Interpretation of Cerebrospinal Fluid White Blood Cell Counts in Young Infants With a Traumatic Lumbar Puncture.

STUDY OBJECTIVE: We determine the optimal correction factor for cerebrospinal fluid WBC counts in infants with traumatic lumbar punctures. METHODS: We performed a secondary analysis of a retrospective cohort of infants aged 60 days or younger and with a traumatic lumbar puncture (cerebrospinal fluid RBC count ≥10,000 cells/mm3) at 20 participating centers. Cerebrospinal fluid pleocytosis was defined as a cerebrospinal fluid WBC count greater than or equal to 20 cells/mm3 for infants aged 28 days or younger and greater than or equal to 10 cells/mm3 for infants aged 29 to 60 days; bacterial meningitis was defined as growth of pathogenic bacteria from cerebrospinal fluid culture. Using linear regression, we derived a cerebrospinal fluid WBC correction factor and compared the uncorrected with the corrected cerebrospinal fluid WBC count for the detection of bacterial meningitis. RESULTS: Of the eligible 20,319 lumbar punctures, 2,880 (14%) were traumatic, and 33 of these patients (1.1%) had bacterial meningitis. The derived cerebrospinal fluid RBCs:WBCs ratio was 877:1 (95% confidence interval [CI] 805 to 961:1). Compared with the uncorrected cerebrospinal fluid WBC count, the corrected one had lower sensitivity for bacterial meningitis (88% uncorrected versus 67% corrected; difference 21%; 95% CI 10% to 37%) but resulted in fewer infants with cerebrospinal fluid pleocytosis (78% uncorrected versus 33% corrected; difference 45%; 95% CI 43% to 47%). Cerebrospinal fluid WBC count correction resulted in the misclassification of 7 additional infants with bacterial meningitis, who were misclassified as not having cerebrospinal fluid pleocytosis; only 1 of these infants was older than 28 days. CONCLUSION: Correction of the cerebrospinal fluid WBC count substantially reduced the number of infants with cerebrospinal fluid pleocytosis while misclassifying only 1 infant with bacterial meningitis of those aged 29 to 60 days.

High level of heterogeneity among Listeria monocytogenes isolates from clinical and food origin specimens in Greece.

In order to examine the genetic variation of clinical and food isolates of Listeria monocytogenes in Greece, a total of 61 L. monocytogenes non-duplicate isolates, recovered from clinical specimens (n=19) and food (n=42), were serotyped and genotyped using two different Random Amplification of Polymorphic DNA (RAPD) protocols and Multiple Locus Variable Number Tandem Repeat Analysis (MLVA). Serotype group 4b, 4d, 4e prevailed (39.4%), among both clinical and food isolates, followed by serotype group 1/2a, 3a (23.0%), which nevertheless was detected only among food isolates. The most discriminatory typing protocol was MLVA, which grouped four isolates into two pairs, while the remaining isolates produced unique fingerprints. Similar results were obtained when taking into account the combination of the two RAPD protocols (Simpson index 0.999); six isolates were grouped into three pairs, two of which were the pairs that were identified also by MLVA. Single use of each RAPD protocol resulted in inferior discrimination (Simpson index 0.978 and 0.997, respectively). In conclusion, the two molecular procedures, MLVA, and the combined RAPD protocols, produced similar results, showing that L. monocytogenes isolates from clinical and food specimens were highly heterogenous and that clustering was very uncommon.

Meningitis and septicemia caused by nontypeable Haemophilus influenzae in a previously healthy 2-year-old girl.

Nontypeable Haemophilus influenzae (NTHi) commonly colonizes the upper respiratory tract of children and causes otitis media, sinusitis, and bronchitis. Invasive NTHi diseases such as meningitis and septicemia have rarely been reported, especially in children with underlying predisposing conditions such as head trauma and immune compromise. However, we report a previously healthy 2-year-old girl who developed meningitis and septicemia caused by NTHi biotype ΙΙΙ. She was treated with dexamethasone, meropenem, and ceftriaxone, and recovered uneventfully. We wish to emphasize that NTHi should be borne in mind as a potential pathogen that can cause meningitis and septicemia, even in previously healthy children.

Rapid diagnosis of sepsis and bacterial meningitis in children with real-time fluorescent quantitative polymerase chain reaction amplification in the bacterial 16S rRNA gene.

A method for the detection of bacterial pathogens in sepsis and bacterial meningitis with 16S rRNA gene- based real-time fluorescent quantitative polymerase chain reaction (FQ-PCR) is developed. A total of 190 blood specimens and 5 cerebrospinal fluid specimens from neonates with suspected sepsis or bacterial meningitis were evaluated with 16S rRNA gene-based real-time FQ-PCR assay. The positive rate of the real-time FQ-PCR assay was significantly higher (25/195, 12.82%) than that of bacterial culture (15/195, 7.69%; P = .002). When bacterial culture was used as a control, the sensitivity of the real-time FQ-PCR was 100%, the specificity was 94.4%, and Youden's index was 0.944. This study suggests that 16S rRNA gene-based real-time FQ-PCR assay is an important and accurate method in the detection of bacterial pathogens of sepsis and bacterial meningitis and should have a promising usage in the diagnosis of sepsis and bacterial meningitis.

Decreasing prevalence of antimicrobial resistance in non-typhoidal Salmonella isolated from children with bacteraemia in a rural district hospital, Kenya.

We analysed 336 non-typhoidal Salmonella (NTS) isolated from children <13 years of age with bacteraemia admitted to a rural district hospital in Kenya from 1994 to 2005. Pulsed-field gel electrophoresis was used to determine genetic relatedness of strains, and antimicrobial susceptibility testing was also performed. Most NTS were either Salmonella enterica serovar Typhimurium (n=114; 33.9%) or S. enterica serovar Enteritidis (n=128; 38.1%), with minimal genotypic diversity over the study period. The NTS showed a remarkable decrease in levels of resistance especially to two commonly available antimicrobials (amoxicillin and co-trimoxazole), from high of 69.2% and 68.4% during 1994-1997 to 11% and 13%, respectively, in 2002-2005 (P<0.01). All NTS remained fully susceptible to cefotaxime and ciprofloxacin. Our findings show that commonly available drugs may still be useful for treatment of invasive NTS infections in this rural population.

Influence of the blood bacterial load on the meningeal inflammatory response in Streptococcus pneumoniae meningitis.

BACKGROUND: Despite bacteraemia is present in the majority of patients with pneumococcal, little is known about the influence of the systemic infection on the meningeal inflammatory response. METHODS: To explore the role of systemic infection on the meningeal inflammation, experimental meningitis was induced by intracisternal injection of approximately 1 x 10(6) CFU Streptococcus pneumoniae, type 3, and the 26 rabbits were either provided with approximately 1 x 10(6) CFU S. pneumoniae intravenously at 0 hour ("bacteraemic" rabbits, n = 9), immunized with paraformaldehyde-killed S. pneumoniae for 5 weeks prior to the experiment ("immunized" rabbits", n = 8), or not treated further ("control" rabbits, n = 9). WBC and bacterial concentrations were determined in CSF and blood every second hour during a 16 hours study period together with CSF IL-8 and protein levels. We also studied CSF and blood WBC levels in 153 pneumococcal meningitis patients with and without presence of bacteraemia. RESULTS: As designed, blood bacterial concentrations were significantly different among three experimental groups during the 16 hours study period (Kruskal Wallis test, P < 0.05), whereas no differences in CSF bacterial levels were observed (P > 0.05). Blood WBC decreased in bacteraemic rabbits between approximately 10-16 hours after the bacterial inoculation in contrast to an increase for both the immunized rabbits and controls (P < 0.05). The CSF pleocytosis was attenuated in bacteraemic rabbits as compared to the two other groups between 12-16 hours from time of infection (P < 0.017), despite accelerated CSF IL-8 levels in bacteraemic rabbits. In patients with pneumococcal meningitis, no significant difference in CSF WBC was observed between patients with or without bacteraemia at admission (n = 103, 1740 cells/microL (123-4032) vs. n = 50, 1961 cells/microL (673-5182), respectively, P = 0.18), but there was a significant correlation between CSF and blood WBC (n = 127, Spearman rho = 0.234, P = 0.008). CONCLUSION: Our results suggest that a decrease in peripheral WBC induced by enhanced bacteraemia in pneumococcal meningitis results in an attenuated CSF pleocytosis.

How do extracellular pathogens cross the blood-brain barrier?

Bacterial invasion of the meninges can occur as a consequence of bloodstream invasion by some bacterial pathogens. Bacteria enter the central nervous system following a direct interaction with the luminal side of the cerebral endothelium, which constitutes the blood-brain barrier. To breach the barriers protecting the brain, extracellular pathogens must cross a monolayer of tight junction-expressing endothelial or epithelial cells. The limited number of pathogens capable of crossing these tight barriers and invading the meninges suggests that they display very specific attributes. For Neisseria meningitidis, type IV pili have been identified as being essential for meningeal invasion and it is believed other, as-yet-unidentified factors are also involved.

A low peripheral blood white blood cell count in infants younger than 90 days increases the odds of acute bacterial meningitis relative to bacteremia.

UNLABELLED: In relying on the peripheral blood white blood cell (WBC) count to identify infants at high risk for acute bacterial meningitis and bacteremia, to the best of the authors' knowledge, it has not been reported previously whether high and low values of the test have similar implications for predicting these separate infections. OBJECTIVE: To analyze the relationship between the peripheral WBC count and the odds of acute bacterial meningitis relative to bacteremia among sick infants aged 3 to 89 days. METHODS: Areas under the receiver operating characteristic curve (AUCs) and likelihood ratios at various intervals of the total peripheral blood WBC count were computed. RESULTS: A pathogen was isolated from blood or cerebrospinal fluid (CSF) from 72 infants aged 3 to 89 days. Fifty-two infants had growth of a pathogen from the blood only, and 20 had growth from the CSF. The most common bacteria isolated were Escherichia coli (32) and group B streptococci (32). The AUC for the peripheral WBC count when differentiating between acute bacterial meningitis and bacteremia was 0.75 (95% CI = 0.63 to 0.88). The odds of acute bacterial meningitis relative to bacteremia were sevenfold higher for a peripheral WBC cutoff below 5,000 cells/mm(3) and threefold lower for a peripheral WBC cutoff at or above 15,000 cells/mm(3). CONCLUSIONS: In young infants, the peripheral blood WBC count is useful for estimating the odds of acute bacterial meningitis relative to isolated bacteremia. A low peripheral blood WBC count should be considered a much more worrisome laboratory finding because it is associated with a relatively high risk for acute bacterial meningitis relative to the potential for bacteremia.

Vancomycin cerebrospinal fluid concentrations after intravenous administration in premature infants.

OBJECTIVE: Staphylococcal species are the most common cause of nosocomial infections in the neonate. Because of staphylococcal resistance patterns, vancomycin has become the drug of choice for treatment. Although the blood stream is the usual site of infection, premature infants are at increased risk for the development of meningitis. The aim of this study was to determine vancomycin cerebrospinal fluid (CSF) concentration and penetration following intravenous (IV) administration in critically ill premature infants. STUDY DESIGN: A multiple-dose, open-label, case series was performed at a level III neonatal intensive care unit in a university teaching hospital. Three critically ill premature infants, 26 to 31 weeks of gestation requiring a course of IV vancomycin for suspected or proved sepsis were studied. Vancomycin was administered intravenously at 20 mg/kg, every 18 to 24 hours over 60 minutes. Serum and CSF vancomycin concentrations were obtained and pharmacokinetic analysis and CSF penetration was calculated. RESULTS: Serum vancomycin pharmacokinetics were consistent with those previously reported. CSF vancomycin concentrations ranged from 2.2 to 5.6 micrograms/ml and the calculated vancomycin CSF penetration ranged from 26% to 68%. CONCLUSIONS: CSF penetration of vancomycin after IV administration was much higher than that reported in older infants and children. This higher penetration may improve clinical outcomes in neonates with central nervous system infections. These data should be encouraging to clinicians who choose to use IV vancomycin for neonatal meningitis.

Identification and medical importance of coagulase-negative staphylococci species.

A total of 126 coagulase-negative staphylococci strains (CNS) were isolated from blood samples and from the intravenous catheters and cerebrospinal fluid of 103 patients admitted to the University Hospital of Ribeirão Preto. Staphylococcus epidermidis (68.2%), S. haemolyticus (11.1%) and S. hominis (3.2%) were the most frequent species. The last two CNS showed greater resistance to antimicrobial agents than S. epidermidis. CNS were the agents of infection in 10. 7% of the patients and the agents of intravenous catheter colonization in 18.4% of the cases.

Predictors of positive cerebrospinal fluid cultures in infants with bacteremia.

BACKGROUND: Meningitis causes substantial morbidity and mortality in hospitalized infants. There is no consensus on the ability of blood cultures to predict results from cerebrospinal fluid (CSF) cultures in hospitalized infants. METHODS: We used the Pediatrix Medical Group database of infants discharged from 333 neonatal intensive care units between 1997 and 2011. We identified all infants with a positive blood culture and a CSF culture obtained within 3 days. We evaluated the odds of a concordant blood-CSF culture pair, controlling for severity of illness, organism type, gestational age, day of blood culture and blood-CSF culture pairing, exposure to CSF-penetrating antibiotics and the presence of a ventriculo-peritoneal shunt. RESULTS: We identified 8839 infants with 9408 blood-CSF culture pairs. Serratia marcescens (24/227, 11%) and Streptococcus pneumoniae (7/64, 11%) had the highest proportion of concordant blood-CSF culture pairs. The presence of a ventriculo-peritoneal shunt, as well as timing of the CSF culture on the same day as the blood culture, were associated with increased odds of blood-CSF culture pair concordance-odds ratio = 3.87 (95% confidence interval; 2.59-5.78) and 6.11 (2.81-13.24), respectively. CONCLUSION: The frequency of blood-CSF culture pair concordance is related to organism type and to the timing of the CSF culture in relation to the blood culture.

Severe invasive listeriosis--case report.

Listeriosis is a rare food borne infection which, in the invasive form, presents as bloodstream infection, central nervous system infection, materno-fetal infection, or focal infection. Certain immunosuppressive conditions have been identified as risk factors for severe invasive disease. The invasive forms of listeriosis are associated with a high case fatality rate. We present the case of a 62-year-old male with an unremarkable medical history admitted to the Iasi Infectious Diseases Hospital for fever. headache, ataxia, and diplopia. Physical examination revealed high temperature, confusion, relative bradycardia, and signs of meningeal irritation. Laboratory test showed leukocyt osis with neutrophilia. pathological CSF findings (high WBC count with predominance of neutrophils, low glucose and high protein levels), increased liver enzymes (ALAT, ASAT, AP, gammaGT), and important renal impairment (normal levels at presentation). No abnormalities at chest x-ray, cranial CT and abdominal ultrasound. CSF and blood cultures were positive for Listeria monocytogenes. Under antibiotics (ampicillin and ciprofloxacin), the course was marked by respiratory failure requiring mechanical ventilation, coma, hypotension, tachycardia. and death 12 days after admission. The particularity of this case consists in the association of the two classical forms of invasive listeriosis, meningitis and bacteriemia, with a focal infection. acute hepatitis, and a course marked by multiple organ dysfunction syndromes and exitus in a previously apparently healthy individual.

Group B streptococcal meningitis: cerebrospinal fluid parameters in the era of intrapartum antibiotic prophylaxis.

OBJECTIVE: Describe cerebrospinal fluid parameters in infants with culture-proven Group B streptococcal meningitis in the era of intrapartum antibiotic prophylaxis. STUDY DESIGN: Cohort study of the first lumbar puncture from 13,495 infants cared for at 150 neonatal intensive care units. We compared cerebrospinal fluid parameters [white blood cell count, red blood cell count, glucose, and protein], demographics, and outcomes between infants with and without Group B streptococcal meningitis. RESULTS: We identified 46 infants with Group B streptococcal meningitis. The median cerebrospinal fluid white blood cell count was 271 cells/mm(3) for infants with Group B streptococcal meningitis and 6 cells/mm(3) for infants without meningitis (p=0.0001). Of the infants with Group B streptococcal meningitis, 9/46 (20%) had negative blood cultures. Meningitis complicated 22/145 (15%) of episodes of early-onset Group B streptococcal sepsis and 13/23 (57%) of episodes of late-onset Group B streptococcal sepsis. CONCLUSIONS: Group B streptococcal meningitis occurs in the presence of negative blood cultures. In hospitalized infants who undergo a lumbar puncture, Group B streptococcal sepsis is frequently complicated by GBS meningitis.

Are routine sensitivity test data suitable for the surveillance of resistance? Resistance rates amongst Escherichia coli from blood and CSF from 1991-1997, as assessed by routine and centralized testing.

Surveillance of antibiotic resistance can be undertaken by compilation of routine data or by central testing of isolates. Routine results can be obtained cheaply and in sufficient quantities for correlation with population and prescribing denominators but there is concern about their quality. As one of a series of ongoing studies to assess this quality, we compared the proportions of resistance amongst Escherichia coli from patients with bacteraemia or meningitis between 1991 and 1997 (i) as recorded in routine data reported to the PHLS and (ii) as found in tests performed at the PHLS Laboratory of Enteric Pathogens (LEP). These two data sets both showed an overall upward trend in the proportion of isolates resistant to ampicillin, trimethoprim, gentamicin and ciprofloxacin. The average annual percentage increase in resistance was estimated in separate logistic regression models, and 95% confidence intervals (CI) were determined. The annual percentage increases in the proportions of isolates reported resistant were similar in the two data sets for trimethoprim, gentamicin and ciprofloxacin but differed for ampicillin. The upward trends were statistically significant except for gentamicin resistance in the LEP data set, where the 95% CI straddled zero. The proportions of resistant isolates for each antibiotic in the two data sets each year were in poorer agreement than the trends; however, the 95% CI of the difference of proportions resistant between the routine and LEP data sets straddled zero in 4 or 5 of the 7 years studied. Some discrepancies might be explained by geographical bias in the sampling or by differences in definitions of resistance. Thus (i) the proportion of resistant isolates tested at LEP almost always fell within the ranges bounded by the highest and lowest proportions for individual Regional Health Authorities, as recorded in the routine data, and (ii) the fact that LEP consistently recorded less gentamicin resistance but more ciprofloxacin resistance than the routine could be explained by breakpoint differences. We conclude that routine susceptibility data for ampicillin, ciprofloxacin, gentamicin and trimethoprim appear sound for E. coli and might be suitable for correlation with other data, e.g. for prescribing.

Phase variation of lic1A, lic2A and lic3A in colonization of the nasopharynx, bloodstream and cerebrospinal fluid by Haemophilus influenzae type b.

The role of phase variation of lic1A, lic2A and lic3A in the ability of Haemophilus influenzae type b to colonize the nasopharynx, bloodstream and cerebrospinal fluid (CSF) of infants was investigated. This was achieved by using PCR to determine the number of 5'-CAAT-3' repeats present in each gene, which is indicative of whether each ORF can be expressed. Multiple PCR products of different intensities were amplified from all three genes at each site sampled. This indicated that the nasopharynx, bloodstream and CSF were colonized by a heterogeneous population of organisms, expressing different combinations of lic genes. At each site however, a predominant PCR product was amplified from each gene, indicating that organisms with this genotype were the most abundant. The number of 5'-CAAT-3' repeats in this predominant product varied depending upon whether organisms were isolated from the nasopharynx, bloodstream or CSF. These observations suggest that the expression of different combinations of lic genes may influence the efficiency with which H. influenzae colonizes the nasopharynx, bloodstream and CSF of infant rats.

The association between meningitis and dural puncture in bacteremic rats.

Clinicians have long been concerned that performance of spinal anesthesia during a period of bacteremia may result in the subsequent development of meningitis. In order to determine whether such an association exists, percutaneous dural puncture was performed in 40 animals during a period of Escherichia coli bacteremia. Twenty-four hours later, spinal fluid was obtained for final analysis by surgically draining the cisterna magna. Twelve animals had E. coli recovered from the surgically drained spinal fluid. Only animals with a circulating bacterial count of at least 50 CFU/ml developed meningitis. Microscopic examination of the brains and spinal cords of animals with infected cerebrospinal fluid showed evidence of central nervous system infection. Bacteremic animals not undergoing percutaneous dural puncture always had sterile spinal fluid (n = 40). Cisternal puncture in the absence of bacteremia did not result in infection (n = 30). Treatment with a single dose of gentamicin before the dural puncture eliminated the risk of meningitis after dural puncture in 30 bacteremic animals. These results demonstrate that dural puncture is associated with the development of meningitis in rats, provided the animals are bacteremic at the time of the puncture. However, antibiotic treatment before the dural puncture appears to eliminate this risk.