Quantitative surveys of Salmonella and Campylobacter on retail raw chicken in Yangzhou,China

To assess the risks to consumers from Salmonella and Campylobacter in whole raw chickens sold in Yangzhou City, 12-month quantitative surveys were performed in succession. In this study, 480 samples were collected from supermarkets and wet markets from 2011 to 2013. The examination method of Salmonella was optimized from the most probable number (MPN), and the level of Campylobacter contamination was tested using the direct plating method. These results showed that the positive rates of Salmonella and Campylobacter were 33.8% and 51.3%, respectively, and the corresponding mean values of enumeration were 0.524 MPN/g and 1473.49 colony-forming units/g. For prevalence and loads of Salmonella, there was no significant difference between supermarkets and wet markets. However, for Campylobacter, the contamination level of wet markets was greater compared to supermarkets. Seasonality was observed in both qualitative and quantitative studies for both pathogens, with summer being the high-incidence season. Diversity among Salmonella isolates was high in terms of serovar, and the dominant serotypes were Salmonella Typhimurium (34.6%) and Salmonella Enteritidis (16.7%). Diversity of Campylobacter isolates demonstrated that Campylobacter jejuni (45.5%) and Campylobacter coli (30.9%) were the most common species, except for the mixed contamination. Survey results indicated that there was a need for more interventions to minimize the exposure of consumers to Salmonella and Campylobacter.     

Low contamination of Campylobacter spp. on chicken carcasses in Minas Gerais state,Brazil: Molecular characterization and antimicrobial resistance

Here, we evaluated Campylobacter contamination on chicken carcasses and phenotypic and genotypic profiles of antimicrobial resistance of the isolated strains. A total of 95 of samples were collected from 19 slaughterhouses from Minas Gerais - Brazil, and analyzed by MPN-PCR method. Campylobacter was found in 16.8% of samples with microbial load ranging from 60 to 184 MPN/carcass. All isolates were resistant to at least 5 (31.2%) of the antimicrobials screened using the disk diffusion method. Thr-86-Ile gyrA mutation, bla_OxA-61 and tet(O) genes were found in 95%, 100% and 40% resistant isolates to ciprofloxacin, ampicillin and tetracycline, respectively. Almost all isolates (90%) showed the three genes required to synthesize the CmeABC efflux system. The use of efflux pump inhibitor (PAβN) resulted in a significant reduction in the MICs of antimicrobials (2–128 fold), indicating the importance of efflux systems in conferring antimicrobial resistance. Campylobacter were detected at low concentrations in Brazilian chicken carcasses. However, high-levels of antimicrobial resistance were observed and associated with several mechanisms. This study provides a baseline survey on contamination of Campylobacter in Brazilian chicken carcasses and its antimicrobial resistance, giving support for actions directed at reducing this pathogen in the food chain.     

Detection of Salmonella spp. in spices and herbs

The detection of microbial contaminations in spices and herbs is a challenging task due to their strong antimicrobial effects, which potentially increase the risk for false-negative results. Therefore, the present study mainly focuses on the detection of Salmonella spiked to cinnamon and oregano. Both condiments completely inhibited the proliferation of Salmonella at a 1:10 (w/w) dilution. Consequently, the supplementation of the buffered peptone water with K₂SO₃ as well as the application of higher initial dilutions was investigated. While no detrimental effect of K₂SO₃ was observed during the growth of 14 different Salmonella isolates, it even improved their detection in condiments. An effect, which was also determined with increased dilution ratios. For detection, a quantitative approach via enumeration of the colony-forming units (CFUs), and qualitative approaches via the culture-based detection according to ISO 6579 and via the nucleic acid-based detection with the 3M Molecular Detection System (MDS) were performed. Subsequently, the limit of detection (LOD) was determined, which was <5 CFU 25 g⁻¹ for both qualitative approaches. Furthermore, the persistence of Salmonella DNA spiked to parsley was determined with the MDS. Despite of the modifications, the LOD for Salmonella spiked to oregano was significantly lower prior than after enrichment, pointing to the requirement for further improvements. Last but not least, a ring trial was performed, which emphasized the importance for a reliable detection.     

Incidence of Salmonella spp. in raw vegetables in Selangor,Malaysia

A total of 43 samples of ‘selom’ (Oenanthe stolonifera), 26 samples of ‘pegaga’ (Centella asiatica), 25 samples of ‘kangkong’ (Ipomoea aquatica) and 18 samples of ‘kesum’ (Polygonum minus) were examined for the presence of Salmonella spp. Salmonellae were detected from 40 (35%) of the vegetables samples examined. The most common serotypes isolated were S. weltevreden (23.5%), S. agona (16.2%), S. senftenberg (10.1%) and S. albany (6.7%). The other 27 Salmonella serovars were isolated at frequencies from 0.6% to 3.4%. Several of the Salmonella serotypes isolated in this study have been implicated in human infections in other countries. Although Salmonella species are frequently detected in foods of animal origin, the detection of 31 Salmonella serovars in four local salad vegetables in this study is not very encouraging, and supported the notion that these vegetables can be potential health hazards.     

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.     

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.     

Mathematical modeling of growth of Salmonella spp. and spoilage microorganisms in raw oysters

The main objective of this study was to develop the primary and secondary models to describe the growth kinetics of Salmonella as well as background microorganisms in raw, shucked oysters. Samples, inoculated with a cocktail of two Salmonella serotypes, S. Typhimurium (CICC22956) and S. Enteritidis (CICC21482), were incubated at 4, 8, 12, 16, 20, 25, 30, 33, 37, 40, and 43 °C. Growth of Salmonella was observed at all temperatures, except at 4 °C. The background microorganisms grew at all temperatures. All growth curves clearly exhibited lag, exponential and stationary phases, and were analyzed using the Huang growth model. Three secondary models (Ratkowsky square-root, Huang square-root, and Cardinal parameter models) were compared for evaluating the effect of temperature on bacterial growth rates. Data analysis was performed using IPMP 2013, a free predictive microbiology software tool developed by the USDA ARS.The Cardinal parameters model underestimated the specific rates of the microorganisms at low temperatures. The Huang square-root model was more suitable than the Ratkowsky square-root model for describing the effect of temperature on growth of Salmonella, while the Ratkowsky square-root model, on the other hand, was more suitable for background microorganisms. For both Salmonella and background microorganisms, the logarithms of the lag phase were expressed as linear functions of the logarithms of specific growth rates. The results of this study can be used by the food retailers and regulatory agencies to estimate the microbial shelf-life of raw, shucked oysters.     

Campylobacter spp. isolation from infected poultry livers with and without necrotic lesions

This study was developed in order to understand the possible intervention of Campylobacter spp. as etiological agent of necrotic lesions in poultry livers.This way, Campylobacter spp. was isolated from poultry livers with and without necrotic lesions. Additionally, virulence factors (cadF and cdtB) and antimicrobial resistance profile of the isolated strains were analyzed. From a total of 39 liver samples analyzed, 21 presented lesions and 18 were clean. Campylobacter spp. was isolated from 80.9% of liver samples with necrotic lesions (17/21) and from 38.9% of liver samples without lesions (7/18). These results indicate poultry liver as a potential source of human Campylobacter infection, since this bacteria may remain viable in the internal liver tissue in undercooked conditions.A high resistance to nalidixic acid (100%), norfloxacin (100%), ciprofloxacin (95.8%), ampicillin (91.6%) and tetracycline (75%) was observed among Campylobacter spp. isolates. Also, PCR detection of cdtB and cadF virulence and toxin genes, revealed 75% and 68.8% of positive samples, respectively. Strains isolated from livers with and without lesions presented similar results with respect to virulence factors and to antimicrobial resistance profiles, evidencing that these putative pathogenic determinants are widespread among the isolates from poultry livers.Phi coefficient calculated in order to measure the degree of association, revealed a highly significant association (Phi = 0.472; p-value < 0.01) between the presence of livers with hepatic necrosis lesions and Campylobacter isolation. This result indicates the possibility of using these macroscopic lesions as visible and reliable indicator of Campylobacter spp. presence in poultry flock, and, thus, becoming an important tool to support the implementation of corrective measures at poultry farms level. This methodology could contribute for an accurate time-efficient monitoring and the development of effective prevention and intervention measures for Campylobacter spp. infection with reduced cost.     

Prevalence and counts of Campylobacter spp. in poultry meat at retail level in Estonia

Campylobacter contamination of poultry meat at retail level was studied in two surveys during the twelve-month period of 2012 in Estonia. The data from these surveys were combined and analyzed, partially together, in order to comprehensively estimate the prevalence and possible seasonality of Campylobacter in poultry and in poultry meat products in Estonia. Mostly Estonian, Lithuanian and Latvian products, representing the most typical origins of poultry products on the Estonian retail market, were sampled and analyzed in these surveys. The first survey, organized by the Estonian Veterinary and Food Board, focused on Campylobacter prevalence in poultry meat at retail level. The second survey, at the Estonian University of Life Sciences, focused on Campylobacter prevalence and counts in fresh broiler chicken meat at retail level. Additionally, broiler chicken caecal samples were collected at slaughterhouse level for the estimation of the seasonal variation of Campylobacter colonization. Caecal samples were collected weekly from a broiler chicken slaughterhouse belonging to a company representing over 95% of all commercial broiler production in Estonia. A total of 606 poultry meat samples at retail level and 380 broiler chicken caecal samples at slaughterhouse level were collected and analyzed. A total of 20.8% of the poultry meat and 39.2% of the caecal samples were found positive for Campylobacter spp. The mean number of Campylobacters in fresh broiler chicken meat in the positive samples was 3.20 log₁₀CFU/g. A distinct seasonal variation in the Campylobacter contamination of broiler chicken meat was observed, which peaked during the warm summer period.     

Biofilm formation of Campylobacter strains isolated from raw chickens and its reduction with DNase I treatment

Campylobacter is a well-known bacterial agent that causes foodborne gastroenteritis. Its biofilm-forming ability is known to be important for its survival in harsh conditions. Poultry is a main reservoir of Campylobacter. In this study, we evaluated the biofilm-forming ability, motility, and antibiotic susceptibility of Campylobacter strains isolated from commercially purchased chickens of various sources in South Korea. From 37 (30%) out of 124 chickens, a total of 78 Campylobacter isolates were obtained, and the ability of these strains to form biofilms was studied on polystyrene surfaces. We identified seven biofilm-forming strains of Campylobacter jejuni and Campylobacter coli, respectively, out of 60 C. jejuni and 18 C. coli strains. Our study demonstrated that motility is inconsistent with biofilm-forming ability, suggesting that motility is not a single factor affecting biofilm formation of Campylobacter. Moreover, there was no clear relationship between antibiotic resistance and biofilm-forming ability. DNase I treatment significantly inhibited the biofilm formation or degraded the mature biofilms of 3 C. coli and 1 C. jejuni biofilm-forming strains (p < 0.05). It suggests that extracellular DNA plays a significant role in the biofilm formation of these strains. Collectively, our study demonstrated that biofilm-forming ability is not strongly correlated with motility and antibiotic resistance in Campylobacter and that extracellular DNA is required for biofilm formation of the isolated Campylobacter strains. It also suggests that DNase I is a potential method for the control of Campylobacter biofilms.     

Comparison of microbial transfer rates from Salmonella spp. biofilm growth on stainless steel to selected processed and raw meat

Salmonella biofilm cells can serve as a serious source of cross-contamination, both in the home and at food production sites. The objectives of this study were to determine the transfer rates (RTs) of Salmonella biofilm cells and to model the transfer process of biofilm cells from stainless steel surfaces to raw meat. The results showed that the RTs were significantly influenced by the types of meat products, with bacon and emulsified sausage showing higher RTs and roast pork showing lower RTs. Higher RTs of biofilm grown in a meat-based medium, Meat Thawing-Loss Broth (MTLB), were observed as compared to that in a standard growth medium (TSB). The logistic, exponential and multi-roots models could be used to satisfactorily describe the transfer of biofilm cells as demonstrated by use of MSE, F-test and R². There was no difference in attachment strength (reflected by the coefficients of transfer models) of biofilm grown in TSB or MTLB, as shown by the coefficients of r, D and B in three models. Compared with the exponential and the multi-roots models, the logistic model was able to more accurately fit the whole transfer process of biofilm cells. Our findings highlight the occurrence of cross-contamination with biofilm cells, and the models may provide useful tools in quantitative microbiological risk assessment of meat products.     

Prevalence of Listeria spp. and antibiotic susceptibility of Listeria monocytogenes isolated from raw chicken and ready-to-eat chicken products in Jordan

Listeria monocytogenes is the causal agent of listeriosis, a disease that can be serious and is often fatal in susceptible individuals. The objective of the study was to determine the prevalence of Listeria spp. in raw chicken and ready-to-eat (RTE) chicken products in Amman, Jordan and the antimicrobial resistance of L. monocytogenes isolates. A total of 280 raw chicken and RTE chicken products (chicken-shawirma, chicken-burger, chicken-sausage and mortadella) were collected from Amman abattoir and local retail markets in Amman city. Listeria spp. were isolated by the conventional International Organization for Standardization (ISO) method and L. monocytogenes identified by biochemical and Polymerase Chain Reaction (PCR). Results of conventional method showed that out of total 280 samples, 141 (50%) were found to be contaminated with Listeria spp. [L. monocytogenes (18.2%), Listeria ivanovi (26.1%), Listeria grayi (3.5%), Listeria seeligeri (1.8), Listeria welshimeri (0.7%)]. The PCR confirmed all L. monocytogenes isolates (51 isolates: 15 from raw dressed broiler chicken, 23 from chicken-burger, 9 from chicken-sausage, and 4 from chicken-shawirma). Five of the tested L. monocytogenes isolates were resistance to two antibiotics (tilimicosin and tetracycline) among the ten tested antibiotics as determined by microbroth dilution method. The results presented in this study indicate the potential risk of contamination of RTE chicken products with L. monocytogenes.     

Isolation,identification and antimicrobial resistance of Cronobacter spp. isolated from various foods in China

Cronobacter spp. are important foodborne pathogens that can cause severe diseases such as meningitis, sepsis, and necrotizing enterocolitis in neonates. In this study, 195 food samples, including cereals, cereal products, powdered infant formula (PIF), infant food formula, herbs, spices, vegetables, and fruits, were analyzed for the presence of Cronobacter spp. by culture-based method. The presumptive isolates were further confirmed by targeting the 16S rDNA gene using PCR. Out of 195 samples, 13 samples (6.7%) were positive for Cronobacter species. 12 of 85 cereal and cereal products (14.1%), and 1 of 22 herbs and spices (4.5%) were contaminated. In contrast, no Cronobacter was detected in commercial powdered infant formula, infant food formula, vegetables, or fruits. Alignment of 16S rRNA gene sequences showed that 13 isolates was most closely related to the genus Cronobacter. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis revealed that Cronobacter sakazakii was the only Cronobacter species isolated from various food samples. The antimicrobial susceptibility of 13 Cronobacter isolates was determined by the standard disk diffusion method. All isolated strains, except one resistant to ampicillin, were sensitive or displayed intermediate susceptibility to the 10 antimicrobial agents investigated. No multiple drug resistance was observed.     

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.     

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.     

Detection of acylated homoserine lactones in gram-negative proteolytic psychrotrophic bacteria isolated from cooled raw milk

Through a mechanism called quorum sensing, bacteria are able to express specific genes in response to population density. Cell-to-cell communication in bacteria is mediated by signal molecules such as acylated homoserine lactones (AHLs). This work aimed to detect AHL production in Gram-negative psychrotrophic bacteria isolated from raw milk. A total of 84.9% of the bacteria were identified as AHL producers eliciting a diversity of responses in the AHL-monitor systems. These results demonstrate that AHL-production is common among psychrotrophic bacteria isolated from milk, and indicate that quorum sensing may play an important role in the spoilage of this product.     

Recovery of associated and internalized Salmonella in broiler skin by stomaching and grinding

The objective of this study was to evaluate the recovery of associated and internalized Salmonella by stomaching and grinding broiler skin during exposure at 4 °C and at room temperature, using a two-strain green fluorescent protein (GFP) labeled cocktail of Salmonella Enteritidis. In the first experiment, broiler skins were immediately taken from eviscerated carcasses and exposed to a Salmonella cocktail containing ∼1 × 10⁹ CFU/ml for 0.5, 6, 12, 24, and 48 h at 4 °C. After each exposure, two 1-min stomachings and subsequent grinding of the stomached skin were conducted to quantify loosely associated (from two stomachings) and tightly associated (from grinding) Salmonella on the skin, respectively. Broiler skins exposed to Salmonella for 24 and 48 h were also examined by confocal microscopy before and after the two stomachings. The 1st and 2nd stomachings recovered an average of 71 and 17% of the Salmonella population, respectively, with an additional 12% of the cells recovered after subsequent grinding, regardless of incubation time. Based on the confocal images, most Salmonella were removed after two stomachings, however a few cells further penetrated from 9 to 29 μm into the skin. In the second experiment, broiler skins were immersed in the same two-strain Salmonella cocktail (∼1 × 10⁸ cells/ml) and dip-inoculated for 2 min with/without stomaching at room temperature. Based on the confocal images, Salmonella penetrated the flat skin surfaces and crevices up to 10 and 68 μm without stomaching, respectively, and up to 62 and 132 μm with stomaching. The presence of free-floating Salmonella cells in the skin crevices indicates that entrapped water is important for bacterial translocation in poultry skin. These findings indicated that extent of observable Salmonella association, penetration, and subsequent recovery from poultry skin is related to both surface topography of poultry skin and method of sample processing.     

Detection and characterization of virulence factors in lactose positive and lactose negative Salmonella serovars isolated from seafood

This study is aimed to understand the prevalence of lactose positive (lac⁺) and lactose negative (lac^?) Salmonella serovars in seafood and to determine the presence of virulence traits by PCR assay. Salmonella serovars were isolated from fish, shrimp, crab, clam, mussel, oyster, squid and cuttlefish of fish market and fish landing centers of Cochin, India. Lac^? Salmonella were identified in 18.9% of seafood samples, whereas, 2% of seafood samples harboured lac⁺ Salmonella. The virulence factors in lac⁺ and lac^? Salmonella were characterized by amplification of three virulence genes i.e. invA, stn and fimA genes. Results exhibited that except fim A gene in Salmonella IIIa isolates, all other lac⁺ and lac^? Salmonella serovars showed the presence of invA, stn and fimA genes. Thus, study highlighted the prevalence of virulent lac⁺ and lac^? Salmonella serovars in seafood.     

Prevalence of L. monocytogenes and Salmonella spp. in Tulum cheese

Tulum cheese, which is produced from raw milk, is one of the most popular semi-hard cheeses in Turkey. The growth of some food pathogens such as Listeria monocytogenes and Salmonella spp. in cheese and other dairy products may cause serious health problems for consumers. The aim of this study was to assess the presence of L. monocytogenes and Salmonella spp. in Tulum cheese sold in Istanbul. During the period March 2004–March 2005, a total of 250 Tulum cheese samples were obtained from various markets located in Istanbul and the presence of L. monocytogenes and Salmonella spp. was analyzed according to “The US Food and Drug Administration” (FDA) methods. The results were positive for L. monocytogenes and Salmonella spp. in 12 (4.8%) and 6 (2.4%) samples respectively.     

Prevalence of Salmonella in raw minced meat,raw fresh sausages and raw burger patties from retail outlets in Gaborone,Botswana

The prevalence of Salmonella in raw minced meat, raw burger patties and raw fresh sausages was determined by analysing 122 minced meat, 120 sausages and 58 burger patties obtained from retail outlets in Gaborone, Botswana. The prevalence rate was 20%. The most prevalent serogroups were B, followed by C and E/G. The Salmonella enterica serovars isolated were S. Typhi, S. Enteritidis, S. Anatum, S. Reading, S. Melagridis, S. Typhimurium, S. Paratyphi B, S. Newport, S. Bovis-morbificans, S. Braenderup, S. Infantis, S. Tennessee and S. Montevideo. The presence of S. Typhi and Paratyphi in meat products indicate human origin and therefore poor personal hygiene during handling of the meat products. Multidrug resistance patterns involving sulphatriad, sulphafurazole, tetracycline and cotrimoxazole were observed. Isolates in serogroups B and C were resistant to a greater number of antibiotics than isolates from other serogroups.