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PubMed1998

Vasculitic basilar artery thrombosis in chronic Candida albicans meningitis.

BACKGROUND: Cerebrovascular complications of meningitis have been most extensively documented in the setting of acute bacterial or chronic tuberculous meningitis. Involvement of major cerebral vessels is rare and basilar artery thrombosis has not been reported in fungal meningitis secondary to candida infection. METHODS: We describe the clinical course and neuropathological findings in a woman with chronic meningitis due to Candida albicans. RESULTS: The diagnosis remained elusive antemortem despite analysis of 7 large volume CSF samples and examination of a meningeal and cortical biopsy. Death followed extensive brainstem and temporo-occipital infarction secondary to basilar artery thrombosis. The basilar artery occlusion was secondary to an intense, granulomatous and necrotizing basal meningitis focally extending to the media and intima. CONCLUSIONS: This paroxysmal and devastating complication of untreated chronic candida meningitis reinforces that a trial of empirical therapy with both antituberculous and antifungal agents should be considered in most cases of chronic culture-negative lymphocytic meningitis.

Adult↗
PubMed2002

Cryptococcal meningitis: an analysis among 5,521 consecutive organ transplant recipients.

Cryptococcal meningitis has been reported to be an important cause of morbidity and mortality in renal transplant recipients. However, additional studies of recipients of other organ transplants suggested that these patients might be at low risk for cryptococcal meningitis. We examined the incidence and clinical features of cryptococcal meningitis among different groups of organ transplant patients at the University of Pittsburgh Medical Center. From January 1989 through July 1999, 28 patients were diagnosed with cryptococcal meningitis among 5,521 transplant recipients. These included liver (11/2,539), heart (8/372), kidney (7/2,122), lung (1/432), and small bowel (1/56) recipients. The incidence of cryptococcal meningitis was higher in heart and small bowel recipients compared to other transplant populations (P = 0.005). The cryptococcal meningitis-related mortality in transplant recipients was 50% and was associated with altered mental status (P = 0.001), absence of headache (P = 0.02), and liver failure (P = 0.002). Multivariable analysis indicated that liver failure was the only independent risk factor for poor prognosis (P = 0.043). All cases of liver failure occurred among liver transplant recipients. Cryptococcal meningitis is associated with significant mortality among organ transplant recipients. The presence of allograft failure in liver transplant recipients with cryptococcal meningitis may be an indicator of poor prognosis in this patient population.

Cryptococcus neoformans↗
PubMed2006

A comparison of neonatal Gram-negative rod and Gram-positive cocci meningitis.

OBJECTIVE: Neonatal meningitis is an illness with potentially devastating consequences. Early identification of potential risk factors for Gram-negative rod (GNR) infections versus Gram-positive cocci (GPC) infection prior to obtaining final culture results is of value in order to appropriately guide expirical therapy. We sought to compare laboratory and clinical parameters of GNR and GPC meningitis in a cohort of term and premature infants. STUDY DESIGN: We evaluated lumbar punctures from neonates cared for at 150 neonatal intensive care units managed by the Pediatrix Medical Group Inc. We compared cerebrospinal fluid (CSF) parameters (white blood cell count, red blood cell count, glucose, and protein), demographics, and outcomes between infants with GNR and GPC meningitis. CSF cultures positive with coagulase-negative staphylococci were excluded. RESULTS: We identified 77 infants with GNR and 86 with GPC meningitis. There were no differences in gestational age, birth weight, infant sex, race, or rate of Caesarean section. GNR meningitis was more often diagnosed after the third postnatal day and was associated with higher white blood cell and red blood cell counts. GNR meningitis diagnosed in the first 3 days of life was associated with antepartum antibiotic exposure. No difference was noted in either CSF protein or glucose levels. After correcting for gestational age, there was no observed difference in mortality between infants infected with GNR or GPC. CONCLUSION: Compared to GPC meningitis, GNR meningitis was associated with several aspects of the clinical history and laboratory findings including older age of presentation, antepartum exposure to antibiotics, and elevated CSF white blood cell and red blood cell counts.

Anti-Bacterial Agents↗
PubMed2005

Histopathological alterations in ciliary ganglions in meningitis: an experimental study.

BACKGROUND: Although it is well known that meningitis frequently results in optic nerve (ON) and oculomotor nerve (OMN) dysfunctions, the effects of meningitis on the ciliary ganglion (CG) have not been studied. It is expected that the CG may be affected due to the involvement of these cranial nerves in meningitis. In this study, we aimed to investigate the effect of meningitis on the CG. METHODS: This study was conducted on thirteen rabbits. Experimental meningitis has been achieved with Streptococcus pneumonias inoculation into the cisterna magna of the animals. After follow-up of two months, all animals were sacrificed. CGs of all animals were examined histopathologically. Neuron numbers and morphological changes of the CGs were examined. RESULTS: Arachnoiditis and axonal degeneration at the cisternal segments of both oculomotor and optic nerves were observed. Neuronal irregularity, cellular angulation, shrinkage, nuclear irregularity and cytoplasmic condensation were observed in neurons of the CG. The mean number of live neurons in a CG was 3200 in healthy rabbits, whereas it was 2800 in animals with meningitis. CONCLUSION: Cisternal segments of the ON and OMN have a meningeal sleeve and a rich vascular supply. Meningitis may cause vasculitis or vasospasm at these arteries and may result in infectious neuropathy of the OMN and ON, and also afferent and efferent loops of the light reflex were structurally interrupted. Consequently, parasympathetic preganglionic denervation of the CG may occur and may result in degeneration in the neurons of the CG.

Animals↗
PubMed2003

PCR of cerebrospinal fluid for diagnosis of bacterial meningitis during meningococcal epidemics; an example from Sudan.

Meningococcal disease is feared due to its rapid progression and high case fatality rate, especially in the African meningitis belt, where epidemics of meningococcal meningitis appear cyclically. Culture, direct microscopy and antigen detection are the basic methods for diagnosis and species identification of bacterial meningitis. These methods are known to have limitations, especially in developing countries. The aim of the present study was to document the application of PCR technology for the diagnosis of bacterial meningitis in cerebrospinal fluid (CSF) samples (n = 52) collected during epidemics in Sudan. In the application of PCR for detection of the causative agent of bacterial meningitis (based on the 16S rRNA gene), bacterial DNA was identified in 49 samples. Common bacterial species causing bacterial meningitis could be detected in 31 of the CSF samples (27 meningococci), while 18 contained DNA, mainly from normally contaminating bacteria. A specific PCR for group A meningococci (based on the sacC gene) was positive in 27 of the CSF samples. The results show that PCR technology is a sharp-edged tool for confirmation of a diagnosis of meningococcal meningitis and for obtaining a direct genogrouping of group A meningococci in CSF. It is important to stress the use of direct and specific PCRs to avoid interference by contaminating bacteria, a great problem in samples from areas in the meningitis belt.

Cerebrospinal Fluid↗
PubMed1998

Prospective study of nosocomial fungal meningitis in children--report of 10 cases.

Within an 8-year period, 10 cases of fungal nosocomial meningitis in children 0-13 y old were prospectively identified, 3 caused by yeasts other than Candida spp. (Rhodotorula rubra, Aureobasidium mansoni, Clavispora lusitaniae) and 7 by Candida albicans. Seven patients survived. whereas 3 neonates with fungal meningitis (all due to C. albicans) died. Risk factors for fungal nosocomial meningitis included cancer (2 children), previous neurosurgery (2 children), cranial trauma (1 case) and prematurity with low birthweight (5 cases). All patients except 1 had received broad-spectrum antibiotics before onset of meningitis. In addition to yeasts, bacteria were isolated from CSF of 4 children. One child had additional fungaemia. Univariate analysis was used to compare 10 cases of fungal to 91 cases of bacterial nosocomial meningitis. Except for concurrent bacteraemia, (60 vs 25.3%, P < 0.03), which was more frequently observed among fungal meningitis, there were no significant differences in risk factors, sequelae or outcome (mortality) between patients with fungal vs bacterial meningitis. A review of fungal meningitis reported within the last 20 y is included.

Adolescent↗
PubMed1989

Hospital-acquired neonatal bacterial meningitis: the impacts of cefotaxime usage on mortality and of amikacin usage on incidence.

All cases of bacterial meningitis in the neonatal unit at King Edward VIII Hospital, Durban for the period 1 January 1981 to 31 December 1987 were reviewed. In particular, we looked at the impact of cefotaxime on mortality rates and amikacin on the incidence of hospital-acquired Gram-negative bacillary (GNB) meningitis. Klebsiella was found to be the commonest cause of neonatal meningitis, followed by Escherichia coli and Streptococcus agalactiae. Eighty-four per cent of all cases of GNB meningitis presented more than 3 days after birth, with the vast majority being caused by gentamicin-resistant Klebsiella. A decline in the incidence of meningitis from 1.27/1000 live births in 1981 and 0.95/1000 for the period 1981-1986 to 0.22/1000 live births in 1987, with no cases of Klebsiella meningitis being seen in that year, coincided with the exclusive use of amikacin as the parenteral aminoglycoside in place of gentamicin in the unit after August 1986. The initial decline in the incidence of meningitis from 0.93/1000 in 1985 to 0.46/1000 in 1986 was attributed to the introduction in 1985 of strict hand disinfection measures to prevent cross-infection in the unit. The case mortality rate (CMR) fell from 0.65 for the period 1981-1984 to 0.42 for the period 1985-1987, and we believe this was largely a result of the introduction of cefotaxime in 1984 as first-line therapy for GNB meningitis, together with better patient care facilities.(ABSTRACT TRUNCATED AT 250 WORDS)

Amikacin↗
PubMed2001

Bacterial meningitis in Saudi Arabia: the impact of Haemophilus influenzae type b vaccination.

Bacterial meningitis is one of the major causes of morbidity and mortality in children. A retrospective chart review of all cases of culture-proven bacterial meningitis in children was conducted in a tertiary care facility in the King Fahad National Guard Hospital (KFNGH), Riyadh. Sixty-seven patients with culture-proven meningitis were reviewed. Bacterial meningitis is more common in children under 2 years of age (85%). Haemophilus influenzae type b (Hib) was the most common organism causing meningitis in children (57%). Streptococcus pneumoniae was the second most common organism (31%) followed by group B streptococcus in (7.5%). Fever, lethargy and vomiting were the most common presenting symptoms, occurring in 95%, 72%, and 66% respectively. The calculated incidence of Hib in KFNGH is 40/100,000. This incidence decreased dramatically after the initiation of routine infant vaccination in KFNGH with the conjugate Hib vaccine in April 1998. Outcome of Hib meningitis was good in 85% while outcome of Streptococcus pneumoniae was good in (53%). 43% of S. pneumoniae were resistant to penicillin. There was no cephalosporin-resistant isolate identified during the study period. Mortality due to meningitis was 4 (6%), 3 patients died due to S. pneumoniae and one due to Hib. Since Hib is the most common organism causing meningitis in Saudi Arabian children, mass vaccination of all Saudi children should be mandatory.

Adolescent↗
PubMed2001

Community-acquired bacterial meningitis in adults: categorization of causes and timing of death.

The relationship between cause and timing of death in 294 adults who had been hospitalized with community-acquired bacterial meningitis was investigated. For 74 patients with community-acquired bacterial meningitis who died during hospitalization, the underlying and immediate causes of death were identified according to the criteria of the World Health Organization and National Center for Health Statistics. Patients were classified into 3 groups: category I, in which meningitis was the underlying and immediate cause of death (59% of patients; median duration of survival, 5 days); category II, in which meningitis was the underlying but not immediate cause of death (18%; median duration of survival, 10 days); and category III, in which meningitis was neither the underlying nor immediate cause of death (23%; median duration of survival, 32 days). In a substantial proportion of adults hospitalized with community-acquired bacterial meningitis, meningitis was neither the immediate nor the underlying cause of death. A 14-day survival end point discriminated between deaths attributable to meningitis and those with another cause.

Adolescent↗
PubMed2006

Viral meningitis.

Viruses probably account for most cases of acute meningitis. Viral meningitis is often assumed to be a largely benign disease. For the commonest pathogens causing meningitis, enteroviruses, this is usually the case; however, for many of the other pathogens causing viral meningitis, and for common pathogens in the immunocompromised or infants, viral meningitis is frequently associated with substantial neurological complications and a significant mortality. Diagnostic methods for rapid and accurate identification of pathogens have improved over recent years, permitting more precise and earlier diagnoses. There have been fewer developments in therapies for viral meningitis, and there remain no effective therapies for most pathogens, emphasising the importance of prevention and early diagnosis. This review focuses on the presentation, diagnosis and management of viral meningitis and also covers the prevention of meningitis for pathogens where effective vaccines are available.

Antiviral Agents↗
PubMed1995

Steroid therapy for bacterial meningitis.

Routine dexamethasone therapy for bacterial meningitis in pediatric patients is controversial. Two experts debated this topic at the 1993 meeting of the Infectious Diseases Society of America. Both experts agreed that for management of Haemophilus influenzae meningitis, dexamethasone significantly reduced sensorineural hearing loss and probably reduced other long-term sequelae. Because relatively few patients with pneumococcal and meningococcal meningitis have been studied, no conclusions could be reached regarding the effectiveness of dexamethasone. Dr. Urs Schaad emphasized the impressive anti-inflammatory effects of dexamethasone in experimental pneumococcal meningitis and the lack of any adverse events when given to children for 2 or 4 days. He recommended routine use of dexamethasone in treating pediatric patients with bacterial meningitis. Dr. Sheldon Kaplan expressed concern regarding the effectiveness of steroids in treating pneumococcal meningitis, especially when penicillin-resistant and cephalosporin-resistant isolates are present, and he addressed the question of the long-term effects of administration of dexamethasone in children with viral meningitis. He advised against the routine use of dexamethasone for non-H. influenzae meningitis.

Dexamethasone↗
PubMed1987

Possible association of mycoplasma and viral respiratory infections with bacterial meningitis.

The presence of viral infection was evaluated in 160 children older than three months with bacterial meningitis who were admitted to Children's Medical Center or Parkland Memorial Hospital, Dallas, TX, between October 1979 and March 1982. Results were compared with a single serologic specimen in 138 children without meningitis. A recent history of upper respiratory infection was obtained from 60% of patients, including 10/13 with pneumococcal, 9/16 with meningococcal, and 77/131 with Haemophilus influenzae meningitis. Viral infection was documented by serologic response (23.8%) or viral isolation (13.2%) in 63/160 (40%) of patients with meningitis. There were 23 positive cultures (one patient with both adenovirus and respiratory syncytial virus). Picornaviruses, including two rhinoviruses, were isolated from six of the 24 subjects without meningitis who had viral cultures. There were 69 serologic conversions in meningitis patients, with 12 patients converting to two organisms and four patients converting to three organisms. Viral diagnoses included: adenovirus, 32 children; respiratory syncytial virus, 14; influenza A, 8; influenza B, 4; parainfluenza (1, 2, and 3), 12; picornaviruses, 9; herpes simplex virus, 1; and cytomegalovirus, 1. Additionally, 6/15 seroconverted to Mycoplasma pneumoniae. The acute geometric mean serum antibody titers of meningitis patients were lower than those of the comparison group for adenovirus (3.5 vs. 6.6, p less than or equal to 0.001) and influenza B (1.2 vs. 1.6, p less than or equal to 0.05). Twenty nine of 131 patients with H. influenzae had evidence of recent adenovirus infection. Primary infection with adenoviruses and possibly influenza B or mycoplasma precedes development of bacterial meningitis in some patients and may be a predisposing factor.

Adenoviridae↗
PubMed1996

Meningeal architecture of the cavernous sinus: clinical and surgical implications.

OBJECTIVE: The meningeal structure of the cavernous sinus (lateral sellar compartment) was anatomically and histologically studied. We discuss the clinical and surgical significance and present clinical examples of cranial base tumors. METHODS: Ten adult cadaveric heads were used for microsurgical dissection or histological studies. Specimens of the cavernous sinus were continuously sectioned in three dimensions and stained by Masson's trichrome method. The findings are anatomically discussed as they pertain to presented clinical cases. RESULTS: The cavernous sinus, located in an interdural space between periosteal and meningeal dura, is properly accessed by detachment of the periosteal bridge between the superior orbital fissure and the middle fossa. The lateral meningeal dura is dissected under minimal hemorrhage from the sinus, with a surgically important cleaving plane between the "deep layer," a semitransparent meningeal sheath with which the cranial nerves are covered and protected. It has various degrees of meningeal pockets, of which Meckel's cave is the largest example. Adventitia of the carotid artery in the sinus, uncovered with protective meninges, is considered to contact directly with tumors of the sinus origin. The meningeal wall of the cavernous sinus anatomically has three weak points as far as tumor invasion and extension are concerned: the venous plexus around the superior orbital fissure, the loose texture of the medial wall around the pituitary body, and dural pockets of the IIIrd and Vth cranial nerves. The dural wall is extremely thin or missing at those points. CONCLUSION: A surgical technique based on the meningeal anatomy is important for cavernous sinus surgery. The cavernous apex and Meckel's cave, which are spaces of convergence of cranial nerves, however, are weak points for surgical dissection. The presence or absence of tumor invasion into those areas may influence the microsurgical results.

Adult↗
PubMed2002

Outbreak of aseptic meningitis associated with echovirus 13.

BACKGROUND: Before 2001, echovirus 13 accounted for only 65 of approximately 45,000 reported enteroviral isolates in the United States. During spring 2001, several outbreaks of echovirus 13 meningitis occurred, primarily affecting children. We investigated a large outbreak in Shelby County, TN, to determine the characteristics and clinical manifestations of echovirus 13 meningitis. METHODS: We identified cases of aseptic meningitis at a children's hospital from April through August 2001 by reviewing discharge records. For patients with laboratory-confirmed echovirus 13 meningitis, we reviewed charts and interviewed parents. RESULTS: We identified 303 hospitalizations caused by aseptic meningitis at the children's hospital from April through August. Hospitalizations peaked in May. Twenty-six percent of hospitalized patients were infants age <4 months; 63% were male. Hospitalization rates were 3 times greater among black children than among white children (140 vs. 47 per 100,000). Echovirus 13 was isolated from specimens from 37 (80%) of 46 patients with positive viral cultures. Of those with laboratory-confirmed echovirus 13, 35 (95%) had fever, 26 (70%) had vomiting, 20 (54%) had headache, 16 (43%) had stiff neck and 16 (43%) had irritability. No sequelae or deaths were identified. CONCLUSIONS: Echovirus 13 emerged as a predominant strain of enterovirus associated with aseptic meningitis in the United States in 2001. In this outbreak echovirus 13 meningitis appeared to be clinically indistinguishable from aseptic meningitis caused by other enteroviruses.

Adolescent↗
PubMed2004

Meningitis in cochlear implant recipients: the North American experience.

INTRODUCTION: Until recently, postimplant meningitis was infrequently reported and felt to be uncommon. However, in the spring of 2002, there was a sudden increase in the number of reported cases of postimplantation meningitis in both Europe and North America. OBJECTIVE: Because complications of surgery often tend to be underreported, we decided to survey all cochlear implant centers in North America to determine the true incidence of postimplant meningitis and to learn more about the demographics and risk factors. STUDY DESIGN: We conducted a prospective study. A survey instrument was designed asking surgeons the number of implants performed and whether they had seen any cases of meningitis after implantation. If the answer was affirmative, they were asked to respond to a 20-point questionnaire. This instrument was sent to all 401 cochlear implant centers in North America. SETTING: Tertiary care referral centers. PATIENTS: We studied all patients having received cochlear implants in North America. MAIN OUTCOME MEASURES: Number of cases of postimplant meningitis, age of patients, device used, cochlear and temporal bone abnormalities, treatment, and outcomes. RESULTS: Meningitis is more common than previously thought. Risk factors included young age, cochlear dysplasia, temporal bone abnormalities, and the use of a two-part electrode system. This survey led to the involvement by the U.S. Food and Drug Administration and the Centers for Disease Control and Prevention in a much more intensive analysis of a subset of the cases. CONCLUSIONS: Postimplant meningitis is related to patient, surgical, and device factors. By being aware of the risk factors involved, adhering to sound surgical principles such as packing of the cochleostomy with soft tissue, appropriately vaccinating patients, and eliminating any potentially traumatic electrode arrays, the incidence of meningitis should be significantly diminished.

Age Factors↗
PubMed2006

Comparison of diagnostic criteria of tuberculous meningitis in human immunodeficiency virus-infected and uninfected children.

INTRODUCTION: Tuberculous (TB) meningitis is sometimes difficult to diagnose in young children. The decision to start anti-TB treatment of TB meningitis is usually made on clinical grounds and results of special investigations, such as cerebrospinal fluid examination and cranial computerized tomography (CT), because bacteriologic yield is low and the results delayed. AIM: To determine whether the clinical, laboratory, and radiologic criteria used in the diagnosis of TB meningitis in human immunodeficiency virus (HIV)-uninfected children apply to HIV-infected children. METHODS: Retrospective, case-control study. Clinical, laboratory, and radiologic features of TB meningitis were compared in 34 HIV-infected and 56 HIV-uninfected patients matched for age and stage of TB meningitis. RESULTS: All clinical differences found between the 2 groups at admission were related to the underlying HIV disease. Neurologic presentation and cerebrospinal fluid findings at admission did not differ significantly between the 2 groups. Significantly more HIV-infected than HIV-uninfected children had evidence of TB on chest radiography. The classic CT signs of TB meningitis (obstructive hydrocephalus and basal enhancement) were significantly less prominent in the HIV-infected group (P < 005). CONCLUSION: The diagnostic criteria for clinical diagnosis of TB meningitis apply to HIV-infected children. However, cranial CT findings in this group may be misleading and delay the diagnosis of TB meningitis.

Case-Control Studies↗
PubMed2005

Rapid diagnosis of pneumococcal meningitis: implications for treatment and measuring disease burden.

BACKGROUND: Streptococcus pneumoniae is the leading cause of childhood pneumonia and meningitis worldwide. Isolation of this organism, however, is uncommon in resource-poor countries, in part because of extensive use of prior antibiotics. A rapid, highly sensitive immunochromatographic test (ICT) for S. pneumoniae was evaluated for the diagnosis of meningitis. METHODS: Cerebrospinal fluid (CSF) from 450 children with suspected meningitis was tested with ICT, and results were compared with CSF culture, latex agglutination test (LAT) and/or polymerase chain reaction (PCR). Serial CSF specimens from 11 patients were also evaluated for duration of positive results during effective antimicrobial therapy. FINDINGS: All 122 cases of pyogenic pneumococcal meningitis positive either by culture (N = 87) or PCR (N = 35) were positive by ICT, yielding 100% (122 of 122) sensitivity. All purulent CSF specimens from patients with meningitis caused by other bacteria by culture (N = 149) or by LAT (N = 48) or those negative by culture, LAT and LytA and thus of unknown etiology (N = 20), and normal CSF specimens (N = 104) were negative by ICT. Thus the specificity of ICT also was 100% (321 of 321), although negativity of ICT was not confirmed by PCR, if it was positive for other organisms either by culture or LAT. Serotyping of S. pneumoniae strains revealed 28 different serotypes, indicating that outcome of ICT are independent of diverse capsular serotype of pneumococcus. Antigen was detected by ICT for at least 10 days after presentation, and 1 was still positive on day 20, which was longer than for either LAT or PCR. INTERPRETATION: ICT for pneumococcal antigen in CSF is 100% sensitive and specific in diagnosing pyogenic pneumococcal meningitis and can detect approximately 30% more pneumococcal meningitis cases than with culture alone. The simplicity of the test procedure and the longevity of CSF antigen detection suggest the potential utility of ICT to estimate the true burden of pneumococcal disease, as for Haemophilus influenzae type b using data from meningitis, and to guide selection of appropriate antibiotic treatment, especially in resource-poor countries with widespread prehospital antimicrobial use.

Antigens, Bacterial↗
PubMed2006

Pneumococcal meningitis threshold model: A potential tool to assess infectious risk of new or existing inner ear surgical interventions.

HYPOTHESIS: A minimal threshold of Streptococcus pneumoniae is required to induce meningitis in healthy animals for intraperitoneal (hematogenous), middle ear, and inner ear inoculations, and this threshold may be altered via recent inner ear surgery. BACKGROUND: There has been an increase in the number of reported cases of cochlear implant-related pneumococcal meningitis since 2002. The pathogenesis of pneumococcal meningitis is complex and not completely understood. The bacteria can reach the central nervous system (CNS) from the upper respiratory tract mucosa via either hematogenous route or via the inner ear. The establishment of a threshold model for all potential routes of infection to the CNS in animals without cochlear implantation is an important first step to help us understand the pathogenesis of the disease in animals with cochlear implantation. METHODS: Fifty-four otologically normal adult Hooded Wistar rats (27 receiving cochleostomy and 27 controls) were inoculated with different amounts of bacterial counts via three different routes (intraperitoneal, middle ear, and inner ear). Rats were monitored during 5 days for signs of meningitis. Blood, cerebrospinal fluid, and middle ear swabs were taken for bacterial culture, and brains and cochleae were examined for signs of infection. RESULTS: The threshold of bacterial counts required to induce meningitis is lowest in rats receiving direct inner ear inoculation compared with both intraperitoneal and middle ear inoculation. There is no change in threshold between the group of rats with cochleostomy and the control (Fisher's exact test, p < 0.05). CONCLUSION: A minimal threshold of bacteria is required to induce meningitis in healthy animals and is different for three different routes of infection (intraperitoneal, middle ear, and inner ear). Cochleostomy performed 4 weeks before the inoculation did not reduce the threshold of bacteria required for meningitis in all three infectious routes. This threshold model will also serve as a valuable tool, assisting clinicians to quantitatively analyze if the presence of a cochlear implant or other CNS prostheses alter the risk of meningitis.

Animals↗