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16S rRNA Methyltransferases in Clinical Gram-negative Bacilli from a Tertiary Care Hospital in the Caribbean




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.


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e-Published: 08 Mar, 2019


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