Haemophilus influenzae meningitis. A comparison between chloramphenicol and ampicillin therapy with special reference to impaired hearing

Global Case Fatality of Bacterial Meningitis During an 80-Year Period: A Systematic Review and Meta-Analysis

Importance

The impact of vaccination, antibiotics, and anti-inflammatory treatment on pathogen distribution and outcome of bacterial meningitis over the past century is uncertain.

Objective

To describe worldwide pathogen distribution and case fatality ratios of community-acquired bacterial meningitis.

Data Sources

Google Scholar and MEDLINE were searched in January 2022 using the search terms bacterial meningitis and mortality.

Study Selection

Included studies reported at least 10 patients with bacterial meningitis and survival status. Studies that selected participants by a specific risk factor, had a mean observation period before 1940, or had more than 10% of patients with health care-associated meningitis, tuberculous meningitis, or missing outcome were excluded.

Data Extraction and Synthesis

Data were extracted by 1 author and verified by a second author. The study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. Random-effects models stratified by age (ie, neonates, children, adults), Human Development Index (ie, low-income or high-income countries), and decade and meta-regression using the study period's year as an estimator variable were used.

Main Outcome and Measure

Case fatality ratios of bacterial meningitis.

Results

This review included 371 studies performed in 108 countries from January 1, 1935, to December 31, 2019, describing 157 656 episodes. Of the 33 295 episodes for which the patients' sex was reported, 13 452 (40%) occurred in females. Causative pathogens were reported in 104 598 episodes with Neisseria meningitidis in 26 344 (25%) episodes, Streptococcus pneumoniae in 26 035 (25%) episodes, Haemophilus influenzae in 22 722 (22%), other bacteria in 19 161 (18%) episodes, and unidentified pathogen in 10 336 (10%) episodes. The overall case fatality ratio was 18% (95% CI, 16%-19%), decreasing from 32% (95% CI, 24%-40%) before 1961 to 15% (95% CI, 12%-19%) after 2010. It was highest in meningitis caused by Listeria monocytogenes at 27% (95% CI, 24%-31%) and pneumococci at 24% (95% CI, 22%-26%), compared with meningitis caused by meningococci at 9% (95% CI, 8%-10%) or H influenzae at 11% (95% CI, 10%-13%). Meta-regression showed decreasing case fatality ratios overall and stratified by S pneumoniae, Escherichia coli, or Streptococcus agalactiae (P < .001).

Conclusions and Relevance

In this meta-analysis with meta-regression, declining case fatality ratios of community-acquired bacterial meningitis throughout the last century were observed, but a high burden of disease remained.

Rapid disappearance of Haemophilus influenzae type b meningitis after routine childhood immunisation with conjugate vaccines

Mortality from meningitis caused by Haemophilus influenzae type b (Hib), a disease that affects mainly infants and young children, can reach 5% in industrialised countries and ten times that in non-industrialised countries. To determine the efficacy of vaccination against Hib, we carried out a retrospective survey of the incidence of Hib meningitis over five decades in the Greater Helsinki area of Finland, where all children with bacterial meningitis are treated in one of three centres. Except for a meningococcal epidemic in the early 1970s, Hib was the leading cause of childhood bacterial meningitis until the Hib conjugate vaccines changed the picture profoundly. In 1986-87 the polysaccharide-diphtheria toxoid conjugate (PRP-D) was given experimentally to 50% of infants. In 1988-89 all infants were vaccinated, 50% with PRP-D, 50% with another conjugate vaccine, the oligosaccharide-CRM197 protein conjugate (HbOC). Since 1990 a third conjugate vaccine, the polysaccharide-tetanus toxoid (PRP-T), has been administered routinely to all infants. The vaccines were administered at age 3-6 months, with a booster dose at 14-18 months. In the first 5 years of the Hib vaccination programme the number of cases of Hib meningitis in children aged 0-4 years fell sharply, from 30 in 1986 (the first year of the programme) to none in 1991. The decline contrasts sharply with the rising trend up to the mid 1980s. Vaccination seems to be the only explanation for the observed change in the epidemiology of Hib meningitis.

Bacterial meningitis and hearing impairment: A prospective study

The purpose of this study is to demonstrate the incidence and the pattern of post-meningitis hearing impairment. A prospective study of 68 meningitis patients was performed. The patients' hearing was evaluated immediately following acute illness and periodically checked for two years. The incidences of the initial sensorineural and conductive deafness were 26.4% and 20.6%, respectively. Two patients (3%) suffered from mixed deafness. No consistent audiometric pattern was found in the cases of sensorineural hearing loss. Serial hearing evaluations demonstrated complete recovery of all cases of conductive hearing loss with only a slight improvement in the low tones noted in one patient with sensorineural hearing loss. No late development of sensorineural loss has occurred.

Increased incidence of childhood bacterial meningitis. A 25-year study in a defined population in Sweden

In a retrospective study in Orebro, Sweden 1956-1980, 201 cases of bacterial meningitis in children over the age of 1 month were analysed. The aetiology was Haemophilus influenzae in 123 cases, Neisseria meningitidis in 55 cases and Streptococcus pneumoniae in 19 cases. We registered a significant increase in incidence of H. influenzae meningitis from 5.6 (1956-1965) to 13.0 (1971-1980) per 100,000 children and year (p less than 0.01). The mortality decreased from 19% to 4% during the period studied. This decrease was primarily due to a reduced mortality in hospital later than 12 h after admission. Hearing impairment was the most frequent sequel (10%) and no change in frequency was observed during the 25 years studied. Hearing impairment was registered significantly more often in cases with a late admission to hospital (greater than 48 h) as compared to cases with an earlier admission (p less than 0.001).

Progressive hearing loss following Haemophilus influenzae meningitis

Loss of hearing is a sequelae of meningitis. This hearing loss has been known to fluctuate for as long as one year following the acute infection. This paper presents a case of an 11-year documented downward fluctuating hearing loss following Haemophilus influenzae meningitis. The case indicates that patients should be followed audiologically for years following meningitis. A review of the literature of hearing loss in meningitis is presented with special emphasis on cases in which the hearing loss fluctuated. The cases in the literature were usually not followed for more than one year. In this case of acquired hearing loss secondary to Haemophilus influenzae meningitis, the patient's hearing fluctuated over 11 years, in a downward progression. It is not clear what type of mechanism is involved in the ongoing damage to the cochlea that could account for this gradual fluctuation. It is suggested that as the possibility of long-term fluctuation exists, patients with meningitis should be monitored audiologically for many years.

Prospective evaluation of hearing impairment as a sequela of acute bacterial meningitis

As part of a prospective study of acute bacterial meningitis in children, we studied for five years the hearing of 185 infants and children who had acute bacterial meningitis when they were more than one month of age. Nineteen (10.3 per cent) of the patients had persistent bilateral or unilateral sensorineural hearing loss. The incidence of hearing loss as determined by electric-response audiometry and conventional tests was 31 per cent with Streptococcus pneumoniae, 10.5 per cent with Neisseria meningitidis, and 6 per cent with Hemophilus influenzae infections. Transient conductive hearing impairment was found in 16 per cent of the sample, but in no case was there apparent improvement in a sensorineural deficit over time. The site of disease resulting in impaired hearing cannot be stated with certainty, but involvement of the inner ear or auditory nerve was suspected. The number of days of illness (symptoms) before hospitalization and institution of antibacterial treatment was not correlated with the development of sensorineural deafness.

Hearing loss after Hemophilus influenzae meningitis. Follow-up study with auditory brainstem potentials

Hearing loss was studied prospectively using auditory brainstem potentials in 34 children with Hemophilus influenzae meningitis treated with chloramphenicol and in 36 children with purulent meningitis caused by microorganisms other than H influenzae treated with ampicillin. Our results indicate that high doses of ampicillin are not associated with permanent hearing loss. Moreover, no statistically significant difference was found in the incidence of hearing loss following H influenzae meningitis and that following meningitis caused by other microorganisms, either during the acute phase or in the convalescent period. Neurological damage, when present, was probably located in the inner ear or in the auditory nerve. Finally, early hearing loss in purulent meningitis does not always constitute an irreversible lesion.

Chloramphenicol kills Haemophilus influenzae more rapidly than does ampicillin or cefamandole

The bactericidal effects of chloramphenicol and three beta-lactams (ampicillin, cefamandole, and penicillin G) were measured for 27 strains of Haemophilus influenzae type b isolated from the blood or cerebrospinal fluid of infected infants. Of the ampicillin-susceptible strains, 75% were killed by less than 2.0 micrograms of each antibiotic per ml; however, the concentration of the beta-lactam agents required for bactericidal activity was higher than that required for inhibitory activity. Chloramphenicol was the only agent which had no marked discrepancy between inhibitory and bactericidal concentrations regardless of beta-lactamase production. Importantly, chloramphenicol was more rapidly bactericidal than either ampicillin or cefamandole. The bactericidal requirement of ampicillin was increased by the presence of chloramphenicol for about one-third of the isolates examined. Neither the inhibitory nor the bactericidal activity of chloramphenicol was influenced by ampicillin. Synergy occurred for only two beta-lactamase-positive isolates. The more rapid bactericidal action of chloramphenicol persisted even in the presence of ampicillin. The rapid bactericidal action of chloramphenicol with or without ampicillin supports the use of chloramphenicol alone or with ampicillin for H. influenzae infections.