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Revista da Sociedade Brasileira de Medicina Tropical

versão impressa ISSN 0037-8682versão On-line ISSN 1678-9849

Rev. Soc. Bras. Med. Trop. vol.52  Uberaba  2019  Epub 18-Jul-2019 


New sequence types of Acinetobacter baumannii in two emergency hospitals in the Central-West region of Brazil

Francisco Kennedy Scofoni Faleiros de Azevedo1

Valéria Dutra2 

Luciano Nakazato2 

Marco Andrey Pepato1 

Alessandra Tammy Hayakawa Ito de Sousa2 

Cassius Clay Scofoni Faleiros de Azevedo1 

Francisco José Dutra Souto1 

1Departamento de Clínica Médica, Universidade Federal de Mato Grosso, Cuiabá, MT, Brasil.

2Hospital Veterinário e Laboratório de Microbiologia Veterinária e Biologia Molecular, Universidade Federal de Mato Grosso, Cuiabá, MT, Brasil.

Dear Editor:

Acinetobacter baumannii, a common causal agent of ventilator-associated pneumonia, is related with high hospital costs and mortality1. The 2016 surveillance report of the European Centre for Disease Prevention and Control reported that 49% of A. baumannii isolates were carbapenem resistant2. In Brazil, the percentage of this species with resistance to carbapenems is approximately 71%, with similar data for Chile and Argentina3. The genes bla OXA-23, bla OXA-24 (and its variants bla OXA-40 and bla OXA-72), bla OXA-58, bla OXA-143, and bla OXA-235 of the Ambler class D β-lactamases are responsible for carbapenem resistance in A. baumannii4. Multilocus sequence typing (MLST) is used to determine the sequence type (ST) of isolates, with A. baumannii ST15, ST25, ST79, and ST1 being the most common in South America5. These clones are clustered in MLST clonal complexes (CC) CC15, CC25, CC79, and CC1, respectively5. In Brazil, A. baumannii ST15, ST79, and ST1 are also frequently found6.

A total of nine Acinetobacter spp. isolates were extracted from rectal swab and wound secretion samples from nine patients hospitalized in intensive care units at two public emergency hospitals in Cuiaba and Varzea Grande, Mato Grosso State, Central Brazil: the Municipal Hospital and Emergency Room of Cuiaba, and the Municipal Hospital and Emergency Room of Varzea Grande. Rectal swabs and wound secretion samples were collected from the patients for routine surveillance by the hospital infection control committees between June 2012 and August 2012. Microorganism identification was performed, and drug resistance profiles based on the minimum inhibitory concentration were obtained using the Bact/Alert 3D and Vitek2 systems (BioMérieux, Marcy l’Etoile, France) in the Microbiology Laboratory of the Júlio Muller University Hospital, Cuiaba, Mato Grosso, Brazil. Isolates identified as Acinetobacter spp. were tested for their sensitivity to antimicrobials according to the 2017 Clinical and Laboratory Standards Institute Guidelines7. The genomic DNA extraction, polymerase chain reaction (PCR) for the detection of A. baumannii genes, and application of the MLST technique for genotypic analysis of the isolates were performed in the Laboratory of Veterinary Microbiology and Molecular Biology, College of Veterinary Medicine, Federal University of Mato Grosso, Mato Grosso, Brazil8-10.

The research protocol (#850.791) was approved by the Ethics Research Committee of the Julio Muller Hospital, and was registered in the National System of the Ethical Evaluation of Human Research Projects (CAAE 28637414.0.0000.5541). The A. baumannii isolates were confirmed by the PCR-based amplification of the bla OXA-51 gene. The patient demographics and the isolates’ in vitro resistance to antimicrobials are detailed in Table 1.

TABLE 1: Clinical characteristics of the nine hospitalized patients, and in vitro susceptibility to imipenem, resistance genes, sequence types, and clonal complexes of Acinetobacter baumannii isolates, from two emergency hospitals in the Center-West region of Brazil. 

Patient Age Sample Imipenem Time to Hospital Prior Outcom bla OXA-23/ bla OXA-24 bla OXA-143 Sequence Clonal
(year),Sexa b c isolation (day) d treatmente e ISAba1 type (ST) complexf (CC)
1 67, F RS R 20 A IMP Recovery + - + 984 Singletong
2 35, M RS R 19 A PIPE/TAZ, IMP, VAN Recovery + - - 108 108
3 78, F RS R 05 A CEFA Death + + - 1 1
4 41, F RS R 20 A PIPE/TAZ, VAN Recovery + + - 108 108
5 45, M RS R 50 B PIPE/TAZ, VAN Recovery + + - 162 162
6 23, M WS S 33 B CEFE Recovery + - - 985 79
7 21, M RS R 14 B CEFE, VAN Recovery + + - 409 1
8 23, M RS R 18 B CEFI, CEFE, VAN Recovery + + + 987 987
9 42, F RS R 27 B PIPE/TAZ Recovery + + + NPh NP

a F: female; M: male; b RS: rectal swab; WS: wound secretion; c R: resistant; S: sensitive; d A: Municipal Hospital and Emergency Room of Varzea Grande; B: Municipal Hospital and Emergency Room of Cuiaba; e IMP: imipenem; PIPE/TAZ: piperacillin/tazobactam; CEFE: cefepime; CEFA: cephalothin; CEFI: ceftriaxone; VAN: vancomycin; f Clonal complex according to the eBurst classification; g ST984: identified for the first time in this study and classified as a singleton by eBurst; h NP: not performed.

The A. baumannii isolates analyzed in this study showed resistance to imipenem and other drugs, as well as sensitivity to polymyxin B, similar to the trends reported in other regions of Brazil and in other countries2,3,9. The bla OXA-23 gene was most frequently found. These data are similar to those of other international and Brazilian studies5,6,9. Other genes associated with carbapenem resistance were bla OXA-24 and bla OXA-143 . The bla OXA-24 gene is more prevalent in some countries, such as Ecuador and Mexico, and is uncommon in Brazil5,6,11. However, it was the second most prevalent carbapenem resistance gene found in another study conducted in the Center-West region of Brazil9. The bla OXA-143 gene, which has been detected in southeastern, southern, and central Brazil, was again found in the Center-West region of the country9,10. The bla OXA-58, bla KPC, and bla NDM genes were not found. Phylogenetic classification by MLST revealed the presence of ST108, ST162, and ST1, which are commonly found in South American countries, including Brazil5,6,9. Interestingly, one of the isolates corresponded to ST409, a sequence type first described in Egypt, and was never described in Brazil until now12. Three new STs (ST984, ST985, and ST987) were found.

The isolates reported here were recovered form surveillance cultures, and only one patient evolved to death. However, the finding of isolates of different multidrug-resistant A. baumannii STs deserves the attention and concern of local health authorities owing to the extended antimicrobial resistance profile of this microorganism. More research is warranted to assess the impact of this multidrug-resistant bacterium on the generation of threatening infections in the study region.

Accession numbers of new sequences reported in the article ( ST984, ST985, and ST987.


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Financial Support: This research had financial support from the BrazilianNational Council for Scientific and Technological Development (CNPq), a federal agency for research support, through a research incentive grant for Francisco José Dutra Souto.

Conflict of Interest: The authors declare that there is no conflict of interest.

Creative Commons License This is an open-access article distributed under the terms of the Creative Commons Attribution License