Campylobacter Spp. As a Foodborne Pathogen: a Review
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REVIEW ARTICLE published: 27 September 2011 doi: 10.3389/fmicb.2011.00200 Campylobacter spp. as a foodborne pathogen: a review Joana Silva, Daniela Leite, Mariana Fernandes, Cristina Mena, Paul Anthony Gibbs and PaulaTeixeira* CBQF/Escola Superior de Biotecnologia, Universidade Católica Portuguesa, Porto, Portugal Edited by: Campylobacter is well recognized as the leading cause of bacterial foodborne diarrheal Kostas Koutsoumanis, Aristotle disease worldwide. Symptoms can range from mild to serious infections of the children University, Greece and the elderly and permanent neurological symptoms. The organism is a cytochrome Reviewed by: Sandra Torriani, Università degli Studi oxidase positive, microaerophilic, curved Gram-negative rod exhibiting corkscrew motil- di Verona, Italy ity and is carried in the intestine of many wild and domestic animals, particularly avian Alexandra Lianou, Aristotle University species including poultry. Intestinal colonization results in healthy animals as carriers. In of Thessaloniki, Greece contrast with the most recent published reviews that cover specific aspects of Campy- *Correspondence: lobacter/campylobacteriosis, this broad review aims at elucidating and discussing the (i) Paula Teixeira, CBQF/Escola Superior de Biotecnologia, Universidade genus Campylobacter, growth and survival characteristics; (ii) detection, isolation and con- Católica Portuguesa, R. Dr. António firmation of Campylobacter; (iii) campylobacteriosis and presence of virulence factors; and Bernardino de Almeida, 4200-072 (iv) colonization of poultry and control strategies. Porto, Portugal e-mail: [email protected] Keywords: Campylobacter spp., foodborne pathogens, virulence factors, antimicrobial susceptibility, control measures THE GENUS CAMPYLOBACTER humans and domestic animals (Vandamme, 2000). The genus It is believed that the first report concerning Campylobacter was Campylobacter contains small (0.2–0.8 μm × 0.5–5 μm) Gram- back in 1886 by Theodore Escherich who observed and described negative, slender spirally curved rods. When two or more bacterial non-culturable spiral-shaped bacteria (Vandamme, 2000; King cells are grouped together, they form an “S” or a “V” shape of gull- and Adams, 2008; Vandamme et al., 2010). After this, Campy- wing. The majority of the species have a corkscrew-like motion by lobacter was identified for the first time in 1906 when two British means of a single polar unsheathed flagellum at one or both ends veterinarians reported the presence of “large numbers of a pecu- of the cell. The only exceptions are Campylobacter gracilis which is liar organism” in the uterine mucus of a pregnant sheep (Skirrow, non-motile and Campylobacter showae which has multiple flagella 2006; Zilbauer et al., 2008). In 1913, McFadyean and Stockman (see Debruyne et al., 2005 for a comprehensive description of the isolated these microorganisms from aborted bovine fetuses. Later taxonomy of Campylobacteraceae). Oxidase activity is present in in 1927, Smith and Orcutt named a group of bacteria, isolated all species except for C. gracilis. They neither ferment nor oxidize from the feces of cattle with diarrhea, as Vibrio jejuni.Seven- carbohydrates; instead they obtain energy from amino acids, or teen years later, in 1944, Doyle isolated a different vibrio from tricarboxylic acid cycle intermediates (Vandamme,2000). Campy- feces of pigs with diarrhea and classified them as Vibrio coli (Van- lobacter jejuni hydrolyzes hippurate, indoxyl acetate and reduces damme, 2000; Vandamme et al., 2010). Due to their low DNA nitrate. Most strains are resistant to cephalothin, and also resis- base composition, their non-fermentative metabolism and their tance to fluoroquinolones, a category of antibiotics normally used microaerophilic growth requirements, the genus Campylobacter to treat animal and human illness, has been reported (Koenraad was first proposed in 1963 by Sebald and Véron, distinguishing et al., 1995). them from the “true” Vibrio spp. (On, 2001). After that, the study Under unfavorable growth conditions, these microorganisms of Butzler et al. (1973) raised the interest in Campylobacter by have the ability to form viable but non-culturable cells (VBNC; noting their high incidence in human diarrhea (On, 2001). Since Portner et al., 2007). Cappelier (1997), observed under labora- its inception, the taxonomic structure of the genus Campylobacter tory conditions, that Campylobacter strains, isolated from the has experienced extensive changes and even some parts of the cur- soil around the broiler house, may have been transformed into rent genus taxonomy remain a matter of controversy and require viable but non-cultivable forms and might have become cultivable further investigation (On, 2001; Debruyne et al., 2005). According after passing through the intestinal tract of chickens. Many ques- to these latter authors, Debruyne et al. (2005), there are 14 validly tions have been raised on whether non-culturability equates to described Campylobacter species. More recently, Fernández et al. non-viability (McKay, 1992), whether it is possible to convert the (2008) stated that the genus comprises 20 species and subspecies. VBNC form to a culturable form (Jones et al., 1991; Beumer et al., However, other authors have stated that there are 16 species with a 1992; Stern et al., 1994), and whether, indeed, a VBNC form of further six subspecies within the genus Campylobacter (On, 2001; Campylobacter actually exists (ACMSF, 2004). Foster et al., 2004). Campylobacters have been known to be the cause of diseases GROWTH AND SURVIVAL CHARACTERISTICS in animals since 1909, but they have been generally recognized as Thermophilic Campylobacter species are able to grow between a cause of human disease, only since about 1980. 37 and 42˚C, but incapable of growth below 30˚C (absence of The family Campylobacteraceae consists of two genera,Campy- cold shock protein genes which play a role in low-temperature lobacter and Arcobacter and occur primarily as commensals in adaptation), with an optimum temperature of 41.5˚C. Levin www.frontiersin.org September 2011 | Volume 2 | Article 200 | 1 Silva et al. Campylobacter spp.: a review (2007) suggested that these organisms should be referred to pyruvate, etc., and selective agents, particularly antibiotics. Most as “thermotolerant” since they do not exhibit true thermophily methods involve a pre-enrichment in a liquid medium, before (growth at 55˚C or above). However, a study by De Cesare et al. plating on agar. The developments of methods for Campylobacter (2003) revealed that C. jejuni survived for more than 4 h at 27˚C have been well-described by Corry et al. (1995). and 60–62% relative humidity on some common clean or soiled In some protocols, in order to ameliorate the inhibitory effects food contact surfaces. These characteristics, reduce the ability of of the selective agents on potentially damaged cells, initial suspen- campylobacters to multiply (i) outside of an animal host and (ii) sion of samples is made into a basal broth without selective agents, in food during their processing and storage (Park, 2002). Growth with the latter being gradually added after a short period of incuba- does not occur in environments with water activity (aw)lower tion. In order to permit recovery of damaged cells, the incubation than 0.987 (sensitive to concentrations of sodium chloride (NaCl) temperature may also be gradually increased from 37˚C to the final greater than 2%w/v), while optimal growth occurs at aw = 0.997 incubation temperature of 41.5˚C. This methodology is the basis (approximately 0.5% w/v NaCl). for one of the ISO standard methods (ISO, 1995, 2006a). However, Campylobacter spp. are easily inactivated by heat treatments for chicken samples, such a protocol was not necessary as maxi- with their D-value being less than 1 min (Table 1). mal numbers were obtained by using a selective broth followed by Freezing–thawing also reduces the population of Campylobac- plating on selective agars (Mason et al., 1999). ter spp. (Stern and Kazmi, 1989). In pure cultures, Campylobacter Several of the selective broths, e.g., Bolton broth (BB), Campy- spp. are normally inactivated by frozen storage at −15˚C in as lobacter enrichment broth (CEB), and Preston broth (PB), have fewas3days(Stern and Kotula, 1982); however, freezing does not been compared for their efficacy (Baylis et al., 2000). The incor- eliminate the pathogen from contaminated foods (Lee et al., 1998). poration of the enzyme Oxyrase in selective broths is particularly Hazeleger et al. (1995) revealed that aged C. jejuni cells survived effective in reducing the levels of oxygen and improving the isola- the longest at 4˚C. Campylobacter spp. will not survive below a tion of Campylobacter spp. from naturally contaminated samples pH of 4.9 and above pH 9.0 and grow optimally at pH 6.5–7.5. (Abeyta et al., 1997). However, a blood free enrichment broth not These non-spore-forming and fastidious bacteria are essentially requiring the addition of Oxyrase, nor special atmospheres has microaerophilic, growing best in an atmosphere with low oxy- been tested and found to perform well against other more complex gen tension (5% O2, 10% CO2, and 85% N2; Garénaux et al., isolation methods (Tran, 1998). 2008). Several selective agars have been formulated and tested for their efficacy in isolating campylobacters. For example, Preston, char- DETECTION, ISOLATION AND CONFIRMATION choal cefoperazone deoxycholate (CCDA) and Butzler agars have The sensitivity of Campylobacter