Survival and detection of Bacillus cereus in the presence of Escherichia coli, Salmonella enteritidis, Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans after rechallenge in make-up removers.

OBJECTIVE: Pathogenic contamination of cosmetics intended to be applied on or around the eye area, including make-up removers, may lead to severe eye infections. To assess the efficacy of antimicrobial preservatives in these products, we investigated the survival and detection of Bacillus cereus F 4227A spiked into make-up removers, alone and in the presence of other relevant micro-organisms. METHODS: Four brands of make-up removers, A, B, C and D, were challenged three times (day 0, day 7 and day 14) using B. cereus, in pure and mixed cultures, at a final concentration of 5 log CFU per mL of Bacillus cereus or 6 log CFU per mL for other micro-organisms. Inoculated samples were diluted and spiral-plated after 30 min and 24 h of each challenge onto selective media for recovery of surviving micro-organisms: BACARA (B. cereus), MacConkey (E. coli), ChromID (P. aeruginosa), XLT4 (S. enteritidis), Baird Parker agar (Staph. aureus) and PDA+chlortetracycline HCL (C. albicans). RESULTS: The population of B. cereus spiked as a pure culture increased significantly from the first to the third challenge after 30-min exposure time, going from 0.73 to 2.59 in A, from 0.80 to 2.69 in B and from 0.80 to 1.67 log CFU per mL in C (P < 0.05). Likewise, the B. cereus population from the mixed cultures had a significantly higher survival count at the third challenge: from 0.12 log MPN per mL to 2.16 log CFU per mL in A, 0.57 to 2.27 log CFU per mL in B and from undetected (LOD = 0.48 log MPN) to 0.98 log CFU per mL in C, respectively. After challenges, Staph. aureus, C. albicans and P. aeruginosa increased in B; Staph. aureus and C. albicans in C; and E. coli and Staph. aureus in D. The growth of other bacteria types was unaffected by the number of challenges, but B. cereus population was detected with the third challenge. CONCLUSION: It is appropriate to assess the antimicrobial efficacy of preservatives using at least three challenges, especially for cosmetics that are subjected to repetitive contamination by users.

Analysis of Bacillus cereus toxicity using PCR, ELISA and a lateral flow device.

AIMS: The aim of this study was to evaluate the performance of immunodetection methods and PCR analysis of enterotoxigenic Bacillus cereus strains. METHODS AND RESULTS: Eighty-eight enterotoxigenic B. cereus group strains linked to food-borne outbreaks and illnesses were studied with 30 exclusivity nonenterotoxigenic strains including Bacillus amyoliquifaciens, Bacillus subtilis, Staphylococcus aureus, Salmonella and Escherichia coli for this assessment. The PCR results showed 80% agreement with immunoassays for the Nhe target and 84% for the Hbl product. All exclusivity strains were PCR and serologically negative. CONCLUSIONS: PCR has proven to be a valuable tool when used in conjunction with immunoassays to quickly identify enterotoxigenic B. cereus group strains. SIGNIFICANCE AND IMPACT OF THE STUDY: This study assessed the utility of rapid methods to characterize enterotoxigenic profiles of B. cereus group strains. The identification of enterotoxigenic bacteria and any associated toxins detected from food products is essential in food defense programs as public health officials search for methods to rapidly and accurately screen a global food supply.

Prevalence of enterotoxins and toxin gene profiles of Staphylococcus aureus isolates recovered from a bakery involved in a second staphylococcal food poisoning occurrence.

AIMS: The study objective was to characterize and analyse the distribution of enterotoxins and genes encoding enterotoxins in Staphylococcus aureus strains recovered from the 601 environment and ingredient samples obtained during multiple inspections of a bakery implicated in two separate staphylococcal food poisoning incidents. METHODS AND RESULTS: Staphylococcus aureus isolates were evaluated using serological assays for identification of classical staphylococcal enterotoxins (SEs) SEA-SEE and polymerase chain reaction for the detection of newly described SE and SE-like enterotoxin genes seg-seu. Pulsed field gel electrophoresis identified thirteen pattern types. During these investigations, a total of 585 environmental swabs and 16 raw ingredient samples were collected by investigators, 85 of which were confirmed to contain Staph. aureus; of those isolates, 95·3% (81/85) harboured enterotoxin genes and 4·7% (4/85) carried newly described SE and SE-like enterotoxin genes in the absence of classical enterotoxins. CONCLUSIONS: Our research demonstrates the prevalence and diversity of classical SEs and the probable underestimated impact of nonclassical SE and SE-like enterotoxins role in domestic staphylococcal food poisoning outbreaks. SIGNIFICANCE AND IMPACT OF THE STUDY: Given the abundance of SEs and SE-like toxins, these findings illustrate the utilization of PCR for enterotoxin gene identification and its significance in outbreak investigations.

The complete genomes of Staphylococcus aureus bacteriophages 80 and 80α--implications for the specificity of SaPI mobilization.

Staphylococcus aureus pathogenicity islands (SaPIs) are mobile elements that are induced by a helper bacteriophage to excise and replicate and to be encapsidated in phage-like particles smaller than those of the helper, leading to high-frequency transfer. SaPI mobilization is helper phage specific; only certain SaPIs can be mobilized by a particular helper phage. Staphylococcal phage 80α can mobilize every SaPI tested thus far, including SaPI1, SaPI2 and SaPIbov1. Phage 80, on the other hand, cannot mobilize SaPI1, and ϕ11 mobilizes only SaPIbov1. In order to better understand the relationship between SaPIs and their helper phages, the genomes of phages 80 and 80α were sequenced, compared with other staphylococcal phage genomes, and analyzed for unique features that may be involved in SaPI mobilization.

Clonal spread of methicillin-resistant Staphylococcus aureus in a large geographic area of the United States.

Methicillin resistance in Staphylococcus aureus has rapidly increased over the last two decades. This increase is paralleled by the emergence of unique multi-resistant MRSA clones. In Brazil, Argentina, Uruguay, Portugal and Czech Republic a specific MRSA clone is widely spread, the so-called Brazilian epidemic clone. Another epidemic clone, the Iberian clone, is disseminated in Spain, Portugal, Belgium, Scotland, Italy, Germany and New York. Thus, a large number of hospital-acquired infections have been caused by specific MRSA clones. Using different molecular techniques for MRSA typing, we verified that two unique epidemic clones are spread over large geographic area in the US. In addition, we showed that a previously described MRSA clone type, the New York clone (I::A:A), is widely spread beyond the New York frontiers.