeper layers and potentially causing severe infections in the cranial cavity. This study investigated the relationship between scalp skin microbiota composition and the risk of SSI after TBI surgery in sub-Saharan Africa (SSA). METHODS: This was a prospective cohort study, enrolling patients scheduled for TBI surgery. Sterile skin swabs were taken from the surrounding normal skin of the head and stored for analysis at -80°Celcius. Patients were monitored postoperatively for up to three months to detect any occurrences of SSI. 16S rRNA sequencing was used to analyze the skin microbiota composition, identifying different taxonomic microorganisms at the genus level. The analysis compared two groups: those who developed SSI and those who did not. RESULTS: A total of 57 patients were included, mostly male (89.5%) with a mean age of 26.5 years, predominantly from urban areas in Uganda and victims of assault. Graphical visualization and metagenomic metrics analysis revealed differences in composition, richness, and evenness of skin microbiota within samples (α) or within the community (ß), and showed specific taxa (phylum and genera) associated with either the group of SSI or the No SSI. CONCLUSIONS: Metagenomic sequencing analysis uncovered several baseline findings and trends regarding the skin microbiome's relationship with SSI risk. There is an association between scalp microbiota composition (abundancy and diversity) and SSI occurrence following TBI surgery in SSA. We hypothesize under reserve that the scalp microbiota dysbiosis could potentially be an independent predictor of the occurrence of SSI; we advocate for further studies with larger cohorts.

Validation of 18F-FDG PET at conventional and delayed intervals for the discrimination of high-grade from low-grade gliomas: a stereotactic PET and MRI study.

AIM: The aim of this study was to validate 18F-FDG PET imaging for differentiating high-grade gliomas (HGGs) from low-grade gliomas (LGGs). METHODS: Twenty-one patients with gliomas undergoing a stereotactic biopsy underwent PET scanning at conventional and delayed intervals, diagnostic and stereotactic MR examinations. To calculate the uptake at the biopsy site, a 2-mm voxel was selected. Uptake in this voxel was expressed as a percentage of the average uptake per voxel in the normal brain. The difference in uptake between HGG and LGG at conventional and late intervals and the difference in uptake difference between HGG and LGG at both intervals were analyzed using t tests as well as a mixed-model analysis of variance. RESULTS: At conventional intervals, uptake in LGG was 67% of that in the normal brain. Between early and late intervals, a significant decrease in uptake of 11% (±2.5%) was noted (P = 0.001). Uptake in HGG at conventional intervals was 138% of that in the normal brain. Between early and late intervals, a significant increase in uptake of 43% (±11%) was noted (P = 0.005). The difference in uptake between HGG and LGG was significant both at conventional and delayed intervals (P < 0.001). Moreover, the difference in uptake between both groups was significantly greater (31%) at delayed than at conventional intervals (2%) (P < 0.001). CONCLUSIONS: The results of this correlative study between tumor grade and 18F-FDG uptake both determined at the stereotactic biopsy site indicate that PET, particularly at delayed intervals, is valid for discriminating LGG from HGG.

Distribution patterns of 18F-labelled fluoromethylcholine in normal structures and tumors of the head: a PET/MRI evaluation.

PURPOSE: To evaluate the distribution of 18F-labelled fluoromethylcholine (FCho) in normal structures and tumors of the head region using positron emission tomography (PET) and magnetic resonance imaging. MATERIALS AND METHODS: We retrospectively reviewed the positron emission tomography, magnetic resonance imaging, and the coregistered images obtained in 17 patients with suspected high-grade gliomas. The accumulation of 18F-FCho in the normal structures and in brain lesions was visually and semiquantitatively assessed. A 4-point grading system was used for the visual analysis. A standardized uptake value (SUV) was used to quantify uptake. RESULTS: In the normal brain parenchyma, 18F-FCho uptake was faint (SUVmean, 0.15 ± 0.03 (SD)). Uptake was generally moderate in the choroid plexus (SUVmean, 0.82 ± 0.16), cavernous sinus (SUVmean, 0.87 ± 0.19), extraocular eye muscles (SUVmean, 1.10 ± 0.27), masticatory muscles (SUVmean, 0.99 ± 0.22), and bone marrow (SUVmean, 1.06 ± 0.26), whereas uptake was usually moderately intense in the pituitary gland (SUVmean, 1.90 ± 0.21). Uptake was variable in the lacrimal glands and the mucosa of the nasal cavity (for SUVmean of subgroups see text). Intense uptake was observed in the parotid glands (SUVmean, 3.27 ± 0.73). (Moderately) intense 18F-FCho uptake was observed in glioblastomas (range SUVmax, 2.26-6.37) and typical meningiomas (range SUVmax, 3.75-5.81). Uptake was globally faint in grade II and III gliomas (range SUVmax, 0.33-0.78). 18F-FCho uptake was also demonstrated in benign lesions, such as a tumefactive demyelinating brain lesion. CONCLUSIONS: 18F-FCho uptake was faint in the normal brain parenchyma and usually moderate in the choroid plexus, cavernous sinus, extraocular eye muscles, masticatory muscles, and bone marrow. Uptake in the pituitary gland was generally moderately intense, whereas uptake in the lacrimal glands and the mucosa of the nasal cavity was variable. Parotid glands had intense uptake. Also, uptake in glioblastomas and meningiomas was usually (moderately) intense, whereas uptake in grade II and III gliomas was globally faint. However, 18F-FCho uptake was not tumor specific.