Objective: 16S rRNA methyltransferase enzymes or RMT confer pan-resistance to the aminoglycoside class of antibiotics. Multidrug-resistant Gram-negative bacilli with these methyltransferase genes have been identified from clinical settings in Europe, Asia and the Americas. This study reports their detection and characterization in Jamaican Multidrug-resistant Gram-negative bacilli.
Methodology: Retrospective review of clinical isolates collected between April 2009 and November 2011 at the University Hospital of the West Indies (UHWI), Kingston, Jamaica, revealed 370 multidrug-resistant Gram-negative bacilli with resistance to one or more aminoglycosides. Screening for high-level amikacin resistance [HLAR] (MIC ≥ 256 mg/L) by agar gradient MIC testing using Etest strips, identified potential RMT carrying isolates. Species level identification of HLAR isolates was confirmed by Vitek MS MALDI-TOF mass spectrometry. Conventional multiplex PCR was used for detection of rmtA, rmtB, rmtC, rmtD, npmA and armA genes with positives confirmed by sequencing.
Results: Of the 370 multidrug-resistant Gram-negative bacilli, 27 (7.3%) showed HLAR (22 Acinetobacter baumannii, two Acinetobacter heamolyticus, two Pseudomonas aeruginosa and a Klebsiella pneumoniae). 16S rRNA methyltransferase PCR revealed 18 (67%) armA positive A. baumanii spp. and one (4%) rmtC positive K. pneumoniae.
Conclusions: The identification of 16S rRNA methyltransferase genes in Jamaican multidrug-resistant Gram-negative bacilli further confirms the widespread distribution of these genes. Identification of 16S rRNA methyltransferase genes in these multidrug-resistant organisms, indicates that adjunctive therapy of β-lactam antibiotics with aminoglycosides may no longer be a treatment option for some patients in Jamaica. Active surveillance and effective infection control will be necessary to limit its spread.
Manuscripts that are Published Ahead of Print have been peer reviewed and accepted for publication by the Editorial Board of the West Indian Medical Journal. They may appear in their original format and may not be copy edited or formatted in the style guide of this Journal. While accepted manuscripts are not yet assigned a volume, issue or page numbers, they can be cited using the DOI and date of e-publication. See our Instructions for Authors on how to properly cite manuscripts at this stage. The contents of the manuscript may change before it is published in its final form. Manuscripts in this section will be removed once they have been issued to a volume and issue, but will still retain the DOI and date of e-publication.