- Volume 72, Issue 9, 2023

Introduction. There is emerging evidence of a potential role for PET-CT scan as an imaging biomarker to characterise the spectrum of tuberculosis infection (TBI) in humans and animal models.

Gap Statement. Synthesis of available evidence from current literature is needed to understand the utility of PET-CT for characterising TBI and how this may inform application of PET-CT in future TBI research.

Aim. The aims of this review are to summarise the evidence of PET-CT scan use in immunocompetent hosts with TBI, and compare PET-CT features observed in humans and animal models.

Methodology. MEDLINE, Embase and PubMed Central were searched to identify relevant publications. Studies were selected if they reported PET-CT features in human or animals with TBI. Studies were excluded if immune deficiency was present at the time of the initial PET-CT scan.

Results. Six studies – four in humans and two in non-human primates (NHP) were included for analysis. All six studies used 2-deoxy-2-[18F]fluoro-d-glucose (2-[18F]FDG) PET-CT. Features of TBI were comparable between NHP and humans, with 2-[18F]FDG avid intrathoracic lymph nodes observed during early infection. Progressive TBI was characterised in NHP by increasing 2-[18F]FDG avidity and size of lesions. Two human studies suggested that PET-CT can discriminate between active TB and inactive TBI. However, data synthesis was generally limited by human studies including inconsistent and poorly characterised cohorts and the small number of eligible studies for review.

Conclusion. Our review provides some evidence, limited primarily to non-human primate models, of PET-CT utility as a highly sensitive imaging modality to reveal and characterise meaningful metabolic and structural change in early TBI. The few human studies identified exhibit considerable heterogeneity. Larger prospective studies are needed recruiting well characterised cohorts with TBI and adopting a standardized PET-CT protocol, to better understand utility of this imaging biomarker to support future research.

Background. The spread of Enterobacteriaceae coproducing carbapenemases, 16S rRNA methylase and mobile colistin resistance proteins (MCRs) has become a serious public health problem worldwide. This study describes two clinical isolates of Klebsiella pneumoniae coharbouring bla IMP-1, armA and mcr-10.

Methods. Two clinical isolates of K. pneumoniae resistant to carbapenems and aminoglycosides were obtained from two patients at a hospital in Myanmar. Their minimum inhibitory concentrations (MICs) were determined by broth microdilution methods. The whole-genome sequences were determined by MiSeq and MinION methods. Drug-resistant factors and their genomic environments were determined.

Results. The two K. pneumoniae isolates showed MICs of ≥4 and ≥1024 µg ml−1 for carbapenems and aminoglycosides, respectively. Two K. pneumonaie harbouring mcr-10 were susceptible to colistin, with MICs of ≤0.015 µg ml−1 using cation-adjusted Mueller–Hinton broth, but those for colistin were significantly higher (0.5 and 4 µg ml−1) using brain heart infusion medium. Whole-genome analysis revealed that these isolates coharboured bla NDM-1, armA and mcr-10. These two isolates showed low MICs of 0.25 µg ml−1 for colistin. Genome analysis revealed that both bla NDM-1 and armA were located on IncFIIs plasmids of similar size (81 kb). The mcr-10 was located on IncM2 plasmids of sizes 220 or 313 kb in each isolate. These two isolates did not possess a qseBC gene encoding a two-component system, which is thought to regulate the expression of mcr genes.

Conclusion. This is the first report of isolates of K. pneumoniae coharbouring bla NDM-1, armA and mcr-10 obtained in Myanmar.

Introduction. The FilmArray blood culture identification panel (BCID) panel is a multiplex PCR assay with high sensitivity and specificity to identify the most common pathogens in bloodstream infections (BSIs).

Hypothesis. We hypothesize that the BCID panel has good diagnostic performance for BSIs and can be popularized in clinical application.

Aim: To provide summarized evidence for the diagnostic accuracy of the BCID panel for the identification of positive blood cultures.

Methodology. We searched the MEDLINE, EMBASE and Cochrane databases through March 2021 and assessed the efficacy of the diagnostic test of the BCID panel. We performed a meta-analysis and calculated the summary sensitivity and specificity of the BCID panel. Systematic review protocols were registered in the International Prospective Register of Systematic Reviews (PROSPERO) (registration number CRD42021239176).

Results. A total of 16 full-text articles were eligible for analysis. The overall sensitivities of the BCID panel on Gram-positive bacteria, Gram-negative bacteria and fungi were 97 % (95 % CI, 0.96–0.98), 100 % (95 % CI, 0.98–01.00) and 99 % (95 % CI, 0.87–1.00), respectively. The pooled diagnostic specificities were 99 % (95 % CI, 0.97–1.00), 100 % (95 % CI, 1.00–1.00) and 100 % (95 % CI, 1.00–1.00) for Gram-positive bacteria, Gram-negative bacteria and fungi, respectively.

Conclusions. The BCID panel has high rule-in value for the early detection of BSI patients. The BCID panel can still provide valuable information for ruling out bacteremia or fungemia in populations with low pretest probability.

Introduction. Irritable bowel syndrome (IBS) is a common gastrointestinal disorder that affects the quality of life of numerous people worldwide.

Gap statement. The therapeutic role of gut microbiota modulation in IBS remains controversial.

Aim. We aimed to assess the efficacy of probiotics, prebiotics or synbiotics in patients with IBS.

Methodology. We searched MEDLINE and EMBASE up to 1 August 2023, to identify the randomized, double-blind, placebo-controlled trials investigating the effectiveness of probiotics, prebiotics or synbiotics among patients with IBS. Pooled analyses of the effects of probiotics in relieving IBS symptoms were calculated using a random-effects model. Further subgroup analyses were performed by different genera, doses and duration of treatment.

Results. Our final analysis included 52 trials involving 6289 IBS patients. Probiotics significantly increased the overall response rate (RR:1.64; P<0.00001), subjective relief rate (RR:1.50; P=0.0002) and abdominal pain relief rate (RR:1.69; P<0.00001). As for specific genera, mixed probiotics (RR:1.41; P=0.0001), Bifidobacterium (RR:1.76; P<0.00001), Lactobacillus (RR:1.97; P=0.0004) and Saccharomyces (RR:1.31; P=0.0004) markedly relieved IBS symptoms. Mixed probiotics (RR:1.31; P=0.005), Lactobacillus (RR:2.22; P=0.04) and Bifidobacterium (RR:1.62; P<0.0001) elevated patients’ subjective relief rate. Besides, probiotics effectively relieved the abdominal pain in IBS patients (RR:1.69; P<0.00001). Probiotics appeared to show a remarkable beneficial role at a dose of 109 c.f.u./day or above (RR:1.662; P<0.0001) and started to work at 4 weeks (RR 1.72; P<0.00001). Efficacy of prebiotics and synbiotics in IBS remained uncertain, due to the deficiency of available RCTs.

Conclusions. Probiotics have a therapeutic role in IBS. However, the effect of different probiotics varies. The minimal effective dose of probiotics may be 109 c.f.u./day. With appropriate probiotic formula, the therapeutic effect can occur at 4 weeks. These data provide a basis for further research on the optimal probiotic therapy in IBS.