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Oct 27, 2014 - ... and aadB reverse primers, as described (13). 54. PCR was additionally performed for Tn7 transposition genes (tnsA, tnsB, tnsC, tnsD and. 55 ...
AAC Accepts, published online ahead of print on 27 October 2014 Antimicrob. Agents Chemother. doi:10.1128/AAC.02415-14 Copyright © 2014, American Society for Microbiology. All Rights Reserved.

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Antimicrobial Agents and Chemotherapy, Short-form

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Association of Class 1 and 2 integrons with multidrug-resistant (MDR)

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Acinetobacter baumannii international clones and Acinetobacter nosocomialis isolates

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Running title: Integrons in A. baumannii and A. nosocomialis

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Natacha Martins1, Renata Cristina Picão1, Sheila Adams-Sapper2, Lee W. Riley2 and

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Beatriz Meurer Moreira1*

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Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil, 2School of Public

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Health, University of California, Berkeley, CA, USA.

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*Corresponding author. Beatriz M Moreira, MD PhD, Centro de Ciências da Saúde,

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Bloco I. Av. Carlos Chagas Filho 373. Postal code 21941-902, Cidade Universitária, RJ,

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Brazil. Phone: +5521-25608344. Fax: +5521-25608344. Email: [email protected]

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Abstract (75 words)

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Acinetobacter baumannii clonal complex (CC) 113/79 and class 2 integrons predominate

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in Latin America; a relationship between these characteristics was explored. Presence of

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integrases was determined in successive hospital Acinetobacter isolates (163 A.

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baumannii and 72 A. nosocomialis). Most had integrons, but class 1 and 2 were

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significantly more frequent in CC109/1 and CC113/79, respectively. Class 2 integron

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predominance in Latin America may be accounted for the high prevalence of CC113/79.

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Keywords:

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Acinetobacter nosocomialis

Integrons,

MLST,

international

clones,

Acinetobacter

baumannii,

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The dissemination of multidrug-resistant (MDR) Acinetobacter baumannii

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international clones (IC) and Acinetobacter nosocomialis have challenged healthcare (1,

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2). MDR phenotype in Acinetobacter has been related to class 1 and 2 integrons (3, 4, 5);

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class 2 integrons predominate in A. baumannii from Latin America (5, 6). This finding is

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possibly related to local clonal groups (6), a hypothesis not yet addressed. Class 2

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integron structure seems less diverse than class 1 (7), and is usually embedded within

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transposon Tn7 (5, 8).

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Four A. baumannii and one A. nosocomialis IC characterized by MLST has been

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described and spread in Rio de Janeiro, Brazil (9, 10). The purpose of the present study

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was to explore the association of class 2 integrons and gene cassettes with these clonal

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lineages. Between 2007-2008, 163 A. baumannii and 72 A. nosocomialis hospital isolates

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were investigated (10); 153 (94%) of the A. baumannii and 21 (29%) of the A.

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nosocomialis isolates were MDR. Among A. nosocomialis, antimicrobial resistance was

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higher for trimethoprim-sulphametoxazole (66%), cefepime (23%) and ciprofloxacin

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(23%) (10).

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The presence of class 1 and 2 integrons was screened in all isolates by multiplex-

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PCR with intI1 and intI2 gene-specific primers (11). The intI amplicons of two A.

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baumannii isolates were sequenced as controls. The variable region for intI2 gene

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positive isolates was characterized by amplification with primers Hep74 and Hep51 (12)

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and sequence analyses by BLAST (http://blast.ncbi.nlm.nih.gov/Blast.cgi). Isolates with

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no amplification of the variable region were further studied by PCR mapping with Hep74

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primer combined with dfrA1, sat2, aadA1 and aadB reverse primers, as described (13).

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PCR was additionally performed for Tn7 transposition genes (tnsA, tnsB, tnsC, tnsD and

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tnsE), where the 3’CS region is located (7). One positive amplicon of each tns gene was

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sequenced, as control.

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All isolates had been typed by RAPD-PCR (10), and a few by MLST (University

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of Oxford, UO and Institut Pasteur, IP schemes) (9, 10). In the present study, MLST was

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performed for all A. baumannii isolates. Proportions were compared by Fisher’s or chi-

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square test (http://www.openepi.com), p