Work-related flow and its correlates among frontline nurses during the COVID-19 pandemic.

BACKGROUND: Ample evidence across non-healthcare fields highlights the role of work-related flow in enhancing resilience against work stress and work engagement. Understanding flow and its factors can support staff development and management. AIMS: This study aimed to investigate the level of work-related flow and its associated factors among frontline nurses during the COVID-19 pandemic. METHODS: A cross-sectional multicenter study included 336 nurses caring for COVID-19 patients between March and April 2022. Cluster random sampling was used to select 9 nurse groups from 29 Taiwanese hospitals specialized in COVID-19 care. A web survey link was shared on the selected nurses' social media. Hierarchical regression analyses examined predictor-outcome relationships, following the STROBE checklist for reporting findings. RESULTS: Among demographic characteristics, sex (ß = -0.11; p = 0.016) and living arrangement (ß = -0.12; p = 0.017) reached statistical significance in model 3. Social support from family, friends, and significant others, managerial position, and sufficiency of personal protective equipment showed significant associations with work-related flow (all ß > 0.12; p < 0.05). The variables included in the final model accounted for 35% of the variance in work-related flow for COVID-19 patient care tasks. CONCLUSIONS: Flow experience is influenced by factors associated with demographics, work conditions, and social support. Nurse administrators should consider these factors when evaluating nurses' flow at work. IMPLICATIONS FOR NURSING PRACTICE AND MANAGEMENT: Allocating care tasks to nurses based on their flow levels can be beneficial, particularly during healthcare crises. Ensuring a sufficient supply of personal protective equipment and offering social support to nurses are vital strategies for facilitating their flow experience in the workplace.

Symptom perception and self-care practice for uraemic pruritus in patients receiving haemodialysis.

BACKGROUND: Due to the recurrent nature of uraemic pruritus among patients receiving haemodialysis, self-care can offer patients a means to ameliorate this symptom. Qualitative data on self-care of uraemic pruritus are limited. OBJECTIVE: To explore how patients on haemodialysis perceive uraemic pruritus, implement self-care practice, and appraise the outcome of self-caring uraemic pruritus. DESIGN: The Common Sense Model of Self-Regulation guided the study design. PARTICIPANTS AND APPROACHES: Data were collected through face-to-face interviews with 30 patients receiving haemodialysis who were aged from 50 to 89 years and had had uraemic pruritus for more than 6 weeks. Interviews were audio recorded, and verbatim transcriptions of interviews were analysed. FINDINGS: Our participants generally used life-related analogies to describe uraemic pruritus, which they reviewed as a momentarily controllable symptom with an endless timeline. Most participants reported limited knowledge of the aetiology and multifaceted impacts of uraemic pruritus on their daily life and emotional status. The impacts on daily life included decreased zest for activities and sleep disturbances. Physical management of uraemic pruritus involved daily substance use and interventions employed during pruritic episodes. Psychological managements involved preferences for indoor activities and a fatalistic outlook. Unsatisfactory outcomes and psychological burdens from self-care practice were reported. CONCLUSIONS: Life experiences shape symptom presentation and self-care practice in patients on haemodialysis. The modalities for self-caring for uraemic pruritus are diverse but not remarkably effective. Performing self-care tasks places a substantial burden on patients. Individualised educational programs should be developed to improve the outcome of self-care practice.

New insight into chronic pruritus' characteristics and association with the demographic characteristics and sleep of community-dwelling older adults in Taiwan.

This study aimed to understand the characteristics of chronic pruritus (CP), its correlations with sleep quality and demographic characteristics, and its impacts on sleep of older adults. This study used convenience sampling to recruit adults aged 65 or older and living at home. The prevalence rate of CP in older adults was 25.8%. Most subjects with CP reported mild pruritus on 1-2 anatomical parts, especially the lower extremities. Overall, the five domains of CP were correlated with the seven components of sleep quality (r > .14; p > .05) except for sleep disturbance. The global itchy scores were significantly different between different sexes, educational attainments, and marital statuses (p<.05-.001). CP, sex, and the number of comorbid diseases significantly contributed to global sleep quality (ß = .26, -.19, .15, respectively; .000 ≤ p ≤ .011). This study provides new insight into the correlations of CP with marital status and educational attainment.

The effectiveness of learning portfolios in learning participation and learners' perceptions of skills and confidence in the mother of preterm infant.

OBJECTIVE: The purpose of this study was to investigate the effectiveness of preterm infant learning portfolios in enabling mothers to develop infant care knowledge and skills, as well as confidence in their abilities. DESIGN: This study used a quasi-experimental design. SETTING AND PARTICIPANTS: The sample consisted of 52 mothers with preterm infants recruited at a neonatal intermediate unit of a medical centre in central Taiwan. Among those, 26 participants in the control group received regular health education and 26 participants in the experimental group received learning portfolios and regular care. INTERVENTION: The Preterm Infant Care Learning Portfolio (PICLP) is a semi-structured learning portfolio which was provided by nurses. Intervention started with 15 min of instructions on how to use PICLP, including a list of learning task and methods of self-assessment. Follow-up sessions of 5-10 min were conducted after each learning task. The frequency of learning skills could be adjusted depending on participants' learning needs. MEASUREMENTS: Self-administered questionnaires regarding knowledge of and skills in preterm infant care and maternal confidence were used to evaluate the effectiveness of the intervention; the questionnaires were conducted before the intervention, 1 day before discharge and 1 month after discharge. We also tracked the frequency with which participants attended instructional sessions before discharged. FINDINGS: Mothers' preterm infant care knowledge and skills and confidence improved in both groups after the intervention. The experimental group showed greater improvement than the control group by post-test 2; there was no statistical difference between groups at 1 day before discharge and 1 month after discharge. However, participants in the experimental group came for instructional sessions on baby care for more frequently than the control group. The frequency of learning sessions attended was a predictor of improved scores of the skill assessment before discharge. CONCLUSIONS: Both programmes led to improvements in preterm infant care knowledge and skills and maternal confidence. Giving mothers learning portfolios appears to stimulate significantly greater participation in hospital-based instructional programmes, which should in turn lead to greater long-term retention of learning. The learning portfolios may have an additional benefit in promoting acquisition of care abilities for mothers with preterm infant before hospital discharge and application of these abilities at home. IMPLICATION FOR PRACTICE: At-home care for preterm infants requires specialized care skills and confidence. Learning portfolios can be used as an effective learner-centred strategy for teaching these health care abilities.

Falls and Related Injuries in Hospitalized Patients With Cancer in Taiwan.

BACKGROUND: Falls and fall-related injuries are important indicators for quality of nursing care in institutions. Few studies have been conducted specifically on this topic for hospitalized patients with cancer in Taiwan. PURPOSE: The aims of this study were to understand falls and levels of injury; to identify associations among fall-related injuries, demographics, and causes of falling; and to predict fall-related injuries in hospitalized patients with cancer. METHODS: A retrospective survey design was used. Data were retrieved from the Taiwan Patient-Safety Reporting system query fall incidences for persons hospitalized with cancer at a medical center in northern Taiwan from 2010 to 2012. Data were encoded and analyzed with descriptive statistics, the chi-square test, and multiple stepwise logistic regression analysis using IBM SPSS Statistics version 18.0. RESULTS: One hundred fifty-six (85%) of the 184 hospitalized patients with cancer had fall-related injuries. Falling tended to be more frequent in men without a history of falls and more prevalentat night. The results of regression analysis showed that the variables being with companions at the time of a fall (OR = 5.411, 95% CI [1.619, 18.081]), lower limb weakness (OR = 0.284, 95% CI [0.097, 0.832]), postural hypotension (OR = 0.101, 95% CI [0.014, 0.733]), total score of fall risk factors (OR = 1.688, 95% CI [1.071, 2.660]), and a fall occurring at the bedside (OR = 3.493, 95% CI [1.119, 10.903]) were all positively associated with fall-related injuries, with a Nagelkerke R of 42.8%. CONCLUSIONS/IMPLICATIONS FOR PRACTICE: The risk factors for falls that affect hospitalized patients with cancer are complex. Nursing staff must evaluate the risk factors and treatment methods for each patient and facilitate fall prevention measures to achieve safety-centered quality of care. This study provides an example for nursing staff when assessing factors associated with falls and working to reduce fall-related injuries among patients with cancer.

[Learning Portfolio: A New Strategy in Health Education].

Health education is the teaching by healthcare professionals of healthcare-related knowledge and skills to students in order that these students learn to help patients self-manage their disease and maintain health. This article introduces a new strategy in health education known as the learning portfolio and presents the theoretical basis and function of the learning portfolio and the current application of this approach in academic and health education. The learning portfolio is a learner-centric approach that collects evidence related to an individual's learning process systematically. This approach helps educators understand learner needs and conditions, while allowing the learner to observe his / her learning process in a manner that promotes self-reflection, continual inspection, and behavioral modification throughout the learning process. The results enhance the motivation of learners and strengthen their care confidence in accomplishing learning tasks.

Stable Expression of Lentiviral Antigens by Quality-Controlled Recombinant Mycobacterium bovis BCG Vectors.

The well-established safety profile of the tuberculosis vaccine strain, Mycobacterium bovis bacille Calmette-Guérin (BCG), makes it an attractive vehicle for heterologous expression of antigens from clinically relevant pathogens. However, successful generation of recombinant BCG strains possessing consistent insert expression has encountered challenges in stability. Here, we describe a method for the development of large recombinant BCG accession lots which stably express the lentiviral antigens, human immunodeficiency virus (HIV) gp120 and simian immunodeficiency virus (SIV) Gag, using selectable leucine auxotrophic complementation. Successful establishment of vaccine stability stems from stringent quality control criteria which not only screen for highly stable complemented BCG ΔleuCD transformants but also thoroughly characterize postproduction quality. These parameters include consistent production of correctly sized antigen, retention of sequence-pure plasmid DNA, freeze-thaw recovery, enumeration of CFU, and assessment of cellular aggregates. Importantly, these quality assurance procedures were indicative of overall vaccine stability, were predictive for successful antigen expression in subsequent passaging both in vitro and in vivo, and correlated with induction of immune responses in murine models. This study has yielded a quality-controlled BCG ΔleuCD vaccine expressing HIV gp120 that retained stable full-length expression after 10(24)-fold amplification in vitro and following 60 days of growth in mice. A second vaccine lot expressed full-length SIV Gag for >10(68)-fold amplification in vitro and induced potent antigen-specific T cell populations in vaccinated mice. Production of large, well-defined recombinant BCG ΔleuCD lots can allow confidence that vaccine materials for immunogenicity and protection studies are not negatively affected by instability or differences between freshly grown production batches.

Predictors of sleep quality and successful weaning from mechanical ventilation among patients in respiratory care centers.

BACKGROUND: Poor quality of sleep may result in more problems for patients who undergo weaning from mechanical ventilation because it could result in disabled muscle relaxation and affect the function of the respiratory muscles. Few studies have specifically investigated what factors contributed to quality of sleep and weaning outcomes. PURPOSE: This study investigates the predictors of quality of sleep and successful weaning from mechanical ventilation in patients at respiratory care centers. METHODS: We used a cross-sectional design to recruit 94 patients who were in the process of weaning from ventilation at three respiratory care centers in a medical center in central Taiwan. A structured questionnaire was used to collect data. Disease severity during the first 24 hours after commencing the weaning process was assessed using the Acute Physiology and Chronic Health Evaluation II. Level of consciousness was evaluated using the Glasgow Coma Scale, and quality of sleep was measured using the Verran and Snyder-Halpern Sleep Scale. Stepwise multiple regression and logistic regression were used for multivariate analysis. RESULTS: Fifty-three (56.4%) of the 94 participants successfully completed the weaning process. Participants who successfully weaned within 72 hours were younger (p = .038), had a lower level of disease severity (p < .001), and had a better quality of sleep (p = .004) than their counterparts who failed to wean. Factors including disease severity (B = -1.32), current use of hypnotic drugs (B = -10.71), and having three-to-four coexisting chronic diseases (B = -9.91) contributed negatively to quality of sleep. Factors including level of consciousness (odds ratio [OR] = 1.64), quality of sleep (OR = 1.05), disease severity (OR = 0.81), and alcohol consumption history (OR = 0.21) were found to significantly impact weaning success. CONCLUSIONS/IMPLICATIONS FOR PRACTICE: A strong relationship was identified between disease severity and quality of sleep. Both factors are significant predictors of successful weaning from mechanical ventilation. A better understanding of the related risk factors will help improve the care provided by nurses and medical personnel to patients undergoing the weaning process.

Subjective and Objective Sleep Quality in Individuals with Osteoarthritis in Taiwan.

OBJECTIVES: The negative effects of osteoarthritis (OA), such as pain and depression, interfere with an individual's sleep quality. The main objective of the present study was to investigate the prevalence of poor quality of sleep in individuals with OA in Taiwan and identify potential predictors. A secondary objective was to examine agreement between objective and subjective measures of sleep quality. METHODS: In a cross-sectional survey, OA outpatients in Taiwan completed a self-administered questionnaire, incorporating validated measurements for assessing quality of sleep (the Pittsburgh Sleep Quality Index (PSQI)), pain and physical functioning, anxiety and depression, and health-related quality of life. In a nested feasibility study, a sub-sample of participants wore an Actigraph wrist monitor to measure sleep objectively over a three-day period. RESULTS: Of 192 individuals with OA who completed the survey, 30 completed the Actigraph study. The mean PSQI global score was 9.0 (standard deviation 4.5); most participants (135, 70.3%) had poor quality of sleep (global PSQI >5). Key predictors of poor quality of sleep included role limitation due to poor physical functioning, poor social functioning, higher anxiety levels and higher pain levels. There were moderate correlations between subjective and objective measures of sleep quality, although participants underestimated their true sleeping time by two hours. CONCLUSIONS: Health professionals need to discuss sleep issues with individuals with OA and include strategies for coping with these difficulties. For reduced night-time pain which may interfere with sleep, additional and appropriate advice about medication is required. Copyright © 2014 John Wiley & Sons, Ltd.

Identification of early interactions between Francisella and the host.

The adaptive immune response to Francisella tularensis is dependent on the route of inoculation. Intradermal inoculation with the F. tularensis live vaccine strain (LVS) results in a robust Th1 response in the lungs, whereas intranasal inoculation produces fewer Th1 cells and instead many Th17 cells. Interestingly, bacterial loads in the lungs are similar early after inoculation by these two routes. We hypothesize that the adaptive immune response is influenced by local events in the lungs, such as the type of cells that are first infected with Francisella. Using fluorescence-activated cell sorting, we identified alveolar macrophages as the first cell type infected in the lungs of mice intranasally inoculated with F. novicida U112, LVS, or F. tularensis Schu S4. Following bacterial dissemination from the skin to the lung, interstitial macrophages or neutrophils are infected. Overall, we identified the early interactions between Francisella and the host following two different routes of inoculation.

Infection with Francisella tularensis LVS clpB leads to an altered yet protective immune response.

Bacterial attenuation is typically thought of as reduced bacterial growth in the presence of constant immune pressure. Infection with Francisella tularensis elicits innate and adaptive immune responses. Several in vivo screens have identified F. tularensis genes necessary for virulence. Many of these mutations render F. tularensis defective for intracellular growth. However, some mutations have no impact on intracellular growth, leading us to hypothesize that these F. tularensis mutants are attenuated because they induce an altered host immune response. We were particularly interested in the F. tularensis LVS (live vaccine strain) clpB (FTL_0094) mutant because this strain was attenuated in pneumonic tularemia yet induced a protective immune response. The attenuation of LVS clpB was not due to an intracellular growth defect, as LVS clpB grew similarly to LVS in primary bone marrow-derived macrophages and a variety of cell lines. We therefore determined whether LVS clpB induced an altered immune response compared to that induced by LVS in vivo. We found that LVS clpB induced proinflammatory cytokine production in the lung early after infection, a process not observed during LVS infection. LVS clpB provoked a robust adaptive immune response similar in magnitude to that provoked by LVS but with increased gamma interferon (IFN-γ) and interleukin-17A (IL-17A) production, as measured by mean fluorescence intensity. Altogether, our results indicate that LVS clpB is attenuated due to altered host immunity and not an intrinsic growth defect. These results also indicate that disruption of a nonessential gene(s) that is involved in bacterial immune evasion, like F. tularensis clpB, can serve as a model for the rational design of attenuated vaccines.

A strategy for reduction of antibiotic use in new patients admitted to a neonatal intensive care unit.

BACKGROUND: In order to reduce the unnecessary use of and provide appropriate guidance for the administration of antibiotics, the neonatal bacterial infections screening score (NBISS) was developed to assess each new patient that is admitted to the neonatal intensive care unit (NICU). METHODS: NBISS was designed based on maternal risk factors, clinical presentations, and laboratory data. The total score of each new patient is calculated at the time of admission. The first period of this study was an observational survey. Receiver operating characteristic (ROC) curves were used to determine the best cut-off NBISS for the diagnosis of bacterial infection (BI) and guide the use of antibiotics during the second period of this study. RESULTS: Of 250 neonates who were admitted to the NICU, 237 (94.8%) received antibiotics during the first period of study. The initial total scores were not statistically different between the BI and non-BI groups (p = 0.155). We weighted C-reaction protein (CRP) (by 8×), the presence of a bulging fontanelle, pus from the ear canal, redness around the umbilicus, reduced movement, and being unable to feed (each by 5×) as significantly different between the BI and non-BI groups (p = 0.015). Weighted scores >8 points demonstrated the best diagnostic accuracy for indicating BI. After introducing NBISS for predicting BI in new patients admitted to NICU, the rate of antibiotic use significantly decreased from 94.8% to 60.3% between the two periods. CONCLUSION: Using this simple screening strategy, we were able to clinically reduce the use of unnecessary antibiotics.

Ultra-low dose of Mycobacterium tuberculosis aerosol creates partial infection in mice.

A murine low dose (LD) aerosol model is commonly used to test tuberculosis vaccines. Doses of 50-400 CFU (24h lung CFU) infect 100% of exposed mice. The LD model measures progression from infection to disease based on organ CFU at defined time points. To mimic natural exposure, we exposed mice to an ultra-low dose (ULD) aerosol. We estimated the presented dose by sampling the aerosol. Female C57BL/6 mice were exposed to Mycobacterium tuberculosis H37Rv aerosol at 1.0, 1.1, 1.6, 5.4, and 11 CFU presented dose, infecting 27%, 36%, 36%, 100%, and 95% of mice, respectively. These data are compatible with a stochastic infection event (Poisson distribution, weighted R(2)=0.97) or with a dose-response relationship (sigmoid distribution, weighted R(2)=0.97). Based on the later assumption, the ID50 was 1.6CFU presented dose (95% confidence interval, 1.2-2.1). We compared organ CFU after ULD and LD aerosols (5.4 vs. 395CFU presented dose). Lung burden was 30-fold lower in the ULD model at 4 weeks (3.4 vs. 4.8 logs, p<0.001) and 18 weeks (≤3.6 vs. 5.0 logs, p=0.01). Mice exposed to ULD aerosols as compared to LD aerosols had greater within-group CFU variability. Exposure to ULD aerosols leads to infection in a subset of mice, and to persistently low organ CFU. The ULD aerosol model may resemble human pulmonary tuberculosis more closely than the standard LD model, and may be used to identify host or bacterial factors that modulate the initial infection event.

Vaccines for gonorrhea: can we rise to the challenge?

Immune responses to the gonococcus after natural infection ordinarily result in little immunity to reinfection, due to antigenic variation of the gonococcus, and redirection or suppression of immune responses. Brinton and colleagues demonstrated that parenteral immunization of male human volunteers with a purified pilus vaccine gave partial protection against infection by the homologous strain. However, the vaccine failed in a clinical trial. Recent vaccine development efforts have focused on the female mouse model of genital gonococcal infection. Here we discuss the state of the field, including our unpublished data regarding efficacy in the mouse model of either viral replicon particle (VRP) vaccines, or outer membrane vesicle (OMV) vaccines. The OMV vaccines failed, despite excellent serum and mucosal antibody responses. Protection after a regimen consisting of a PorB-VRP prime plus recombinant PorB boost was correlated with apparent Th1, but not with antibody, responses. Protection probably was due to powerful adjuvant effects of the VRP vector. New tools including novel transgenic mice expressing human genes required for gonococcal infection should enable future research. Surrogates for immunity are needed. Increasing antimicrobial resistance trends among gonococci makes development of a vaccine more urgent.

Sampling port for real-time analysis of bioaerosol in whole body exposure system for animal aerosol model development.

INTRODUCTION: Multiple factors influence the viability of aerosolized bacteria. The delivery of aerosols is affected by chamber conditions (humidity, temperature, and pressure) and bioaerosol characteristics (particle number, particle size distribution, and viable aerosol concentration). Measurement of viable aerosol concentration and particle size is essential to optimize viability and lung delivery. The Madison chamber is widely used to expose small animals to infectious aerosols. METHODS: A multiplex sampling port was added to the Madison chamber to measure the chamber conditions and bioaerosol characteristics. Aerosols of three pathogens (Bacillus anthracis, Yersinia pestis, and Mycobacterium tuberculosis) were generated under constant conditions and their bioaerosol characteristics were analyzed. Airborne microbes were captured using an impinger or BioSampler. The particle size distribution of airborne microbes was determined using an aerodynamic particle sizer (APS). Viable aerosol concentration, spray factor (viable aerosol concentration/inoculum concentration), and dose presented to the mouse were calculated. Dose retention efficiency and viable aerosol retention rate were calculated from the sampler titers to determine the efficiency of microbe retention in lungs of mice. RESULTS: B. anthracis, Y. pestis, and M. tuberculosis aerosols were sampled through the port. The count mean aerodynamic sizes were 0.98, 0.77, and 0.78 µm with geometric standard deviations of 1.60, 1.90, and 2.37, and viable aerosol concentrations in the chamber were 211, 57, and 1 colony-forming unit (CFU)/mL, respectively. Based on the aerosol concentrations, the doses presented to mice for the three pathogens were 2.5e5, 2.2e4 and 464 CFU. DISCUSSION: Using the multiplex sampling port we determined whether the animals were challenged with an optimum bioaerosol based on dose presented and respirable particle size.

Successful mechanical ventilation weaning experiences at respiratory care centers.

A phenomenological qualitative study was conducted on the experiences of patients who had been successfully weaned from mechanical ventilation, including essential elements of the patient support system during the weaning process. In-depth interviews were conducted with 20 participants who had been recruited through purposive sampling from three respiratory care centers in Taiwan. The experiences of participants who had been successfully weaned from mechanical ventilation could be categorized into five themes, which were (a) dealing with the unfamiliar context presented by the weaning program, (b) experiencing various psychological responses and self-endurance ambiguity, (c) being tortured by helplessness, (d) wondering whether to continue or give up, (e) and release from self-breathing. Findings were intended to give nurses an increased understanding of patient experiences and help in raising their competence in managing patient emotional reactions that arise during the weaning process. As patient conditions gradually improve, nurses should assess the criteria for mechanical ventilation weaning and provide preparatory information and clarify patient questions to avoid potential negative responses during the process. Participants also reported that the professionalism of nurses and concern from family members were essential sources of support for successful weaning. Nurses can apply recommendations to develop effective patient support systems that encourage family members to accompany patients at critical times during the weaning process. Therefore, the results of this study may assist healthcare personnel to develop strategies to ensure successful weaning from mechanical ventilation.

Comparison of immune responses to gonococcal PorB delivered as outer membrane vesicles, recombinant protein, or Venezuelan equine encephalitis virus replicon particles.

Porin (PorB) is a major outer membrane protein produced by all Neisseria gonorrhoeae strains and has been a focus of intense interest as a vaccine candidate. In this study, the immunogenicity of PorB in mice was investigated after several immunization regimens. Outer membrane vesicles (OMV), recombinant renatured PorB (rrPorB), and PorB-expressing Venezuelan equine encephalitis (VEE) virus replicon particles (PorB VRP) were delivered intranasally (i.n.) or subcutaneously (s.c.) into the dorsal area or the hind footpad in three-dose schedules; the PorB VRP-immunized mice were given a single additional booster dose of rrPorB in Ribi adjuvant. Different delivery systems and administration routes induced different immune responses. Mice immunized s.c. with rrPorB in Ribi had the highest levels of PorB-specific serum immunoglobulin G (IgG) by enzyme-linked immunosorbent assay. Surprisingly, there was an apparent Th1 bias, based on IgG1/IgG2a ratios, after immunization with rrPorB in Ribi in the footpad while the same vaccine given in the dorsal area gave a strongly Th2-biased response. PorB VRP-immunized mice produced a consistent Th1 response with a high gamma interferon response in stimulated splenic lymphocytes and very low IgG1/IgG2a ratios. Immunization by OMV delivered i.n. was the only regimen that resulted in a serum bactericidal response, and it generated an excellent mucosal IgA response. Serum from mice immunized with rrPorB preferentially recognized the surface of whole gonococci expressing a homologous PorB, whereas serum from PorB VRP-immunized mice had relatively low whole-cell binding activity but recognized both heterologous and homologous PorB equally. The data resulting from this direct comparison suggested that important aspects of the immune response can be manipulated by altering the form of the antigen and its delivery. This information coupled with an understanding of protective antigonococcal immune responses will enable the design of the optimal vaccine for N. gonorrhoeae.

A mutant form of the Neisseria gonorrhoeae pilus secretin protein PilQ allows increased entry of heme and antimicrobial compounds.

A spontaneous point mutation in pilQ (pilQ1) resulted in phenotypic suppression of a hemoglobin (Hb) receptor mutant (hpuAB mutant), allowing gonococci to grow on Hb as the sole source of iron. PilQ, formerly designated OMP-MC, is a member of the secretin family of proteins located in the outer membrane and is required for pilus biogenesis. The pilQ1 mutant also showed decreased piliation and transformation efficiency. Insertional inactivation of pilQ1 resulted in the loss of the Hb utilization phenotype and decreased entry of free heme. Despite the ability of the pilQ1 mutant to use Hb for iron acquisition and porphyrin, there was no demonstrable binding of Hb to the cell surface. The pilQ1 mutant was more sensitive to the toxic effect of free heme in growth medium and hypersensitive to the detergent Triton X-100 and multiple antibiotics. Double mutation in pilQ1 and tonB had no effect on these phenotypes, but a double pilQ1 pilT mutant showed a reduction in Hb-dependent growth and decreased sensitivity to heme and various antimicrobial agents. Insertional inactivation of wild-type pilQ also resulted in reduced entry of heme, Triton X-100, and some antibiotics. These results show that PilQ forms a channel that allows entry of heme and certain antimicrobial compounds and that a gain-of function point mutation in pilQ results in TonB-independent, PilT-dependent increase of entry.

Point mutations in HpuB enable gonococcal HpuA deletion mutants to grow on hemoglobin.

Neisseria gonorrhoeae ordinarily requires both HpuA and HpuB to use hemoglobin (Hb) as a source of iron for growth. Deletion of HpuA resulted in reduced Hb binding and failure of growth on Hb. We identified rare Hb-utilizing colonies (Hb(+)) from an hpuA deletion mutant of FA1090, which fell into two phenotypic classes. One class of the Hb(+) revertants required expression of both TonB and HpuB for growth on Hb, while the other class required neither TonB nor HpuB. All TonB/HpuB-dependent mutants had single amino acid alterations in HpuB, which occurred in clusters, particularly near the C terminus. The point mutations in HpuB did not restore normal Hb binding. Human serum albumin inhibited Hb-dependent growth of HpuB point mutants lacking HpuA but did not inhibit growth when expression of HpuA was restored. Thus, HpuB point mutants internalized heme in the absence of HpuA despite reduced binding of Hb. HpuA facilitated Hb binding and was important in allowing use of heme from Hb for growth.