An external ventricular drainage catheter impregnated with rifampicin, trimethoprim and triclosan, with extended activity against MDR Gram-negative bacteria: an in vitro and in vivo study.

BACKGROUND: External ventricular drainage (EVD) carries a high risk of ventriculitis, increasingly caused by MDR Gram-negative bacteria such as Escherichia coli and Acinetobacter baumannii. Existing antimicrobial EVD catheters are not effective against these, and we have developed a catheter with activity against MDR bacteria and demonstrated the safety of the new formulation for use in the brain. OBJECTIVES: Our aim was to determine the ability of a newly formulated impregnated EVD catheters to withstand challenge with MDR Gram-negative bacteria and to obtain information about its safety for use in the CNS. METHODS: Catheters impregnated with three antimicrobials (rifampicin, trimethoprim and triclosan) were challenged in flow conditions at four weekly timepoints with high doses of MDR bacteria, including MRSA and Acinetobacter, and monitored for bacterial colonization. Catheter segments were also inserted intracerebrally into Wistar rats, which were monitored for clinical and behavioural change, and weight loss. Brains were removed after either 1 week or 4 weeks, and examined for evidence of inflammation and toxicity. RESULTS: Control catheters colonized quickly after the first challenge, while no colonization occurred in the impregnated catheters even after the 4 week challenge. Animals receiving the antimicrobial segments behaved normally and gained weight as expected. Neurohistochemistry revealed only surgical trauma and no evidence of neurotoxicity. CONCLUSIONS: The antimicrobial catheter appears to withstand bacterial challenge for at least 4 weeks, suggesting that it might offer protection against infection with MDR Gram-negative bacteria in patients undergoing EVD. It also appears to be safe for use in the CNS.

Comparison of different human tissue processing methods for maximization of bacterial recovery.

Tissues are valuable microbiological samples that have proved superiority over swabs. Culture of tissue samples is used in the diagnosis of a variety of infections. However, as well as factors such as the site of obtaining the sample, the number of samples, and previous antibiotic use, the method of tissue processing may have an important effect on sensitivity. Data from the literature comparing different tissue processing methods is very limited. This study aimed to compare different mechanical and chemical methods of tissue processing in terms of efficacy and retaining the viability of the bacteria in the tissues. Standard suspensions of Staphylococcus aureus and Escherichia coli were prepared and treated differently to test the effect of that treatment on bacterial viability. Artificially inoculated pork tissue and known infected human tissue samples were then processed by different methods prior to culture, and results were compared. Percentages of reduction in the number of viable bacteria compared to the control by homogenization was similar to 5-min dithiothreitol treatment but significantly lower than bead beating. Bacterial recovery from homogenized human tissues was significantly higher than from any other method of treatment. Although bead beating could be the most efficient method in obtaining a homogeneous tissue product, it significantly reduces the number of viable bacteria within tissues. Homogenization offers the most effective easily controllable retrieval of bacteria from tissue and retains their viability. Guidelines for diagnosing infections using tissue samples should include a standardized processing method.

Propidium monoazide-polymerase chain reaction for detection of residual periprosthetic joint infection in two-stage revision.

False negative culture results in periprosthetic joint infection (PJI) are not uncommon particularly when patients have received long term antibiotics. Polymerase chain reaction (PCR) has a lower specificity partly due to detection of residual DNA from dead bacteria. Propidium monoazide (PMA) prevents DNA from dead bacteria from being amplified during the PCR. This study aimed to determine the role of PMA in PCR for diagnosis of PJI. Clinical samples were tested by PCR with and without prior treatment with PMA and compared to conventional microbiological culture. The PCR assay included genus-specific primers for staphylococci and enterococci and species-specific primers for Cutibacterium acnes. The validated conditions of PMA treatment used in this study were 20 µM concentration and 5 and 10 min of dark incubation and photo-activation respectively. 202 periprosthetic tissues and explanted prostheses from 60 episodes in 58 patients undergoing revision arthroplasties for either PJI or non-infective causes were tested, by culture, PCR, and PMA-PCR. 14 of the 60 episodes satisfied the Musculoskeletal Infection Society (MSIS) criteria for PJI and 46 did not. Sensitivity of culture, PCR, and PMA-PCR were 50%, 71%, and 79% respectively. Specificities were 98%, 72%, and 89% respectively. All figures were calculated for episodes rather than samples. PMA-PCR enhanced both the specificity and the sensitivity of PCR. It has the potential to detect residual bacterial viability prior to reimplantation in the two-stage revision for PJI.

Preoperative inflammatory biomarkers reveal renal involvement in postsurgical mortality in hip fracture patients: an exploratory study.

Background: Hip fractures in frail patients result in excess mortality not accounted for by age or comorbidities. The mechanisms behind the high risk of mortality remain undetermined but are hypothesized to be related to the inflammatory status of frail patients. Methods: In a prospective observational exploratory cohort study of hospitalized frail hip fracture patients, 92 inflammatory markers were tested in pre-operative serum samples and markers were tested against 6-month survival post-hip fracture surgery and incidence of acute kidney injury (AKI). After correcting for multiple testing, adjustments for comorbidities and demographics were performed on the statistically significant markers. Results: Of the 92 markers tested, circulating levels of fibroblast growth factor 23 (FGF-23) and interleukin-15 receptor alpha (IL15RA), both involved in renal disease, were significantly correlated with 6-month mortality (27.5% overall) after correcting for multiple testing. The incidence of postoperative AKI (25.4%) was strongly associated with 6-month mortality, odds ratio = 10.57; 95% CI [2.76-40.51], and with both markers plus estimated glomerular filtration rate (eGFR)- cystatin C (CYSC) but not eGFR-CRE. The effect of these markers on mortality was significantly mediated by their effect on postoperative AKI. Conclusion: High postoperative mortality in frail hip fracture patients is highly correlated with preoperative biomarkers of renal function in this pilot study. The effect of preoperative circulating levels of FGF-23, IL15RA, and eGFR-CYSC on 6-month mortality is in part mediated by their effect on postoperative AKI. Creatinine-derived preoperative renal function measures were very poorly correlated with postoperative outcomes in this group.

Social Determinants of Clinical Visits After Left Main Percutaneous Coronary Intervention Versus Coronary Artery Bypass Grafting.

This study aims to investigate the social determinants of clinical visits after LM-PCI versus CABG and their impact on post-treatment care and outcomes. We identified all adult patients who underwent LM-PCI or CABG between January 1, 2015, and December 31, 2022, and were in follow-up at our institute. We collected data on clinical visits, including outpatient visits, emergency department visits, and hospitalizations, in the years following the procedure. The study included 3816 patients, of which 1220 underwent LM-PCI and 2596 underwent CABG. The majority of patients were Punjabi (55.8%), males (71.8%), and had low socioeconomic status (69.2%). The strongest predictors of having a follow-up visit were age (OR (95%CI): 1.41 (0.87-2.35); P value = 0.03), female gender (OR (95%CI): 2.16 (1.58-4.21); P value = 0.07), LM-PCI (OR (95%CI): 2.32 (0.94-3.64); P-value = 0.01), government entitlement (OR (95%CI): 0.67 (0.15-0.84); P value = 0.16), high SYNTAX (OR (95%CI): 1.07 (0.83-2.58); P value = 0.02), 3-vessel disease (OR (95%CI): 1.76 (1.05-2.95); P value <0.01), and peripheral arterial disease (OR (95%CI): 1.52 (0.91-2.45); P value = 0.01). Hospitalizations, outpatient, and emergency visits were more in the LM-PCI cohort as compared to CABG. In conclusion, the social determinants of health, including ethnicity, employment, and socioeconomic status were associated with differences in clinical follow-up visits after LM-PCI and CABG.

Bullying in Cardiology: Pakistan's Perspective.

This survey aimed to investigate the extent of bullying among junior physicians in cardiology departments, by way of an anonymous web-based questionnaire in Pakistan. A survey of Pakistan cardiology trainees was piloted as a cross-sectional qualitative survey of junior cardiologists (including resident physicians and senior registrars) from teaching institutes all over Pakistan. Negative Acts Questionnaire-Revised was used as the tool for monitoring and reporting bullying nationwide. Of 1852 trainees, bullying was reported by 10.2% of males and 13.4% of females. Women had higher odds of reporting being bullied (odds ratio [OR] {95% confidence interval [CI]}: 1.42 [1.07-2.36]; P-value = 0.018), and the religious minority group (Hindu) reported more bullying (OR [95% CI]: 3.27 [2.16-4.73]; P-value < 0.001). Women were more likely than men to report sexist language (24.1% vs 7.5%; P-value < 0.001) while men reported more racist language (4.2% vs 16.5%; P-value < 0.001). Consultants in cardiology (75.4%) and other specialties (68.3%) commonly perpetrated bullying on cardiology trainees. Bullying in cardiology is a common finding and proportionally affects both males and females, religious minorities, and trainees working in tertiary care hospitals. In addition, females are reporting more sexist language being used by consultants as the majority.

Social determinants of pacemaker reuse among patients and family members in Pakistan.

OBJECTIVES: This survey aimed to quantify the opinions of CIED reuse among patients and family members in Pakistan and to identify the social determinants which may predict these views. METHODS: A questionnaire formulating attitudes toward PPM reuse was administered to patients and family members at cardiology institutes in Pakistan from 1 July 2022 to 30 September 2022. The eligibility criteria (age > 18 years; inline for PPM placement) were taken into account and incomplete responses were excluded from the final analysis. RESULTS: A total of 9,246 participants recorded their responses, of which 7,152 (78.16%) accepted pre-used PPMs. The lower social class had more PPM reuse acceptance rate than the middle and upper class (92.72% vs. 60.52% vs. 35.38%), respectively. Age ≥ 65 (OR(95%CI): 0.68 (0.41-0.99); P-value = 0.023), male gender (OR(95%CI): 0.55 (0.35-0.72), P-value = 0.016), unemployment (OR(95%CI): 0.47 (0.25-0.64); P-value = 0.007), poor health status (OR(95%CI): 0.72 (0.53-0.92); P-value = 0.041), and lower social class (OR(95%CI): 0.36 (0.28-0.53); P-value = 0.003) were social determinants of PPM reuse acceptance. CONCLUSION: Patients and their family members endorse the concept of PPM reuse in Pakistan who cannot afford new devices.

Sociodemographic determinants of gender disparity in primary percutaneous coronary intervention in Pakistan.

OBJECTIVES: This study aims to contribute to the body of literature on gender disparities after acute myocardial infarction (AMI) undergoing primary percutaneous coronary intervention (PPCI). METHODS: We identified all adult patients who had AMI between January 2017, and December 2022 and were in follow-up at our institute. We collected data on PPCI, revascularization strategy, sociodemographic characteristics, and in-hospital complications in the years following the procedure. RESULTS: A total of 5,872 patients who underwent PCI for AMI were included in the study, out of which 2,058 (35%) were women and 3,814 (65%) were men. Regarding the timing of PCI, female patients had a significantly longer median door-to-balloon time compared to male patients (136 minutes vs 108 minutes, P-value = 0.006). Female patients had a significantly higher rate of in-hospital mortality compared to male patients (5.5% vs 1.2%, P-value = 0.011). Multivariate logistic regression analysis showed that female gender, older age, and lower household income were independent predictors of longer door-to-balloon time. CONCLUSION: This study highlights gender disparities in PPCI in Pakistan, with female patients facing longer door-to-balloon times and higher in-hospital mortality rates. The findings suggest the need for targeted interventions to improve the access and quality of care for female patients with AMI.

Action of linezolid or vancomycin on biofilms in ventriculoperitoneal shunts in vitro.

Cerebrospinal fluid (CSF) shunts used to treat hydrocephalus have an overall infection rate of about 10% of operations. The commonest causative bacteria are Staphylococcus epidermidis, followed by Staphylococcus aureus and enterococci. Major difficulties are encountered with nonsurgical treatment due to biofilm development in the shunt tubing and inability to achieve sufficiently high CSF drug levels by intravenous administration. Recently, three cases of S. epidermidis CSF shunt infection have been treated by intravenous linezolid without surgical shunt removal, and we therefore investigated vancomycin and linezolid against biofilms of these bacteria in vitro. A continuous-perfusion model of shunt catheter biofilms was used to establish mature (1-week) biofilms of Staphylococcus aureus, Staphylococcus epidermidis (both methicillin resistant [MRSA and MRSE]), Enterococcus faecalis, and Enterococcus faecium. They were then "treated" with either vancomycin or linezolid in concentrations achievable in CSF for 14 days. The biofilms were then monitored for 1 week for eradication and for regrowth. Enterococcal biofilms were not eradicated by either vancomycin or linezolid. Staphylococcal biofilms were eradicated by both antibiotics after 2 days and did not regrow. No resistance was seen. Linezolid at concentrations achievable by intravenous or oral administration was able to eradicate biofilms of both S. epidermidis (MRSE) and S. aureus (MRSA). Neither vancomycin at concentrations achievable by intrathecal administration nor linezolid was able to eradicate enterococcal biofilms. It is hoped that these in vitro results will stimulate further clinical trials with linezolid, avoiding surgical shunt removal.

Activity of an antimicrobial hydrocephalus shunt catheter against Propionibacterium acnes.

Shunt infection is a major complication affecting approximately 10% of procedures. Propionibacterium acnes, an anaerobic skin bacterium, is increasingly recognized as a shunt pathogen, causing up to 14% of infections. Though susceptible to penicillin and cephalosporins, P. acnes shunt infections are not preventable by means of perioperative prophylaxis, due to poor cerebrospinal fluid penetration. Antimicrobial shunts with activity against staphylococci are available, but their activity against P. acnes is unknown, and the study was designed to determine this. Three methods of evaluation were used in order to determine the emergence of resistance when exposure is to high inocula for long periods, the time taken to kill 100% of the bacteria attached to the shunt, and the duration of activity under constant flow conditions with repeated bacterial challenge. Despite repeated exposure to high bacterial inocula over 70 days, no resistance was seen. The time taken to kill all attached bacteria, 96 h, was twice that taken to kill attached staphylococci. Nevertheless, under constant flow conditions with repeated challenges, the antimicrobial catheters resisted colonization by P. acnes for 56 days. Using tests that were designed to be clinically predictive when done together, the results suggest that the antimicrobial catheters will be able to prevent colonization of hydrocephalus shunts by P. acnes.

In vitro antimicrobial activity of silver-processed catheters for neurosurgery.

OBJECTIVES: To investigate the in vitro antibacterial activity of silver-processed catheters for use in neurosurgery using clinically predictive tests. METHODS: The antimicrobial activity of a commercially available silver-processed external ventricular drain catheter was evaluated against Staphylococcus epidermidis, methicillin-resistant Staphylococcus aureus (MRSA), Escherichia coli and Propionibacterium acnes. Non-impregnated catheters were used as controls. Two assays were performed: (i) testing the ability of the catheter to kill 100% of the attached bacteria (tK100); and (ii) in vitro challenge to determine the ability to prevent colonization under flow conditions. High and low inocula (10(4) and 10(7) cfu/mL) were used. Silver-processed and control catheters were examined by scanning electron microscopy and focused ion beam scanning electron microscopy; electron back-scatter and energy-dispersive X-ray analyses were used to investigate the distribution of silver within the processed catheter. RESULTS: The silver-processed catheters were not able to kill any of the bacteria tested in the tK100 assay at high inoculum. At low inoculum S. epidermidis was eradicated and some activity was seen against E. coli but without complete eradication. MRSA was also not eradicated even at low inoculum. The in vitro challenge test showed no prevention of colonization for any of the strains. Silver particles were shown to be >500 nm in size. CONCLUSIONS: The commercial silver-impregnated catheter was not able to eradicate MRSA or E. coli and while it showed activity against S. epidermidis in one assay it was unable to prevent colonization in vitro under in-flow conditions. This is consistent with clinical studies on silver-processed catheters.

Development of dual anti-biofilm and anti-bacterial medical devices.

The rising occurrence of antimicrobial resistance demands new strategies for delivering antibiotics to ensure their effective use. In this study, a multi-functional strategy to address medical device associated infections is explored whereby an anti-attachment and an antibacterial mechanism have been combined. Silicone catheters impregnated with multiple antibiotics are coated with polyacrylate coatings previously shown to reduce bacterial attachment and biofilm formation. Antibiotics are delivered through the applied coating and the delivery rate depends on the coating thickness and the calculated log P. Coated devices achieve a zone of inhibition and TK100 to Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus similar to those of uncoated devices, whilst maintaining anti-attachment properties. No adverse immunological responses of the coatings were observed. The multi-functional nature of the device developed in the study represents an important approach to combatting medical device associated infections.

An antimicrobial impregnated urinary catheter that reduces mineral encrustation and prevents colonisation by multi-drug resistant organisms for up to 12 weeks.

Two major complications of indwelling urinary catheterisation include infection and mineral encrustation of the catheter. Our antimicrobial urinary catheter (AUC) impregnated with rifampicin, triclosan, and sparfloxacin has demonstrated long-term protective activity against major uropathogens. This study aimed to firstly assess the ability of the AUC to resist mineral encrustation in the presence and absence of bacteria. Secondly, it aimed to investigate the AUC's anti-biofilm activity against multi-drug resistant organisms. There was no difference in surface roughness between AUC and control segments. In a static and a perfusion model, phosphate deposition was significantly reduced on AUCs challenged with P. mirabilis. Furthermore, none of the AUCs blocked during the 28 day test period, unlike controls. The AUC prevented colonisation by methicillin-resistant Staphylococcus aureus, methicillin-resistant Staphylococcus epidermidis, extended-spectrum beta-lactamase producing E. coli, and carbapenemase-producing E. coli for 12 consecutive weekly challenges. All three drugs impregnated into the catheter continued to exert protective activity throughout 12 weeks of constant perfusion. The drugs appear to migrate into the crystalline biofilm to continually protect against bacteria not it direct contact with the catheter surface. In conclusion, the AUC reduces mineral encrustation and may increase time to blockage in the presence of P. mirabilis, and does not predispose to mineral deposition under other conditions. It also offers 12 weeks of protection against multi-drug resistant bacteria. STATEMENT OF SIGNIFICANCE: Infection and associated mineral encrustation of urinary catheters are two serious complications of indwelling urinary catheters. Others have attempted to address this through various technologies such as coatings, dips, and surface modifications to prevent infection and/or encrustation. However, all current 'anti-infective' urinary catheter technologies are limited to short-term use. Some patients with spinal injuries, multiple sclerosis, stroke survivors and others use long-term catheters for 4-12 weeks at a time with multiple catheterisation possibly throughout the rest of their life. We present a urinary catheter for long-term use that is impregnated with three antimicrobials by a patient-protected process to prevent infection and encrustation for up to 12 weeks, the maximum lifetime of a long-term catheter before it is changed.

Validation and assessment of an antibiotic-based, aseptic decontamination manufacturing protocol for therapeutic, vacuum-dried human amniotic membrane.

Amniotic membrane (AM) is used to treat a range of ophthalmic indications but must be presented in a non-contaminated state. AM from elective caesarean sections contains natural microbial contamination, requiring removal during processing protocols. The aim of this study was to assess the ability of antibiotic decontamination of AM, during processing by innovative low-temperature vacuum-drying. Bioburden of caesarean section AM was assessed, and found to be present in low levels. Subsequently, the process for producing vacuum-dried AM (VDAM) was assessed for decontamination ability, by artificially loading with Staphylococcus epidermidis at different stages of processing. The protocol was highly efficient at removing bioburden introduced at any stage of processing, with antibiotic treatment and drying the most efficacious steps. The antibacterial activity of non-antibiotic treated AM compared to VDAM was evaluated using minimum inhibitory/biocidal concentrations (MIC/MBC), and disc diffusion assays against Meticillin-resistant Staphylococcus aureus, Meticillin-resistant S. epidermidis, Escherichia coli, Pseudomonas aeruginosa and Enterococcus faecalis. Antibacterial activity without antibiotic was low, confirmed by high MIC/MBC, and a no inhibition on agar lawns. However, VDAM with antibiotic demonstrated effective antibacterial capacity against all bacteria. Therefore, antibiotic decontamination is a reliable method for sterilisation of AM and the resultant antibiotic reservoir is effective against gram-positive and -negative bacteria.

Biofilm formation by Propionibacterium acnes on biomaterials in vitro and in vivo: impact on diagnosis and treatment.

Propionibacterium acnes is found increasingly as a cause of delayed infection, usually involving implanted biomaterials. Despite susceptibility to common antibiotics, such infections are very difficult to treat and usually require surgical removal of the device. Three clinical isolates of P. acnes were assessed for ability to adhere to titanium, surgical steel and silicone, with and without a plasma conditioning film. After adherence, the biomaterials were then incubated for a further 6 days and examined for biofilm development. All three isolates adhered to all three biomaterials similarly. Importantly, we were able to demonstrate biofilm formation, including production of exopolymer similar in appearance to the polysaccharide intercellular adhesin of Staphylococcus epidermidis. A case summary also demonstrated failure to eradicate P. acnes infection in a hydrocephalus shunt after prolonged treatment. The removed shunt showed obvious biofilm formation, initially obscured by exopolymer when viewed by environmental scanning electron microscopy. Biofilm development by P. acnes explains the difficulties encountered in clinical management of such infections.