Filtration performance, fit test and side effects of respiratory personal protective equipment following decontamination: Observations for user safety and comfort.

OBJECTIVE: While facing personal protective equipment (PPE) shortages during the COVID-19 pandemic, several institutions looked to PPE decontamination and reuse options. This study documents the effect of two hydrogen peroxide treatments on filtration efficiency and fit tests as well as the side effects for volunteers after the decontamination of N95 filtering facepiece respirators (FFRs). We also propose an efficient and large-scale treatment protocol that allows for the traceability of this protective equipment in hospitals during PPE shortages. METHODS: The effects of low-temperature hydrogen peroxide sterilization and hydrogen peroxide vapor (HPV) on two FFR models (filtration, decontamination level, residual emanation) were evaluated. Ten volunteers reported comfort issues and side effects after wearing 1h FFRs worn and decontaminated up to five times. RESULTS: The decontamination process does not negatively affect FFR efficiency, but repeated use and handling tend to lead to damage, limiting the number of times FFRs can be reused. Moreover, the recommended 24-h post-treatment aeration does not sufficiently eliminate residual hydrogen peroxide. Prolonged aeration time increased user comfort when using decontaminated FFRs. CONCLUSIONS: HPV and low-temperature hydrogen peroxide sterilization seem to be appropriate treatments for FFR decontamination when the PPE is reused by the same user. PPE decontamination and reuse methods should be carefully considered as they are critical for the comfort and safety of healthcare workers.

Main outcomes from the first 2 years of France's screening programme for neonatal permanent hearing loss through a descriptive study.

AIM: This study aimed to evaluate the implementation of France's neonatal hearing loss screening programme years after its launch, and to estimate permanent bilateral neonatal hearing loss (PBNHL) prevalence and distribution by severity. METHODS: This descriptive study used aggregated regional data on all births in France in 2015-2016. Screening coverage, refusal rate, positive predictive value (PPV), proportion of children with suspected PBNHL, PBNHL prevalence and distribution by severity were calculated. RESULTS: Eight hundred thousand neonates were eligible for the screening programme per year. Between 2015 and 2016, screening coverage increased (83.3% vs. 93.8%; p < 0.001), and the refusal rate remained stable (0.1%). In 2016, when considering the additional tests performed several weeks after birth, the proportion of suspected PBNHL neonates decreased (1.4% vs. 0.9%) while the PPV increased (4.7% vs. 7.6%). In 2015, the estimated prevalence of PBNHL (moderate to profound) was 0.09% (95% CI 0.08-0.10). Among neonates with >= 41 decibels deficit, 56.8%, 16.6%, and 26.6% had moderate, severe and profound hearing loss, respectively. CONCLUSION: The national target of 90% screening coverage was exceeded. The additional test could be useful to avoid overcrowding in diagnostic structures. Diagnostic data quality must be improved to confirm PBNHL prevalence and distribution by severity.

The frequency of severe Fetal Alcohol Spectrum Disorders in the neonatal period using data from the French hospital discharge database between 2006 and 2013.

BACKGROUNDS: At birth, only complete Fetal Alcohol Syndrome (FAS) can be properly diagnosed. However, other Consequences of prenatal Alcohol Exposure (CAE) can also be recorded. Our objective was to describe the frequency of diagnoses highly suggestive of "potential Fetal Alcohol Syndrome Disorder" (pFASD, i.e., FAS and CAE) among hospitalized neonates, during the neonatal period, in France, between 2006 and 2013. METHODS: We used the French national hospital discharge database to identify the Q86.0 (FAS) and P04.3 (CAE) ICD-10 codes in hospital stays occurring in the first 28 days of life. FAS, CAE and pFASD rates were estimated per 1000 live births at the national level for the 2009-2013 period. We compared the 2006-2009 and 2010-2013 rates. The pFASD rates were also estimated at the regional level. RESULTS: Overall, 3,207 cases of pFASD were diagnosed during the neonatal period (i.e., 0.48 cases per 1000 live births, including 0.07 cases of FAS per 1000). Between 2006-2009 and 2010-2013, pFASD remained stable, despite a moderate decrease in reported FAS (0.08 vs 0.06 cases per 1000, p < 0.001). At the regional level, pFASD rates varied between 0.13 and 1.22 cases per 1000. CONCLUSIONS: This study provides the first national estimate of neonatal diagnosis of FAS, and more broadly pFASD, in France. Although our data certainly underestimate the real prevalence of FASD, they provide a minimal estimate of the burden of alcohol use during pregnancy. Observed variations deserve to be analyzed in the light of concomitant prevention and public information campaigns.

Risks of 23 specific malformations associated with prenatal exposure to 10 antiepileptic drugs.

OBJECTIVE: To assess the association between exposure to monotherapy with 10 different antiepileptic drugs (AEDs) during the first 2 months of pregnancy and the risk of 23 major congenital malformations (MCMs). METHODS: This nationwide cohort study, based on the French health care databases, included all pregnancies ≥20 weeks and ending between January 2011 and March 2015. Women were considered to be exposed when an AED had been dispensed between 1 month before and 2 months after the beginning of pregnancy. The reference group included pregnant women with no reimbursement for AEDs. MCMs were detected up to 12 months after birth (24 months for microcephaly, hypospadias, and epispadias). Odds ratios (ORs) were adjusted for potential confounders for MCMs with at least 5 cases. Otherwise, we calculated crude ORs with exact confidence intervals (CIs). RESULTS: The cohort included 1,886,825 pregnancies, 2,997 of which were exposed to lamotrigine, 1,671 to pregabalin, 980 to clonazepam, 913 to valproic acid, 579 to levetiracetam, 517 to topiramate, 512 to carbamazepine, 365 to gabapentin, 139 to oxcarbazepine, and 80 to phenobarbital. Exposure to valproic acid was associated with 8 specific types of MCMs (e.g., spina bifida, OR 19.4, 95% CI 8.6-43.5), and exposure to topiramate was associated with an increased risk of cleft lip (6.8, 95% CI 1.4-20.0). We identified 3 other signals. We found no significant association for lamotrigine, levetiracetam, carbamazepine, oxcarbazepine, and gabapentin. CONCLUSIONS: These results confirm the teratogenicity of valproic acid and topiramate. Because of the small numbers of cases and possible confounding, the other 3 signals should be interpreted with appropriate caution.

FranceCoag: a 22-year prospective follow-up of the national French cohort of patients with inherited bleeding disorders.

FranceCoag is an ongoing open prospective multicentre cohort project aimed at improving epidemiological knowledge about inherited bleeding disorders in France. The main objective of this article was to evaluate the project's progress as of the 30th December 2016. Between 1994 and this date, of the 10,047 patients included in the study, 384 (3.8%) were reported by clinicians to have died and 159 (1.6%) to be lost to follow-up. Among the remaining 9504 patients still being followed up, 5748 (60.5%) had haemophilia A, 1300 (13.7%) haemophilia B, 1980 (20.8%) von Willebrand Disease while 476 (5.0%) had another clotting factor deficiency (Factor I, II, V, combined V and VIII, VII, X, XI and XIII). The median age of the population was 32 years (Inter-quartile range (IQR) 18-50 years) at data extraction on December 30th, 2016. The subgroup of children (i.e., < 18 years old) with severe haemophilia and comprehensive information available since the first exposure to treatment was identified as the PUPs (Previously Untreated Patients) cohort. Data for the 643 children included in the PUPs' cohort had been collected since their birth. Follow-up data were collected by the clinicians in haemophilia treatment centres (HTC) every 12.9 months on median (IQR 11.4-21.3). In the PUPS cohort, data were updated every 6.2 months on median (IQR 3.7-11.7). A unique patient number assigned at study inclusion was kept at individual HTC by participating clinicians. The data collected included demographic, clinical, therapeutic and biological items on standard electronic forms. As of December 30th 2016, a plasma and serum samples was available for 2581 patients (27.1%).

Clinical features and prognostic factors of listeriosis: the MONALISA national prospective cohort study.

BACKGROUND: Listeriosis is a severe foodborne infection and a notifiable disease in France. We did a nationwide prospective study to characterise its clinical features and prognostic factors. METHODS: MONALISA was a national prospective observational cohort study. We enrolled eligible cases declared to the National Reference Center for Listeria (all microbiologically proven) between Nov 3, 2009, and July 31, 2013, in the context of mandatory reporting. The outcomes were analysis of clinical features, characterisation of Listeria isolates, and determination of predictors of 3-month mortality or persisting impairment using logistic regression. A hierarchical clustering on principal components was also done for neurological and bacteraemic cases. The study is registered at ClinicalTrials.gov, number NCT01520597. FINDINGS: We enrolled 818 cases from 372 centres, including 107 maternal-neonatal infections, 427 cases of bacteraemia, and 252 cases of neurolisteriosis. Only five (5%) of 107 pregnant women had an uneventful outcome. 26 (24%) of 107 mothers experienced fetal loss, but never after 29 weeks of gestation or beyond 2 days of admission to hospital. Neurolisteriosis presented as meningoencephalitis in 212 (84%) of 252 patients; brainstem involvement was only reported in 42 (17%) of 252 patients. 3-month mortality was higher for bacteraemia than neurolisteriosis (hazard ratio [HR] 0·54 [95% CI 0·41-0·69], p<0·0001). For both bacteraemia and neurolisteriosis, the strongest mortality predictors were ongoing cancer (odds ratio [OR] 5·19 [95% CI 3·01-8·95], p<0·0001), multi-organ failure (OR 7·98 [4·32-14·72], p<0·0001), aggravation of any pre-existing organ dysfunction (OR 4·35 [2·79-6·81], p<0·0001), and monocytopenia (OR 3·70 [1·82-7·49], p=0·0003). Neurolisteriosis mortality was higher in blood-culture positive patients (OR 3·67 [1·60-8·40], p=0·002) or those receiving adjunctive dexamethasone (OR 4·58 [1·50-13·98], p=0·008). INTERPRETATION: The severity of listeriosis is higher than reported elsewhere. We found evidence of a significantly reduced survival in patients with neurolisteriosis treated with adjunctive dexamethasone, and also determined the time window for fetal losses. MONALISA provides important new data to improve management and predict outcome in listeriosis. FUNDING: Programme Hospitalier Recherche Clinique, Institut Pasteur, Inserm, French Public Health Agency.

Increased incidence of congenital hypothyroidism in France from 1982 to 2012: a nationwide multicenter analysis.

PURPOSE: Recent studies have shown an increased incidence of congenital hypothyroidism over the past 2 or 3 decades. The etiology of this change is unknown, but it has been related by several authors to lowering of cutoffs. We sought to determine whether the incidence of congenital hypothyroidism (CH) in France has changed. METHODS: We analyzed data from the nationwide neonatal screening program for CH during the period 1982-2012. We included all children having thyroid-stimulating hormone values above the threshold and for whom diagnosis of CH confirmed by the pediatrician. We estimated multicentric temporal trends in the annual incidence rates adjusted for screening methods for thyroid dysgenesis and eutopic gland. RESULTS: We found 6622 cases of CH (28.0 per 100,000 newborns); 1895 had a eutopic gland, and 4727 had thyroid dysgenesis. The incidence of eutopic glands showed a significant annual average increase of (5.1%; 95% confidence interval: 4.3-5.9) regardless of the screening method or screening center. This increase was confirmed in severe cases (thyroid-stimulating hormone ≥ 50: 2.1%; 95% confidence interval, 1.4-2.9). The incidence of dysgenesis remained constant. CONCLUSIONS: The incidence of eutopic glands increased in France, not only in mild forms but also in severe cases.

Recombinant factor VIII products and inhibitor development in previously untreated boys with severe hemophilia A.

Six recombinant factor VIII (rFVIII) products have been marketed worldwide. In 2013, the Research of Determinants of Inhibitor Development (RODIN) study group reported an unexpectedly high risk of inhibitor development with a second-generation full-length rFVIII (Product D) in previously untreated patients (PUPs) with severe hemophilia A (HA). In 1994, French public health authorities established a prospective cohort to monitor hemophilia treatment safety. A PUP subgroup was designed to investigate inhibitor risk factors. We analyzed this subcohort in view of the RODIN findings. After excluding 50 patients who participated in the RODIN study, the primary analysis focused on 303 boys with severe HA first treated with a rFVIII product. A clinically significant inhibitor was detected in 114 boys (37.6%). The inhibitor incidence was higher with Product D vs the most widely used rFVIII product (adjusted hazard ratio [aHR], 1.55; 95% confidence interval [CI], 0.97-2.49). Similar results were found for high-titer inhibitors and in 10 sensitivity analyses. No heterogeneity was observed between RODIN and our results. Combined aHRs were 1.58 (95% CI, 1.17-2.14) for all inhibitors and 1.70 (95% CI, 1.15-2.52) for high-titer inhibitors. Our results confirm the higher immunogenicity of Product D vs other rFVIII products in PUPs with severe HA.

[Current epidemiology of bacterial STIs in France]. / Épidémiologie actuelle des infections sexuellement transmissibles bactériennes en France.

Sexually transmitted infections (STIs) remains a major problem of public health in France. Voluntary networks of physicians (RésIST) and laboratories (Rénago, Rénachla, lymphogranuloma venereum: LGV network) produce indicators showing the evolution of the main bacterial STIs. In 2010, the main findings were the following. The number of gonococcal infections has increased throughout the decade 2000 to 2010. The decrease in susceptibility of gonococcal strains to first-line antibiotics (extended-spectrum cephalosporins) needs to keep great attention. The number of screening and diagnosis of chlamydial urogenital infections also continues to rise in both sexes, particularly due to increased screening among young people. The relatively stable number of cases of early syphilis and of rectal LGV needs to be confirmed over the coming years. Both of these STIs affect overwhelmingly homo/bisexual men. There is still a high level of HIV co-infection with LGV and syphilis, and to a lesser extent with gonorrhea. We observe that condom use is still inadequate, especially during oral sex.

What is the incubation period for listeriosis?

BACKGROUND: Listeriosis is a foodborne infection with a low incidence but a high case fatality rate. Unlike common foodborne diseases, the incubation period can be long. The first incubation periods were documented during a large listeriosis outbreak published in 1987 by Linnan and al. in the New England Journal of Medicine (range: 3 days to 70 days). Data on the incubation period of listeriosis are scarce. Our study aim was to estimate precisely the incubation period of listeriosis using available data since 1987. METHODS: We estimated the incubation period of listeriosis using available published data and data from outbreak investigations carried out by the French National Institute for Public Health Surveillance. We selected cases with an incubation period calculated when a patient had a single exposure to a confirmed food source contaminated by Listeria monocytogenes. RESULTS: We identified 37 cases of invasive listeriosis (10 cases with central nervous system involvement (CNS cases), 15 bacteraemia cases and 12 pregnancy-associated cases) and 9 outbreaks with gastroenteritis. The overall median incubation period of invasive listeriosis was 8 days (range: 1-67 days) and differed significantly by clinical form of the disease (p<0.0001). A longer incubation period was observed for pregnancy-associated cases (median: 27.5 days; range: 17-67 days) than for CNS cases (median: 9 days; range: 1-14 days) and for bacteraemia cases (median: 2 days; range: 1-12 days). For gastroenteritis cases, the median incubation period was 24 hours with variation from 6 to 240 hours. CONCLUSIONS: This information has implications for the investigation of food borne listeriosis outbreaks as the incubation period is used to determine the time period for which a food history is collected. We believe that, for listeriosis outbreaks, adapting the exposure window for documenting patients' food histories in accordance with the clinical form of infection will facilitate the identification of food products as the source of contamination. We therefore propose to take an exposure window of 14 days before the diagnosis for CNS and bacteraemia cases, and of 6 weeks before the diagnosis, for pregnancy-associated cases.

Outbreak of Shiga toxin-producing Escherichia coli O104:H4 associated with organic fenugreek sprouts, France, June 2011.

BACKGROUND: On 22 June 2011, 8 patients with hemolytic uremic syndrome (HUS) or bloody diarrhea were reported in France. All 8 were attendees of a community center event on 8 June near Bordeaux. Three Escherichia coli cases were confirmed by isolation of Shiga toxin-producing E. coli O104:H4 stx2 aggR producing a cefotaximase (CTX-M) ß-lactamase (STEC O104:H4); the same rare serotype caused the outbreak in Germany in May-July 2011. An investigation was initiated to describe the outbreak, identify the vehicle for infection, and guide control measures. METHODS: We conducted a retrospective cohort study among all adults attending the event, including food handlers. A standardized questionnaire was administered to participants. A case was an attendee who developed HUS or diarrhea between 8 and 24 June. Cases were confirmed by isolation of STEC O104:H4 or O104 serology. Relative risks (RRs) and 95% confidence intervals (CIs) by exposure were calculated using a Poisson regression model. RESULTS: Twenty-four cases were identified (14% attack rate). Of these, 18 (75%) were women, 22 (92%) were adults, 7 (29%) developed HUS, 5 (21%) developed bloody diarrhea, and 12 (50%) developed diarrhea. Ten (42%) cases were confirmed. Fenugreek was the only sprout type with an independent association to illness (RR, 5.1; 95% CI, 2.3-11.1) in multivariable analysis. CONCLUSIONS: This investigation identified a point-source STEC O104:H4 outbreak associated with consumption of fenugreek sprouts. Comparison of results from French and German STEC O104:H4 outbreak investigations enabled identification of a common food vehicle, fenugreek sprouts, and resulted in implementation of Europe-wide control measures in July 2011.

Listeria monocytogenes-associated joint and bone infections: a study of 43 consecutive cases.

BACKGROUND: Little is known about Listeria monocytogenes-associated bone and joint infections. Only case reports of this infection have been published. METHODS: Retrospective study of culture-proven bone and joint cases reported to the French National Reference Center for Listeria from 1992 to 2010. RESULTS: Forty-three patients were studied: 61% were men, and the median age was 72 (range, 16-89); 24 patients exhibited comorbidities (56%). Thirty-six patients (84%) had orthopedic implant devices: prosthetic joints (n = 34) or internal fixation (n = 2); the median time after insertion was 9 years (0.1-22). Subacute infection was more frequent (median, 4 weeks [range, 2-100], 74%) than acute infection (<7 days, 23%), with nonspecific clinical features; 45% of patients had no fever. Blood cultures were positive in 3 of 19 cases. Isolate polymerase chain reaction genogrouping revealed 4 patterns: IVb (21 of 42, 50%), IIa (17 of 42, 40%), IIb (2 of 42, 5%), and IIc (2 of 42, 5%). Five groups of strains with similar pulsotype patterns were identified without an epidemiological link. Antibiotics, primarily amoxicillin (80%) with aminoglycosides (48%), were prescribed for a median duration of 15 weeks (range, 2-88). Eighteen patients (50%) underwent prosthesis replacement; all were successful after median follow-up of 10 months (range, 1-75). Five of 13 patients for whom material was not removed had protracted infection despite prolonged antibiotherapy; 3 of these patients later underwent prosthesis replacement with sustained recovery. CONCLUSIONS: Osteoarticular listeriosis primarily involves prosthetic joints and occurs in immunocompromised patients. It requires intensive treatment with antibiotherapy and usually requires implant removal or replacement for cure.

[Foodborne infections in France]. / Les infections d'origine alimentaire en France.

Prevention and control measures implemented along the human food chain in recent decades have been largely successful, as shown by the dramatic decrease in the incidence of listeriosis and certain Salmonella serotypes. However, foodborne illness continues to be a serious public health threat, due mainly to Salmonella, Listeria monocytogenes and Campylobacter. Infections caused by less frequent micro-organisms such as shigatoxin-producing E. coli are also a concern, because of their serious health consequences and epidemic potential. Surveillance of foodborne illness has revealed several important trends, including a substantial recent increase in infections by monophasic variants of Salmonella typhimurium, a continuing increase in the incidence of Campylobacter infections, and a rapid increase in the frequency and antibiotic resistance of Salmonella and Campylobacter isolates. These developments highlight the importance of epidemiological and microbiological surveillance of humain foodborne infections; as well as the need for very close collaboration among all those responsible for the surveillance of animal health and the human foodchain.

Incidence of listeriosis and related mortality among groups at risk of acquiring listeriosis.

BACKGROUND: Listeriosis is a foodborne disease of significant public health concern that primarily affects persons with recognized underlying conditions or diseases that impair cell-mediated immunity. The degree of risk posed by the different underlying conditions is crucial to prioritize prevention programs that target the highest risk populations. METHODS: We reviewed cases of listeriosis reported in France from 2001 to 2008. Numbers of cases and deaths were tabulated by age and underlying condition. Measures of the impact of specific underlying conditions on the occurrence of listeriosis were calculated. For estimating the total number of persons living with specific diseases, we applied prevalence estimates of these diseases to the French population. Underlying conditions were ranked by the degree to which they increased the risk of listeriosis. RESULTS: From 2001 to 2008, 1959 cases of listeriosis were reported in France (mean annual incidence 0.39 per 100,000 residents). Compared with persons <65 years with no underlying conditions, those with chronic lymphocytic leukemia had a >1000-fold increased risk of acquiring listeriosis, and those with liver cancer; myeoloproliferative disorder; multiple myeloma; acute leukemia; giant cell arteritis; dialysis; esophageal, stomach, pancreas, lung, and brain cancer; cirrhosis; organ transplantation; and pregnancy had a 100-1000-fold increased risk of listeriosis. CONCLUSIONS: To be effective and acceptable to physicians and patients, listeriosis prevention strategies should be targeted based on evidence of increased risk. Stringent dietary guidance, to avoid specific foods with a high risk for Listeria contamination, should be targeted to pregnant women and to others at highest risk of listeriosis.

Changes in sexual behaviours: from secular trends to public health policies.

OBJECTIVE: To explore the relative contribution of secular trends and public health policies to changes in sexual behaviour. DESIGN: Three random probability surveys of the sexual behaviour of people aged 18-69 years were conducted in 1970, 1992 and 2006 in France. METHODS: Data of the 2006 survey (n = 12,364) were compared with those from two surveys carried out in 1970 (n = 2625) and 1992 (n = 20,055). RESULTS: Over the last decades, median age at first intercourse has decreased by 4 years for women (22.0 in the 1930s vs. 17.6 in the 2000s) and 1 year for men (18.1 vs. 17.2). Lifetime number of sexual partners increased for women (1.8 in 1970 vs. 4.4 in 2006), but not for men (11.8 vs. 11.6). At the same time, the proportion of respondents, especially women, who reported nonpenetrative sexual practices and considered sexual intercourse essential to well being was on the increase. These changes are mainly attributed to an increase in women's social status. A marked increase in condom use was observed following the first AIDS/HIV prevention campaigns in the 1980s. CONCLUSION: Public health interventions that are synergistic with trends in social norms are likely to be more effective than those that run counter to them. In France, sexual health and HIV prevention policies aimed at harm limitation appear to have chimed with secular trends. The evidence of greater diversification of sexual practices offers potential to increase the range of safer sex messages used in public health interventions.

Quantitative risk assessment of Listeria monocytogenes in French cold-smoked salmon: II. Risk characterization.

A model for the assessment of exposure to Listeria monocytogenes from cold-smoked salmon consumption in France was presented in the first of this pair of articles (Pouillot et al., 2007, Risk Analysis, 27:683-700). In the present study, the exposure model output was combined with an internationally accepted hazard characterization model, adapted to the French situation, to assess the risk of invasive listeriosis from cold-smoked salmon consumption in France in a second-order Monte Carlo simulation framework. The annual number of cases of invasive listeriosis due to cold-smoked salmon consumption in France is estimated to be 307, with a very large credible interval ([10; 12,453]), reflecting data uncertainty. This uncertainty is mainly associated with the dose-response model. Despite the significant uncertainty associated with the predictions, this model provides a scientific base for risk managers and food business operators to manage the risk linked to cold-smoked salmon contaminated with L. monocytogenes. Under the modeling assumptions, risk would be efficiently reduced through a decrease in the prevalence of L. monocytogenes or better control of the last steps of the cold chain (shorter and/or colder storage during the consumer step), whereas reduction of the initial contamination levels of the contaminated products and improvement in the first steps of the cold chain do not seem to be promising strategies. An attempt to apply the recent risk-based concept of FSO (food safety objective) on this example underlines the ambiguity in practical implementation of the risk management metrics and the need for further elaboration on these concepts.

Increasing incidence of listeriosis in France and other European countries.

From 1999 through 2005, the incidence of listeriosis in France declined from 4.5 to 3.5 cases/million persons. In 2006, it increased to 4.7 cases/million persons. Extensive epidemiologic investigations of clusters in France have ruled out the occurrence of large foodborne disease outbreaks. In addition, no increase has occurred in pregnancy-associated cases or among persons <60 years of age who have no underlying disease. Increases have occurred mainly among persons >or=60 years of age and appear to be most pronounced for persons >or=70 years of age. In 8 other European countries, the incidence of listeriosis has increased, or remained relatively high, since 2000. As in France, these increases cannot be attributed to foodborne outbreaks, and no increase has been observed in pregnancy-associated cases. European countries appear to be experiencing an increased incidence of listeriosis among persons >or=60 years of age. The cause of this selective increased incidence is unknown.

Use of DNA arrays for the analysis of outbreak-related strains of Listeria monocytogenes.

We evaluated the discriminative power and usefulness of the DNA array technology as compared to DNA macrorestriction pattern analysis for monitoring epidemiologically related clusters of Listeria monocytogenes strains that differ slightly in DNA macrorestriction patterns. We show that this approach allows clarifying the genetic basis of the pattern variations. In the reported outbreak, the differences were due to phage excision, showing the power of this technique in epidemiological studies.