Main title - Socio-economic effects on informal caregivers of long-term hospitalized adult patients: A cross-sectional study.

Introduction: A significant proportion of patients are being treated at hospitals in the government sector in Sri Lanka. Informal caregivers play a major role in taking care of hospitalized surgical patients while facing physical, social, and psychological challenges. Objective: To describe the socio-economic effects on informal caregivers of long-term hospitalized adult patients. Methods: A cross-sectional descriptive study was conducted among 202 informal caregivers of long-term hospitalized patients in a tertiary care hospital in Sri Lanka, using an interviewer-administered questionnaire. Sociodemographic assessment of both caregiver and care recipient, the health status of the care recipient, effects on social life, and economic aspect of informal caregiver were assessed. Results: Most of the caregivers were married (n=164, 81.2%), first degree relative of the care receiver (n=139, 68.8%), employed (n=115, 56.9%) and sole caregivers (n=130, 64.4%). Four out of 5 caregivers (n=181, 89.6%) showed moderate to severe socio-economic maladaptation. Increasing age (p=0.00), marital status (p=0.00) and sole caregiving (p=0.01) are significantly associated with the level of maladaptation. Conclusion: Moderate to severe levels of maladaptation is present among a substantial number of informal caregivers of long-term hospitalized patients. Sole caregiving is one of the contributing factors and can be addressed by adequate formal caregivers appointed by health care authorities or from voluntary services to minimize informal caregiver burnout.

Multidrug-resistant pathogenic Escherichia coli isolated from wild birds in a veterinary hospital.

Wild birds are carriers of Escherichia coli. However, little is known about their role as reservoirs for extra-intestinal pathogenic E. coli (ExPEC). In this work we investigated E. coli strains carrying virulence genes related to human and animal ExPEC isolated from free-living wild birds treated in a veterinary hospital. Multidrug resistance was found in 47.4% of the strains, but none of them were extended-spectrum beta-lactamase producers. Not only the virulence genes, but also the serogroups (e.g. O1 and O2) detected in the isolates of E. coli have already been implicated in human and bird diseases. The sequence types detected were also found in wild, companion and food animals, environmental and human clinical isolates in different countries. Furthermore, from the 19 isolates, 17 (89.5%) showed a degree of pathogenicity on an in vivo infection model. The isolates showed high heterogeneity by pulsed-field gel electrophoresis indicating that E. coli from these birds are clonally diverse. Overall, the results showed that wild birds can be reservoirs and/or vectors of highly pathogenic and multidrug-resistant E. coli that have the potential to cause disease in humans and poultry.

Analysis of high caesarean section rates: the second step after audits using the Ten Group Classification System

Objective: To identify possible methods of reducing high caesarean section rates in a tertiary care hospital. Methods: Analysis of birth weight of neonates, maternal age and indications for caesarean section in the groups identified by a modification of Robson's 10 Group Classification of caesarean section (TGCS), which contribute significantly to the high caesarean section rates in the University Obstetric Unit, Teaching Hospital Mahamodara, Galle Sri Lanka during 2010 - to 2014. Results: Among nulliparous women, at term, having a singleton fetus, with a vertex presentation (NTSV) who underwent a caesarian section 25.6% delivered neonates weighing between 2500g and 2999g. Among multiparous women, at term, with no previous caesarean section, having a singleton fetes with a vertex presentation (MTSV) who underwent a caesarian section, those delivering neonates weighing between 2500g and 2999g ranged from 25.6% to 34.6%. Indications for ante part caesarean section included fetal distress, sub fertility, increased maternal age and cephalon-pelvic disproportion in NTSV, and fetal distress, vaginal varices, and a bad obstetric history in MTSV. Among multiparous women with one previous caesarean section undergoing repeat caesarean section, 29.8% delivered neonates weighing between 2500g and 2999g. Women >35 years had a higher risk of caesarean section, irrespective of whether they were nulliparous or multiparous, and whether they had a previous caesarean section or not. Conclusions: A reduction in caesarean section rates in NTSV and MTSV, and women with one previous caesarean section, especially in those with foetuses weighing 2500g - 2999g, should be considered. Increased maternal age and subfertility per se should not be routine indications for antepartum caesarean section. Antepartum caesarean section for vaginal varices and cephalo-pelvic disproportion should be avoided. The diagnosis of fetal distress should be improved.

Characterizing the pathotype of neonatal meningitis causing Escherichia coli (NMEC).

BACKGROUND: Neonatal meningitis-causing Escherichia coli (NMEC) is the predominant Gram-negative bacterial pathogen associated with meningitis in newborn infants. High levels of heterogeneity and diversity have been observed in the repertoire of virulence traits and other characteristics among strains of NMEC making it difficult to define the NMEC pathotype. The objective of the present study was to identify genotypic and phenotypic characteristics of NMEC that can be used to distinguish them from commensal E. coli. METHODS: A total of 53 isolates of NMEC obtained from neonates with meningitis and 48 isolates of fecal E. coli obtained from healthy individuals (HFEC) were comparatively evaluated using five phenotypic (serotyping, serum bactericidal assay, biofilm assay, antimicorbial susceptibility testing, and in vitro cell invasion assay) and three genotypic (phylogrouping, virulence genotyping, and pulsed-field gel electrophoresis) methods. RESULTS: A majority (67.92%) of NMEC belonged to B2 phylogenetic group whereas 59% of HFEC belonged to groups A and D. Serotyping revealed that the most common O and H types present in NMEC tested were O1 (15%), O8 (11.3%), O18 (13.2%), and H7 (25.3%). In contrast, none of the HFEC tested belonged to O1 or O18 serogroups. The most common serogroup identified in HFEC was O8 (6.25%). The virulence genotyping reflected that more than 70% of NMEC carried kpsII, K1, neuC, iucC, sitA, and vat genes with only less than 27% of HFEC possessing these genes. All NMEC and 79% of HFEC tested were able to invade human cerebral microvascular endothelial cells. No statistically significant difference was observed in the serum resistance phenotype between NMEC and HFEC. The NMEC strains demonstrated a greater ability to form biofilms in Luria Bertani broth medium than did HFEC (79.2% vs 39.9%). CONCLUSION: The results of our study demonstrated that virulence genotyping and phylogrouping may assist in defining the potential NMEC pathotype.

Antimicrobial resistance, virulence determinants and genetic profiles of clinical and nonclinical Enterococcus cecorum from poultry.

Enterococcus cecorum has been implicated as a possible cause of disease in poultry. However, the characteristics that contribute to pathogenesis of Ent. cecorum in poultry have not been defined. In this study, Ent. cecorum from carcass rinsates (n = 75) and diseased broilers and broiler breeders (n = 30) were compared based upon antimicrobial resistance phenotype, the presence of virulence determinants and genetic relatedness using pulsed-field gel electrophoresis (PFGE). Of the 16 antimicrobials tested, Ent. cecorum from carcass rinsates and clinical cases were resistant to ten and six of the antimicrobials, respectively. The majority of Ent. cecorum from carcass rinsates was resistant to lincomycin (54/75; 72%) and tetracycline (46/75; 61.3%) while the highest level of resistance among clinical Ent. cecorum was to tetracycline (22/30; 73.3%) and erythromycin (11/30; 36.7%). Multidrug resistance (resistance to ≥2 antimicrobials) was identified in Ent. cecorum from carcass rinsates (53/75; 70.7%) and diseased poultry (18/30; 60%). Of the virulence determinants tested, efaAfm was present in almost all of the isolates (104/105; 99%). Using PFGE, the majority of clinical isolates clustered together; however, a few clinical isolates grouped with Ent. cecorum from carcass rinsates. These data suggest that distinguishing the two groups of isolates is difficult based upon the characterization criteria used.

Urinalysis and culture results of free-catch urine samples in dogs: a randomised controlled trial.

OBJECTIVES: To evaluate the prevalence of bacterial presence in free-catch urine samples preceded by either a standardised prepped ("clean-catch") protocol versus unprepped (non-cleaned) voiding. MATERIALS AND METHODS: The study was a single-centre prospective single-blinded randomised controlled trial. Urine samples were obtained from 100 client-owned dogs presenting for routine evaluation. Dogs were randomly assigned to either the prepped group (preputial or peri-vulvar area cleaned with sterile saline before collection) or the unprepped group (no preliminary cleansing) stratified by sex. Urinalysis and urine culture (blood and MacConkey agar) were performed on all samples. Significant bacterial presence on urine culture was defined as >104 colony forming units (CFU)/mL. RESULTS: There were no statistically significant associations between prepped versus unprepped collection method or sex with a urinalysis positive for bacteriuria. However, on culture, significant bacterial growth was almost five times more likely to be associated with males relative to females (odds ratio 4.59, 95% confidence interval 1.61 to 13.10). The probability of finding a positive culture was not statistically associated with prep method (odds ratio 1.43, 95% confidence interval 0.50 to 4.08). CLINICAL SIGNIFICANCE: For the majority of dogs without clinical signs of urinary tract infection, free-catch urine collection does not result in significant bacteriuria found on analysis or culture. The presence of bacteria found in free-catch samples may be secondary to sample contamination or subclinical bacteriuria. Sample contamination or subclinical bacteriuria may be more prevalent in male dogs.

Good outcome following emergency decompressive craniectomy in a case of malignant middle cerebral artery infarction in a 14-month-old infant.

We report the case of a 14-month-old infant presenting with unresponsiveness and seizure following thoracic surgery. Imaging showed full territory left middle cerebral artery infarct and signs of raised intracranial pressure (ICP) that required emergency decompressive craniectomy (DC). The child made a good functional recovery. We discuss the case.

Multicystic ovaries and pituitary pseudo-adenoma associated with primary hypothyroidism.

Ovarian hyperstimulation syndrome (OHSS) is a well known but poorly understood iatrogenic complication of superovulation. Spontaneous OHSS has been reported with pregnancy, polycystic ovary syndrome, primary hypothyroidism and pituitary adenoma. Only a few cases of massive ovarian enlargement in non-pregnant women with primary hypothyroidism have been reported in the English literature. A definitive pathophysiology remains uncertain, although several postulations were proposed. A 23-year-old nulliparous woman presented with transient bloating of her abdomen associated with menstruation for the last four cycles. She had nausea, headache, faintness, galactorrhoea and clinical signs and symptoms of hypothyroidism (swelling in the hands and feet, cold intolerance, decreased activity, excessive sleepiness, loss of hair and dry skin) for 6 months. Thyroid stimulating hormone and serum prolactin levels were highly elevated (> 100 µg/l and 4,095 µg/l, respectively) and free thyroxine level was low. Abdominal ultrasound showed bilateral multiple thin-walled ovarian cysts. Contrast enhanced CT of brain showed a pituitary macroadenoma. Treatment with levothyroxine was started and showed marked clinical improvement with return to normal menstruation within 4 months. Serial ultrasound showed gradual regression of the ovarian cysts within 6 months. Serum prolactin level was gradually diminished. Awareness that ovarian and pituitary enlargement may be associated with severe hypothyroidism which can be managed successfully, will spare patients dangerous and unnecessary operative intervention for ovarian cysts or pituitary adenoma.

Is colonoscopy still mandatory after a CT diagnosis of left-sided diverticulitis: can colorectal cancer be confidently excluded?

BACKGROUND: It is routine practice to perform colonoscopy as a follow-up after an attack of diverticulitis, with the main aim to exclude any underlying malignancy. PURPOSE: This study aimed to determine whether colonoscopy is necessary and what additional information is gained from this procedure. DESIGN: This is a study of a retrospective cohort. SETTINGS AND PATIENTS: From January 2003 to June 2009, patients in whom left-sided diverticulitis was diagnosed on CT scan were matched with colonoscopy reports within 1 year from the date of CT by the use of radiology and endoscopy databases. Patients who had colonoscopy within 1 year before the CT scan were excluded. The Western Australian Cancer Registry was cross-referenced to identify patients who subsequently received diagnoses of cancers for whom colonoscopy reports were unavailable. MAIN OUTCOME MEASURES: The main outcome measures were the number of patients in whom colorectal cancers were diagnosed and other incidental findings, eg, polyps, colitis, and stricture. RESULTS: Left-sided diverticulitis was diagnosed in 1088 patients on CT scan, whereas follow-up colonoscopy reports were available for 319 patients. Eighty-two (26%) patients had incidental findings of polyps (9 polyps >1 cm), and 9 patients (2.8%) received diagnoses of colorectal cancers on colonoscopy. After cross-referencing with the cancer registry, the overall prevalence of colorectal cancer among the cohort within 1 year of CT scan was 2.1% (23 cases). The odds of a diagnosis of colorectal cancer were 6.7 times (95% CI 2.4-18.7) in patients with an abscess reported on CT, 4 times (95% CI 1.1-14.9) in patients with local perforation, and 18 times (95% CI 5.1-63.7) in patients with fistula compared with patients with uncomplicated diverticulitis. LIMITATIONS: This study was limited by the unavailability of data for private/interstate hospitals, and the relatively small number of cancer cases reduced the statistical power of the study. CONCLUSIONS: We recommend routine colonoscopy after an attack of presumed left-sided diverticulitis in patients who have not had recent colonic luminal evaluation. The rate of occult carcinoma is substantial in this patient population, in particular, when abscess, local perforation, and fistula are observed.

Molecular epidemiological analysis of Mycoplasma bovis isolates from the Pennsylvania Animal Diagnostic Laboratory showing genetic diversity.

We have examined the genetic variability of Mycoplasma bovis strains submitted to the Pennsylvania Animal Diagnostics Laboratory, University Park (PA-ADL), between December 2007 and December 2008. Of 4,868 total samples submitted for Mycoplasma testing, 302 were determined to be culture positive. Mycoplasma bovis (63.6%), Mycoplasma californicum (7.3%), Mycoplasma bovirhinis (2.7%), Mycoplasma bovigenitalium (0.7%), Mycoplasma alkalescens (4.9%), Mycoplasma putrefaciens (0.3%), and Mycoplasma dispar (1.3%) and unidentified Mycoplasma sp. (19.2%) were identified using PCR. Mycoplasma bovis represented the largest portion of the positive samples submitted. Each of the 192 M. bovis isolates was examined for variations in the BglII and MfeI restriction sites of the DNA using amplified fragment length polymorphism fingerprinting and subsequently compared with the M. bovis type strain PG45 (ATCC 25523). Similarity between strains was calculated using the Dice similarity coefficient, which ranged from approximately 0.7 to 1.0. When clustering the isolates at greater than 95% similarity, it was determined that 11 distinct clusters were present. The results are consistent with the existence of at least 2 clonally distinct groups. No clear geographical, month of isolation, or source origination relationship was identified, indicating that a currently unclassified characteristic is responsible for the strain heterogeneity. These data indicate strong heterogeneity of M. bovis isolates submitted to PA-ADL. Additionally, multiple sites throughout Pennsylvania had isolates of separate clonal lineages present concomitantly, indicating the ability of multiple overlapping outbreaks to occur at a single location. Mycoplasma bovis represents the largest portion of Mycoplasma species isolated from PA-ADL samples. We propose that amplified fragment length polymorphism may serve as a valuable tool for molecular characterization of M. bovis strains from the United States.

Prevalence and Spatial Distribution of Salmonella Infections in the Pennsylvania Raccoon (Procyon lotor).

A study was conducted to determine the prevalence and spatial distribution of Salmonella infection in Pennsylvania raccoons (Procyon lotor), common wildlife mammals known to occupy overlapping habitats with humans and domestic food animals. The Pennsylvania Game Commission provided a total of 371 raccoon intestinal samples from trapped and road-killed raccoons collected between May and November 2011. Salmonella was isolated from the faeces of 56 (15.1%) of 371 raccoons in 35 (54%) of 65 counties across Pennsylvania. The five most frequently isolated serotypes were Newport (28.6%), Enteritidis (19.6%), Typhimurium (10.7%), Braenderup (8.9%) and Bareilly (7.1%). Pulsed-field gel electrophoresis (PFGE) analysis of the Salmonella isolates and subsequent comparison to the Pennsylvania Department of Health human Salmonella PFGE database revealed 16 different pulsetypes in Salmonella isolates recovered from raccoons that were indistinguishable from pulsetypes of Salmonella collected from clinically ill humans during the study period. The pulsetypes of seven raccoon Salmonella isolates matched those of 56 human Salmonella isolates by month and geographical region of sample collection. Results from Clustered Regularly Interspaced Short Palindromic Repeats and Multi-Virulence Locus Sequence Typing (CRISPR-MVLST) analysis corroborated the PFGE and serotyping data. The findings of this study show that several PFGE pulsetypes of Salmonella were shared between humans and raccoons in Pennsylvania, indicating that raccoons and humans might share the same source of Salmonella.

Quinolinic acid inhibits DOI-induced head shakes in mice.

Quinolinic acid, a metabolite of tryptophan in the kynurenine pathway, inhibited the 5-HT(2A/2C) direct agonist (+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2-amino propane hydrochloride (DOI) induced head shakes in mice in a dose-dependent manner. This effect was observed 10 min after intracerebroventricular (i.c.v.) administration of 0.0625-1 microg/mouse. 3-Hydroxyanthranilic acid, which is the immediate stable precursor of quinolinic acid in the kynurenine pathway, showed a similar effect 60-120 min after subcutaneous (s.c.) administration, without showing any effect 10 min after i.c.v. administration or 20-40 min after s.c. administration. These observations suggest that quinolinic acid can alter central effects mediated via 5-HT2A receptors.

Resistance of broiler chickens to Escherichia coli respiratory tract infection induced by passively transferred egg-yolk antibodies.

Egg-yolk antibodies induced by immunizing hens with selected Escherichia coli antigens were evaluated for their ability to protect broiler chickens against respiratory/septicemic disease caused by avian pathogenic E. coli (APEC). Seven groups of broiler breeder hens were vaccinated three times, 1 week apart with live E. coli, killed E. coli, E. coli antigens [lipopolysaccharide (LPS), type 1 pilus adhesin (FimH), P pilus adhesin (PapG), aerobactin outer membrane receptor (IutA)] or phosphate buffered saline (PBS). An O78 APEC strain was used for preparation of all the antigens. Egg yolk immunoglobulins (IgY) were purified from eggs of each group and antibody activity in serum and purified IgY was determined by enzyme-linked immunosorbent assay (ELISA). IgY (100mg) was injected intramuscularly into 11-day-old broiler chickens, which were challenged 3 days later with homologous (O78) or heterologous (O1 or O2) E. coli by the intra-air sac route. Mortality was recorded and surviving chickens were euthanized 1 week after the challenge and examined for macroscopic lesions. Passive antibodies against all antigens except FimH were protective (90-100%) against the homologous challenge, but only anti-PapG and anti-IutA were effective against heterologous challenge. Anti-PapG IgY provided the greatest protection against the three serogroups of E. coli used for challenge. Hence vaccination of broiler breeders to induce anti-PapG and anti-IutA antibodies may provide passive protection of progeny chicks against respiratory/septicemic disease caused by APEC.

Effect of IRM root end fillings on healing after replantation.

The effect of IRM as a root end filling placed in teeth prior to replantation was examined in 21 molar teeth in monkeys. After extraction, root ends were resected, the canals contaminated with oral bacteria, root end cavities prepared, and fillings of IRM or amalgam placed prior to replantation. After 8 wk the jaws were removed and prepared for histological examination. Bacteria were demonstrated in only 9 of 15 teeth filled with IRM; 18 of the roots (60%) were associated with inflammation, which was only moderate or severe around 5 (17%), and extended > 0.1 mm around only 2 roots. In contrast, of the 6 teeth filled with amalgam, all contained bacteria in the root canals and 11 roots were associated with moderate or severe inflammation, which around 8 roots extended > 0.5 mm. The difference in severity of inflammation for the two materials was statistically significant (p < 0.001). The tissue response to root end fillings of IRM in replanted teeth was less severe and less extensive than that to amalgam.

Tissue reaction to implanted root-end filling materials in the tibia and mandible of guinea pigs.

The purpose of this study was to examine the tissue reaction to implanted mineral trioxide aggregate (MTA), amalgam, Intermediate Restorative Material, and Super-EBA in the tibias and mandibles of guinea pigs. After anesthetizing 20 guinea pigs, raising tissue flaps, and preparing bony cavities, the test materials were placed in Teflon cups and implanted in the tibias and 10 days later in the mandibles. The animals were euthanized 80 days later and the tissues prepared for histological examination. The presence of inflammation, predominant cell type, and thickness of fibrous connective tissue adjacent to each implant were recorded. The tissue reaction to MTA implantation was the most favorable observed at both sites; as in every specimen, it was free of inflammation (p < 0.01). In the tibia, MTA was the material most often observed with direct bone apposition. Based on these results, MTA seems to be a biocompatible material.

Effect of super-EBA as a root end filling on healing after replantation.

The effect of Super-EBA cement as a root-end filling placed in teeth before replantation was examined in eight molar roots in monkeys. After extraction, root ends were resected, the canals contaminated with oral bacteria, root-end cavities prepared, and fillings of Super-EBA placed before replantation. After 8 wk, the jaws were removed and prepared for histological examination. The tissue response to Super-EBA was very mild, with only a few inflammatory cells being observed at the root end of 3 of the 8 roots filled. Previous work showed a similarly mild response to Intermediate Restorative Material and a very much more severe response to amalgam. It is concluded that the tissue response to Super-EBA as a root-end filling is acceptable and considerably more favorable than that to amalgam.

Prophylactic treatment of dens evaginatus using mineral trioxide aggregate.

Two case reports with dens evaginatus are presented. Each patient had one tooth affected. There was a prominent tubercle on the occlusal surface of the mandibular second premolar. Under local anesthesia and rubber dam isolation a partial pulpotomy was conducted and mineral trioxide aggregate was placed. After 6 months the teeth were removed as part of planned orthodontic treatment. Histological examination of these teeth showed an apparent continuous dentin bridge formation in both teeth, and the pulps were free of inflammation. These cases show that mineral trioxide aggregate can be used as an alternative to existing materials in the proplylactic treatment of dens evaginatus.

Histologic assessment of mineral trioxide aggregate as a root-end filling in monkeys.

Mineral Trioxide Aggregate (MTA) has been shown in a number of experiments to be a potential root-end filling material. The purpose of this study was to examine the periradicular tissue response of monkeys to MTA and amalgam as root-end fillings. The pulps were removed from all the maxillary incisors of three monkeys. The root canals were prepared and filled with laterally condensed guttapercha and sealer, and the access cavities were restored with amalgam. Buccal mucoperiosteal flaps were raised, and root-end resections were performed before root-end cavity preparation with burs. The root-end cavities in half of the teeth were filled with MTA, while amalgam was placed in the other cavities. After 5 months the periradicular tissue response was evaluated histologically. The results showed no periradicular inflammation adjacent to five of six root ends filled with MTA; also five of six root ends filled with MTA had a complete layer of cementum over the filling. In contrast, all root ends filled with amalgam showed periradicular inflammation, and cementum had not formed over the root-end filling material, although it was present over the cut root end. Based on these results and previous investigations, MTA is recommended as a root-end filling material in man.

Construction, characterization, and evaluation of the vaccine potential of three genetically defined mutants of avian pathogenic Escherichia coli.

The delta galE, delta purA, and delta aroA derivatives of avian septicemic Escherichia coli EC99 strain (O78 serogroup) were constructed with a suicide vector containing the pir-dependent R6K replicon and the sacB gene of Bacillus subtilis. The resultant isogenic mutants were stable and lacked approximately 45%, 36%, and 52% of the genes for galE, purA, and aroA, respectively. The delta purA and delta aroA mutants did not grow on minimal medium, whereas the delta galE mutant grew on minimal medium but was sensitive to galactose-induced lysis. The reversion frequencies of all three mutants were <10(-12). The mutants were highly attenuated for virulence as determined by administration of approximately 10(7) colony-forming units of each mutant to 1-day-old chicks by the subcutaneous route. Chickens were vaccinated with the mutants by spray (droplet size approximately 20 microm) at 1 and 14 days of age to determine safety, immunogenicity, and efficacy. The mutants were found to be safe. Seven days after a second vaccination, immunoglobulin (Ig)Y antibodies to E. coli in serum and air sac washings were detected by enzyme-linked immunosorbent assay. In both serum and air sac washings, IgY antibodies were significantly higher in chickens vaccinated with the mutants as compared with phosphate-buffered saline-treated controls but were significantly lower compared with chickens that were vaccinated with the parent strain. In serum, but not in air sac washings, IgY antibodies were significantly lower in chickens vaccinated with the mutants compared with the parent strain. The vaccinated chickens were given infectious bronchitis virus intranasally at 17 days of age and were challenged with homologous (EC99 strain) or heterologous (O2 serogroup) E. coli 4 days later. Chickens that received wild-type EC99 strain or its mutant derivatives were protected from homologous but not from heterologous challenge. This study indicates that the delta galE, delta purA, and delta aroA mutants are safe and moderately immunogenic but the protection conferred by the mutants is serogroup specific.