Evaluation of Telephone Visits in Primary Care: Satisfaction of Pediatricians and Family Physicians and Their Perceptions of Quality of Care and Safety

Telehealth has accelerated since the outbreak of the COVID-19 virus. As telephone visits become more common, it is important to examine the challenges involved in using this modality of care. In this study, we examined family physicians' and pediatricians' perceptions regarding three aspects of the use of telephone visits: quality of care, safety of care, and physicians' satisfaction. A total of 342 family physicians and pediatricians responded to an online survey. Respondents were asked to rate their degree of agreement with 17 statements inquiring about quality, safety, and satisfaction with telephone visits on a Likert scale ranging from 1 (strongly disagree) to 5 (strongly agree). This was followed by in-depth interviews between January and April 2023 with 26 physicians. Participants expressed satisfaction (3.66 ± 0.80) with the use of telephone visits and lower assessments of safety (3.03 ± 0.76) and quality (2.27 ± 0.76) of care using the telephone modality. Eighty percent of the respondents think combining a face-to-face visit with a telephone visit is recommended, and 51% noted that the inability to examine patients closely affects and impedes a physician's decision making. Most interviewees indicated that telephone visits are safe only with former patients they had already seen in the clinic. The findings shed light on the perceptions of family physicians and pediatricians regarding telephone visits. The lower assessments of quality and safety compared to the assessment of satisfaction underscore the need for careful use of telephone visits in healthcare. A proper and balanced selection of patients, implementing technological upgrades to the modality, and performing patient education practices are recommended.

Safety of monovalent and bivalent BNT162b2 mRNA COVID-19 vaccine boosters in at-risk populations in Israel: a large-scale, retrospective, self-controlled case series study

BACKGROUND

COVID-19 continues to be a major health threat, particularly among at-risk groups, including individuals aged 60 years or older and people with particular medical conditions. Nevertheless, the absence of sufficient vaccine safety information is one of the key contributors to vaccine refusal. We aimed to assess the short-term safety profile of the BNT162b2 mRNA COVID-19 vaccine booster doses.

METHODS

In this self-controlled case series study, we used a database of members of the largest health-care organisation in Israel. We analysed the medical records of individuals at risk of COVID-19 complications who had received two doses of the monovalent BNT162b2 mRNA COVID-19 vaccine (tozinameran, Pfizer-BioNTech) as their primary course of vaccination and then also received BNT162b2 mRNA COVID-19 vaccine boosters between July 30, 2021, and Nov 28, 2022, as a monovalent first or second booster, or as a bivalent first, second, or third booster, or a combination of these. We included individuals who had active membership of the health-care organisation and who were alive (excluding COVID-19 deaths) throughout the entire study period. We excluded individuals who, during the study period, were either not active Clalit Health Services members or died of non-COVID-19 causes, and those who were infected with COVID-19 during the 7-day period after vaccination. Individuals' at-risk status was assessed on the day before the baseline period started. The primary outcome was non-COVID-19 hospitalisation for 29 adverse events that might be associated with vaccination. For each adverse event, we compared the risk difference of hospitalisation during a 28-day pre-vaccination baseline period versus during a 28-day post-vaccination period, using a non-parametric percentile bootstrap method.

FINDINGS

Of the 3 574 243 members of the health-care organisation, 1 073 110 received a first monovalent booster, 394 251 received a second monovalent booster, and 123 084 received a bivalent first, second, or third booster. Overall, we found no indication of an elevated risk of non-COVID-19 hospitalisation following administration of any of the booster vaccines (risk difference in events per 100 000 individuals: first monovalent booster -37·1 [95% CI -49·8 to -24·2]; second monovalent booster -37·8 [-62·2 to -13·2]; and bivalent booster -18·7 [-53·6 to 15·4]). Except for extremely rare elevated risks after the first monovalent booster-of myocarditis (risk difference 0·7 events per 100 000 individuals [95% CI 0·3-1·3]), seizures (2·2 [0·4-4·1]), and thrombocytopenia (2·6 [0·7-4·7])-we found no safety signals in other adverse events, including ischaemic stroke.

INTERPRETATION

This study provides the necessary vaccine safety assurances for at-risk populations to receive timed roll-out booster vaccinations. These assurances could reduce vaccine hesitancy and increase the number of at-risk individuals who opt to become vaccinated, and thereby prevent the severe outcomes associated with COVID-19.

FUNDING

Israel Science Foundation and Israel Precision Medicine Partnership programme.

Risk assessment of human mpox infections: Retrospective cohort study

OBJECTIVES

The global supply of vaccines against mpox (previously called monkeypox virus infection) was significantly lower than the demand. Therefore, evidence-based vaccine prioritization criteria, based on risk assessment were needed. Our objective was therefore to identify the characteristics of individuals at the highest risk for mpox.

METHODS

This population-based cohort study included all Clalit Health Services (CHS) subjects assumed to be at risk for mpox. The eligibility criteria for inclusion were determined based on known characteristics of people with infection worldwide and insights of LGBTQ+ -specialized CHS clinicians. Cox hazards models were used to identify risk factors for mpox within the study cohort. The study commenced on June 6, 2022, the date of the first known mpox in CHS members, until July 31, 2022, when the mpox vaccination campaign started.

RESULTS

8,088 individuals of 4.7 Million CHS members (0.18%) were identified according to the study inclusion criteria. Of those, 69 (0.85%) developed infection during the study period. Risk factors for mpox were birth in 1980 or later (HR 5.04 95%CI: 2.11-12.02), history of syphilis (2.62, 1.58-4.35), registeration to primary healthcare clinics in the Tel-Aviv district (2.82, 1.44-5.54), HIV-PrEP use (3.96, 2.14-7.31), PDE5 inhibitors use (2.92, 1.77-4.84), and recent STIs within the last 18 months (2.27, 1.35-3.82). No infections were observed in individuals with none of the factors. Individuals with 3+ risk factors had a 20.30-fold (10.39-39.69) higher risk for mpox compared to those with 0-2, with 85.5% (75.0% -92.8%) sensitivity and 77.8% (76.9%-78.7%) specificity.

CONCLUSION

Weighting individuals' risk levels based on validated risk factors against vaccine availability can assist health systems in the equitable prioritization of vaccine allocation in various future outbreaks, given supply-demand gaps.

Effectiveness of a bivalent mRNA vaccine booster dose to prevent severe COVID-19 outcomes: a retrospective cohort study

BACKGROUND

In late 2022, the SARS-CoV-2 omicron (B.1.1.529) BA.5 sublineage accounted for most of the sequenced viral genomes worldwide. Bivalent mRNA vaccines contain an ancestral SARS-CoV-2 strain component plus an updated component of the omicron BA.4 and BA.5 sublineages. Since September, 2022, a single bivalent mRNA vaccine booster dose has been recommended for adults who have completed a primary SARS-CoV-2 vaccination series and are at high risk of severe COVID-19. We aimed to evaluate the effectiveness of a bivalent mRNA vaccine booster dose to reduce hospitalisations and deaths due to COVID-19.

METHODS

We did a retrospective, population-based, cohort study in Israel, using data from electronic medical records in Clalit Health Services (CHS). We included all members of CHS who were aged 65 years or older and eligible for a bivalent mRNA COVID-19 booster vaccination. We used hospital records to identify COVID-19-related hospitalisations and deaths. The primary endpoint was hospitalisation due to COVID-19, which we compared between participants who received a bivalent mRNA booster vaccination and those who did not. A Cox proportional hazards regression model with time-dependent covariates was used to estimate the association between the bivalent vaccine and hospitalisation due to COVID-19 while adjusting for demographic factors and coexisting illnesses.

FINDINGS

Between Sept 27, 2022, and Jan 25, 2023, 569 519 eligible participants were identified. Of those, 134 215 (24%) participants received a bivalent mRNA booster vaccination during the study period. Hospitalisation due to COVID-19 occurred in 32 participants who received a bivalent mRNA booster vaccination and 541 who did not receive a bivalent booster vaccination (adjusted hazard ratio 0·28, 95% CI 0·19-0·40). The absolute risk reduction for hospitalisations due to COVID-19 in bivalent mRNA booster recipients versus non-recipients was 0·089% (95% CI 0·075-0·101), and the number needed to vaccinate to prevent one hospitalisation due to COVID-19 was 1118 people (95% CI 993-1341).

INTERPRETATION

Participants who received a bivalent mRNA booster vaccine dose had lower rates of hospitalisation due to COVID-19 than participants who did not receive a bivalent booster vaccination, for up to 120 days after vaccination. These findings highlight the importance of bivalent mRNA booster vaccination in populations at high risk of severe COVID-19. Further studies with longer observation times are warranted.

FUNDING

None.

Real-world effectiveness of a single dose of mpox vaccine in males

The recent global outbreak of the monkeypox (mpox) virus in humans was declared a public health emergency by the World Health Organization in July 2022. The smallpox and mpox vaccine (JYNNEOS; Modified Vaccinia Ankara-Bavarian Nordic; MVA-BN), provided as a two-dose regimen, is currently the primary vaccine utilized against mpox. However, the efficacy of MVA-BN against mpox has never been demonstrated in clinical trials to date. Due to the limited supply of vaccines, the World Health Organization has recommended prioritizing the vaccination of high-risk groups. We evaluated the real-world effectiveness of a single, subcutaneous dose of MVA-BN in this observational, retrospective cohort study, which included the analysis of electronic health records of all members of Clalit Health Services eligible for the vaccine on 31 July 2022. We used a Cox proportional hazards regression model with time-dependent covariates to estimate the association between vaccination and mpox while adjusting for sociodemographic and clinical risk factors. In an analysis of 2,054 male individuals who met vaccine eligibility criteria, 1,037 (50%) were vaccinated during the study recruitment period and completed at least 90 d of follow-up. During the study period, 5 and 16 infections were confirmed in vaccinated and unvaccinated individuals, respectively. The adjusted vaccine effectiveness was estimated at 86% (95% confidence interval, 59-95%). Our results suggest that a single dose of subcutaneous MVA-BN in this high-risk cohort is associated with a significantly lower risk of MPXV infection.

Chronic Spontaneous Urticaria in Patients With Interstitial Cystitis/Bladder Pain Syndrome: Insights From Big Data Analyses

OBJECTIVE

To examine the association between chronic spontaneous urticaria (CSU) and interstitial cystitis/bladder pain syndrome (IC/BPS).

METHODS

A population-based retrospective cross-sectional study was performed using the Clalit Health Services medical database. The prevalence of CSU was compared between patients diagnosed with IC/BPS and age- and gender-matched controls. Univariate analysis was performed using Chi-square and Student t test and a multivariable analysis was performed using a logistic regression model.

RESULTS

The study included 681 patients with IC/BPS and 3376 demographically matched controls. The mean age of IC/BPS patients was 60 years old. The prevalence of CSU among patients with IC/BPS was higher as compared to the control group (20% vs 13.7%; P <.001). The adjusted OR for CSU in patients with IC/BPS was 1.58 (95% CI 1.28-1.97). Female gender and Jewish ethnicity were associated with the coexistence of these disorders (OR 1.7 95% CI 1.36-2.13, and 1.6 95% CI 1.28-2, respectively).

CONCLUSION

A significant association was found between IC/BPS and CSU. This finding may support the presence of allergic/immune components in the pathogenesis of IC/BPS.

Nirmatrelvir Use and Severe Covid-19 Outcomes during the Omicron Surge

BACKGROUND

The oral protease inhibitor nirmatrelvir has shown substantial efficacy in high-risk, unvaccinated patients infected with the B.1.617.2 (delta) variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Data regarding the effectiveness of nirmatrelvir in preventing severe coronavirus disease 2019 (Covid-19) outcomes from the B.1.1.529 (omicron) variant are limited.

METHODS

We obtained data for all members of Clalit Health Services who were 40 years of age or older at the start of the study period and were assessed as being eligible to receive nirmatrelvir therapy during the omicron surge. A Cox proportional-hazards regression model with time-dependent covariates was used to estimate the association of nirmatrelvir treatment with hospitalization and death due to Covid-19, with adjustment for sociodemographic factors, coexisting conditions, and previous SARS-CoV-2 immunity status.

RESULTS

A total of 109,254 patients met the eligibility criteria, of whom 3902 (4%) received nirmatrelvir during the study period. Among patients 65 years of age or older, the rate of hospitalization due to Covid-19 was 14.7 cases per 100,000 person-days among treated patients as compared with 58.9 cases per 100,000 person-days among untreated patients (adjusted hazard ratio, 0.27; 95% confidence interval [CI], 0.15 to 0.49). The adjusted hazard ratio for death due to Covid-19 was 0.21 (95% CI, 0.05 to 0.82). Among patients 40 to 64 years of age, the rate of hospitalization due to Covid-19 was 15.2 cases per 100,000 person-days among treated patients and 15.8 cases per 100,000 person-days among untreated patients (adjusted hazard ratio, 0.74; 95% CI, 0.35 to 1.58). The adjusted hazard ratio for death due to Covid-19 was 1.32 (95% CI, 0.16 to 10.75).

CONCLUSIONS

Among patients 65 years of age or older, the rates of hospitalization and death due to Covid-19 were significantly lower among those who received nirmatrelvir than among those who did not. No evidence of benefit was found in younger adults.

Trends in the Volume and Types of Primary Care Visits during the Two Years of the COVID-19 Pandemic in Israel

BACKGROUND

The outbreak of the COVID-19 pandemic led to a decrease in primary health care in-person visits and a simultaneous increase in virtual encounters.

OBJECTIVE

To quantify the change in the total volume of primary care visits and mix of visit types during the two years of the pandemic in Israel.

DESIGN

Cross-sectional study.

PARTICIPANTS

All primary care visits by members of the largest healthcare organization in Israel, during three one-year periods: the pre-COVID-19 year (March 2019-February 2020), the first year of COVID-19 (March 2020-February 2021), and the second year of COVID-19 (March 2021-February 2022).

MAIN MEASURES

Total volume of primary care visits and mix of visit types.

RESULTS

More than 112 million primary care visits were included in the study. The total visit rate per 1000 members did not change significantly between the pre-COVID year (19) and the first COVID year (19.8), but was 21% higher in the second COVID-19 year (23). The rate of in-person visits per 1000 members decreased from 12.0 in the pre-COVID year to 7.7 in the first COVID year and then increased to 9.6 in the second. The rate of phone visits and asynchronous communication increased from 0.7 and 6.3, respectively, in the pre-COVID year, to 4.1 and 8, respectively, in the first COVID year, and remained unchanged in the second. There was substantial variation across age groups and sectors in the adoption of virtual platforms.

CONCLUSIONS

The rapid introduction of virtual encounters in primary care tended to displace in-person visits in the first year of the pandemic, but they appear to have been additive in the second. This transition should be monitored, with the goal of ensuring appropriate planning efforts and resource allocation to deal with the potential added burden on medical staff. Efforts should be invested in encouraging the use of virtual platforms in patient groups that currently underutilize it, such as minorities.

Effectiveness of the BNT162b2 mRNA COVID-19 vaccine among adolescents with juvenile-onset inflammatory rheumatic diseases

OBJECTIVES

The effectiveness of the BNT162b2 mRNA COVID-19 vaccine for adolescents with juvenile-onset inflammatory or immune rheumatic diseases (IRDs) is unknown. Several studies have suggested attenuated immunogenicity in patients with IRD. This study evaluated the effectiveness of the BNT162b2 mRNA COVID-19 vaccine in preventing COVID-19 infection in adolescents with juvenile-onset IRD compared with controls without immune rheumatic disease.

METHODS

We used data from Clalit Health Services, the largest health-care organization in Israel, to conduct an observational cohort study from February to December 2021, involving 12-18 year-old adolescents diagnosed with IRD. Study outcomes included documented COVID-19 infection in relation to vaccination status and immunomodulatory therapy. We estimated vaccine effectiveness as one minus the risk ratio. Adolescents aged 12-18 years without immune rheumatic disease served as controls.

RESULTS

A total of 1639 adolescents with IRD (juvenile idiopathic arthritis, SLE, or familial Mediterranean fever) were included and compared with 524 471 adolescents in the same age range without IRD. There was no difference in COVID-19 infection rates after the second dose of vaccine between those with IRD and controls (2.1% vs 2.1% respectively, P = 0.99). The estimated vaccine effectiveness for adolescents with IRD was 76.3% after the first dose, 94.8% after the second and 99.2% after the third dose.

CONCLUSION

We found that the BNT162b2 mRNA vaccine was similarly effective against COVID-19 infection in adolescents with and without IRD. Immunomodulatory therapy did not affect its effectiveness. These results can encourage adolescents with IRD to get vaccinated against COVID-19.

BNT162b2 Vaccine Effectiveness against Omicron in Children 5 to 11 Years of Age

BACKGROUND

Limited evidence is available on the real-world effectiveness of the BNT162b2 vaccine against coronavirus disease 2019 (Covid-19) and specifically against infection with the omicron variant among children 5 to 11 years of age.

METHODS

Using data from the largest health care organization in Israel, we identified a cohort of children 5 to 11 years of age who were vaccinated on or after November 23, 2021, and matched them with unvaccinated controls to estimate the vaccine effectiveness of BNT162b2 among newly vaccinated children during the omicron wave. Vaccine effectiveness against documented severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and symptomatic Covid-19 was estimated after the first and second vaccine doses. The cumulative incidence of each outcome in the two study groups through January 7, 2022, was estimated with the use of the Kaplan-Meier estimator, and vaccine effectiveness was calculated as 1 minus the risk ratio. Vaccine effectiveness was also estimated in age subgroups.

RESULTS

Among 136,127 eligible children who had been vaccinated during the study period, 94,728 were matched with unvaccinated controls. The estimated vaccine effectiveness against documented infection was 17% (95% confidence interval [CI], 7 to 25) at 14 to 27 days after the first dose and 51% (95% CI, 39 to 61) at 7 to 21 days after the second dose. The absolute risk difference between the study groups at days 7 to 21 after the second dose was 1905 events per 100,000 persons (95% CI, 1294 to 2440) for documented infection and 599 events per 100,000 persons (95% CI, 296 to 897) for symptomatic Covid-19. The estimated vaccine effectiveness against symptomatic Covid-19 was 18% (95% CI, -2 to 34) at 14 to 27 days after the first dose and 48% (95% CI, 29 to 63) at 7 to 21 days after the second dose. We observed a trend toward higher vaccine effectiveness in the youngest age group (5 or 6 years of age) than in the oldest age group (10 or 11 years of age).

CONCLUSIONS

Our findings suggest that as omicron was becoming the dominant variant, two doses of the BNT162b2 messenger RNA vaccine provided moderate protection against documented SARS-CoV-2 infection and symptomatic Covid-19 in children 5 to 11 years of age. (Funded by the European Union through the VERDI project and others.).

Effectiveness of a second BNT162b2 booster vaccine against hospitalization and death from COVID-19 in adults aged over 60 years

The rapid emergence of the B.1.1.529 (Omicron) variant of SARS-CoV-2 led to a global resurgence of coronavirus disease 2019 (COVID-19). Israeli authorities approved a fourth COVID-19 vaccine dose (second-booster) for individuals aged 60 years and over who had received a first booster dose four or more months earlier. Evidence regarding the effectiveness of a second-booster dose in reducing hospitalizations and mortality due to COVID-19 is warranted. This retrospective cohort study included all members of Clalit Health Services, aged 60 to 100 years, who were eligible for the second-booster on January 3, 2022. Hospitalizations and mortality due to COVID-19 among participants who received the second-booster were compared with participants who received one booster dose. Cox proportional-hazards regression models with time-dependent covariates were used to estimate the association between the second-booster and hospitalizations and death due to COVID-19 while adjusting for demographic factors and coexisting illnesses. A total of 563,465 participants met the eligibility criteria. Of those, 328,597 (58%) received a second-booster dose during the 40-day study period. Hospitalizations due to COVID-19 occurred in 270 of the second-booster recipients and in 550 participants who received one booster dose (adjusted hazard ratio 0.36; 95% confidence interval (CI): 0.31 to 0.43). Death due to COVID-19 occurred in 92 second-booster recipients and in 232 participants who received one booster dose (adjusted hazard ratio 0.22; 95% CI 0.17 to 0.28). This study demonstrates a substantial reduction in hospitalizations and deaths due to Covid-19 conferred by a second-booster in Israeli adults aged 60 years and over.

Effectiveness of the BNT162b2 Vaccine after Recovery from Covid-19

BACKGROUND

The risk of infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) decreases substantially among patients who have recovered from coronavirus disease 2019 (Covid-19). However, it is unknown how long protective immunity lasts. Current guidelines recommend vaccination of recovered patients even though data regarding vaccine effectiveness in such cases are still limited.

METHODS

In this retrospective cohort study, we reviewed electronic medical records from a large health care organization in Israel to assess reinfection rates in patients who had recovered from SARS-CoV-2 infection before any vaccination against Covid-19. We compared reinfection rates among patients who had subsequently received the BNT162b2 vaccine (Pfizer-BioNTech) and those who had not been vaccinated between March 1 and November 26, 2021. We used a Cox proportional-hazards regression model with time-dependent covariates to estimate the association between vaccination and reinfection after adjustment for demographic factors and coexisting illnesses. Vaccine effectiveness was estimated as 1 minus the hazard ratio. In a secondary analysis, we evaluated the vaccine effectiveness of one dose as compared with two doses.

RESULTS

A total of 149,032 patients who had recovered from SARS-CoV-2 infection met the eligibility criteria. Of these patients, 83,356 (56%) received subsequent vaccination during the 270-day study period. Reinfection occurred in 354 of the vaccinated patients (2.46 cases per 100,000 persons per day) and in 2168 of 65,676 unvaccinated patients (10.21 cases per 100,000 persons per day). Vaccine effectiveness was estimated at 82% (95% confidence interval [CI], 80 to 84) among patients who were 16 to 64 years of age and 60% (95% CI, 36 to 76) among those 65 years of age or older. No significant difference in vaccine effectiveness was found for one dose as compared with two doses.

CONCLUSIONS

Among patients who had recovered from Covid-19, the receipt of at least one dose of the BNT162b2 vaccine was associated with a significantly lower risk of recurrent infection.

BNT162b2 Vaccine Booster and Mortality Due to Covid-19

BACKGROUND

The emergence of the B.1.617.2 (delta) variant of severe acute respiratory syndrome coronavirus 2 and the reduced effectiveness over time of the BNT162b2 vaccine (Pfizer-BioNTech) led to a resurgence of coronavirus disease 2019 (Covid-19) cases in populations that had been vaccinated early. On July 30, 2021, the Israeli Ministry of Health approved the use of a third dose of BNT162b2 (booster) to cope with this resurgence. Evidence regarding the effectiveness of the booster in lowering mortality due to Covid-19 is still needed.

METHODS

We obtained data for all members of Clalit Health Services who were 50 years of age or older at the start of the study and had received two doses of BNT162b2 at least 5 months earlier. The mortality due to Covid-19 among participants who received the booster during the study period (booster group) was compared with that among participants who did not receive the booster (nonbooster group). A Cox proportional-hazards regression model with time-dependent covariates was used to estimate the association of booster status with death due to Covid-19, with adjustment for sociodemographic factors and coexisting conditions.

RESULTS

A total of 843,208 participants met the eligibility criteria, of whom 758,118 (90%) received the booster during the 54-day study period. Death due to Covid-19 occurred in 65 participants in the booster group (0.16 per 100,000 persons per day) and in 137 participants in the nonbooster group (2.98 per 100,000 persons per day). The adjusted hazard ratio for death due to Covid-19 in the booster group, as compared with the nonbooster group, was 0.10 (95% confidence interval, 0.07 to 0.14; P<0.001).

CONCLUSIONS

Participants who received a booster at least 5 months after a second dose of BNT162b2 had 90% lower mortality due to Covid-19 than participants who did not receive a booster.

Survival of pathogenic Escherichia coli on basil, lettuce, and spinach

The contamination of lettuce, spinach and basil with pathogenic E. coli has caused numerous illnesses over the past decade. E. coli O157:H7, E. coli O104:H4 and avian pathogenic E. coli (APECstx- and APECstx+) were inoculated on basil plants and in promix substrate using drip and overhead irrigation. When overhead inoculated with 7 log CFU/ml of each strain, E. coli populations were significantly (P = 0.03) higher on overhead-irrigated plants than on drip-irrigated plants. APECstx-, E. coli O104:H4 and APECstx+ populations were recovered on plants at 3.6, 2.3 and 3.1 log CFU/g at 10 dpi (days post-inoculation), respectively. E. coli O157:H7 was not detected on basil after 4 dpi. The persistence of E. coli O157:H7 and APECstx- were similar when co-inoculated on lettuce and spinach plants. On spinach and lettuce, E. coli O157:H7 and APEC populations declined from 5.7 to 6.1 log CFU/g and 4.5 log CFU/g, to undetectable at 3 dpi and 0.6-1.6 log CFU/g at 7 dpi, respectively. The detection of low populations of APEC and E. coli O104:H4 strains 10 dpi indicates these strains may be more adapted to environmental conditions than E. coli O157:H7. This is the first reported study of E. coli O104:H4 on a produce commodity.

Salmonella enterica serotype Virchow: epidemiology, resistance patterns and molecular characterisation of an invasive Salmonella serotype in Israel

This study outlines the unique epidemiology of Salmonella enterica serotype Virchow in Israel. Between 1997 and 2002, the overall incidence of non-typhoid Salmonella enterica (NTS) decreased from 69.3 to 53.3 infections/100,000 population, but the incidence of S. Virchow increased (from 7.2 to 9.1 infections/100,000). Since 2000, S. Virchow has become the second-ranking NTS isolate, accounting for 17% and 27% of all stool and blood NTS isolates, respectively. Infants aged < 1 year had the highest incidence of isolation from stools (92.8/100,000). The incidence of isolation from blood was highest for infants aged <1 year (4.4/100,000). Only 6% of isolates were susceptible to all ten antibiotic agents tested; 34% were resistant to one agent, 54% to one to three agents, and 40% to four to six agents. A high proportion of the tested isolates were resistant to nalidixic acid (89%), streptomycin (56%), tetracycline (43%), trimethoprim-sulphamethoxazole (38%) and chloramphenicol (28%), but none to ciprofloxacin or ceftriaxone. Pulsed-field gel electrophoresis revealed two closely related clusters, each containing a predominant pulsotype. Coupled with its invasive propensity, the increasing incidence of highly resistant S. Virchow in Israel is of real concern. Future research should focus on the sources of S. Virchow in the food chain in order to institute effective control measures.

Crystallization and preliminary X-ray analysis of a cohesin domain of the cellulosome from Clostridium thermocellum

Recombinant cohesin-2, a unique type of protein-recognition domain from the cellulosome of Clostridium thermocellum, has been crystallized by the hanging-drop vapor-diffusion method. The crystals are monoclinic, space group C2 with unit-cell dimensions a = 79.91, b = 47.86, c = 51.13 A, beta = 126.77 degrees. There is most likely to be one molecule per asymmetric unit, corresponding to a packing density of 2.16 A(3) Da(-1). The crystals diffract to beyond 2.3 A on a conventional laboratory rotating-anode source.

A reverse transcriptase-polymerase chain reaction assay for detection of viable Escherichia coli O157:H7: investigation of specific target genes

AIMS

To determine suitable target genes for detection of the pathogen Escherichia coli O157:H7 by reverse transcriptase-polymerase chain reaction (RT-PCR).

METHODS AND RESULTS

Potential genes used as indicators for viability included rfbE, fliC, stx1, stx2, mobA, eaeA, hly and 16S rRNA. Under normal growth conditions, rfbE, stx1, hly and 16S rRNA amplicons were detected in association with all growth phases. The products of 16S rRNA, mobA, rfbE and stx1 were readily visualized in RNA isolated from viable but non-culturable cells. The 16S rRNA gene was not amplified following heat treatment of cells at 121 degrees C for 15 min and mRNA targets were not amplified after treatment at 60 degrees C for 20 min. In this instance, genes that are not amplified are good targets for determining viability.

CONCLUSIONS

The results of RT-PCR amplification indicate that, under the conditions examined, the rfbE gene is the most appropriate target for detection of viable E. coli O157:H7.

SIGNIFICANCE AND IMPACT OF THE STUDY

Prior to detection or identification from an environmental or food sample E. coli O157:H7 may be exposed to many harsh conditions that influence nucleic acid (RNA and DNA) stability. This study gives an insight into the effects of temperature and nutrient deprivation on identification of viable cells using RT-PCR. It also suggests that, if RT-PCR is to be used for detection of live cells in a sample without enrichment, 10(7) cfu of the target organism are required.

Use of green fluorescent protein expressing Salmonella Stanley to investigate survival, spatial location, and control on alfalfa sprouts

Laser scanning confocal microscopy (LSCM) was used to observe the interaction of Salmonella Stanley with alfalfa sprouts. The green fluorescent protein (gfp) gene was integrated into the chromosome of Salmonella Stanley for constitutive expression, thereby eliminating problems of plasmid stability and loss of signal. Alfalfa seeds were inoculated by immersion in a suspension of Salmonella Stanley (ca. 10(7) CFU/ml) for 5 min at 22 degrees C. Epifluorescence microscopy demonstrated the presence of target bacteria on the surface of sprouts. LSCM demonstrated bacteria present at a depth of 12 microm within intact sprout tissue. An initial population of ca. 10(4) CFU/g seed increased to 7.0 log CFU/g during a 24-h germination period and then decreased to 4.9 log CFU/g during a 144-h sprouting period. Populations of Salmonella Stanley on alfalfa seeds decreased from 5.2 to 4.1 log CFU/g and from 5.2 to 2.8 log CFU/g for seeds stored 60 days at 5 and 22 degrees C, respectively. The efficacy of 100, 200, 500, or 2,000 ppm chlorine in killing Salmonella Stanley associated with sprouts was determined. Treatment of sprouts in 2,000 ppm chlorine for 2 or 5 min caused a significant reduction in populations of Salmonella Stanley. Influence of storage on Salmonella Stanley populations was investigated by storing sprouts 4 days at 4 degrees C. The initial population (7.76 log CFU/g) of Salmonella Stanley on mature sprouts decreased (7.67 log CFU/g) only slightly. Cross-contamination during harvest was investigated by harvesting contaminated sprouts, then directly harvesting noncontaminated sprouts. This process resulted in the transfer of ca. 10(5) CFU/g Salmonella Stanley to the noncontaminated sprouts.

Nonproteolytic cleavage of aspartyl proline bonds in the cellulosomal scaffoldin subunit from Clostridium thermocellum

Previous work from our group [Morage (Morgenstern), E., Bayer, E. A., and Lamed, R. (1991), Appl. Biochem. Biotechnol. 30, 129-136] has demonstrated an anomalous electrophoretic mobility pattern for scaffoldin, the 210-kDa cellulosome-integrating subunit of Clostridium thermocellum. Subsequent evidence [Morag, E., Bayer, E. A., and Lamed, R. (1992), Appl. Biochem. Biotechnol. 33, 205-217] indicated that the effect could be attributed to a nonproteolytic fragmentation of the subunit into a defined series of lower-molecular-weight bands. In the present work, a recombinant segment of the scaffoldin subunit was employed to determine the site(s) of bond breakage. An Asp-Pro sequence within the cohesin domain was identified to be the sensitive peptide bond. This sequence appears quite frequently in the large cellulosomal proteins, and the labile bond may be related to an as yet undescribed physiological role in the hydrolysis of cellulose by cellulosomes.

Vesicle-mediated transfer of virulence genes from Escherichia coli O157:H7 to other enteric bacteria

Membrane vesicles are released from the surfaces of many gram-negative bacteria during growth. Vesicles consist of proteins, lipopolysaccharide, phospholipids, RNA, and DNA. Results of the present study demonstrate that membrane vesicles isolated from the food-borne pathogen Escherichia coli O157:H7 facilitate the transfer of genes, which are then expressed by recipient Salmonella enterica serovar Enteritidis or E. coli JM109. Electron micrographs of purified DNA from E. coli O157:H7 vesicles showed large rosette-like structures, linear DNA fragments, and small open-circle plasmids. PCR analysis of vesicle DNA demonstrated the presence of specific genes from host and recombinant plasmids (hly, L7095, mobA, and gfp), chromosomal DNA (uidA and eaeA), and phage DNA (stx1 and stx2). The results of PCR and the Vero cell assay demonstrate that genetic material, including virulence genes, is transferred to recipient bacteria and subsequently expressed. The cytotoxicity of the transformed enteric bacteria was sixfold higher than that of the parent isolate (E. coli JM109). Utilization of the nonhost plasmid (pGFP) permitted the evaluation of transformation efficiency (ca. 10(3) transformants microg of DNA(-1)) and demonstrated that vesicles can deliver antibiotic resistance. Transformed E. coli JM109 cells were resistant to ampicillin and fluoresced a brilliant green. The role vesicles play in genetic exchange between different species in the environment or host has yet to be defined.

Cohesin-dockerin recognition in cellulosome assembly: experiment versus hypothesis

The cohesin-dockerin interaction provides the basis for incorporation of the individual enzymatic subunits into the cellulosome complex. In a previous article (Pagés et al., Proteins 1997;29:517-527) we predicted that four amino acid residues of the approximately 70-residue dockerin domain would serve as recognition codes for binding to the cohesin domain. The validity of the prediction was examined by site-directed mutagenesis of the suspected residues, whereby the species-specificity of the cohesin-dockerin interaction was altered. The results support the premise that the four residues indeed play a role in biorecognition, while additional residues may also contribute to the specificity of the interaction. Proteins 2000;39:170-177.

Demented patients' participation in a clinical trial: factors affecting the caregivers' decision

Clinical trials for Alzheimer's disease take place in medical centers all over the world. Patients and caregivers have to decide whether or not to agree to participate in clinical trials. This study aimed to investigate the motivation that determines the caregivers' choice. Nineteen caregivers of demented patients who consented to participate in a clinical trial in our Memory Clinic and 10 caregivers who refused to participate were interviewed. The data were gathered by a self-report questionnaire covering various aspects of the caregivers' decision-making process. Among the reasons for agreeing to participate in the clinical trial were the respondents' belief that it would improve or help to maintain the patients' condition. Most of the respondents of both groups indicated that information regarding side effects and success probability was adequately provided in advance. The primary reason for refusal was the potential side effects of the drug. The implications of the findings are discussed.

Matrix-assisted refolding of single-chain Fv- cellulose binding domain fusion proteins

We describe a method for the isolation of recombinant single-chain antibodies in a biologically active form. The single-chain antibodies are fused to a cellulose binding domain as a single-chain protein that accumulates as insoluble inclusion bodies upon expression in Escherichia coli. The inclusion bodies are then solubilized and denatured by an appropriate chaotropic solvent, then reversibly immobilized onto a cellulose matrix via specific interaction of the matrix with the cellulose binding domain (CBD) moiety. The efficient immobilization that minimizes the contact between folding protein molecules, thus preventing their aggregation, is facilitated by the robustness of the Clostridium thermocellum CBD we use. This CBD is unique in retaining its specific cellulose binding capability when solubilized in up to 6 M urea, while the proteins fused to it are fully denatured. Refolding of the fusion proteins is induced by reducing with time the concentration of the denaturing solvent while in contact with the cellulose matrix. The refolded single-chain antibodies in their native state are then recovered by releasing them from the cellulose matrix in high yield of 60% or better, which is threefold or higher than the yield obtained by using published refolding protocols to recover the same scFvs. The described method should have general applicability for the production of many protein-CBD fusions in which the fusion partner is insoluble upon expression.

A cohesin domain from Clostridium thermocellum: the crystal structure provides new insights into cellulosome assembly

BACKGROUND

The scaffoldin component of the cellulolytic bacterium Clostridium thermocellum is a non-hydrolytic protein which organizes the hydrolytic enzymes in a large complex, called the cellulosome. Scaffoldin comprises a series of functional domains, amongst which is a single cellulose-binding domain and nine cohesin domains which are responsible for integrating the individual enzymatic subunits into the complex. The cohesin domains are highly conserved in their primary amino acid sequences. These domains interact with a complementary domain, termed the dockerin domain, one of which is located on each enzymatic subunit. The cohesin-dockerin interaction is the crucial interaction for complex formation in the cellulosome. The determination of structural information about the cohesin domain will provide insights into cellulosome assembly and activity.

RESULTS

We have determined the three-dimensional crystal structure of one of the cohesin domains from C. thermocellum (cohesin 2) at 2.15 A resolution. The domain forms a nine-stranded beta sandwich with a jelly-roll topology, somewhat similar to the fold displayed by its neighboring cellulose-binding domain.

CONCLUSIONS

The compact nature of the cohesin structure and its lack of a defined binding pocket suggests that binding between the cohesin and dockerin domains is characterized by interactions between exposed surface residues. As the cohesin-dockerin interaction appears to be rather nonselective, the binding face would presumably be characterized by surface residues which exhibit both intraspecies conservation and interspecies dissimilarity. Within the same species, unconserved surface residues may reflect the position of a given cohesin domain within the scaffoldin subunit, its orientation and interactions with neighboring domains.

Expression, purification and crystallization of a cohesin domain from the cellulosome of Clostridium thermocellum

The cellulosome of the cellulolytic bacterium, Clostridium thermocellum, is a multi-enzyme complex in which the enzymatic (cellulolytic) subunits are attached to a unique nonhydrolytic subunit called scaffoldin. The attachment is mediated by two mutually interacting domains: namely multiple cohesin domains on the scaffoldin subunit and a dockerin domain on each of the enzymatic subunits. Knowledge of the three-dimensional structure of each of the interacting components would be critical to a better understanding of the cohesin-dockerin interaction at the molecular level. In this report, we describe the purification of one of the nine cohesin domains of the scaffoldin subunit from C. thermocellum. A DNA segment containing the cohesin 2 sequence was fused to a hexa-histidine tag, and the resultant construct was expressed in Escherichia coli. The expressed peptide was efficiently isolated by metal-chelate affinity chromatography. The purified recombinant form of the cohesin was crystallized pending determination of its structure.

Expression, purification and subunit-binding properties of cohesins 2 and 3 of the Clostridium thermocellum cellulosome

The enzymatic subunits of the cellulosome of Clostridium thermocellum are integrated into the complex by a major non-catalytic polypeptide, called scaffoldin. Its numerous functional domains include a single cellulose-binding domain (CBD) and nine subunit-binding domains, or cohesin domains. Two of the cohesin domains, together with the adjacent CBD, have been cloned and expressed in Escherichia coli, and the recombinant constructs were purified by affinity chromatography on a cellulosic matrix. Both cohesin domains, which differ by about 30% in their primary structure, showed a similar binding profile to the cellulosomal subunits. Calcium ions enhanced dramatically this binding. Under the conditions of the assay, only one major catalytic subunit of the cellulosome failed to bind to either cohesin domain. The results indicate a lack of selectivity in the binding of cohesin domains to the catalytic subunits and also suggest that additional mechanisms may be involved in cellulosome assembly.