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.
1
Antimicrobial Agents and Chemotherapy, Short-form
2 3
Association of Class 1 and 2 integrons with multidrug-resistant (MDR)
4
Acinetobacter baumannii international clones and Acinetobacter nosocomialis isolates
5 6
Running title: Integrons in A. baumannii and A. nosocomialis
7 8
Natacha Martins1, Renata Cristina Picão1, Sheila Adams-Sapper2, Lee W. Riley2 and
9
Beatriz Meurer Moreira1*
10 11
1
Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil, 2School of Public
12
Health, University of California, Berkeley, CA, USA.
13 14
*Corresponding author. Beatriz M Moreira, MD PhD, Centro de Ciências da Saúde,
15
Bloco I. Av. Carlos Chagas Filho 373. Postal code 21941-902, Cidade Universitária, RJ,
16
Brazil. Phone: +5521-25608344. Fax: +5521-25608344. Email:
[email protected]
17 18 19 20 21 22
1
23
Abstract (75 words)
24
Acinetobacter baumannii clonal complex (CC) 113/79 and class 2 integrons predominate
25
in Latin America; a relationship between these characteristics was explored. Presence of
26
integrases was determined in successive hospital Acinetobacter isolates (163 A.
27
baumannii and 72 A. nosocomialis). Most had integrons, but class 1 and 2 were
28
significantly more frequent in CC109/1 and CC113/79, respectively. Class 2 integron
29
predominance in Latin America may be accounted for the high prevalence of CC113/79.
30 31
Keywords:
32
Acinetobacter nosocomialis
Integrons,
MLST,
international
clones,
Acinetobacter
baumannii,
2
33
The dissemination of multidrug-resistant (MDR) Acinetobacter baumannii
34
international clones (IC) and Acinetobacter nosocomialis have challenged healthcare (1,
35
2). MDR phenotype in Acinetobacter has been related to class 1 and 2 integrons (3, 4, 5);
36
class 2 integrons predominate in A. baumannii from Latin America (5, 6). This finding is
37
possibly related to local clonal groups (6), a hypothesis not yet addressed. Class 2
38
integron structure seems less diverse than class 1 (7), and is usually embedded within
39
transposon Tn7 (5, 8).
40
Four A. baumannii and one A. nosocomialis IC characterized by MLST has been
41
described and spread in Rio de Janeiro, Brazil (9, 10). The purpose of the present study
42
was to explore the association of class 2 integrons and gene cassettes with these clonal
43
lineages. Between 2007-2008, 163 A. baumannii and 72 A. nosocomialis hospital isolates
44
were investigated (10); 153 (94%) of the A. baumannii and 21 (29%) of the A.
45
nosocomialis isolates were MDR. Among A. nosocomialis, antimicrobial resistance was
46
higher for trimethoprim-sulphametoxazole (66%), cefepime (23%) and ciprofloxacin
47
(23%) (10).
48
The presence of class 1 and 2 integrons was screened in all isolates by multiplex-
49
PCR with intI1 and intI2 gene-specific primers (11). The intI amplicons of two A.
50
baumannii isolates were sequenced as controls. The variable region for intI2 gene
51
positive isolates was characterized by amplification with primers Hep74 and Hep51 (12)
52
and sequence analyses by BLAST (http://blast.ncbi.nlm.nih.gov/Blast.cgi). Isolates with
53
no amplification of the variable region were further studied by PCR mapping with Hep74
54
primer combined with dfrA1, sat2, aadA1 and aadB reverse primers, as described (13).
55
PCR was additionally performed for Tn7 transposition genes (tnsA, tnsB, tnsC, tnsD and
3
56
tnsE), where the 3’CS region is located (7). One positive amplicon of each tns gene was
57
sequenced, as control.
58
All isolates had been typed by RAPD-PCR (10), and a few by MLST (University
59
of Oxford, UO and Institut Pasteur, IP schemes) (9, 10). In the present study, MLST was
60
performed for all A. baumannii isolates. Proportions were compared by Fisher’s or chi-
61
square test (http://www.openepi.com), p
