Related Experiment Videos
Concentrations of bacteria in cerebrospinal fluid of patients with bacterial meningitis
Abstract:
Concentrations of bacteria in cerebrospinal fluid ranged from 4.5 X 10(3) to 3 X 10(8) colony-forming units/ml in 27 patients with bacterial meningitis before antibiotic therapy and from 4 X 10(1) to 1.4 X 10(6) CFU/ml in four patients after one to two days of antibiotic therapy. All patients with persistent positive cultures had pretreatment concentrations of 10(7) CFU/ml or greater. A significant association was observed between cerebrospinal fluid lactic acid dehydrogenase activity and concentrations of bacteria (p less than 0.01). Large inocula of Hemophilus influenzae type b (10(7)) increased the minimal inhibitory concentration for penicillin and ampicillin but not for chloramphenicol. The minimal inhibitory concentration of each of the three antibiotics increased when group B streptococci were assayed. These data indicate that persistence of a positive culture may be related to large initial concentrations of bacteria. The relative "resistance" in vitro of large inocula possibly contributes to this persistence. These observations are also consistent with the hypothesis that lactic acid dehydrogenase activity in cerebrospinal fluid is derived from bacteria.
Insights
High initial bacterial concentrations in cerebrospinal fluid correlate with persistent meningitis infections. Large bacterial inocula may also increase antibiotic resistance, impacting treatment outcomes.
Area of Science:
- Microbiology
- Infectious Diseases
- Clinical Medicine
Background:
- Bacterial meningitis is a serious infection requiring prompt antibiotic treatment.
- Understanding factors influencing treatment efficacy and bacterial persistence is crucial.
Purpose of the Study:
- To investigate the relationship between initial bacterial concentrations in cerebrospinal fluid (CSF) and the persistence of infection.
- To explore the impact of bacterial inoculum size on antibiotic minimal inhibitory concentrations (MICs).
Main Methods:
- Quantifying bacterial concentrations in CSF from patients with bacterial meningitis before and after antibiotic therapy.
- Assessing the association between CSF lactic acid dehydrogenase (LDH) activity and bacterial load.
- Determining the MICs of penicillin, ampicillin, and chloramphenicol for large inocula of *Hemophilus influenzae* type b and group B streptococci.
Main Results:
- Patients with persistent positive CSF cultures had pretreatment bacterial concentrations of ≥10^7 CFU/ml.
- A significant positive correlation was found between CSF LDH activity and bacterial concentrations (p < 0.01).
- Large inocula of *H. influenzae* type b increased MICs for penicillin and ampicillin, but not chloramphenicol. Group B streptococci also showed increased MICs for all tested antibiotics.
Conclusions:
- High initial bacterial loads in CSF may be a key factor in the persistence of bacterial meningitis.
- Increased in vitro resistance of large bacterial inocula might contribute to treatment failure.
- CSF LDH activity may originate from bacteria, serving as a potential biomarker.