Cereus Contamination Research Articles

Safety assessment of recalled Haemophilus influenzae type b (Hib) conjugate vaccines—United States, 2007–2008

On 13 December 2007, Merck & Co., Inc. voluntarily recalled 1.2 million doses of Haemophilus influenzae type b (Hib) vaccines that had been distributed since April 2007 for concerns regarding potential Bacillus cereus contamination. Enhanced postrecall surveillance was conducted to detect vaccine-associated B. cereus infections. We reviewed reports involving recalled Hib vaccines received by the Vaccine Adverse Event Reporting System (VAERS) during 1 April 2007-29 February 2008. For each reported death, autopsy review sought evidence of B. cereus infections. For each specified outcome, the proportional reporting ratios (PRRs) were calculated to compare the recalled Hib vaccines with the manufacturer's nonrecalled Hib vaccines in the VAERS databases. On 20 December 2007, we used the Epidemic Information Exchange (Epi-X) to solicit nongastrointestinal vaccine-associated B. cereus infections, and requested B. cereus isolates for genotyping to compare with the manufacturing facility isolate. VAERS received 75 reports involving recalled Hib vaccines; none described a confirmed B. cereus infection. Comparative analyses did not reveal disproportionate reporting of specified outcomes for recalled Hib vaccines. The Epi-X posting triggered one report of vaccine-associated B. cereus bacteremia from a child who received a nonrecalled Hib vaccine manufactured by Merck; the genotypes of isolates from the patient and the manufacturing facility differed. No evidence of vaccine-associated B. cereus infection had been found in recipients of recalled Hib vaccines. Conducting laboratory surveillance through Epi-X was feasible and may enhance public health response capacities for future vaccine safety emergencies.

Reduction of Bacillus cereus Contamination in Biofilms on Stainless Steel Surfaces by Application of Sanitizers and Commercial Detergent

We established the effectiveness of a washing, detergent and sanitizer treatments for reducing Bacillus cereus (B. cereus) contamination in biofilms on stainless steel surfaces. A water treatment did not affect biofilms and chlorine treatments at 200 ppm for 10 min and 300 ppm for 5 min, iodophor at 200 ppm for 10 min, and QAC at 400 ppm for 10 min were used to eliminate all B. cereus cells. B. Cereus cells after detergent treatment were eliminated by chlorine at 100 ppm for 10 min, 200 ppm for 5 min, and 300 ppm for 3 min, and with iodophor at 100 ppm for 10 min and 200 ppm for 10 min, and QAC at 400 ppm for 10 min.

病院タオルの<i>Bacillus cereus</i>汚染を測定する方法の比較検討

病院で使用するタオルには，加熱処理が義務づけられている．しかし，熱に耐性であるBacillus cereusの芽胞が病院タオルを汚染することがある．さらに，病院タオルのB. cereus汚染は医療関連感染の原因となりうる．したがって，病院タオルのB. cereus汚染を定期的に評価する必要がある．しかし，その評価のための標準方法は確立されていない．今回の研究において，我々は4つの測定方法(スタンプ法・スワブ法・単純抽出法・ビーズ抽出法)を用いて，病院タオルのB. cereus汚染の評価を行なった．スタンプ法ではタオル汚染を定量評価することが不可能であった．また，スワブ法では病院タオルから少数のB. cereusしか検出できなかった．一方，抽出法では病院タオルから多数のB. cereusを検出することができた．特に，ビーズ抽出法では単純抽出法の2倍の菌数を検出することができた．以上の結果より，ビーズ抽出法は病院タオルのB. cereus汚染の評価に最も適した測定方法と考えられる．さらに本研究の結果から，タオル中のB. cereusの分布密度が不均一であることが判明した．したがって，タオルのB. cereus汚染を評価する場合，1枚のタオルから複数のサンプル断片を採取して調べる必要がある．

Contamination of milk with Bacillus cereus by post-pasteurization surface exposure as evaluated by automated ribotyping

Over the last decade, increased transportation of refrigerated raw milk from farms to factories has raised concerns over Bacillus cereus contamination in the Brazilian dairy industry. Twelve isolates from pasteurized milk and 30 isolates from the post-pasteurization equipment surfaces of a dairy processing unit were characterized as B. cereus. Seven ribotypes were identified, demonstrating the genetic variability of this microorganism. Most of the isolates belonged to the same ribogroup (RIBO1222-73-S4), and they were found on four surfaces and also in the milk, indicating the role of the equipment surfaces as reservoirs for milk recontamination.

Bacillus cereus nosocomial infection from reused towels in Japan

It was noticed that there was an increase in Bacillus cereus nosocomial infections in the summer from 2000 to 2005. In 2005, five bloodstream infections occurred in five patients related to catheter use. The causative strains were distinct from each other and belonged to novel multilocus sequence types (ST): ST365, ST366, ST367 and ST368. Two ST365 strains from two patients were further distinguished by pulsed-field gel electrophoresis. B. cereus contamination was observed with reused (dried and steamed) towels (>10(6)cfu/towel) and washing machines in hospital linen rooms. B. cereus strains from towels belonged to ST167, ST365, ST380 and ST382, and a proportion of these were the same, or similar, to strains from patients. All the hospital strains of B. cereus were distinct from those from food-poisoning strains (ST26, ST142, ST381). Ciprofloxacin resistance was observed only in hospital strains. Neither emetic toxin nor cytotoxin K gene, usually present in food poisoning strains, were found in the hospital strains, except for one patient isolate. The data suggest that specific B. cereus strains are circulating within a hospital, with genotypes, antibiotic susceptibilities and virulence gene patterns generally distinct from those of food poisoning, and that in Japan, towels are an important source of contamination, especially in summer.

Prevalence and characterisation of Bacillus cereus in vacuum packed potato puree

SummaryRefrigerated processed foods of extended durability (REPFED) potato puree was analysed for Bacillus cereus contamination along the production line and during the product shelf‐life. Isolated B. cereus strains were tested for their psychrotrophic character and the ability to produce enterotoxins. Bacillus cereus contamination during four subsequent productions was in the range of 2.3–4.0 log cfu g−1. Productions five and six were significantly less contaminated with B. cereus (≤1 log cfu g −1). All B. cereus isolates from the first four productions were able to grow at 7 ° and 10 °C, whereas the majority of the isolates from productions five and six did not. No B. cereus isolates grew at 4 °C. randomly amplified polymorphic DNA (RAPD) fingerprinting showed that the most of B. cereus contamination originated from one source. In total, 30.4% of isolates expressed enterotoxic character. The present study points out the necessity to prevent an ‘in house’ colonisation and contamination during food processing in order to accomplish the safety of REPFED throughout the shelf‐life. It also indicates the most critical steps in the production line of ready‐to‐eat potato puree and impact of failures regarding the food safety. The data provided can be used for risk assessment studies regarding B. cereus in REPFED.

Efficacy of Amphoteric Surfactant– and Peracetic Acid–Based Disinfectants on Spores of Bacillus cereus In Vitro and on Food Premises of the German Armed Forces

In mass catering facilities of the German Armed Forces, foodborne outbreaks are commonly attributed to Bacillus cereus, and spores of this organism are regularly found on equipment surfaces. B. cereus is the causative agent of foodborne emetic or diarrheic disease. Hence, the use of sporicidal disinfectants may provide a starting point for successful risk mitigation of diseases associated with B. cereus. In this study, the amphoteric surfactant–based disinfectant (product A) that has been routinely used in catering facilities of the German Armed Forces and a peracetic acid–based disinfectant (product B) were compared for their efficacy against B. cereus spores in laboratory tests and under field conditions. In a carrier test for B. cereus spores, product A displayed no efficacy against spores of the test strain. In contrast, a substantial reduction in spore concentration (>5-log reduction) was achieved with product B. In a controlled trial conducted in seven Army catering facilities, the reduction in the number of B. cereus–positive samples was significantly greater (P < 0.001) for product B (from 28% initial contamination to 3% after application) than for product A (from 33 to 21%). Product B was estimated to be 6.25 times more efficacious than product A. Field trials confirmed the higher efficacy of the peracetic acid–based disinfectant to reduce B. cereus contamination on surfaces as found for the in vitro experiments. The tests used to assess the sporicidal effects of disinfectants were adequate under practice conditions and could be used for sporicidal testing of disinfectants for catering and food production establishments.

Presence of Bacillus cereus in Street Foods in Gaborone, Botswana

The purpose of this study was to evaluate the microbiological safety and quality of street foods sold in Gaborone, Botswana. A total of 148 point-of-sale composite street food samples were bought and analyzed between June 2001 and May 2002. The analysis focused on the level of contamination of various street foods with Bacillus cereus. The B. cereus (vegetative and spores), total spore, and total viable counts were determined on all the samples. Also B. cereus isolates from 444 individual point-of-sale food samples were characterized with respect to their biochemical profiles and enterotoxigenic properties. The B. cereus contamination rate for point-of-sale foods was 65%. The B. cereus counts ranged from not detectable to levels as high as 9.1 log CFU/g. Despite the high rate of contamination of some samples, generally, most samples had B. cereus counts of less than 4 log CFU/g; hence, they were of acceptable microbiological quality. Bacillus diarrheal enterotoxin was detected from 52 isolates from individual portions of meals using the B. cereus enterotoxin reversed passive latex agglutination kit. Results of the assay revealed that 59.6% of the B. cereus isolates were enterotoxigenic. Most of the enterotoxigenic isolates were obtained from vegetable samples.

Relevance of Routine Bacterial Screening of Pooled Random Platelet Concentrates with the Bactalert® System.

Background: Transfusion of bacterial contaminated platelet (PLT) units can cause serious transfusion reactions. To prevent this complication, bacterial screening by the automated BacTalert® system of platelet concentrates was implemented in the southwest part of the Netherlands since october 2001. Despite this system, two severe transfusion reactions caused by bacterial contaminated PLT units occurred. Therefore, evaluation of the efficacy of this approach was done.Material and Methods: PLT products in the Netherlands are produced by the Sanquin Bloodbanks. In the Southwest part of the Netherlands PLT products mainly consist of pooled products derived from five random donors. Of all produced platelet products, samples were taken and cultured (aerobic and anaerobic) for seven days using the automated BacTalert® system. The PLT products were issued to the hospitals on a "negative-to-date" basis. In case of positive cultures, conformation and identification cultures were taken. At the same time, involved and related products thet were derived from the same donor were also withdrawn. In case of delivery of possibly contaminated products to the hospitals, these were notified and the products were recalled. If the products were already transfused, treating physicians were notified and asked if adverse reactions had occurred in these patients.Results: From October 2001 to 2003, a total of 28,104 produced pooled PLT units were tested for bacterial contamination using the BacTalert® system. Positive signals were found in 203 (0,72%) samples. At the time of a positive signal, 125 PLT products were already issued to the hospitals and of these 125 products, 113 units were already administered to patients. Analysis of all positive cultures revealed mainly skin-derived bacteria, but in 15 sample Bacillus cereus (7%). In 9.4% (=19) of the samples with a postive BacTalert® signal, bacterial growth could not be confirmed. None of the PLT units with a postive bacterial culture that were already administered to patients caused clinically significant transfusion reactions. Nevertheless, two neutropenic patients due to leukemia treatment, suffered from life-threatening B. cereus sepsis after PLT transfusion. In both cases, B.cereus was cultured from the PLT bags, whereas the BacTalert® tested samples remained negative.Conclusions: Issuing pooled PLT units on a negative-to-date basis for bacterial screening resulted in a significant amount of recall procedures. The BacTalert® system failed to detect B. cereus contamination in at least two cases that resulted in sever transfusion reactions. Other strategies, including pathogen reduction, might be applied to guarantee a better degree of bacterial safety.

Characterization of Bacillus cereus isolates from fresh vegetables and refrigerated minimally processed foods by biochemical and physiological tests

Bacillus cereus contamination has been evaluated in a total of 56 samples of fresh peppers, cucumbers, tomatoes, carrots, zucchini, garlic and onions, used commonly as ingredients to manufacture refrigerated minimally processed foods. It has been also evaluated in some of these products, such as gazpacho (Mediterranean vegetable cold soup made from fresh vegetables), salmorejo (vegetable cold purée containing bread and egg), ajoblanco (cold cream containing bread, almond, and olive oil as main ingredients) and zanaranja (carrot and orange juice mixture). The average counts did not exceed 10 4 cfu g −1 in any case and all the vegetables and processed products except garlic and zanaranja presented contamination of this foodborne pathogen. Cucumbers presented the highest count among all the vegetable products analysed, followed by carrots. According to the ISO 7932:1993(F) confirmation procedure, a total of 36 presumptive B. cereus strains were isolated from the 85 samples of various vegetable products analysed. Isolates were further characterized and identified by API 50CH/20E phenotypic system using APILAB Plus software, combined with additional tests of motility, oxidase activity and anaerobic growth. Of the 36 presumptive B. cereus isolates, 32 (88·9%) were confirmed to be B. cereus, two strains (5·5%) were identified as B. licheniformis, and other two strains (5·5%) were identified as B. firmus. About 81·3% (26 strains) of 32 B. cereus tested isolates hydrolysed starch and 71·9% (23 strains) produced diarrheal enterotoxin in TSB culture as detected by the BCET-RPLA test. The heat resistance at 90°C for spores of the 32 B. cereus strains ranged from 1·4 to 21·2 min. Strains unable to hydrolyse starch were the most heat-resistant, with D 90 values higher than 10·8 min. All the enterotoxin-positive strains were able to hydrolyse starch.

Bacillus cereus keratitis associated with contact lens wear

Objective We report the first case of contact lens-related Bacillus cereus keratitis and ulcer associated with B. cereus contamination of the contact lens case. This is also the first study to investigate and establish the genetic identity of an organism isolated from the cornea and contact lens case in a patient with contact lens-associated keratitis. Design Case report. Intervention and testing Conjunctival swabs and corneal scrapings from the left eye were inoculated for culture. The contact lens case was also cultured. Antibiotic susceptibility testing was determined by agar disk diffusion method. Initial treatment with topical ciprofloxacin and fortified tobramycin was given. Genetic analysis of the bacterial isolates was performed using polymerase chain reaction (PCR) with enterobacterial repetitive intergenic consensus primers (ERIC; ERIC-PCR). Susceptibility of B. cereus to heat and contact lens disinfecting solutions containing hydrogen peroxide, hydrogen peroxide-catalase, polyquaternium-1, and polyaminopropyl biguanide (PAPB) was tested. Main outcome measures Clinical features, culture results, and antibiotic susceptibility testing were analyzed. The ERIC-PCR amplification products were visualized in ethidium bromide-stained agarose gel. Bacterial growth after exposure to heat and contact lens disinfecting solutions was assessed on blood agar plates. Results B. cereus was grown from the conjunctiva, corneal ulcer, and contact lens case. All isolates were sensitive to gentamicin, tobramycin, ciprofloxacin, clindamycin, and vancomycin. The corneal ulcer gradually healed over the next 6 days. Results of ERIC-PCR showed that the isolates from the cornea and contact lens case were indistinguishable, thus demonstrating the source of infecting organism to be the contaminated contact lens case. Exposure to a temperature of 80°C for 20 minutes and incubation with hydrogen peroxide-catalase, polyquaternium-1, and PAPB for the minimum recommended time failed to kill B. cereus. Only exposure to hydrogen peroxide for 4 hours eradicated the organism. Conclusions B. cereus should be considered a possible etiologic agent of contact lens-associated keratitis. Heat and many types of contact lens disinfecting solutions may be ineffective in eradicating B. cereus from contaminated contact lens cases. Only prolonged exposure to hydrogen peroxide appeared to be sporicidal to B. cereus in this study.

Evaluation of Methods for Recognising Strains of the Bacillus cereus Group with Food Poisoning Potential Among Industrial and Environmental Contaminants

Toxin production, biochemical properties and ribotypes of Bacillus cereus group (B. cereus, B. thuringiensis, B. mycoides) strains originating from industrial and environmental sources (n = 64), from food poisoning incidents (n = 22) and from reference sources (n = 7) were analysed. Forty ribotypes were found among the 93 strains. Eleven strains from food poisoning incidents produced emetic (mitochondrio) toxin, as determined by the boar spermatozoa toxicity test. These strains possessed closely similar ribotypes which were rare among strains of other origins. Sperm toxin producing (cereulide positive) strains did not hydrolyse starch and did not produce haemolysin BL, as determined by the reverse passive latex agglutination test. Sixteen different ribotypes were found among B. cereus strains from board machines (n = 16) and from packaging board (n = 16), indicating many different sources of B. cereus contamination in board mills. Strains originating from packaging board had predominantly different ribotypes from those of dairy and dairy product originating strains. Nine (53%) out of 17 strains from a single dairy process shared the same ribotype whereas strains from milk and milk products from different dairies had different ribotypes indicating that B. cereus group populations were dairy specific. Twenty-two percent of strains isolated from the paperboard industry on non-selective medium were lecithinase negative, including enterotoxin producing strains. This stresses the importance of other detection methods not based on a positive lecithinase reaction.

Occurrence and survival of enterotoxigenic Bacillus cereus in some Nigerian flour-based foods

Flours that form the staple foods of Nigerians were sampled from the market to assay for Bacillus cereus contamination and the ability of the toxigenic strain to survive their normal cooking temperatures. Out of a total of 300 samples collected, five (2.0%) were without detectable levels of B. cereus, 84 (28.0%) were present at 1 × 10 3 cells/g; 194 (64.7%) were present at 1 × 10 4 cells/g and 22(7.3%) at 1 × 10 5 cells/g. All the samples were equally contaminated with high levels of bacteria. Of the 72 isolates tested for enterotoxin production, 33 (45.8%) were toxigenic by the ileal loop test. One of the toxigenic strains tested survived the preparation temperature of the ‘foo-foo’ and was able to initiate growth in the sample ‘tuwo’.

Use of plasmid profiles to differentiate between strains of Bacillus cereus

Bacillus cereus was isolated from raw and pasteurized liquid whole egg and from omelettes and retailed foods which included liquid whole egg as an ingredient. Of 101 isolates, 93 contained plasmids which varied in size from 2.2 to 43 MDa and gave 10 distinct profiles. In 37 strains isolated from raw egg, 10 profiles were found in the 30 strains in which plasmids were detected. However, in 15 strains isolated after pasteurization only 2 profiles were detected, both of which were present as minor profiles before pasteurization. These profiles also formed 70% of those found in strains from omelettes manufactured at the egg pasteurization plant. Neither profile was present in 40 strains isolated from the retailed foods. Two of four food poisoning strains examined contained plasmids, one of which had a profile similar to that of a strain isolated from the raw egg. The results suggest that plasmid profiling provides a simple and rapid method for determining the source of B. cereus contamination in retail foods.

Occurrence of Bacillus cereus in Meat Products, Raw Meat and Meat Product Additives

One thousand nine hundred and sixty three samples of meat products, raw meat and meat product additives from different slaughterhouses, meat processing factories and retail meat shops in six prefectures of Japan, were examined for the presence and number of Bacillus cereus. Although B. cereus was found in meat products (18.3%) and raw meat (6.6%), the contamination levels were generally lower than 102 per gram. In contrast, meat product additives showed contamination levels ranging from 102 to 104/g with the highest values (104/g) in samples of spices and animal proteins. On the basis of these results, we suggest that the main source of B. cereus contamination in meat products is contaminated meat product additives.

Bacillus Keratitis Associated With Contaminated Contact Lens Care Systems

We examined two soft contact lens wearers who developed keratitis associated with Bacillus contamination of their contact lens care systems. Patient 1 developed a corneal ulcer caused by B. subtilis, and Patient 2 demonstrated multiple, diffuse, punctate corneal epithelial opacities associated with B. cereus contamination in the contact lens and lens case compartment. The contact lens cases of both patients contained Bacillus spores that survived multiple heat disinfection treatments. Three different contact lens chemical disinfection systems used for the minimum recommended time failed to kill the Bacillus organisms.