Antimicrobial resistance of Escherichia coli and Staphylococcus aureus isolated from food handler's hands

The aim of this study was to determine the antimicrobial resistance of Escherichia coli and Staphylococcus aureus isolates from food handlers' hands at primary schools in Hulu Langat district, Selangor (Malaysia). Disc diffusion methods were used to examine the antimicrobial resistance of the bacteria by using ten types of antibiotic discs with different concentrations. The results show that the prevalence of S. aureus (65.88–74.12%) was far higher than the prevalence of E. coli (9.41–14.12%). The percentage isolates of E. coli that were resistant to the antibiotics was 85.71% Penicillin and Chloramphenicol, 57.14% Sulfamethoxazole-Trimethoprim, Ampicillin and Trimethoprim, 28.57% Kanamycin and Tetracycline and 14.29% Ciprofloxacin. All of the isolates had shown susceptible to Gentamicin and Nitrofurantoin. For S. aureus, the percentage isolates that were resistant to the antibiotics was 72.30% Ampicillin, 53.38% Penicillin, 4.73% Nitrofurantoin,1.35% Chloramphenicol and Trimethoprim and 0.68% Kanamycin and Tetracycline. None of the isolates had shown resistant to Ciprofloxacin, Sulfamethoxazole-Trimethoprim and Gentamicin. Multidrug resistant Escherichia coli represented a high percentage (85.71%) of the total positive strains revived whereas multidrug resistant S. aureus strains were only 5.41% of the total positive strains. The existence of multidrug resistant bacteria is quite worrying as they may pose serious threat to the patients. Hence, the microbiological quality of food handlers' hands from foodservice operations should be maintained in a good condition to reduce the existence of multidrug resistance bacteria.     

Prevalence and antimicrobial resistance of Staphylococcus aureus isolated from raw milk and dairy products

The objectives of this study were to determine the prevalence and antimicrobial resistance of Staphylococcus aureus isolated from raw milk (cow and sheep) and dairy products (traditional cheese and kashk) in Mazandaran Province, Iran. A total of 2650 samples, including 1930 raw milk and 720 dairy products were purchased from retail stores. Out of 2650 samples, S. aureus was detected in 328 samples (12.4%) in which 53 (16.2%) were positive for methicillin-resistant S. aureus. The S. aureus isolates showed resistance to tetracycline (56.1%), followed by penicillin G (47.3%), oxacillin (16.2%), lincomycin (11.9%), clindamycin (11.3%), erythromycin (7.9%), streptomycin (5.8%), cefoxitin (5.5%), kanamycin (4%), chloramphenicol (3.7%), and gentamicin (2.1%). A high frequency of blaZ (46%) and tetM (34.8%) resistance genes was found in S. aureus isolates. The findings of this study revealed consumption of raw milk and dairy products as a potential risk of foodborne infection in this region.     

Carriage and dissemination of Clostridium difficile and methicillin resistant Staphylococcus aureus in pork processing

Community associated Clostridium difficile and MRSA are among the most common infection causing pathogens encountered in developed nations. It has been proposed that both pathogens may be foodborne with supporting evidence being based on the carriage in animals and recovery from meat at retail. The following reports on the incidence and dissemination routes of C. difficile and MRSA within a high capacity pork processing facility. Sampling of carcasses and processing environment was performed over two visits to the facility. C. difficile was isolated 80% (16/20) of manure samples taken within the holding area, with 45% (9/20) of holding area floor and wall samples testing positive for the pathogen. Three of the twenty carcasses (15%) sampled at post-bleed and a further 3 at post-evisceration also tested positive for C. difficile. No C. difficile were recovered from scald water samples, polisher/scraper units or on carcasses in the cold room at the end of the line. Ribotype 078 was the predominant C. difficile recovered with the remaining belonging to other ribotypes. MRSA was recovered from a single carcass at post-bleed and within the cold room, in addition to one sample taken from the holding area (overall prevalence of 2.7%). The MRSA isolates recovered from carcasses was spa t034 which is a commonly associated with pigs. The results of the study confirm that the holding area of slaughterhouse acts as a reservoir for C. difficile and MRSA although there was no evidence to suggest that the pathogens were disseminated into the processing lines. Consequently, it can be concluded that pork processing does not represent a significant risk of disseminating MRSA and C. difficile between carcasses.     

Antimicrobial resistance patterns of Campylobacter spp. isolated from raw chicken,turkey, quail,partridge, and ostrich meat in Iran

This study was conducted to determine the prevalence and antimicrobial resistance pattern of Campylobacter spp. isolated from retail raw poultry meats in Iran. From July 2009 to March 2010, a total of 494 raw meat samples from chicken (n = 200), turkey (n = 170), quail (n = 86), partridge (n = 17), and ostrich (n = 21) were purchased from randomly selected retail outlets in Shahrekord, Iran. Using cultural method, 187 meat samples (37.9%) were contaminated with Campylobacter. The highest prevalence of Campylobacter spp. was found in chicken meat (47.0%) followed by quail (43.0%), partridge (35.3%), turkey (28.8%), and ostrich (4.8%) meat. The most prevalent Campylobacter species was Campylobacter jejuni (92.0%). The PCR assay could identify 38 Campylobacter-contaminated samples that were negative using the cultural method. Antimicrobial susceptibility test results showed that 98.4% of isolates were resistant to one or more antimicrobial agents. Resistance to tetracycline was the most common findings (70.6%), followed by resistance to nalidixic acid (54.0%), and ciprofloxacin (49.7%). Significantly higher prevalence rates of Campylobacter spp. (P < 0.05) were found in meat samples taken in summer (51.1%). To our knowledge, the present study is the first report of the isolation of Campylobacter spp. from raw partridge meat in Iran.     

Slime production,DNase activity and antibiotic resistance of Staphylococcus aureus isolated from raw milk,pasteurised milk and ice cream samples

In this study, a total of 180 samples of raw milk, pasteurised milk and ice cream were analysed for the presence of Staphylococcus aureus. There were 110 S. aureus isolated from these samples, which were investigated for DNase activity, slime production and antibiotic resistance. DNase agar that was used to investigate for DNase activity revealed DNase activity in 94.5% of 110 S. aureus. Slime production of S. aureus that was investigated by using Congo Red Agar method revealed slime production in 52.7% of S. aureus. Resistance of S. aureus to different antibiotics was determined by the Kirby–Bauer disc diffusion test. Resistance to penicillin G, methicillin and bacitracin was frequent for S. aureus strains. Few numbers of the strains were resistant to erythromycin. All strains were susceptible to vancomycin, sulbactam–ampicillin, ciprofloxacin and cefaperazone–sulbactam. Slime production positive strains were tested against penicillin G, methicillin and bacitracin. No difference was found between the antibiotic resistance of slime positive and slime negative S. aureus. There was a high rate of resistance for all S. aureus isolates against penicillin G, methicillin and bacitracin.     

Biofilm-forming ability and resistance to industrial disinfectants of Staphylococcus aureus isolated from fishery products

Adhesion and biofilm-forming ability of twenty six S. aureus strains previously isolated from fishery products on stainless steel was assessed. All strains reached counts higher than 10⁴ CFU/cm² after 5 h at 25 °C. Most strains also showed a biofilm-forming ability higher than S. aureus ATCC 6538 – reference strain in bactericidal standard tests – by crystal violet staining. In addition, it seems that food-processing could have produced a selective pressure and strains with a high biofilm-forming ability were more likely found in highly handled and processed products.The efficacy of the industrial disinfectants benzalkonium chloride (BAC), sodium hypochlorite (NaClO) and peracetic acid (PAA) against biofilms and planktonic counterparts was also examined in terms of minimum biofilm eradication concentration (MBEC) and minimum bactericidal concentration (MBC), respectively. Biofilms showed an antimicrobial resistance higher than planktonic cells in all cases. However, no correlation was found between MBEC and MBC, likely due to differences in biofilm extracellular matrix (composition, content and architecture) between strains. BAC resistance increased as biofilms aged. Generally, biofilm formation seemed to attenuate the effect of low temperatures on BAC resistance. PAA was found to be most effective against both biofilms and planktonic cells, followed by NaClO and BAC. Resistance did not follow the same order for each biocide, which remarks the need of using a wide collection of strains in standard tests of bactericidal activity to ensure a proper application of disinfectants. Doses recommended by manufacturers for BAC, PAA and NaClO to disinfect food-contact surfaces were lower than doses for complete biofilm removal (i.e. MBEC) under some environmental conditions common in the food industry, which questions bactericidal standard tests and promotes the search for new strategies for biofilm removal.     

Tracing contamination of Methicillin-resistant Staphylococcus aureus (MRSA) into seafood marketing chain by staphylococcal protein A typing

Methicillin resistant Staphylococcus aureus (MRSA) is not a resident flora of fish. Its presence is endorsed to post-harvest contamination viz., handlers, handling equipment and environment. Earlier investigation revealed the presence of MRSA in seafood sold in retail fish markets in Kerala, India. Further studies were conducted to understand and identify the source of contamination into seafood sold in the retail markets by a pilot study. Seventeen samples which includes seafood and fishery environment samples from a landing centre and a retail fish market were collected to identify the source of contamination of MRSA. The whole experiment was repeated with same sampling plan for validation of the procedure, a week later from the same landing centre to the point of sale at fish market. MRSA was isolated from 35.2% to 23.5% of samples during first and second visits respectively. spa typing of the MRSA isolates revealed that MRSA from the landing centre (t311 and t15669) were carried to the retail fish market. Ice and water were the probable source for contamination during handling at the landing centre. This is first study to trace the source of contamination of MRSA in seafood and fishery environment. It is imperative that spa typing can be implemented for studying the local spread of MRSA clones at specific geographical locations only after establishing its diversity. To better understand the complexity of local spread of MRSA and reproducibility of this experiment, studies has to be conducted in other landing centre and retail markets.     

Antimicrobial resistance in thermotolerant Campylobacter isolated from different stages of the poultry meat supply chain in Argentina

The objective of this study was to investigate the antimicrobial resistance in thermotolerant Campylobacter spp. isolated from different stages of the poultry meat supply chain in Argentina. Six poultry meat chains were studied from the reproductive farm to the chicken at the retail. Chickens sampled along each food chain were from the same batch. Samples collected were: a) cloacal samples from hens and chickens on the farm, b) chicken carcasses from the slaughterhouse and retail market. Samples obtained were examined for Campylobacter spp. Antimicrobial resistance was evaluated using the disk diffusion method. Almost all isolates were resistant to nalidixic acid (91.2%) and ciprofloxacin (88.2%). A large proportion of thermotolerant Campylobacter isolated from hens and broilers <1 wk showed resistance to erythromycin in comparison with the rest of the stages of the poultry meat supply chain (P = 0.031). Campylobacter isolated from broilers (both <1 wk and >5 wk) and carcasses at slaughterhouse and at retail showed a proportion of resistance to ciprofloxacin and enrofloxacin higher than isolates from hens (P = 0.015 and P = 0.031, respectively). One strain was resistant to all the antibiotics analyzed, and 46.1% of the isolates were resistant to three or more drug classes. Almost 50% of the isolates were resistant to all quinolones tested (ciprofloxacin, nalidixic acid, and enrofloxacin), and 13.2% were resistant to all quinolones and erythromycin. Campylobacter strains isolated from carcasses at retail showed higher resistance to all quinolones than strains isolated from hens (P = 0.016). These results reflect an alarming situation with potential serious consequences to the public health.     

Toxigenicity and genetic diversity of Staphylococcus aureus isolated from Vietnamese ready-to-eat foods

The aim of this study was to investigate the prevalence and genetic diversity of Staphylococcus aureus and staphylococcal enterotoxins (SEs) in ready-to-eat foods marketed in Hanoi, Vietnam. Out of 212 samples tested, 45 were contaminated with this bacterium and 18 contained strains having classical SEs. Among different food products, the bacterial occurrence ranged between 12.5% and 35.4% and milk samples had the highest prevalence. The production of SEs varied according to the food types and 26 different ribotype patterns were observed among the 45 strains. Our dendogram analysis showed the existence of many clones without clear-cut affiliation to any particular food type indicating both diverse primary and secondary contamination sources. The SEs also occurred in a wide variety of genetically different S. aureus strains which might facilitate the bacterium with better ecological fitness to cause epidemics. It can be concluded that Vietnamese ready-to-eat foods pose a high risk of contamination by toxigenic S. aureus population urging the need of implementing proper hygienic practices.     

Prevalence and antibiotic susceptibility of Listeria spp. isolated from raw meat and retail foods

Listeria and particularly Listeria monocytogenes is an important foodborne pathogen that can cause listeriosis with flu-like symptoms in healthy people, and severe complications in immunocompromised subjects, children, pregnant women and the elderly. A research survey was conducted to check the presence of Listeria spp. in raw meat and retail products and to analyse their antibiotic resistances. Total prevalence was 11.7%: in raw meat was 21.4%; in ham it was 5.2%; in fresh soft cheese it was 3.49%; in sandwiches it was 5.88%, while we found no isolates in smoked salmon and only two in ready salads (1.23%). The highest percentage of prevalence of L. monocytogenes was found in samples of ham (37.5%), lower percentages were in sandwiches (25.0%), in raw meat samples (23.6%), in fresh soft cheeses (20.0%), while ready salads and smoked salmons were not contaminated. The susceptibility of 168 strains of Listeria spp. was determined by disk diffusion method: we found 51 (30.4%) strains resistant to three or more antibiotics. All isolated strains, except one, are susceptible or at least to one of the first choice antibiotics (ampicillin and gentamycin) or to trimethoprim–sulfamethoxazole used as antibiotic of second choice in the treatment of human listeriosis. Strains isolated from ready-to-eat food show high level of resistance to ampicillin, gentamycin and meticillin. Meticillin is used normally, in treatment of Enterococcus spp. human infection; L. monocytogenes can transfer antibiotic resistance genes from plasmids and transposons to Enterococcus spp. in vitro and in vivo causing an increase of these bacteria resistant to meticillin. L. monocytogenes, in the last decades, is becoming resistant to a lot of antibiotics, a continued surveillance on its incidence on raw foods and on emerging resistances are important to identify food that can represent a risk of infection for the population, particularly for immunocompromised, children, pregnant women and the elderly to ensure effective treatment of human listeriosis with effective antibiotics.     

Antimicrobial resistance of Salmonella spp. and Escherichia coli isolated from table eggs

The antimicrobial sensitivity of Salmonella spp. and Escherichia coli isolated from the shells and contents of table eggs sampled from sale outlets in Trinidad was determined using the disc diffusion method. The phage types of S. Enteritidis isolates, the phenotypic characteristics of E. coli isolates and the presence of O157 strain were also investigated. Of a total of 74 isolates of Salmonella tested, 17 (22.9%) exhibited resistance to one or more of the seven antimicrobial agents used compared with 104 (88.1%) of 118 E. coli isolates. The difference was statistically significant (P < 0.05; X²). For both microorganisms, resistance was relatively high to streptomycin (54.2%) and tetracycline (35.9%) but low to gentamicin (11.5%) and sulphamethoxazole/trimethoprim (9.4%). Only 1 (1.4%) isolate of Salmonella was multi-resistant while 55 (46.6%) of E. coli isolates were resistant to three or more antimicrobial agents. The frequency of resistance to antimicrobial agents amongst both bacteria was not significantly (P > 0.05; X²) affected by the location of isolation on the egg (shell or content) or source of eggs (farms, shopping malls or other retailers). Eight (19.5%) of 41 S. Enteritidis isolates tested were resistant compared to 4 (26.7%) of 15 isolates of S. Ohio. All S. Enteritidis isolates belonged to phage type 1 (PT1) and all E. coli isolates were non-haemolytic, non-mucoid, sorbitol fermenters and non-O157 strains. It was concluded that the relatively high resistance amongst the bacteria tested could pose therapeutic problems in consumers, particularly in egg-borne salmonellosis or colibacillosis.     

A novel reference real-time PCR assay for the relative quantification of (game) meat species in raw and heat-processed food

In order to increase their profit, food producers may be tempted to replace expensive meat species by cheaper ones. Due to their selectivity and sensitivity, PCR based methods are frequently applied to identify and quantify meat species to detect food adulteration. Quantification of meat species in highly processed food products is, however, a difficult task. When we used a previously published reference system to relatively quantify the deer content in heat treated foodstuffs, we obtained recoveries that were substantially >100%. In the present study we aimed to improve the applicability of the reference system, targeting a 97 bp fragment of the myostatin gene, to heat treated products by reducing the length of the target sequence. The novel reference system, targeting a 70 bp fragment of the myostatin gene, was found to amplify the target region in 27 mammals and poultry species. Meat mixtures as well as raw and heat treated model sausages were analysed to demonstrate the applicability of the novel reference system for relatively quantifying the game meat content in processed food products. With the novel reference system, the bias introduced by heat treatment was largely eliminated.     

Identification and antimicrobial resistance of Campylobacter species isolated from poultry meat in Khorasan province,Iran

Campylobacter is the main bacterial cause of acute gastroenteritis in humans. Campylobacter jejuni and Campylobacter coli are the most frequent Campylobacter species isolated from patients with diarrhea. Undercooked poultry meat is one of the main sources of human infection. Contamination of poultry carcasses by Campylobacter during processing occurs directly via intestinal contents or indirectly from bird to bird, via equipment and water. The objective of this study was to determine the prevalence and antimicrobial resistance patterns of Campylobacter spp. isolated from raw poultry meat in Mashhad, Iran. From May 2012 to July 2012, 300 poultry meat samples including chicken (150), turkey (70), partridge (50), and quail (30) were randomly purchased from retail outlets. Using cultural method and a PCR assay 49.7% of poultry meat samples were contaminated with Campylobacter spp. Campylobacter spp. were significantly (P < 0.05) more prevalent in chicken meat (59.3%), followed by partridge (48%), quail (40%), and turkey (34.3%) meat. The most prevalent Campylobacter spp. isolated was C. jejuni (80.8%); the remaining isolates were C. coli (19.3%). Overall, 96.6% Campylobacter isolates were resistant to one or more antimicrobial agent. Resistance to ciprofloxacin was the most common finding (81.9%), followed by resistance to nalidixic acid (73.2%) and tetracycline (67.8%). In conclusion, the results of this study showed the importance of chicken, quail, partridge, and turkey meat as potential sources of Campylobacter spp. infection in people.     

Antimicrobial resistance of Campylobacter spp. isolated from broilers in small poultry processing operations in Trinidad

The study determined the frequency of resistance of Campylobacter spp. isolated from broilers in small processing operations in 6 health divisions of Trinidad using the disc diffusion method. Of 319 isolates of Campylobacter jejuni tested, 312 (97.8%) exhibited resistance to one or more of the six antimicrobial agents used compared with 176 (97.2%) of 181 isolates of C. coli. The frequency of resistance amongst isolates was statistically significantly (P < 0.05, χ²) different across health divisions. Overall, the resistance was highest to sulfamethoxazole/trimetoprim (SXT) (87.0%) and ciprofloxacin (86.6%) and lowest to gentamicin (5.4%) and the differences were statistically significant (P < 0.05, χ²). The relatively high resistance to SXT and ciprofloxacin was not unexpected since both antimicrobial agents are routinely used in the poultry industry in Trinidad and Tobago but may pose therapeutic problems in broiler-borne gastroenteritis in humans.     

Antimicrobial resistance profiles of Listeria monocytogenes isolated from ready-to-eat products in Poland in 2007–2011

The aim of the study was to characterize strains of Listeria monocytogenes isolated from ready to eat (RTE) products collected as part of official food control and monitoring in Poland. A total of 105 L. monocytogenes isolates from RTE products: 54- cakes and 51 – delicatessen products were examined. The presence L. monocytogenes in cakes and delicatessen products was 0.4% and 0.7% respectively suggesting the level of contamination of RTE products with L. monocytogenes is very low.     

Binary combinations of BHA and other natural and synthetic phenolics: Antimicrobial activity against Staphylococcus aureus and antioxidant capacity

Antibacterial activity against nineteen Staphylococcus aureus strains of five phenolic compounds (PCs) (hydroquinone, carvacrol, thymol, gallic acid and octyl gallate) was assessed in binary combinations with butylated hydroxyanisole (BHA). An antagonistic effect between BHA and each of the other PCs tested in combination was observed against 67% (for BHA + thymol) to 95% (BHA + octyl gallate) of the S. aureus strains, and no interaction effect was observed for the rest of the strains. Only slight differences in the antagonistic effect were detected among the strains of the different origins, between 80% (dairy) to 88% (meat). Concerning to the antioxidant activity, the combinations studied were mostly additive, with the exception of BHA + carvacrol and BHA + thymol that were antagonistic. It is concluded that the antagonic/no interaction antimicrobial effects of BHA + PCs against S. aureus are of interest to the food industry as they may determine the effectivity of active antimicrobial individual PCs and then, the safety of foods, when they coincide voluntarily or accidentally in foods.     

A rapid,semi-quantitative test for detection of raw and cooked horse meat residues

Intentional mislabeling and adulteration of meat products with undeclared horse meat is a concern for religious, ethnic, and health reasons and is illegal under regulations mandated and enforced by food regulatory agencies and the Federal Meat Inspection Act. Nonetheless, recent analysis of the meat industry has revealed an apparent increase in the frequency of meat adulteration including intentional horse meat contamination, necessitating a broader use of meat authentication testing. As existing methods for meat speciation are cumbersome and require specialized equipment and/or training, we developed a highly specific lateral flow immunoassay that can rapidly identify raw and cooked horse meat down to 0.01% and 1.0% contamination, respectively in xenogeneic meat sources in about 35 min with no false positive signals observed. Specificity analysis revealed no cross-reactivity with serum albumins or meat derived from chicken, turkey, pig, cow, lamb, and goat. The results of method comparison showed that the assay had similar if not better sensitivity than the commercial ELISA kit and PCR, and required considerably less time to perform than either method. The development of a highly robust and rapid test method capable of detecting trace amounts of horse meat residues should aid food control authorities in their continued efforts to monitor for horse meat adulteration.     

A risk profile of the Australian red meat industry: Approach and management

A risk profile of microbial, chemical and physical hazards across the supply continuum for the Australian beef, sheep and goat meat industries was developed. The aim was to provide risk managers with a risk rating of hazard:meat and meat product combinations, advise on the feasibility and advisability of risk analyses and identify research and development priorities. Hazard:red meat combinations arising from manufacturing and catering settings that have been associated with food-borne illness and their risk ranking are reported elsewhere. The profiling process was completed within a one-year timeframe and involved a planned iterative consultation process between risk managers and assessors to ensure outputs remained relevant to current risk management concerns.     

Prevalence,genetic diversity and antimicrobial resistance of Listeria monocytogenes isolated from ready-to-eat meat products in Nanjing,China

The prevalence of Listeria monocytogenes were investigated in a total of 628 ready-to-eat (RTE) meat products collected from different supermarkets and open-air markets in Nanjing, China. All isolates were further examined for the serogroup, virulence marker gene, genotype and antibiotic resistance. Thirty-three out of 628 samples (5.3%) were positive confirmed by the bacteriological method and PCR including 7.2% (17/236) of sauce pickled products, 4.2% (11/260) of cured products and 5.6% (5/90) of smoked and roasted products. Fifteen isolates (45.5%) belonged to serogroup 1/2a, 3a; 16 (48.5%) belonged to serogroup 1/2b, 3b and 2 (6.1%) belonged to serogroup 1/2c, 3c. All of them were positive for the virulence marker genes-iap, inlA, inlC, inlJ and lmo2672. Thirty-three isolates were grouped into 11 sequence types (STs) by multilocus sequence typing (MLST). The results of the antimicrobial susceptibility revealed that the isolates were sensitive to most of the antimicrobials used in the study except trimethoprim–sulfamethoxazole (100%), chloramphenicol (33.3%), ciprofloxacin (30.3%) and tetracycline (12.1%). Our findings indicated high prevalence of L. monocytogenes especially in sauce pickled products and from open-air markets, high prevalence of serogroups 1/2a, 3a and 1/2b, 3b that involved in the majority of foodborne outbreaks could be a public health concern. In addition, resistance of the isolates to the antimicrobials was also a potential health hazard for consumers.     

Partial characterization of a class IIa pediocin produced by Pediococcus parvulus 133 strain isolated from meat (Mexican “chorizo”)

Pediocin-like bacteriocins are antimicrobial substances produced by some bacteria with high antilisterial activity. Several isolates of Pediococcus acidilactici and two Pediococcus parvulus strains of vegetable origin have been reported to produce this kind of peptide. This work presents the partial characterization of the bacteriocin produced by P. parvulus 133 found in meat and confirms its identity as a heat resistant, antilisterial bacteriocin. This peptide has a relatively narrow inhibitory spectrum but a high antilisterial activity. Pediocin remained active after heating to 121 °C, but its thermoresistance varied with pH. The pH selective adsorption method resulted in a 150-fold concentration of antimicrobial activity. The final extract was obtained by ultrafiltration and resulted in an additional 10-fold concentration of activity. Molecular weight was estimated as 5 kDa and isoelectric point was 8.65. The sequence of the first 17 aminoacids at the N-terminal end of the bacteriocin showed complete coincidence with that previously reported for pediocin A1 (AcH) and with an antilisterial peptide produced by Bacillus coagulans. High sequence similarity was also found with two other antilisterial bacteriocins.