- Volume 74, Issue 6, 2025

Multidrug-resistant (MDR) bacteria pose a growing threat to global health, prompting exploration of alternative therapies. This study uses bioinformatic modelling to assess ozone therapy as an adjunct treatment, analysing both linear and non-linear (chaotic) frameworks. Results suggest that ozone exerts bactericidal effects and modulates immune responses, partly through the production of 4-hydroxynonenal. Simulations indicate that ozone-induced adaptive chaos may enhance immune resilience and accelerate bacterial clearance compared to antibiotics alone. However, the findings are theoretical, and the short half-life of ozone limits direct impact, emphasizing the need for experimental validation. Ozone therapy shows promise, but its role in adaptive chaos requires further study to determine its clinical viability, despite a large number of reports showing an undisputable action of medical ozone against MDR bacteria.

Introduction. Bacterial infections and antimicrobial resistance are significant threats to global public health, both of which spread through contamination of solid surfaces. We have previously developed an antimicrobial surface technology that directly bonds the broad-spectrum biocide chlorhexidine to steel surfaces. These surfaces were shown to kill bacteria within minutes of contact and to be effective against bacteria evolved in the laboratory for resistance to chlorhexidine in solution.

Hypothesis/Gap Statement. We hypothesized that resistance to these surfaces could exist outside of the naive and chlorhexidine-resistant laboratory strains tested previously. We also sought to test whether strains that were resistant to chlorhexidine in solution were also resistant to chlorhexidine-based antimicrobial surfaces.

Aim. To test the efficacy of these surfaces against a range of bacteria isolated from the hospital environment and to compare this to the resistance of these bacteria to chlorhexidine in solution or when dissolved in solid media.

Methodology. Ninety-one isolates of mixed bacterial species were obtained from Queen Elizabeth Hospital Birmingham. The isolates, along with laboratory strains of Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus, were tested for sensitivity to chlorhexidine-coated steel surfaces in a 30-min exposure simulated splash assay. Resistance to chlorhexidine in solution was also assayed by solid and broth media MIC assays.

Results. We demonstrate that within 30 min of incubation, the surfaces reduced the survival of all 91 isolates. Over 85% of these isolates were killed (exhibiting a 7–8 log reduction compared with control surfaces), whilst 12% experienced a 3–4 log reduction. We also show that resistance to the surfaces did not correlate with resistance to freely diffusible chlorhexidine in liquid or solid media.

Conclusion. The results demonstrate the efficacy of chlorhexidine-coated surfaces against a broad range of bacterial isolates from the hospital environment and imply the potential for a mode of exposure to dictate the effectiveness of different antimicrobial resistance mechanisms. Future studies should investigate the genetic mechanisms providing resistance to chlorhexidine-coated surfaces and whether these differ in the capacity to provide resistance to chlorhexidine in different modes of exposure.

Introduction. Antimicrobial resistance (AMR) is an escalating global health crisis, leading to ~700,000 deaths annually. Without significant containment efforts, this number could surge to 10 million by 2050. Carbapenem-resistant organisms, particularly carbapenem-resistant Enterobacterales (CRE), Pseudomonas aeruginosa, and Acinetobacter baumannii, present a critical challenge due to their ability to evade potent carbapenem antibiotics.

Hypothesis and Aim. This study aimed to determine the prevalence of CRE among 1,317 culture-positive patients and to assess the impact of advanced diagnostic techniques, such as RT-PCR, modified carbapenem inactivation method (mCIM), EDTA carbapenem inactivation method (eCIM) and Vitek susceptibility testing, on improving diagnostic stewardship and patient outcomes.

Methodology. A retrospective cross-sectional study was conducted at Peerless Hospitex Hospital and Research Centre Limited, Kolkata, from June 2023 to May 2024. CRE isolates were identified from various clinical samples and subjected to phenotypic (Vitek 2, mCIM and eCIM) and genotypic real time polymerase chain reaction (RT-PCR) testing for carbapenemase genes. Data on demographics, specimen types, bacterial isolates, comorbidities, etc. were analysed.

Results. Out of 20,129 inpatient samples sent for culture during this 1-year period, 3,124 (15.51%) had culture-proven infections. A total of 1,317 Enterobacterales isolates were processed for carbapenem resistance (CR) detection PCR, with 354 (26.88%) identified as CRE. Klebsiella pneumoniae was the predominant isolate (60.17%), followed by Escherichia coli (26.55%). New Delhi metallo-β-lactamase (MBL) (NDM) and OXA-48-like co-production (33.75%) were most commonly seen, followed by NDM gene alone (32.50%). The concordance between phenotypic susceptibility and genotypic PCR method for CRE was 85.88%. Targeted antibiotic therapy could be initiated based on PCR results, in 70.90% of cases. Synergy test guided effective combination therapy of ceftazidime-avibactam and aztreonam for MBL-producing CRE isolates.

Conclusion. The study highlights a significant prevalence of CRE, particularly among older adults. Advanced diagnostic techniques improved diagnostic stewardship, allowing timely and accurate detection of CR. However, discrepancies between phenotypic and genotypic methods and the high cost of certain therapies are notable limitations. Enhanced infection control and early initiation of targeted therapy are crucial to combat AMR.

Introduction. In cases where sputum is non-diagnostic or unavailable, bronchoscopy can yield high-value respiratory samples for tuberculosis (TB) diagnosis. Whilst Mycobacterium tuberculosis (MTB) complex culture remains the gold standard, molecular assays such as Xpert MTB/RIF Ultra (Xpert Ultra) are increasingly being used for rapid diagnosis.

Gap Statement. Xpert Ultra is increasingly used for TB diagnosis and has been extensively evaluated on sputum specimens, but assessment of performance on bronchoscopy samples is more limited.

Aim. To retrospectively evaluate the performance of Xpert Ultra on bronchoscopy specimens in comparison to culture in a low-incidence, high-resource setting.

Methodology. Patients with a clinical suspicion of TB, who had non-diagnostic sputum or limited sputum production and underwent bronchoscopy between March 2019 and October 2023, were included in the study. Bronchoscopy specimens comprised bronchoalveolar lavages, bronchial washings and endobronchial ultrasound lymph node tissue biopsies. All included specimens underwent acid-fast bacilli (AFB) smear, mycobacterial culture and Xpert Ultra. Positive MTB culture was considered the reference standard for TB diagnosis.

Results. One hundred thirty-five bronchoscopy samples from 126 patients were included. Cultures were positive for MTB in 47 out of 126 (37.3%) of included patients. Overall, positive percent agreement (PPA) and negative percent agreement (NPA) of Xpert Ultra to MTB culture were 93.6% and 98.7%, respectively. In 19 AFB smear-positive cases, Xpert Ultra had 100% PPA and NPA, whilst in 28 smear-negative cases, PPA and NPA were 89.3% and 98.6%, respectively. On average, positive culture results were available after 15.2 days of incubation (range, 5–42 days) versus 24 h for Xpert Ultra. Xpert Ultra PCR cycle threshold values correlated strongly with AFB-smear grade and time-to-culture positivity.

Conclusion. Xpert Ultra performed on specimens collected via bronchoscopy demonstrated excellent agreement with culture, even in smear-negative cases. Our results support the use of the Ultra on bronchoscopy specimens for accurate and rapid TB diagnosis in a low-incidence setting.

Introduction. Actinomyces species colonizing the human oropharynx and gastrointestinal and urogenital tract are associated with a wide range of infections. The isolation of Actinomyces spp. from sterile clinical samples is regarded as significant.

Gap Statement. Increased use of advanced diagnostics has caused an increased detection of Actinomyces in the bloodstream, the clinical significance of which is unclear.

Aim. To investigate the clinical factors associated with true Actinomyces bacteraemia that could aid in differentiating it from transient Actinomyces bacteraemia.

Methodology. We conducted a retrospective study of all inpatients with Actinomyces bacteraemia from two tertiary care centres from 1 January 2006 to 26 September 2021. Data were collected on demographic and clinical characteristics, comorbidities, primary source of infection and outcomes. True bacteraemia was defined as Actinomyces bacteraemia with systemic manifestations of infection.

Results. A total of 82 cases of positive blood cultures were identified, of which 33 (40.2%) were true bacteraemia, based on clinical criteria. Patients with true bacteraemia were more likely to be older (P=0.007), have chronic skin ulcers (P<0.001), have a history of central line placement within 3 months of their presentation (P=0.04), have had a fever within 72 h of admission (P=0.05) and have presented with an abscess (P<0.001) compared with patients with transient bacteraemia. True bacteraemia was more likely to be associated with positive tissue cultures (P=0.02) and an infectious disease consultation than transient bacteraemia. Skin and soft tissue (27.3%) was the most common source followed by intra-abdominal (21.1%). Among true bacteraemia, the most common species was Actinomyces meyeri with a ratio of 1:8 (transient versus true bacteraemia). All-cause mortality was 30.3% in patients with true bacteraemia compared with 4.1% in patients with transient bacteraemia (P<0.001).

Conclusion. Predictors of true Actinomyces bacteraemia included older age, fever within 72 h of admission, presence of abscess and chronic skin disease. Actinomyces species exhibit varying degrees of invasiveness, with A. meyeri potentially showing higher invasive potential. Better awareness and involvement of infectious disease specialists is recommended in determining the clinical significance of transient Actinomyces bacteraemia and can help implement antibiotic stewardship and patient safety and improve outcomes. Further research will help to identify the true importance of these isolates.

Introduction. While Mycobacterium tuberculosis cells in sputum in sputum have been studied extensively, little is known of their properties in exhaled aerosols.

Hypothesis. As differentially culturable tubercle bacteria (DCTB) are readily found in sputum, we hypothesized that DCTB might also be present in aerosols and potentially contribute to transmission.

Aim. To test cough aerosols from recently diagnosed pulmonary tuberculosis (TB) patients for DCTB.

Methodology. Cough-generated aerosols and sputum samples were collected from active pulmonary TB patients (n=27). A cough aerosol sampling system was modified to include both an Andersen Cascade Impactor using solid agar and a BioSampler liquid impactor. We performed the most probable number of assays to detect DCTB, using media supplemented with Mycobacterium tuberculosis culture filtrate (CF).

Results. Briefly, 63% of patients (n=17) had advanced TB, and 55.6% (n=15) had a 3+ sputum smear for acid-fast bacilli. Evidence for DCTB was found in 8 patients’ aerosols (29.5%) and more than half of the 19 sputum samples tested (n=10; 52.6%). Two patients had DCTB in only one of the collected samples (cough aerosols or sputum). Among cough aerosol specimens, two patients (7%) only had CF-dependent DCTB.

Conclusion. We detected DCTB in sputum and evidence for their presence in cough samples from pulmonary TB patients. These data suggest that bacilli undetected by traditional mycobacterial cultures may be aerosolized from pulmonary TB patients.

Introduction. The relationship between analgesic use and gut microbiota alterations has garnered increasing attention. However, the causal link between these two factors remains to be elucidated. Given the prevalence of analgesic use and the significant role of gut microbiota in human health, clarifying this relationship is of great importance.

Hypothesis/Gap Statement. Existing observational studies are limited in their ability to establish causality between analgesic use and gut microbiota alterations. Therefore, there is a need for robust causal inference methods to explore this relationship and uncover the underlying mechanisms.

Aim. This study aims to investigate the causal associations between genetic susceptibility to four common analgesics (NSAIDs, salicylic acid, opioids, and anilides) and gut microbiota composition, as well as circulating metabolites, using a two-sample Mendelian randomization approach.

Methodology. A two-sample Mendelian randomization was used to investigate the potential association between genetic susceptibility to four analgesic uses and gut microbiota composition, as well as circulating metabolites. Summary-level statistics of genome-wide association studies were obtained from primarily European ancestry cohorts, including 466,457 participants from the UK Biobank and 18,340 individuals from the MiBioGen consortium.

Results. Only one suggestive causal association was found between NSAID use and elevated abundance of gut microbiota, namely group Eubacterium xylanophilum. In addition, salicylic use was correlated with an increased abundance of the family Prevotellaceae (P=0.006), while it was negatively associated with the abundance of 8 microbiota traits, including genus Clostridiumsensustricto1, Adlercreutzia, Akkermansia, family Clostridiaceae1, Verrucomicrobiaceae, phylum Verrucomicrobia, class Verrucomicrobiae and order Verrucomicrobiales with P value ranging from 0.009 to 0.043. No clear evidence was found between opioid and anilide use and gut microbiota alteration. Meanwhile, salicylic use was potentially causally associated with four metabolites, including acetoacetate, creatinine, omega-3 fatty acids and triglycerides in very large high-density lipoprotein, with P values ranging from 0.005 to 0.046.

Conclusion. The results of this study offer powerful evidence that the long-term use of salicylic acid may substantially impact gut microbiota composition and circulating metabolites. Further investigations are needed to uncover the underlying mechanisms.

Introduction. Pseudomonas aeruginosa contains a wide range of extracellular and cell-associated virulence factors that support its pathogenesis. The most variable portion of lipopolysaccharide, O-polysaccharide, confers serogrouping and is crucial for virulence.

Gap Statement. Despite their importance, P. aeruginosa serotypes and associated virulence factors are not well described at the level of strains obtained from Ethiopian clinical samples.

Aim. To characterize the serotypes and virulence factors of P. aeruginosa isolates from patients admitted to two hospitals in Addis Ababa, Ethiopia.

Methodology. Whole-genome sequencing was performed to characterize genes responsible for serotypes and virulence factors.

Results. Eight distinct serotypes were identified, with O6 (50%) and O11 (14.1%) being the most common and O9 (1.6%) being the least common. Serotype O6 was the most frequent serotype in all infections, and the percentage of O11 (38.5%) was high in burn wound isolates. The percentage of multidrug resistance was 56.6%. High levels of resistance to ciprofloxacin (51.8%) and ceftazidime (50.6%) and low levels of resistance to ceftazidime-avibactam (4.8%) were observed. Multidrug-resistant phenotypes were more common for the O11 (88.9%) and O5 (66.7%) serotypes. There were four (6.3%) exoU+ strains and one (1.6%) exoU+exoS+ multidrug-resistant strain, all of which were O11 serotypes. The frequencies of toxA, exoY, pilA and exoT were 93.8%, 96.9%, 17.2% and 96.9 %, respectively.

Conclusion. This study showed the presence of highly virulent multidrug-resistant P. aeruginosa strains in Ethiopia, and continuous molecular surveillance is essential for monitoring the spread of these strains and creating efficient management strategies.