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Introduction. Carbapenem resistant Enterobacterales (CRE) are one of the leading causes of systemic and nosocomial infections and are multidrug-resistant organisms producing different carbapenemases. There are many genotypic and phenotypic methods for detecting the carbapenemases; however, there is a limitation for each. Modified carbapenem inactivation method (mCIM) assay is a recent phenotypic method which has been published by the Clinical and Laboratory Standards Institute. Hypothesis / Gap Statement. mCIM assay could provide a reliable method for the detection of carbapenemases in CRE. Aim. Evaluation of the mCIM assay performance for the detection of carbapenemases in Enterobacterales and the identification of the common carbapenemase genes at Eastern Province of Saudi Arabia and Kingdom of Bahrain. Methodology. A collection of 197 non-duplicate carbapenem resistant Enterobacterales clinical isolates, were evaluated with the mCIM test comparing its performance to multiplex PCR. The minimum inhibitory concentration susceptibility testing was done by the Etest method for imipenem, meropenem, and ertapenem. Results. The sensitivity of the mCIM assay was 94 % (95 % CI, (89.3–97.1)). In Saudi Arabia and Bahrain, OXA-48 was the most prevalent carbapenemase gene followed by NDM. Coexistence of multiple carbapenemase genes is reported in eleven cases. Conclusion. These findings indicate that the mCIM test is a reliable and simple assay for detecting the activity of carbapenemase in Enterobacterales , especially in resource-limited laboratories.

This study characterized the occurrence of carbapenem resistance of Acinetobacter baumannii isolates in a tertiary care hospital in Saudi Arabia. From January 2010 until February 2012, Acinetobacter spp. isolates were collected from different wards and were identified using Vitek 2 system and 16S rRNA gene sequencing. Vitek 2 system and Etest were used for susceptibility testing. PCR and Pulse field gel electrophoresis (PFGE) were used for detecting and typing genes associated with carbapenem resistance. A total of 141 isolates were identified as A. baumannii. A total of 46 (32.6%) isolates were carbapenem-resistant Acinetobacter baumannii (CRAB) isolates and had wild diversity by PFGE. Metallo ?-lactamase confirmatory test was positive for 43 isolates with negative PCR for blaIMP and blaVIM. Among the 46 CRAB strains, 37 isolates harbored blaOXA-23 which was encoded downstream of ISAba1 and 1 isolate had ISAba1 encoded upstream blaOXA-51. These data reveal that the interhospital transmission of CRAB isolates was apparently insignificant. BlaOXA-23 adjacent to ISAba1 was the main mechanism of carbapenem resistance in these isolates. To our knowledge, this is the first molecular study characterizing carbapenem resistance in A. baumannii in the Eastern Province of Saudi Arabia.