Antibiotic resistance, particularly beta-lactam resistance, is a major problem worldwide. Imipenemase or IMP-type metallo-β-lactamase (MBL) has become a more prominent enzyme, especially in Asia, since it was discovered in the 1990s in Japan. There are currently 88 variants of IMP-type enzymes. The most commonly identified variant of IMP-type enzymes is IMP−1 variant. IMP-type MBLs have been detected in more than ten species in Enterobacterales. Pseudomonas aeruginosa is the most frequent carrier of IMP-type enzymes worldwide. In Asia, IMP-type MBLs have been distributed in many countries. This work investigated a variety of currently available IMP-type MBLs at both a global level and a regional level. Out of 88 variants of IMP-type MBLs reported worldwide, only 32 variants were found to have susceptibility profiles. Most of the bacterial isolates carrying IMP-type MBLs were resistant to Carbapenems, especially Imipenem and Meropenem, followed by the 3rd-generation cephalosporins, and interestingly, monobactams. Our results comprehensively indicated the distribution of IMP-type MBLs in Asia and raised the awareness of the situation of antimicrobial resistance in the region.

Antibiotic resistance, particularly beta-lactam resistance, is a major problem worldwide. Imipenemase or IMP-type metallo-beta-lactamase (MBL) has become a more prominent enzyme, especially in Asia, since it was discovered in the 1990s in Japan. There are currently more than 91 variants of IMP-type enzymes. The most commonly identified variant of IMP-type enzymes is IMP-1 variant. IMP-type MBLs have been identified in more than 10 species in Enterobacterales. Pseudomonas aeruginosa is the most frequent carrier of IMP-type enzymes worldwide. In Asia, IMP-type MBLs have been distributed in many countries in the region. This work investigated a variety of currently available IMP-type MBLs in both global level and regional level. Out of 88 variants of IMP-type MBLs reported worldwide, only 32 variants were found to have susceptibility profiles. Most of the IMP-type MBLs were resistant to Carbapenems, especially Imipenem and Meropenem, followed by the 3rd generation cephalosporins, and interestingly, monobactams. Our results comprehensively indicated the distribution of IMP-type MBLs in Asia and raised the awareness of the situation of antimicrobial resistance in the region.

Background: Antibiotic-loaded polymethylmethacrylate (PMMA) cement spacers are widely used in periprosthetic joint infection and chronic osteomyelitis. Manual prefabrication and sterilisation of non-commercial antibiotic-loaded cement may reduce operative time and cost; however, the effects of sterilisation and storage on antimicrobial efficacy remain unclear. Methods: Manually prefabricated PMMA cement containing vancomycin (2 g or 4 g) underwent formaldehyde gas sterilisation (FO) and storage for one, four or seven days. Antibiotic elution was evaluated over 28 days. Antimicrobial activity against Staphylococcus aureus ATCC 25923 was assessed using minimum inhibitory dilution (MID) testing at predefined time points. Given the small number of specimens per subgroup, all comparisons should be interpreted as preliminary and hypothesis-generating. Results: FO sterilisation significantly reduced antimicrobial activity during the early elution phase. In the 4—g vancomycin group, Day 1 MID values were significantly higher in one day storage sterilised specimens than in specimens stored for four or seven days (1024 µg/mL vs. 213 µg/mL and 213 µg/mL, respectively; P < 0.001). Differences persisted at early time points but were no longer significant during the sustained elution phase (Days 14–28; P > 0.05). Overall, sterilised cement containing 4 g of vancomycin demonstrated higher MID values than 2 g cement during the early and mid-elution phases (Days 1–14; P < 0.01). MID values in all sterilised specimens remained several-fold above inhibitory thresholds for S. aureus throughout the 28-day period. Conclusions: FO sterilisation transiently reduces vancomycin antimicrobial activity during the early elution phase (Days 1–7) but does not affect sustained antimicrobial efficacy compared with non-sterilised cement. Based on these findings, vancomycin-loaded PMMA cement containing 4 g of antibiotic may be sterilised and stored for up to seven days while maintaining MIC values several-fold above inhibitory thresholds for Staphylococcus aureus throughout the 28-day elution period.