Prevalence and antimicrobial susceptibility of Acinetobacter spp. isolated from meat

https://doi.org/10.1016/j.ijfoodmicro.2016.12.001Get rights and content

Highlights

  • Acinetobacter spp. was recovered from all the meat samples analysed.

  • High genetic diversity of Acinetobacter spp. observed

  • Thirteen Acinetobacter species and three putative novel species were identified.

  • 18.7% of the strains belong to the Acinetobacter baumannii group.

  • 51.2% of strains were MDR and 9.6% were XDR.

Abstract

The prevalence and antibiotic resistance of Acinetobacter spp. from fifty samples of meat (chicken, turkey, beef and pork) were evaluated. Acinetobacter spp. was recovered from all samples and the clonal relatedness of 223 isolates identified to belong to the genus Acinetobacter was established by PFGE. A high genetic diversity was observed and 166 isolates from different samples, 141 representing different PFGE profiles, were further identified to the species level by rpoB gene sequencing. Thirteen distinct Acinetobacter species were identified among 156 isolates. The remaining ten isolates may represent three putatively novel species since rpoB sequence homologies with type strains of all available described Acinetobacter species, were < 95%.

The most common species was Acinetobacter guillouiae with a prevalence of 34.9%. However 18.7% of the strains belong to the Acinetobacter baumannii group (n = 31) which include the species Acinetobacter baumannii (n = 7), Acinetobacter pittii (n = 12), Acinetobacter seifertii (n = 8) and Acinetobacter nosocomialis (n = 4) that are the species most frequently associated with nosocomial infections worldwide.

In general, strains were resistant to some of the antimicrobials most frequently used to treat Acinetobacter infections such as piperacillin-tazobactam (64.9% of strains resistant), ceftazidime (43.5%), ciprofloxacin (42.9%), as well as to colistin (41.7%) and polymyxin B (35.1%), the last-resort drugs to treat infections caused by multidrug-resistant Acinetobacter. The percentage of resistant strains to trimethoprim-sulfamethoxazole, tetracycline, aminoglycosides (amikacin and tobramycin) and ampicillin-sulbactam was > 10% (23.2%, 23.2%, 14.3%, 12.5%, 12.5%, respectively). However, resistances to meropenem, imipenem and minocycline were only sporadically observed (8.3%, 1.2% and 1.2%, respectively).

Overall, 51.2% of the strains were considered as multidrug-resistant (MDR) and 9.6% as extensively drug-resistant (XDR). The prevalence of MDR strains within the A. baumannii group (38.7%) was lower than the prevalence within the others species identified (54.1%). Therefore, food of animal origin may be a vehicle of spread Acinetobacter strains resistant to several antibiotics in the community and in the hospital setting environment. This may led to nosocomial and community-acquired infections in susceptible individuals.

Introduction

Members of the genus Acinetobacter are strictly aerobic non-fermenting Gram-negative cocco-bacilli currently including 39 validly named species (Euzéby, 2016). Acinetobacter baumannii group i.e. Acinetobacter baumannii, A. pittii, A. nosocomialis and A. seifertii, includes the species most often associated with nosocomial infections worldwide (Dijkshoorn et al., 2007, Nemec et al., 2015, Peleg et al., 2008). Moreover, these opportunistic pathogens have been implicated in community-acquired infections (Chang et al., 2000, Falagas et al., 2007, Falagas and Rafailidis, 2007, Kang et al., 2012). The ubiquity of A. baumannii in nature has been considered a widespread misconception due to difficulties in unequivocal species identification (Dijkshoorn et al., 2007, Eveillard et al., 2013, Peleg et al., 2008, Towner, 2009, Visca et al., 2011). Identification by molecular methods such rpoB gene sequencing improved the identification across the genus (Gundi et al., 2009, La Scola et al., 2006). Additionally, with the use of more reliable identification methods, other species outside the A. baumannii group, such as A. lwoffii, A.ursingii, A. johnsonii and A. parvus have also been implicated in nosocomial infections, and may represent emerging pathogens (Turton et al., 2010).

Owing to its remarkable ability to resist almost all available antimicrobial agents, Acinetobacter infections are difficult to treat. Indeed, multidrug-resistant or even pan-drug resistant isolates are increasing alarmingly in the hospital environment (Coyne et al., 2010, Dijkshoorn et al., 2007, Kempf and Rolain, 2012, Peleg et al., 2008, Zarrilli et al., 2013). This characteristic, associated with the ability of these organisms to survive under diverse environmental conditions (Bergogne-Bérézin and Towner, 1996, Fournier and Richet, 2006, Jawad et al., 1996), facilitates their survival and spread. Therefore, it is important to identify and monitor the possible sources and routes of transmission to community and hospital settings. Worldwide, the spread of antibiotic resistant bacteria through food is considered a major public health concern since the food chain has an important role in the dissemination of some important human pathogens (Perreten, 2005, Seiffert et al., 2013a, Seiffert et al., 2013b, Verraes et al., 2013). Furthermore, the widespread use of antibiotics in food-producing animals has been linked to the emergence and dissemination of resistant bacteria (Phillips et al., 2004), which can further be spread to community and hospital settings through food.

The prevalence and antimicrobial resistance of Acinetobacter species isolated from human clinical isolates has been reported. However, studies about their prevalence in meat samples are limited. Acinetobacter spp. has been isolated from veterinary clinical specimens of food animals in the UK (Hamouda et al., 2008), Lebanon (Rafei et al., 2015), France (Poirel et al., 2012) and China (Wang et al., 2012, Zhang et al., 2013); in some cases, carbapenemase-producing isolates were described (Poirel et al., 2012, Wang et al., 2012, Zhang et al., 2013). Nevertheless, only a few studies have reported the presence Acinetobacter spp. in raw meat (Hamouda et al., 2008, Houang et al., 2001, Lupo et al., 2014, Rafei et al., 2015, Saha and Chopade, 2001); whereas the antimicrobial susceptibility of the isolates was not determined (Houang et al., 2001, Saha and Chopade, 2001), others refer to the prevalence of the specie A. baumannii (Hamouda et al., 2008, Lupo et al., 2014).

The objective of this study was to evaluate the prevalence and diversity of Acinetobacter spp. in meat samples, as well as their antibiotic resistance.

Section snippets

Samples

Between October 2013 and September 2014, fifty meat samples purchased from five supermarkets located in Porto region (Portugal), belonging to four convenience store groups were analysed. These included chicken breast (n = 14), turkey breast (n = 12), pork steaks (n = 12) and beef steaks (n = 12) samples, all without skin and bones. From each store, no more than one sample of each meat type was collected on the same day.

Isolation method

The isolation of Acinetobacter spp. from meat samples was done according to

Prevalence of Acinetobacter spp. in meat samples

In the current study, Acinetobacter spp. was isolated from all the meat samples analysed. Previous studies reported recovery rates of 75% (from 36 pork and beef samples, purchased from local markets in Hong Kong; Houang et al., 2001) and 28% (from 50 cow meat samples from Lebanon; Rafei et al., 2015). These differences may be explained by the different methodologies used for the isolation. Houang et al. (2001) did not perform a pre-enrichment step; on the other hand, Rafei et al. (2015) used

Conclusions

This study reports the occurrence and antibiotic susceptibility of Acinetobacter spp. isolates outside the hospital and is one of a limited number of studies exploring this population in meat products worldwide. To the best of our knowledge, this is the first report about the prevalence and antimicrobial susceptibility of Acinetobacter spp. in meat retailed in Portugal.

It was demonstrated the presence of several Acinetobacter species, including the species belonging to the pathogenic A.

Acknowledgements

This work was supported by National Funds from FCT - Fundação para a Ciência e a Tecnologia through project UID/Multi/50016/2013. Financial support for authors Ana Carvalheira, Rocio Casquete and Joana Silva was provided by PhD fellowship SFRH/BD/72951/2010 FCT, postdoctoral fellowship PO12018 funded by the Junta de Extremadura and co-funded with Fondo Social Europea (FSE), and postdoctoral fellowship SFRH/BPD/35392/2007, respectively.

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