The potential for developing new antimicrobial resistance from the use of medical devices containing chlorhexidine, minocycline, rifampicin and their combinations: a systematic review

Background

Catheter infections remain one of the most persistent adverse events causing significant morbidity, economic impact and mortality. Several strategies have been proposed to reduce these infections including the use of catheters embedded with antibiotics and/or antiseptics. One reoccurring challenge is the fear that antimicrobial medical devices will induce resistance. The aim of this systematic review is to evaluate the evidence for induced antimicrobial resistance caused by exposure to antimicrobial medical devices.

Methods

Four electronic databases [MEDLINE, Embase, Cumulative Index to Nursing and Allied Health Literature (CINAHL) and Scopus] were screened for studies published between 1983 and 2019 regarding assessment of microbial resistance with use of medical devices containing chlorhexidine, minocycline, rifampicin or combinations thereof. Development of new resistance, selection for tolerant organisms and 'no change in resistance' were assessed.

Results

Forty-four publications, grouped by study type and stratified by drug assessed, were included for analyses. The majority of studies found no change in resistance after exposure to antimicrobial medical devices (13 in vitro, 2 in vivo, 20 clinical). Development of new resistance was commonly reported with the use of rifampicin as a single agent and only reported in one study assessing the minocycline/rifampicin combination (M/R); however, the increase in MIC was well below clinical relevance.

Conclusions

Emergence of new resistance to combinations of M/R, minocycline/rifampicin/chlorhexidine (M/R/CH) and chlorhexidine/silver sulfadiazine (CHXSS) was rare. No clinical trials confirmed its occurrence and some refuted it. The risk of development of new resistance to these antimicrobial combinations appears more fear-based than substantiated by clinical and experimental evidence but warrants continued surveillance.

In vitro activity of imipenem/relebactam and comparator agents against clinical bacterial isolates from patients with cancer

BACKGROUND

Gram-negative bacilli (GNB) are currently the predominant bacterial pathogens in patients with cancer. Many GNB have become problematic due to the widespread emergence of resistance. Imipenem/relebactam (IMP/REL) is a combination of the carbapenem imipenem with relebactam, a non-beta-lactam beta-lactamase inhibitor. It is active against most pathogenic GNB including many that are resistant to other agents. We compared its in vitro activity to 6 other agents against 490 GNB recovered exclusively from patients with cancer, since such data are scarce.

METHODS

CLSI microbroth dilution methods were used for susceptibility testing. Whole genome sequencing (Illumina MiSeq) was performed on 30 selected isolates.

RESULTS

IMP/REL was active against 98 % of Enterobacterales and 87 % of non-Enterobacterales isolates (excluding Stenotrophomonas maltophilia). It had potent activity against ESBL-producing Escherichia coli and Klebsiella pneumoniae, and other Enterobacterales (Enterobacter cloacae, Citrobacter spp., and Serratia spp.), and moderate activity against carbapenem-resistant Enterobacterales. IMI/REL had potent activity against Achromobacter spp., non-MDR Pseudomonas aeruginosa, and Sphingomonas paucimobilis and moderate activity against MDR P. aeruginosa. Overall, imipenem/relebactam was associated with the lowest number of non-susceptible isolates compared to 6 other agents (imipenem, meropenem, cefepime, piperacillin/tazobactam, amikacin, and tigecycline) commonly used in cancer patients. Whole genome sequencing performed on 30 resistant isolates (10 each of E. coli, Klebsiella pneumonia, and P.aeruginosa) did not reveal any predominant mechanism of resistance to imipenem/relebactam.

CONCLUSION

Its in vitro activity indicates that IMI/REL might have a role to play for the treatment of Gram-negative infections in patients with cancer.

1714. In Vitro Activity of Tebipenem Against Clinically Significant Gram-Positive Bacteria Isolated from Patients with Cancer

Background

Carbapenems represent the most potent and broad-spectrum β-lactams and are minimally affected by most β-lactamase enzymes. however, all carbapenems currently in use including meropenem and ertapenem, are parenterally administered. Tebipenem pivoxil (TBPM-PI-HBr) is a new broad-spectrum orally-administered antibiotic, from the carbapenem subgroup of β-lactam antibiotics. It is the only oral carbapenem and could be an alternative to intravenous injection carbapenem antibiotic therapy. This study aimed to evaluate the in vitro activity of tebipenem, a novel oral carbapenem, against recent gram-positive clinical isolates from cancer patients.

Methods

We tested 300 gram-positive isolates are recently isolated (2019-2021) from our cancer patients, collected from blood cultures against tebipenem and comparators. Clinical and laboratory Standards Instituted (CLSI) approved broth microdilution method was used with appropriate ATCC controls. MIC50, MIC90, MIC ranges and percent of susceptibility calculations were made using FDA breakpoints when available. There is no tebipenem susceptibility breakpoint for gram-positive isolates currently.

MIC90 and MICs range of tebipenem and comparators against 300 gram-positive isolates from cancer patients

Results

MIC90 and range of tebipenem and comparators are shown in table(1). Tebipenem gave the lowest MIC90 and MIC ranges against most gram-positive isolates including Bacillus species, Corynebacterium species, Enterococcus faecalis, Micrococcus species, MSSA S.aureus, Staphylococcus lugdunensis. β-hemolytic Streptococcus, Streptococcus pneumonie, Viridans group streptococci, and Rothia species. The comparative potency of tebipenem vs meropenem as a carbapenem in this study showed that, tebipenem MIC values were generally lower at least 2-4 fold.

Conclusion

Our data demonstrate that oral tebipenem has promising activity against clinically significant bacterial pathogens isolated from cancer patients and it has compatible activity to that of meropenem as a carbapenem in this study. Further clinical evolution for oral carbapenem treatment of bacterial infections is warranted.

Disclosures

All Authors: No reported disclosures.

Polygalacturonic acid partially inhibits matrix metalloproteinases and dehydration in wounds

BACKGROUND

Key wound environment parameters include pH, hydration, and the balance between tissue remodeling and deposition of new tissue. When prolonged inflammation is present, the proliferation phase of wound healing can be delayed because excessive protease production due to persistent inflammation can destroy newly formed tissue and prevent wounds from filling and reepithelializing.

OBJECTIVE

To conduct an in vitro study of the ability of polygalacturonic acid (PG), a natural pectin derivative present in ripening fruit, to inhibit 3 destructive wound proteases and prevent dehydration in environments in which significant evaporation can occur.

MATERIALS AND METHODS

In vitro enzyme inhibition assay kits were used to detect the ability of PG to inhibit key wound proteases matrix metalloproteinase (MMP)-2, MMP-9, and neutrophil elastase (NE). Transepidermal evaporative water loss from a polyvinyl alcohol skin substitute hydrogel was gravimetrically measured.

RESULTS

PG could partially inhibit MMP-2 (>50% inhibition relative to negative controls), MMP-9 (>50% inhibition relative to negative controls), and NE (>25% inhibition relative to negative controls) and thereby potentially blunt some of the destructive effects of excess proteases where prolonged inflammation is present. In an in vitro transepidermal evaporative water loss assay, PG also helped retain moisture and inhibited dehydration (>25% reduction relative to negative controls).

CONCLUSIONS

These findings suggest that PG can be a useful addition to ointments and dressings in wound care and warrants further in vivo testing.