1432. Exploring Cell Wall Targets to Overcome Mycobacterium tuberculosis (Mtb): Ceftriaxone (CRO) Inhibits LdtMt2, a Major Peptidoglycan (PG) Synthase

Background

Drug-resistant tuberculosis (DR TB) is a deadly, difficult-to-treat infection, and new treatment strategies are needed. Despite the wide success of β-lactams (BLs), DR TB guidelines only include meropenem (MEM) and imipenem (IPM), given with clavulanate (CLA). BlaC, the Mtb β-lactamase, hydrolyzes CRO less efficiently than other cephems and β-lactamase inhibitors improve the in vitro susceptibility of Mtb to CRO. Surprisingly, CRO has not been evaluated in DR TB clinical studies. Moreover, the mechanisms by which CRO disrupts Mtb PG synthesis are not well characterized. CRO inhibits Ldt_Mt1­, but activity against Ldt_Mt2, an important Mtb PG synthase, is unknown. To explore this knowledge gap, we examined CRO inhibition of Ldt_Mt2. In addition, we investigated if combining CRO with MEM or IPM would lower minimum inhibitory concentrations (MICs) more than each agent alone.

Methods

A panel of Mtb isolates was selected for susceptibility testing with a broth microdilution method. Timed electrospray ionization-mass spectrometry (ESI-MS) and inhibition kinetic assays were performed.

Results

CRO MICs ranged 0.25 to 16 µg/mL and lowered ≤ 0.06 to 2 µg/mL with CLA (Table 1). Fractional inhibitory concentration indices for CRO + MEM or IPM was < 0.5 for six isolates, suggesting synergy. ESI-MS captured CRO-Ldt_Mt2­ acyl-complexes at timepoints 5 to 120 min, and a 158 Da fragment loss was observed; MEM and IPM were unchanged (Table 2, Figure 1). When Ldt_Mt2 was co-incubated with MEM and CRO together, only MEM complexes were captured. Interestingly, K_iapp­ with CRO (0.07 ± 0.01 µM) was comparable to that with MEM (0.09 ± 0.01 µM). Figure 1

Transmission of SARS-CoV-2 in Inpatient and Outpatient Settings in a Veterans Affairs Health Care System

BACKGROUND

Health care personnel and patients are at risk to acquire severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in health care settings, including in outpatient clinics and ancillary care areas.

METHODS

Between May 1, 2020, and January 31, 2021, we identified clusters of 3 or more coronavirus disease 2019 (COVID-19) cases in which nosocomial transmission was suspected in a Veterans Affairs health care system. Asymptomatic employees and patients were tested for SARS-CoV-2 if they were identified as being at risk through contact tracing investigations; for 7 clusters, all personnel and/or patients in a shared work area were tested regardless of exposure history. Whole-genome sequencing was performed to determine the relatedness of SARS-CoV-2 samples from the clusters and from control employees and patients.

RESULTS

Of 14 clusters investigated, 7 occurred in community-based outpatient clinics, 1 in the emergency department, 3 in ancillary care areas, and 3 on hospital medical/surgical wards that did not provide care for patients with known COVID-19 infection. Eighty-one of 82 (99%) symptomatic COVID-19 cases and 31 of 35 (89%) asymptomatic cases occurred in health care personnel. Sequencing analysis provided support for several transmission events between coworkers and in 2 cases supported transmission from health care personnel to patients. There were no documented transmissions from patients to personnel.

CONCLUSIONS

Clusters of COVID-19 with nosocomial transmission predominantly involved health care personnel and often occurred in outpatient clinics and ancillary care areas. There is a need for improved measures to prevent transmission of SARS-CoV-2 by health care personnel in inpatient and outpatient settings.

Scalable in-hospital decontamination of N95 filtering face-piece respirator with a peracetic acid room disinfection system

BACKGROUND

Critical shortages of personal protective equipment, especially N95 respirators, during the coronavirus disease 2019 (COVID-19) pandemic continues to be a source of concern. Novel methods of N95 filtering face-piece respirator decontamination that can be scaled-up for in-hospital use can help address this concern and keep healthcare workers (HCWs) safe.

METHODS

A multidisciplinary pragmatic study was conducted to evaluate the use of an ultrasonic room high-level disinfection system (HLDS) that generates aerosolized peracetic acid (PAA) and hydrogen peroxide for decontamination of large numbers of N95 respirators. A cycle duration that consistently achieved disinfection of N95 respirators (defined as ≥6 log10 reductions in bacteriophage MS2 and Geobacillus stearothermophilus spores inoculated onto respirators) was identified. The treated masks were assessed for changes to their hydrophobicity, material structure, strap elasticity, and filtration efficiency. PAA and hydrogen peroxide off-gassing from treated masks were also assessed.

RESULTS

The PAA room HLDS was effective for disinfection of bacteriophage MS2 and G. stearothermophilus spores on respirators in a 2,447 cubic-foot (69.6 cubic-meter) room with an aerosol deployment time of 16 minutes and a dwell time of 32 minutes. The total cycle time was 1 hour and 16 minutes. After 5 treatment cycles, no adverse effects were detected on filtration efficiency, structural integrity, or strap elasticity. There was no detectable off-gassing of PAA and hydrogen peroxide from the treated masks at 20 and 60 minutes after the disinfection cycle, respectively.

CONCLUSION

The PAA room disinfection system provides a rapidly scalable solution for in-hospital decontamination of large numbers of N95 respirators during the COVID-19 pandemic.

Scalable in-hospital decontamination of N95 filtering face-piece respirator with a peracetic acid room disinfection system

BACKGROUND

Critical shortages of personal protective equipment, especially N95 respirators, during the coronavirus disease 2019 (COVID-19) pandemic continues to be a source of concern. Novel methods of N95 filtering face-piece respirator decontamination that can be scaled-up for in-hospital use can help address this concern and keep healthcare workers (HCWs) safe.

METHODS

A multidisciplinary pragmatic study was conducted to evaluate the use of an ultrasonic room high-level disinfection system (HLDS) that generates aerosolized peracetic acid (PAA) and hydrogen peroxide for decontamination of large numbers of N95 respirators. A cycle duration that consistently achieved disinfection of N95 respirators (defined as ≥6 log10 reductions in bacteriophage MS2 and Geobacillus stearothermophilus spores inoculated onto respirators) was identified. The treated masks were assessed for changes to their hydrophobicity, material structure, strap elasticity, and filtration efficiency. PAA and hydrogen peroxide off-gassing from treated masks were also assessed.

RESULTS

The PAA room HLDS was effective for disinfection of bacteriophage MS2 and G. stearothermophilus spores on respirators in a 2,447 cubic-foot (69.6 cubic-meter) room with an aerosol deployment time of 16 minutes and a dwell time of 32 minutes. The total cycle time was 1 hour and 16 minutes. After 5 treatment cycles, no adverse effects were detected on filtration efficiency, structural integrity, or strap elasticity. There was no detectable off-gassing of PAA and hydrogen peroxide from the treated masks at 20 and 60 minutes after the disinfection cycle, respectively.

CONCLUSION

The PAA room disinfection system provides a rapidly scalable solution for in-hospital decontamination of large numbers of N95 respirators during the COVID-19 pandemic.

Transmission of SARS-CoV-2 on a Patient Transport Van

We report 2 episodes of potential SARS-CoV-2 transmission from infected van drivers to passengers despite masking and physical distancing. Whole genome sequencing confirmed relatedness of driver and passenger SARS-CoV-2. With the heater operating, fluorescent microspheres were transported by airflow >3 meters from the front to the back of the van.

Evaluation of an electrostatic spray disinfectant technology for rapid decontamination of portable equipment and large open areas in the era of SARS-CoV-2

In the setting of the coronavirus disease 2019 pandemic, efficient methods are needed to decontaminate shared portable devices and large open areas such as waiting rooms. We found that wheelchairs, portable equipment, and waiting room chairs were frequently contaminated with potential pathogens. After minimal manual precleaning of areas with visible soiling, application of a dilute sodium hypochlorite disinfectant using an electrostatic sprayer provided rapid and effective decontamination and eliminated the benign virus bacteriophage MS2 from inoculated surfaces.

A Case of Actinomyces Prosthetic Hip Infection

Actinomyces is a species of gram-positive anaerobic commensal organisms found in the human oropharynx, gastrointestinal, and genitourinary tracts, which most often are implicated in cervicofacial infections. Rarely do these organisms cause joint infections. We present the case of a 68-year-old man with a prosthetic hip infection due to Actinomyces species. He underwent surgical incision and drainage with replacement of the prosthetic joint. Cultures grew Actinomyces species, and he was treated with a four-week course of ampicillin-sulbactam followed by eight weeks of amoxicillin-clavulanate. This organism is an uncommon pathogen, and few cases of prosthetic joint infection due to Actinomyces have previously been reported.

Evaluation of Ultraviolet-C Light for Rapid Decontamination of Airport Security Bins in the Era of SARS-CoV-2

Background:

Contaminated surfaces are a potential source for spread of respiratory viruses including SARS-CoV-2. Ultraviolet-C (UV-C) light is effective against RNA and DNA viruses and could be useful for decontamination of high-touch fomites that are shared by multiple users.

Methods:

A modification of the American Society for Testing and Materials standard quantitative carrier disk test method (ASTM E-2197-11) was used to examine the effectiveness of UV-C light for rapid decontamination of plastic airport security bins inoculated at 3 sites with methicillin-resistant Staphylococcus aureus (MRSA) and bacteriophages MS2, PhiX174, and Phi6, an enveloped RNA virus used as a surrogate for coronaviruses. Reductions of 3 log₁₀ on inoculated plastic bins were considered effective for decontamination.

Results:

UV-C light administered as 10-, 20-, or 30-second cycles in proximity to a plastic bin reduced contamination on each of the test sites, including vertical and horizontal surfaces. The 30-second cycle met criteria for decontamination of all 3 test sites for all the test organisms except bacteriophage MS2 which was reduced by greater than 2 log₁₀ PFU at each site.

Conclusions:

UV-C light is an attractive technology for rapid decontamination of airport security bins. Further work is needed to evaluate the utility of UV-C light in real-world settings and to develop methods to provide automated movement of bins through a UV-C decontamination process.

Effectiveness of Ultraviolet-C Light and a High-Level Disinfection Cabinet for Decontamination of N95 Respirators

BACKGROUND

Shortages of personal protective equipment (PPE) including N95 respirators are an urgent concern in the setting of the global COVID-19 pandemic. Decontamination of PPE could be useful to maintain adequate supplies, but there is uncertainty regarding the efficacy of decontamination technologies.

METHODS

A modification of the American Society for Testing and Materials standard quantitative carrier disk test method (ASTM E-2197-11) was used to examine the effectiveness of 3 methods, including ultraviolet-C (UV-C) light, a high-level disinfection cabinet that generates aerosolized peracetic acid and hydrogen peroxide, and dry heat at 70°C for 30 minutes. We assessed the decontamination of 3 commercial N95 respirators inoculated with methicillin-resistant Staphylococcus aureus (MRSA) and bacteriophages MS2 and Phi6; the latter is an enveloped RNA virus used as a surrogate for coronaviruses. Three and 6 log10 reductions on respirators were considered effective for decontamination and disinfection, respectively.

RESULTS

UV-C administered as a 1-minute cycle in a UV-C box or a 30-minute cycle by a room decontamination device reduced contamination but did not meet criteria for decontamination of the viruses from all sites on the N95s. The high-level disinfection cabinet was effective for decontamination of the N95s and achieved disinfection with an extended 31-minute cycle. Dry heat at 70°C for 30 minutes was not effective for decontamination of the bacteriophages.

CONCLUSIONS

UV-C could be useful to reduce contamination on N95 respirators. However, the UV-C technologies studied did not meet pre-established criteria for decontamination under the test conditions used. The high-level disinfection cabinet was more effective and met criteria for disinfection with an extended cycle.

Impact of Reduced Fluoroquinolone Use on Clostridioides difficile Infections Resulting From the Fluoroquinolone-Resistant Ribotype 027 Strain in a Veterans Affairs Medical Center

Background

Fluoroquinolone restriction has been proposed as a control measure for Clostridioides difficile infection (CDI) outbreaks associated with fluoroquinolone-resistant ribotype 027 strains. However, relatively few reports of fluoroquinolone restriction interventions have evaluated the impact on C. difficile strain types and fluoroquinolone resistance.

Methods

In a hospital and affiliated long-term care facility (LTCF), antimicrobial stewardship and environmental cleaning interventions were implemented between 2009 and 2018, and C. difficile isolates during this period (~20 per year) were ribotyped and tested for fluoroquinolone resistance by moxifloxacin minimum inhibitory concentrations (MICs). Pearson's correlation coefficient was used to assess the association between use of fluoroquinolones and the percentage of CDI cases due to the 027 strain over time.

Results

Between 2009 and 2018, prescribing of fluoroquinolones to inpatients decreased by 43%, coinciding with significant reductions in the healthcare-associated CDI rates in the hospital and LTCF and a decline in the percentage of C. difficile isolates that were ribotype 027 from 70% to 10%. Ninety-five percent of ribotype 027 and 6% of non-027 isolates were moxifloxacin resistant. Hospital fluoroquinolone use was strongly correlated with the incidence of hospital-associated CDI (r = 0.79, 95% confidence interval, 0.31-0.95), but LTCF fluoroquinolone use was not correlated with LTCF-associated CDI (r = 0.29, 95% confidence interval, -0.43-0.77). During the study period, there were statistically significant downward trends in the use of penicillins, intravenous vancomycin, carbapenems, and clindamycin.

Conclusion

Our results provide support for fluoroquinolone restriction as a control measure for CDI outbreaks due to fluoroquinolone-resistant 027 strains, but also highlight the need for randomized trials as factors such as reduction in other antibiotic classes and improved cleaning may also impact CDI rates.

SNP genotyping defines complex gene-flow boundaries among African malaria vector mosquitoes

Mosquitoes in the Anopheles gambiae complex show rapid ecological and behavioral diversification, traits that promote malaria transmission and complicate vector control efforts. A high-density, genome-wide mosquito SNP-genotyping array allowed mapping of genomic differentiation between populations and species that exhibit varying levels of reproductive isolation. Regions near centromeres or within polymorphic inversions exhibited the greatest genetic divergence, but divergence was also observed elsewhere in the genomes. Signals of natural selection within populations were overrepresented among genomic regions that are differentiated between populations, implying that differentiation is often driven by population-specific selective events. Complex genomic differentiation among speciating vector mosquito populations implies that tools for genome-wide monitoring of population structure will prove useful for the advancement of malaria eradication.