Circulating innate and adaptive immunity against anti-Haemophilus influenzae type b.

Haemophilus influenzae type b (Hib) are one of most dangerous microbes that occupies the paediatric nasopharyngeal as a commensal opportunistic bacterium, which may lead to meningitis in uncontrolled infection. Colonisation of pharyngeal tissues is the starting point for most H. influenzae infections, which may develop into invasive diseases, such meningitis. The vaccination against Hib in specific, as well as against most of vaccines preventable diseases; in general, play a major role in reducing children (< 5 years old) Hib meningitis from 57/100,000 to the lowest known Hib meningitis incidents in the history. First invented Hib vaccine was licensed in 1985 and contained Hib capsular polysaccharide (CPS); afterward, conjugate vaccines have been innovated and licensed on the road to improve Hib vaccine efficacy. Polyribosylribitol phosphate (PRP) is the main vaccine unite structure. Since anti-CPS antibodies in the serum reflect the extent of the acquired immunity against Hib infections, the concentration of ⩾ 0.15 g/ml of anti-CPS is believed to be an indicator for short-term protection from invasive Hib diseases, whereas one-month post-completion of primary Hib immunization concentration of ⩾ 1.0 g/ml is trusted to be immunological protective. As considered that serum anti-CPS antibodies are effectively linked to protection, the evaluation of antibodies concentration and reconsideration of published worldwide populations antibodies concentration are consider vital strides on the way to accurate valuation of Hib immunity that induced by vaccination; either direct or herd. As documented, some populations; worldwide, still susceptible to invasive Hib infections. Several populations worldwide remain vulnerable to Hib-related infections. We believe that up-to-date review article regarding circulated Hib immunology, represented in anti-Hib antibodies and worldwide Hib incidences will provide a precious information for microbiologists, public health officials, epidemiologists, immunologists, and strategic preventive healthcare executives.

Changes in serotype distribution of Haemophilus influenzae meningitis isolates identified through laboratory-based surveillance following routine childhood vaccination against H. influenzae type b in Brazil.

Following routine childhood vaccination against Haemophilus influenzae type b (Hib) disease in Brazil in 1999, passive laboratory surveillance reported increasing numbers of non-b serotypes and nontypeable H. influenzae (NTHi) from meningitis cases. To characterize this increase, we analyzed data on 3910 H. influenzae isolated from cerebrospinal fluid or blood from meningitis cases that were sent to the national reference laboratory for serotyping from 1990 to 2008. Hib accounted for 98% of H. influenzae meningitis isolates received during 1990-1999 versus 59% during 2000-2008, while non-b serotypes increased from 1% to 19% and NTHi increased from 2% to 22% of H. influenzae isolates received during the two periods. Higher proportions of non-b serotypes and NTHi than Hib were isolated from blood rather than cerebrospinal fluid. Estimated incidence rates for H. influenzae meningitis for Sao Paulo state remained below 1 case per million population during 2000-2008, although annual incidence of NTHi meningitis (mean, 0.03 cases per 100,000 population) increased in several age groups. Changes in surveillance for H. influenzae following introduction of Hib conjugate vaccine likely contributed to increased numbers of non-b and nontypeable H. influenzae meningitis isolates received at the national reference laboratory.

Increase in serum osmolality is possible mechanism for the beneficial effects of glycerol in childhood bacterial meningitis.

BACKGROUND: Oral glycerol reduces severe neurologic sequelae in childhood bacterial meningitis, but the mechanism awaits elucidation. We conducted a prospective, randomized, double-blind study in which the effects of glycerol and intravenous dexamethasone were compared with placebo recipients in an intensive care setting in India. METHODS: Thirty-six children at age 2 months to 12 years with meningitis were treated with ceftriaxone and were randomized to receive also either dexamethasone intravenously, or glycerol orally, or both agents, or neither. The illness was monitored with preset criteria. The primary outcome measures were the changes in plasma osmolality and in urine output. RESULTS: Nine children received glycerol, 8 dexamethasone, 11 both agents, and 8 only placebo. The leading agents identified were Streptococcus pneumoniae, Haemophilus influenzae type b, and Staphylococcus aureus. Only the glycerol recipients increased plasma osmolality by up to 3% from the mean baseline of 294 mOsm/kg in the glycerol and 295 mOsm/kg in the glycerol-dexamethasone group. This change occurred within 6 hours, the critical period of treatment, and lasted <24 hours. Blood pressure was not affected, nor did urine output increase. The dexamethasone-only and placebo-only recipients showed immediate decrease in serum osmolality. CONCLUSIONS: Because excretion of the cerebrospinal fluid is inversely associated with plasma osmolality, we suggest that the glycerol-induced osmolality increase reduce the volume of cerebrospinal fluid, enhanced water movement back to the plasma by osmosis, increased cerebral blood flow, and thus, improved brain oxygenation.

Immunization histories given by adult caregivers accompanying children 3-36 months to the emergency department: are their histories valid for the Haemophilus influenzae B and pneumococcal vaccines?

OBJECTIVE: To obtain immunization histories from adult caregivers accompanying children to the emergency department (ED), to determine the accuracy of the caregiver's report for the Haemophilus influenzae B (Hib)and 7-valent pneumococcal vaccine (PCV7). METHODS: This was a prospective, observational study of children age 3 to 36 months presenting to the Albert Einstein Medical Center ED during the period of November 1, 2004, through January 31, 2005. Caregivers were asked to complete a questionnaire about their child's immunization status and if the child's vaccinations were up-to-date. Immunization records were obtained from the child's most recent primary care physician (PCP) to determine whether the caregiver's report was correct for PCV7 and Hib. Children were considered delayed if they were more than 30 days past due date for one or both vaccines according to the PCP records. RESULTS: Of 205 PCP offices contacted, we were able to obtain 173 immunization records for our analysis. Examination of vaccine records showed that 109 (63.0%) of the 173 children were up-to-date on both immunizations. When the child's caregiver was asked if shots were up-to-date, 159 (91.9%) of 173 said that all shots were given, and only 14 (8.1%) of 173 reported being behind schedule. Of the adults reporting the child up to date, 105 (66.0%) of the 159 children were confirmed to be up-to-date. Thus, 34.0% of caregivers were incorrect in stating that their child's immunization status was up-to-date for both these vaccines. CONCLUSIONS: Caregiver report was determined to be inaccurate for Hib and PCV7. Despite 91.5% of caregivers stating that shots were up-to-date, only 66.0% were correct that their child was up-to-date with these 2 vaccines. The ED physician should use caution in making clinical decisions based on the history given by a caregiver regarding their child's immunization status.

[Rapid diagnosis of the type of meningitis (bacterial or viral) by the assay of serum procalcitonin]. / Diagnostic rapide du type de méningite (bactérienne ou virale) par le dosage de la procalcitonine sérique.

OBJECTIVE: It has been shown that serum procalcitonin (PCT) can be used to differentiate bacterial from viral meningitis in children in all cases. The aim of this study was to demonstrate the interest of PCT in the management of suspected meningitis in adults. PATIENTS AND METHODS: We conducted a prospective study including 179 consecutive patients admitted to the emergency department for suspected meningitis. All samples were taken at patient admission. The discriminant potential between bacterial and viral meningitis was studied for cerebrospinal fluid parameters (cytology, protein, glucose, lactate) and serum parameters (C reactive protein, PCT). RESULTS: Thirty-two patients had bacterial meningitis, 90 had viral meningitis and meningitis was ruled out in 57. Among all studied parameters, the most discriminant for distinguishing between bacterial and viral meningitis in 100% of the cases proved to be serum procalcitonin with a threshold value of 0.93 ng/ml. CONCLUSION: Serum procalcitonin is an interesting parameter in the emergency department for management of meningitis suspicion in adults.

Evaluation of serum levels of IgG subclasses and anti-ribosyl-ribitolphosphate IgG and IgG2 in children with Haemophilus influenzae b meningitis.

In 40 children with Haemophilus influenzae b (Hib) meningitis, we determined serum levels (mg/dl) of IgG subclasses using the radial immunodiffusion method; 67.8 per cent of these children were less than 24 months old. In 14 children of the sample we measured serum IgG and IgG2 anti-ribosyl-ribitolphosphate (anti-PRP) (by enzyme-linked immunosorbent assay, ELISA) in the acute and convalescent phases of the disease. Lower IgG2 levels than those of the control group were obtained in all age ranges: 3-12 months, 1-2 years (p < 0.01), and 2-5 years (p < 0.001). IgG4 was also present in lower levels in patients of all age ranges (p < 0.05, p < 0.001, and p < 0.01 respectively). Serum levels of IgG anti-PRP and IgG2 anti-PRP measured were very low in the acute phase of the disease in all age ranges and there was no notable increase in levels during the convalescent phase of the disease. This result indicates that children less than 24 months old do not produce sufficient levels of IgG and IgG2 anti-PRP even after Hib meningitis.

Evaluation of an extended diagnostic PCR assay for detection and verification of the common causes of bacterial meningitis in CSF and other biological samples.

A seminested polymerase chain reaction (PCR)-based diagnostic assay was evaluated for detection and verification of Neisseria meningitidis, Haemophilus influenzae, Streptococcus pneumoniae, Steptococcus agalactiae and Listeria monocytogenes in cerebrospinal fluid (CSF) and other biological samples. A general bacterial amplicon from the 16S rRNA gene was amplified in a first step, and species-specific regions in a second. The detection level was 4 fg DNA/reaction, corresponding to about one bacterial genome per reaction tube. Sample preparations (Dynabeads DNA DIRECT kit) were assayed from 140 bacterial strains suspended in saline. In CSF the detection level for bacteria was 10(3)CFU ml-1for N. meningitidis, H. influenzae and S. pneumoniae, 10(4)CFU ml-1for Escherichia coli and 10(5)CFU ml-1for S. agalactiae and L. monocytogenes. The detection levels for these bacteria were the same in the other tested biological samples, like blood with or without culture media. Clinical CSF samples were evaluated from 71 patients with proven bacterial meningitis, as were 61 CSF samples from individuals without bacterial meningitis. The diagnostic sensitivity of the assay in detecting bacteria in general was 0.97, and for the specific species in the clinical CSF samples 0.87-0.94. The specificity was 1.0 for detecting bacteria in general. Some cross-reactions were noted within the streptococcus group. The PCR results were verified by banding patterns of Hae III digested PCR products.

Cytokine mRNA profiles during the course of experimental Haemophilus influenzae bacterial meningitis.

Intraperitoneal inoculation of Haemophilus influenzae type b (Hib) to 3-week-old Sprague-Dawley rats resulted in nonlethal meningitis with high levels of leukocytes in the cerebrospinal fluid (CSF) and positive bacterial culture. Using in situ hybridization, levels of cytokine mRNA-expressing cells were determined in the brain, CSF, and spleen from Hib-inoculated and uninfected control rats. IFN-gamma, IL-1 beta, IL-4, IL-6, IL-10, IL-12, and TNF-alpha mRNA levels were elevated at 12 hr postinoculation (pi) in spleen and CSF. At this time point, strong expression of IL-6 and TGF-beta was detected in the brain, and also of IL-10 at 48 hr while IFN-gamma and IL-12 were expressed at very low levels throughout the observation time. Delayed cytokine induction occurred in CSF compared to spleen and brain. TGF-beta was high in CSF at 48 hr, and some elevation of IL-1 beta, IL-6, IL-10, TNF-alpha, IFN-gamma, and IL-12 was evident at 72 hr pi. This may suggest measures that promote production of TGF-beta and/or IL-10 should be evaluated in treatment of bacterial meningitis.

Role of leukocytes in cerebral autoregulation and hyperemia in bacterial meningitis in rabbits.

The effect of leukocytes on regional cerebral blood flow (rCBF) and cerebrovascular autoregulation in experimental meningitis was determined in rabbits. Four groups of animals were studied. Cerebrospinal fluid (CSF) leukocyte migration was prevented in two groups by pretreatment with 1.5 mg/kg of IB4, a monoclonal antibody directed against CD11/18 leukocyte adhesion receptors. Intracisternal inoculation was performed with saline (control and control-IB4 groups) or Haemophilus influenzae type b (Hib and Hib-IB4 groups). Eighteen hours later, rCBF was determined with radiolabeled microspheres. Autoregulation was assessed by graded hemorrhagic hypotension. Compared with untreated meningitis (Hib group), IB4-pretreated meningitis (Hib-IB4 group) was associated with a reduced CSF leukocyte count (1,980 +/- 880 vs. 200 +/- 110 cells/microliter; P < 0.05) and an elevated CSF colony count (2.87 +/- 0.08 vs. 5.63 +/- 0.72 log10colony-forming units/ml; P < 0.05). Compared with control, baseline CBF was elevated in both untreated and IB4-pretreated meningitis (51 +/- 2, 54 +/- 2, 66 +/- 5, and 102 +/- 17 ml.100 g-1.min-1 in control, control-IB4, Hib, and Hib-IB4 groups, respectively). The degree of hyperemia in meningitis was related to the CSF colony count, with a high CBF occurring in animals with high colony counts. During hypotension, CBF remained at or above baseline in the Hib group and both control groups, indicating preservation of cerebrovascular autoregulation in untreated Hib meningitis. In the Hib-IB4 group, the elevated baseline CBF was not maintained during hypotension, falling to 51% of baseline at a cerebral perfusion pressure of 30 mmHg and indicating impairment of cerebrovascular autoregulation. These results suggest that CSF leukocytes are not primarily responsible for the hyperemic response in Hib meningitis. Cerebral hyperemia may be induced either directly by bacterial components or indirectly by components of the inflammatory cascade that precede CSF leukocyte migration.

Blood-brain barrier permeability during the development of experimental bacterial meningitis in the rat.

In an attempt to examine whether routes of bacterial entry into the central nervous system have any bearing on subsequent changes in blood-brain barrier permeability, we examined cerebrospinal fluid (CSF) penetration of circulating 125I-albumin in two different models of experimental meningitis due to K1 Escherichia coli, type III group B streptococcus, or Haemophilus influenzae type b in infant rats: hematogenous meningitis subsequent to subcutaneous inoculation of bacteria vs meningitis induced by direct inoculation of bacteria into the CSF via the cisterna magna. In the model of hematogenous meningitis, the mean CSF penetration was significantly greater in animals with H. influenzae type b meningitis than in those with meningitis due to K1 E. coli or type III group B streptococcus. In contrast, the mean CSF penetration was significantly enhanced in all animals with meningitis induced by intracisternal inoculation regardless of infecting pathogens. Tumor necrosis factor activity in CSF appeared to correlate with the functional penetration of circulating albumin across the blood-brain barrier in both models of experimental meningitis. These findings suggest that the alterations of blood-brain barrier permeability during development of experimental meningitis may vary for different models of inducing meningitis and that the mechanisms responsible for these different permeability changes may be multifactorial.

Childhood bacterial meningitis in Southwestern Greece: a population-based study.

During the 5-year period from 1990 through 1994, we investigated the incidence of childhood bacterial meningitis (beyond the neonatal period) in southwestern Greece. Thirty-seven cases of bacterial meningitis were identified. Fifty-one percent of the cases were caused by Neisseria meningitidis, 41% by Haemophilus influenzae type b (Hib), and 8% by Streptococcus pneumoniae. Fifty-eight percent and 73% of cases of meningococcal and Hib meningitis, respectively, involved children younger than 2 years of age. The average yearly incidences of meningococcal and Hib meningitis were 9.7 and 8 cases, respectively, per 100,000 children < 5 years of age. The main difference between findings in this study and those in other studies in Western European countries is the lower incidence of Hib meningitis observed in our area. This low incidence of Hib meningitis cannot be attributed to the use of vaccine because the Hib vaccine was first introduced in May 1994 and used infrequently through December 1994.

Dexamethasone therapy for bacterial meningitis in children. Swiss Meningitis Study Group.

Routine use of steroids as adjunctive treatment of bacterial meningitis remains controversial. We have carried out a prospective, placebo-controlled, double-blind study of dexamethasone in 115 children with acute bacterial meningitis in Switzerland. The patients were randomly assigned to receive either placebo (n = 55) or dexamethasone (n = 60) in addition to optimum antibiotic treatment (100 mg/kg daily ceftriaxone). Dexamethasone therapy (0.4 mg/kg) was started 10 min before the first dose of ceftriaxone and given every 12 h for 2 days. Baseline demographic, clinical, and laboratory features of the two groups were similar. After 24 h treatment meningeal inflammation as shown by cerebrospinal fluid (CSF) glucose concentration was significantly less with dexamethasone than with placebo (mean increase in glucose 63 [76] vs 40 [75]%, p = 0.008). However, other indices of inflammation showed similar changes in both groups. Addition of dexamethasone did not affect the rate at which CSF became sterile. Both groups showed prompt clinical responses and similar frequencies of complications (15 vs 12%). Monitoring for possible adverse effects of dexamethasone revealed no abnormalities. At follow-up examinations 3, 9, and 15 months after hospital discharge, 9 (16%) of 55 placebo recipients and 3 (5%) of 60 dexamethasone recipients had one or more neurological or audiological sequelae (p = 0.066); the relative risk of sequelae was 3.27 (95% CI 0.93-11.47). Our results and those of similarly designed studies lead us to believe that adjunctive dexamethasone therapy improves outcome from bacterial meningitis in infants and children. We recommend its use, preferably in the dose regimen used in this study.

Lipoprotein alterations in children with bacterial meningitis.

Abnormalities in serum lipids, including hypertriglyceridemia, are common during infectious disorders. However, the lipoprotein pattern during infections, particularly in children, has been investigated to only a limited extent. We have monitored alterations in serum lipoproteins in eight children with a severe bacterial infection (meningitis) by a quantitating method measuring cholesterol and triglycerides in each major class. The levels of triglycerides in serum and in low-density lipoproteins were markedly elevated during the infection, whereas the amount of cholesterol in high-density lipoproteins was decreased. The cholesterol to triglyceride ratio was decreased in low-, as well as in high-density lipoproteins. These lipoprotein abnormalities may, at least in part, be explained by a depressed lipolytic activity of lipoprotein lipase, the key enzyme for removal of triglycerides in man. Serum triglycerides and the levels of cholesterol in high-density lipoproteins, as well as the ratio between these parameters, may be used as indicators of inflammatory activity.

Human macrophage colony-stimulating factor levels in cerebrospinal fluid.

Macrophage colony-stimulating factor (M-CSF) levels in the cerebrospinal fluid of 14 patients with meningitis and of 14 patients suffering from a disease other than meningitis were measured using an enzyme-linked immunosorbent assay. All four bacterial meningitis patients had M-CSF levels in the cerebrospinal fluid which exceeded 1540 U/ml, and the mean value was 3333 +/- 1481 U/ml. The mean M-CSF level in the cerebrospinal fluid of the ten aseptic meningitis patients was 393 +/- 175 U/ml, which was higher than that of patients who suffered from a disease other than meningitis (179 +/- 90 U/ml) (P < 0.01). There was no clear correlation between the M-CSF levels and the numbers of white blood cells, granulocytes, or monocytes in the cerebrospinal fluid. These elevated M-CSF levels were thought to be of a local origin, since most patients with high M-CSF levels in the cerebrospinal fluid had relatively low M-CSF levels in the serum.

Two-dimensional electrophoresis analysis of human serum proteins during the acute-phase response.

The serum of patients with meningitis, due to infection by Haemophilus influenzae type b, was analyzed. Several known acute-phase proteins were separated by two-dimensional electrophoresis and estimated quantitatively. In addition, hitherto undescribed reactants were recognized. Gels were calibrated and relevant spots related to master spot numbers in the human serum protein database.

A review of therapeutic monitoring of chloramphenicol in patients with Haemophilus influenzae meningitis.

Two hundred and seventy-seven serum chloramphenicol concentrations in 90 patients with Haemophilus influenzae type b meningitis were analysed retrospectively. Most patients were given chloramphenicol 25 mg/kg 6 hourly initially. Chloramphenicol concentrations were categorized as pre-dose ('trough') or post-dose ('peak'). Twenty-six per cent of the results were in the potentially toxic range (above 30 mg/L), and 18% were below 10 mg/L. Analysis of 46 pre- and post-dose measurements showed that for the intravenous (i.v.) route of administration, 23% of the pre-dose concentrations were higher than the corresponding post-dose levels and, for the oral route, 42% of the pre-dose levels were higher. Multivariate analysis of covariance demonstrated that chloramphenicol concentrations decreased significantly with increasing number of days of treatment and that the decline was steeper with i.v. administration. The results of this study emphasize the need for therapeutic monitoring of chloramphenicol concentrations, and suggest that chloramphenicol should be given as a loading dose of 40 mg/kg, followed by 25 mg/kg per dose 8 hourly for 3-4 days and then 6 hourly.

Interleukin 6 activity in infants and children with bacterial meningitis. The Collaborative Study on Meningitis.

Concentrations of interleukin 6 (IL-6) in cerebrospinal fluid (CSF) and serum of infants and children with bacterial meningitis were determined and correlations were sought with other indices of inflammation and with outcome. Forty-two patients ages 1 month to 15 years (mean, 2.5 years) were studied. IL-6 activity was detectable (greater than 50 units/ml) in 30 of 36 CSF samples collected at admission from patients with meningitis and in 1 of 23 controls with fever and normal CSF findings. Mean values were 36,000 units/ml (range, 151-156,000). IL-6 activity in CSF persisted during the first 5 days of illness. IL-6 concentrations at admission were not associated with clinical findings, CSF leukocyte, protein and glucose concentrations, serum C-reactive protein concentration and neurologic complications or sequelae. IL-6 was also detected in the serum of 3 of 14 patients with meningitis and in 0 of 7 controls with no infectious disease. The presence of IL-6 was not associated with bacteremia or with duration of fever before admission. The presence of IL-6 in the CSF of pediatric patients with bacterial meningitis is in accordance with available data on other cytokines and suggests their role as mediators of meningeal inflammation.

[Reduction of antibiotic treatment of bacterial meningitis in children. Value of C-reactive protein monitoring]. / Raccourcissement du traitement antibiotique des méningites bactériennes de l'enfant. Intérêt de la surveillance de la C-réactive protéine.

The duration of antibiotic treatment of bacterial meningitis is always a topical issue. In our study (58 children), 21 of 24 meningococcal meningitis were treated for 4 or 5 days, 16 of 22 Haemophilus influenzae and 4 of 6 pneumococcal meningitis were treated for 7 days without increase in neurologic sequelae. A return of blood CRP levels to normal values was observed in all these patients simultaneously. Thus, CRP seems to be a good biological parameter for discussing treatment discontinuation. Furthermore, in some complications such as subdural effusion, a new increase of CRP levels was observed after the 5th day. A sequential follow-up of CRP levels at days J0, 5, 7, 10, seems a very useful tool for management of bacterial meningitis.