Seroprevalence of SARS-CoV-2 antibodies among healthcare workers in Dutch hospitals after the 2020 first wave: a multicentre cross-sectional study with prospective follow-up.

BACKGROUND: We aimed to estimate the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) seroprevalence and describe its determinants and associated symptoms among unvaccinated healthcare workers (HCWs) after the first wave of the pandemic. METHODS: HCWs from 13 Dutch hospitals were screened for antibodies against the spike protein of SARS-CoV-2 in June-July 2020 and after three months. Participants completed a retrospective questionnaire on determinants for occupational and community exposure to SARS-CoV-2 and symptoms suggestive of COVID-19 experienced since January 2020. The seroprevalence was calculated per baseline characteristic and symptom at baseline and after follow-up. Adjusted odds ratios (aOR) for seropositivity were determined using logistic regression. RESULTS: Among 2328 HCWs, 323 (13.9%) were seropositive at enrolment, 49 of whom (15%) reported no previous symptoms suggestive of COVID-19. During follow-up, only 1% of the tested participants seroconverted. Seroprevalence was higher in younger HCWs compared to the mid-age category (aOR 1.53, 95% CI 1.07-2.18). Nurses (aOR 2.21, 95% CI 1.34-3.64) and administrative staff (aOR 1.87, 95% CI 1.02-3.43) had a higher seroprevalence than physicians. The highest seroprevalence was observed in HCWs in the emergency department (ED) (aOR 1.79, 95% CI 1.10-2.91), the lowest in HCWs in the intensive, high, or medium care units (aOR 0.47, 95% CI 0.31-0.71). Chronic respiratory disease, smoking, and having a dog were independently associated with a lower seroprevalence, while HCWs with diabetes mellitus had a higher seroprevalence. In a multivariable model containing all self-reported symptoms since January 2020, altered smell and taste, fever, general malaise/fatigue, and muscle aches were positively associated with developing antibodies, while sore throat and chills were negatively associated. CONCLUSIONS: The SARS-CoV-2 seroprevalence in unvaccinated HCWs of 13 Dutch hospitals was 14% in June-July 2020 and remained stable after three months. A higher seroprevalence was observed in the ED and among nurses, administrative and young staff, and those with diabetes mellitus, while a lower seroprevalence was found in HCWs in intensive, high, or medium care, and those with self-reported lung disease, smokers, and dog owners. A history of altered smell or taste, fever, muscle aches and fatigue were independently associated with the presence of SARS-CoV-2 antibodies in unvaccinated HCWs.

Postoperative Staphylococcus aureus Infections in Patients With and Without Preoperative Colonization.

Importance: Staphylococcus aureus surgical site infections (SSIs) and bloodstream infections (BSIs) are important complications of surgical procedures for which prevention remains suboptimal. Contemporary data on the incidence of and etiologic factors for these infections are needed to support the development of improved preventive strategies. Objectives: To assess the occurrence of postoperative S aureus SSIs and BSIs and quantify its association with patient-related and contextual factors. Design, Setting, and Participants: This multicenter cohort study assessed surgical patients at 33 hospitals in 10 European countries who were recruited between December 16, 2016, and September 30, 2019 (follow-up through December 30, 2019). Enrolled patients were actively followed up for up to 90 days after surgery to assess the occurrence of S aureus SSIs and BSIs. Data analysis was performed between November 20, 2020, and April 21, 2022. All patients were 18 years or older and had undergone 11 different types of surgical procedures. They were screened for S aureus colonization in the nose, throat, and perineum within 30 days before surgery (source population). Both S aureus carriers and noncarriers were subsequently enrolled in a 2:1 ratio. Exposure: Preoperative S aureus colonization. Main Outcomes and Measures: The main outcome was cumulative incidence of S aureus SSIs and BSIs estimated for the source population, using weighted incidence calculation. The independent association of candidate variables was estimated using multivariable Cox proportional hazards regression models. Results: In total, 5004 patients (median [IQR] age, 66 [56-72] years; 2510 [50.2%] female) were enrolled in the study cohort; 3369 (67.3%) were S aureus carriers. One hundred patients developed S aureus SSIs or BSIs within 90 days after surgery. The weighted cumulative incidence of S aureus SSIs or BSIs was 2.55% (95% CI, 2.05%-3.12%) for carriers and 0.52% (95% CI, 0.22%-0.91%) for noncarriers. Preoperative S aureus colonization (adjusted hazard ratio [AHR], 4.38; 95% CI, 2.19-8.76), having nonremovable implants (AHR, 2.00; 95% CI, 1.15-3.49), undergoing mastectomy (AHR, 5.13; 95% CI, 1.87-14.08) or neurosurgery (AHR, 2.47; 95% CI, 1.09-5.61) (compared with orthopedic surgery), and body mass index (AHR, 1.05; 95% CI, 1.01-1.08 per unit increase) were independently associated with S aureus SSIs and BSIs. Conclusions and Relevance: In this cohort study of surgical patients, S aureus carriage was associated with an increased risk of developing S aureus SSIs and BSIs. Both modifiable and nonmodifiable etiologic factors were associated with this risk and should be addressed in those at increased S aureus SSI and BSI risk.

Mixed strain pathogen populations accelerate the evolution of antibiotic resistance in patients.

Antibiotic resistance poses a global health threat, but the within-host drivers of resistance remain poorly understood. Pathogen populations are often assumed to be clonal within hosts, and resistance is thought to emerge due to selection for de novo variants. Here we show that mixed strain populations are common in the opportunistic pathogen P. aeruginosa. Crucially, resistance evolves rapidly in patients colonized by multiple strains through selection for pre-existing resistant strains. In contrast, resistance evolves sporadically in patients colonized by single strains due to selection for novel resistance mutations. However, strong trade-offs between resistance and growth rate occur in mixed strain populations, suggesting that within-host diversity can also drive the loss of resistance in the absence of antibiotic treatment. In summary, we show that the within-host diversity of pathogen populations plays a key role in shaping the emergence of resistance in response to treatment.

Gut to lung translocation and antibiotic mediated selection shape the dynamics of Pseudomonas aeruginosa in an ICU patient.

Bacteria have the potential to translocate between sites in the human body, but the dynamics and consequences of within-host bacterial migration remain poorly understood. Here we investigate the link between gut and lung Pseudomonas aeruginosa populations in an intensively sampled ICU patient using a combination of genomics, isolate phenotyping, host immunity profiling, and clinical data. Crucially, we show that lung colonization in the ICU was driven by the translocation of P. aeruginosa from the gut. Meropenem treatment for a suspected urinary tract infection selected for elevated resistance in both the gut and lung. However, resistance was driven by parallel evolution in the gut and lung coupled with organ specific selective pressures, and translocation had only a minor impact on AMR. These findings suggest that reducing intestinal colonization of Pseudomonas may be an effective way to prevent lung infections in critically ill patients.

Rapid evolution and host immunity drive the rise and fall of carbapenem resistance during an acute Pseudomonas aeruginosa infection.

It is well established that antibiotic treatment selects for resistance, but the dynamics of this process during infections are poorly understood. Here we map the responses of Pseudomonas aeruginosa to treatment in high definition during a lung infection of a single ICU patient. Host immunity and antibiotic therapy with meropenem suppressed P. aeruginosa, but a second wave of infection emerged due to the growth of oprD and wbpM meropenem resistant mutants that evolved in situ. Selection then led to a loss of resistance by decreasing the prevalence of low fitness oprD mutants, increasing the frequency of high fitness mutants lacking the MexAB-OprM efflux pump, and decreasing the copy number of a multidrug resistance plasmid. Ultimately, host immunity suppressed wbpM mutants with high meropenem resistance and fitness. Our study highlights how natural selection and host immunity interact to drive both the rapid rise, and fall, of resistance during infection.

Prevalence of Livestock-Associated Methicillin-Resistant Staphylococcus Aureus (LA-MRSA) Among Farm and Slaughterhouse Workers in Italy.

OBJECTIVE: We measured the prevalence of livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) in swine livestock workers, examined LA-MRSA resistance profile, and associated carriage with the working activities. METHODS: Information was collected on demographics and occupational history. Swabs were collected and tested for the isolation of S. aureus, examined for antimicrobial susceptibility, and all MRSA underwent ST398qPCR assay. RESULTS: LA-MRSA was isolated in 7.3% of the 396 enrolled workers. LA-MRSA colonization was more likely in farmers than in slaughterhouse workers (Fisher exact P = 0.001). Carriage was associated with herd size, being less frequent in small/medium farms (odds ratio = 0.20; 95% confidence interval = 0.07 to 0.53), and with the number of working days per week (OR = 2.11; 95% confidence interval = 1.07 to 4.19). CONCLUSIONS: LA-MRSA carriage is strongly animal-exposure related, and educational intervention informing about the risks related to the activity with livestock is needed.

Uncommon G9P[4] group A rotavirus strains causing dehydrating diarrhea in young children in Italy.

Group A rotaviruses (RVA) are one of the major cause of acute gastroenteritis (AGE) in young children, being responsible for up to 250.000 deaths worldwide, mostly in developing countries. The two outer capsid proteins VP7 (glycoprotein, G-genotype) and VP4 (protease-sensitive protein, P-genotype) are the basis for the binary RVA nomenclature. Although at least 36 G-types and 51 P-types of rotavirus are presently known, most RVA infections in humans, worldwide as well as in Italy, are related to six major G/P combinations: G1P[8], G2P[4], G3P[8], G4P[8], G9P[8] and G12P[8]. In November 2016, in the framework of the Italian 2016/17 rotavirus surveillance season, a total of 22 rotavirus-positive samples from hospitalized children presenting AGE symptoms were collected in a small area of Central Italy (Ancona, Marche). After genotyping, 3 samples presented the G9P[4] genotype. In order to better understand the origin of these uncommon RVA strains causing dehydrating diarrhea in three children, the strains RVA/Human-wt/ITA/AN18/2016/G9P[4], RVA/Human-wt/ITA/AN19/2016/G9P[4] and RVA/Human-wt/ITA/AN22/2016/G9P[4] were subjected to nucleotide sequencing of all the 11 gene segments to define their genomic constellation. Nucleotide sequencing revealed that the genomic constellation of the three strains was G9-P[4]-I2-R2-C2-M2-A2-N2-T2-E2-H2, highlighting human origin for all the gene segments investigated. The molecular characterization of RVAs and the continue monitoring of their circulation is needed to better define the epidemiology of these pathogen and to detect the emergence of viral variants presenting a high spreading potential in humans in the post-vaccination era.

Retrospective analysis of nosocomial infections in an Italian tertiary care hospital.

Nosocomial infections are one of the leading causes of morbidity and mortality in hospitalized patients. Studies of their prevalence in single institutions can reveal trends over time and help to identify risk factors. The aim of this study was to investigate the nosocomial infections trend and identify the prevalence of predominant bacterial microorganisms and their drug resistance patterns in an Italian tertiary care hospital. Infections were classified according to the Centres for Disease Control and Prevention definitions. A retrospective study was carried out from March 2011 to June 2014, based on the bacterial isolate reports of a hospital located in Central Italy. During the 40-month study period, a total of 1547 isolates were obtained from 1046 hospitalized patients and tested for their antibiotic sensitivity. The most common isolates belonged to the Enterobacteriaceae family (61.7%), followed by Enterococcus species (12.4%), Pseudomonas species (10.7%) and S. aureus (10.0%). The incidence density rate of nosocomial infections was 7.4 per 1000 patient days, with a significant difference among the 3 annual infection rates (P<0.001). The highest infection prevalence rate was found in Internal Medicine Unit (41.3%), followed by Intensive Care Units (12.4%), Surgical Units (9.0%,) and Cardiology (7.1%).

Barriers to influenza vaccine uptake in obese people in Italy: Changes 2005-2013.

BACKGROUND: Obesity is an independent risk factor for developing flu-related complications. OBJECTIVE: The aim of this study was to analyze influenza vaccine uptake (VU) in the Italian obese, before and after the introduction of obesity among the national recommendations, and to evaluate factors associated to VU. METHODS: The comparison of two editions of the national survey carried out in 2004-2005, before the inclusion of obese people among the specific high risk categories for flu complications, and in 2013, reaching a sample of 21,857 persons who declared to have a BMI>30. Multilevel logistic regression was used to evaluate potential independent predictors of influenza immunization. RESULTS: Influenza vaccination coverage was 27.16% in 2013, versus 31.61% in 2005. A significant reduction of VU was registered after the introduction of obesity among the high risk conditions, for which flu VU was recommended. Regression modeling, both in adults and in older people, confirmed that barriers to VU in 2013 were younger age, medium level of education, absence of chronic disease, smoking habit, and reporting no contacts with GPs during the previous 12months. Among those aged 65 or more, the role of regional policies was associated to VU. CONCLUSIONS: Immunization rates among young obese population are low, especially if not affected by comorbidities. Moreover, a reduction was registered in 2013 with respect to 2005. Flu vaccine uptake among the older population seems to be influenced by regional vaccination strategies. The development of novel strategy is warranted, especially among the young adults.

May the drain be a way in for microbes in surgical infections?

BACKGROUND: Surgical site infection (SSI) is among the most frequent hospital-acquired infections occurring in surgical patients and leads to increased morbidity, mortality, and costs. We aimed to identify risk factors for SSI in patients undergoing surgical procedures, with a particular attention to the use of drains. METHODS: This study includes all patients undergoing abdominal surgical procedures in 2 surgical wards in a teaching hospital in central Italy. Collected data included patient's demographic and clinical characteristics, procedure characteristics, administration of perioperative antibiotic prophylaxis, and microorganism isolated. The outcome of interest was SSI. FINDINGS: A total of 872 abdominal surgery procedures were surveyed during the study period. Drains were placed in 37.0% of cases. SSI rate was 6.4% globally and 13.6% among the patients with drains, versus 2.4% in those without a drain (P < .001). In 72.1% of cases antibiotic prophylaxis was administered. The logistic regression analysis (P < .001) shown insertion of a drain (odds ratio [OR], 5.14; 95% confidence interval [CI], 2.63-10.08), prolonged surgery (OR, 1.98; 95% CI, 1.09-3.59), and American Society of Anesthesiologists score equal to 3 (OR, 6.13; 95% CI, 2.33-16.11) as independent risk factors for SSI, whereas antibiotic prophylaxis was protective (OR, 0.53; 95% CI, 0.29-0.99). CONCLUSION: This study revealed surgical drains as a risk factor for SSI, pointing out the need of a clearer understanding of drain role in the dynamics of SSI occurrence, with the purpose of decreasing infection risk through targeted preventive interventions.

Risk Factors and Impact on Clinical Outcome of Multidrug-Resistant Acinetobacter Baumannii Acquisition in Cardiac Surgery Patients.

OBJECTIVES: Acinetobacter baumannii recently has emerged as an important nosocomial pathogen. The aim of this study was to assess the impact on mortality of multidrug-resistant A. baumannii (MDR-AB) infection/colonization in patients undergoing cardiac surgery and to investigate microbiologic characteristics, epidemiologic spread of this pathogen, and the relative containment measures. DESIGN: Single-center, retrospective cohort study of prospectively collected data. SETTING: Cardiac surgery tertiary-care center. PARTICIPANTS: Patients with positive MDR-AB cultures from September 1, 2009 to December 31, 2011. INTERVENTIONS: Bivariate and multivariate analyses were performed to individualize the risk factors for MDR-AB-infections in cardiac surgery patients. To evaluate the MDR-AB attributable mortality, a retrospective matched cohort study was performed. Incidence density ratio (IDR) was calculated to compare the MDR-AB infection/colonization before and after the introduction of preventive measures adopted following the first cases. MEASUREMENTS AND MAIN RESULTS: MDR-AB acquisition occurred in 14 patients (0,6%) of 2385 patients. At the multivariate analyses, preoperative use of inotropic drugs (OR 18.2, 95% CI 4.6-71.9) and logistic EuroSCORE (OR 1.09, 95% CI 1.06-1.13) were found as independent risk factors. Patients with MDR-AB had 57% cumulative in-hospital mortality; no statistical differences in mortality were observed in the matched group. IDR revealed a significantly decreased incidence of infection/colonization (0.3 per 1,000 days of stay compared with 0.03/1,000 days of stay, p = 0.0001) after the containment measures became effective. CONCLUSIONS: Sicker patients are more susceptible to be infected by A. baumannii, but mortality is not significantly higher compared with other patients with similar characteristics. Adequate measures are fundamental to control the spread of the infection.

Catheter-associated urinary tract infection: Role of the setting of catheter insertion.

BACKGROUND: This study aimed to describe the epidemiology of catheter-associated urinary tract infections (CAUTIs) in patients admitted to a surgical ward in Central Italy and to analyze the associated risk factors. METHODS: An active surveillance program for CAUTI was carried out in patients catheterized for at least 48 hours. Place of catheter insertion (operating room, hospital ward, cystoscopy room, emergency care unit), indication for catheterization and its duration, among other risk factors were monitored until discharge. Antibiotic resistance profiles of isolates were analyzed. RESULTS: There were 641 catheterized patients monitored for CAUTI onset. Of these, 40 (6.2%) developed a CAUTI (rates were 15.1/1,000 catheter days, 95% confidence interval [CI], 11.9-22.6; 8.7/1,000 patient days, 95% CI, 6.9-13.1). Patients with CAUTI were older (P < .05) and their durations of hospitalization and catheterization were both longer compared with those who were not affected (P < .05). Catheterization >4 days (odds ratio [OR] = 8.21; 95% CI, 3.79-17.73; P < .05) and place of catheter insertion different from the operating room (OR = 7.9; 95% CI, 2.83-22.08; P < .05, for catheters placed in the ward) were associated with CAUTI. Among the micro-organisms isolated in CAUTIs, the most common were Pseudomonas aeruginosa (41.5%), Klebsiella pneumoniae (19.5%), and Escherichia coli (12.2%); 82.5% of them were resistant to different classes of antibiotics. CONCLUSION: These results highlight the role played by the setting of catheter insertion in CAUTIs onset, therefore reflecting the importance of hand hygiene and proper aseptic insertion techniques as crucial determinants in CAUTIs prevention.