Patel, Robin

Periprosthetic joint infection (PJI) is a dreadful complication of joint replacement. Noninvasive identification of infectious pathogens has been traditionnally limited to culture-based testing of synovial fluid which has poor sensitivity.

Multidrug-resistant Pseudomonas aeruginosa isolates are a serious public health concern due to their resistance to nearly all or all of the available antibiotics, including carbapenems. Utilizing molecular approaches in conjunction with antibiotic susceptibility prediction software warrants investigation for use in the clinical laboratory workflow.

Abstract Background Mycoplasma hominis, Ureaplasma urealyticum, and Ureaplasma parvum may cause post-transplant infections in lung transplant recipients. We evaluated routine pretransplant screening for these Mollicutes. Methods We retrospectively reviewed records of lung transplant recipients at our tri-site institution from 01/01/2015 to 11/15/2019. M. hominis and/or Ureaplasma polymerase chain reaction (PCR) was performed on pretransplant recipient urine specimens and donor bronchial swabs at the time of transplantation. Development of Mollicute infection and hyperammonemia syndrome (HS) was recorded. Results A total of 268 patients underwent lung transplantation during the study period, of whom 105 were screened with at least 1 Mollicute PCR. Twelve (11%) screened positive; 10 donors, 1 recipient, and 1 both. Among positive donors, 3 were positive for M. hominis, 5 for U. urealyticum, and 4 for U. parvum. Preemptive therapy included doxycycline, levofloxacin, and/or azithromycin administered for 1–12 weeks. Despite therapy, 1 case of M. hominis mediastinitis and 1 case of HS associated with Ureaplasma infection occurred, both donor-derived. Of those screened before transplant, cases with positive screening were more likely (P < 0.05) to develop Mollicute infection despite treatment (2/12, 17%) than those who screened negative (1/93, 1%). Conclusions Pretransplant recipient urine screening had a low yield and was not correlated with post-transplant Mollicute infection, likely because most M. hominis and U. parvum/urealyticum infections in lung transplant recipients are donor-derived. Routine donor bronchus swab PCR for M. hominis, U. urealyticum, and U. parvum followed by preemptive therapy did not obviously impact the overall incidence of Mollicute infection or HS in this cohort.

Abstract Background Ceftriaxone-resistant (CRO-R) Escherichia coli bloodstream infections (BSIs) are common. Methods This is a prospective cohort of patients with E coli BSI at 14 United States hospitals between November 2020 and April 2021. For each patient with a CRO-R E coli BSI enrolled, the next consecutive patient with a ceftriaxone-susceptible (CRO-S) E coli BSI was included. Primary outcome was desirability of outcome ranking (DOOR) at day 30, with 50% probability of worse outcomes in the CRO-R group as the null hypothesis. Inverse probability weighting (IPW) was used to reduce confounding. Results Notable differences between patients infected with CRO-R and CRO-S E coli BSI included the proportion with Pitt bacteremia score ≥4 (23% vs 15%, P = .079) and the median time to active antibiotic therapy (12 hours [interquartile range {IQR}, 1–35 hours] vs 1 hour [IQR, 0–6 hours]; P < .001). Unadjusted DOOR analyses indicated a 58% probability (95% confidence interval [CI], 52%–63%) for a worse clinical outcome in CRO-R versus CRO-S BSI. In the IPW-adjusted cohort, no difference was observed (54% [95% CI, 47%–61%]). Secondary outcomes included unadjusted and adjusted differences in the proportion of 30-day mortality between CRO-R and CRO-S BSIs (−5.3% [95% CI, −10.3% to −.4%] and −1.8 [95% CI, −6.7% to 3.2%], respectively), postculture median length of stay (8 days [IQR, 5–13 days] vs 6 days [IQR, 4–9 days]; P < .001), and incident admission to a long-term care facility (22% vs 12%, P = .045). Conclusions Patients with CRO-R E coli BSI generally have poorer outcomes compared to patients infected with CRO-S E coli BSI, even after adjusting for important confounders.

Chronic wound biofilm infections represent a major clinical challenge which results in a substantial burden to patients and healthcare systems. Treatment with topical antibiotics is oftentimes ineffective as a result of antibiotic‐resistant microorganisms and biofilm‐specific antibiotic tolerance. Use of biocides such as hypochlorous acid (HOCl) has gained increasing attention due to the lack of known resistance mechanisms. An HOCl‐generating electrochemical bandage (e‐bandage) is designed that delivers HOCl continuously at low concentrations targeting infected wound beds in a similar manner to adhesive antimicrobial wound dressings. A battery‐operated wearable potentiostat is developed that controls the e‐bandage electrodes at potentials suitable for HOCl generation. It is demonstrated that e‐bandage treatment is tunable by changing the applied potential. HOCl generation on electrode surfaces is verified using microelectrodes. The developed e‐bandage shows time‐dependent responses against in vitro Acinetobacter baumannii and Staphylococcus aureus biofilms, reducing viable cells to nondetectable levels within 6 and 12 h of treatment, respectively. The developed e‐bandage should be further evaluated as an alternative to topical antibiotics to treat wound biofilm infections.

Abstract Lack of a gold standard can present a challenge for evaluation of diagnostic test accuracy of some infectious diseases tests, particularly when the test's accuracy potentially exceeds that of its predecessors. This approach may measure agreement with an imperfect reference, rather than correctness, because the right answer is unknown. Solutions consist of multitest comparators, including those that involve a test under evaluation if multiple new tests are being evaluated together, using latent class modeling, and clinically adjudicated reference standards. Clinically adjudicated reference standards may be considered as comparator methods when no predefined test or composite of tests is sufficiently accurate; they emulate clinical practice in that multiple data pieces are clinically assessed together.

Serratia marcescens can cause a range of severe infections and contributes to nosocomial outbreaks. Although whole-genome sequencing (WGS)-based typing is the standard method for molecular surveillance and outbreak investigation, there is no standardized analytic scheme for S. marcescens core genome multilocus sequence typing (cgMLST).

AbstractThe activity of a hypochlorous acid‐producing electrochemical bandage (e‐bandage) in preventing methicillin‐resistant Staphylococcus aureus infection (MRSA) infection and removing biofilms formed by MRSA was assessed using a porcine explant biofilm model. e‐Bandages inhibited S. aureus infection (p = 0.029) after 12 h (h) of exposure and reduced 3‐day biofilm viable cell counts after 6, 12, and 24 h exposures (p = 0.029). Needle‐type microelectrodes were used to assess HOCl concentrations in explant tissue as a result of e‐bandage treatment; toxicity associated with e‐bandage treatment was evaluated. HOCl concentrations in infected and uninfected explant tissue varied between 30 and 80 µM, decreasing with increasing distance from the e‐bandage. Eukaryotic cell viability was reduced by an average of 71% and 65% in fresh and day 3‐old explants, respectively, when compared to explants exposed to nonpolarized e‐bandages. HOCl e‐bandages are a promising technology that can be further developed as an antibiotic‐free treatment for wound biofilm infections.

Drug-resistant Gram-positive bacterial infections are still a substantial burden on the public health system, with two bacteria ( Staphylococcus aureus and Streptococcus pneumoniae ) accounting for over 1.5 million drug-resistant infections in the United States alone in 2017. In 2019, 250,000 deaths were attributed to these pathogens globally. We have developed a preclinical glycopeptide antibiotic, MCC5145, that has excellent potency (MIC 90 ≤ 0.06 μg/ml) against hundreds of isolates of methicillin-resistant S. aureus (MRSA) and other Gram-positive bacteria, with a greater than 1000-fold margin over mammalian cell cytotoxicity values. The antibiotic has therapeutic in vivo efficacy when dosed subcutaneously in multiple murine models of established bacterial infections, including thigh infection with MRSA and blood septicemia with S. pneumoniae , as well as when dosed orally in an antibiotic-induced Clostridioides difficile infection model. MCC5145 exhibited reduced nephrotoxicity at microbiologically active doses in mice compared to vancomycin. MCC5145 also showed improved activity against biofilms compared to vancomycin, both in vitro and in vivo, and a low propensity to select for drug resistance. Characterization of drug action using a transposon library bioinformatic platform showed a mechanistic distinction from other glycopeptide antibiotics.

Abstract Aims Effects of H2O2 producing electrochemical-bandages (e-bandages) on methicillin-resistant Staphylococcus aureus colonization and biofilm removal were assessed using a porcine explant biofilm model. Transport of H2O2 produced from the e-bandage into explant tissue and associated potential toxicity were evaluated. Methods and Results Viable prokaryotic cells from infected explants were quantified after 48 h treatment with e-bandages in three ex vivo S. aureus infection models: (1) reducing colonization, (2) removing young biofilms and (3) removing mature biofilms. H2O2 concentration-depth profiles in explants/biofilms were measured using microelectrodes. Reductions in eukaryotic cell viability of polarized and nonpolarized noninfected explants were compared. e-Bandages effectively reduced S. aureus colonization (p = 0.029) and reduced the viable prokaryotic cell concentrations of young biofilms (p = 0.029) with limited effects on mature biofilms (p > 0.1). H2O2 penetrated biofilms and explants and reduced eukaryotic cell viability by 32–44% compared to nonpolarized explants. Conclusions H2O2 producing e-bandages were most active when used to reduce colonization and remove young biofilms rather than to remove mature biofilms. Significance and Impact of Study The described e-bandages reduced S. aureus colonization and young S. aureus biofilms in a porcine explant wound model, supporting their further development as an antibiotic-free alternative for managing biofilm infections.