Related Experiment Videos
D- and L-lactate in rabbit and human bacterial meningitis
Abstract:
Increased total CSF lactate is an important indicator differentiating bacterial from aseptic meningitis. Bacteria can produce D- and L-lactate; mammalian cells produce only L-lactate. We measured D- and L-lactate production of Streptococcus pneumoniae, Staphylococcus aureus, Neisseria meningitidis and Escherichia coli in vitro, of S. pneumoniae and E. coli in rabbit experimental meningitis and of various common pathogens in CSF from patients with bacterial meningitis. Despite marked in vitro production of D-lactate by S. aureus (maximum: 4.59 mmol/l; i.e. 34.9% of total lactate), N. meningitidis (4.62 mmol/l; i.e. 98.1%) and E. coli (3.14 mmol/l; i.e. 97.2%), minimal amounts were measured in human S. aureus (0.38 mmol/l; i.e. 1.3% of total lactate) or N. meningitidis (0.28 mmol/l; i.e. 3.9%) and experimental E. coli meningitis (0.75 mmol/l; i.e. 4.4%). In only 9 of 54 human CSF samples did D-lactate exceed 0.15 mmol/l. S. pneumoniae did not produce significant amounts of D-lactate in vitro (maximum: 0.55 mmol/l; i.e. 2.7% of total lactate), in experimental meningitis (0.18 mmol/l; i.e. 3%) or in human cases of meningitis (0.28 mmol/l; i.e. 1.9%). In conclusion, increased total CSF lactate in meningitis consists mainly of L-lactate and originates predominantly from host cells. CSF D-lactate is of limited diagnostic value.
Insights
Cerebrospinal fluid (CSF) lactate levels help distinguish bacterial from aseptic meningitis. However, D-lactate, produced by bacteria, is minimally present in human meningitis cases, indicating limited diagnostic value.
Area of Science:
- Microbiology
- Neurology
- Biochemistry
Background:
- Elevated cerebrospinal fluid (CSF) lactate is a key differentiator between bacterial and aseptic meningitis.
- Bacteria produce both D- and L-lactate, while mammalian cells produce only L-lactate.
Purpose of the Study:
- To investigate the production of D- and L-lactate by common bacterial meningitis pathogens in vitro and in vivo.
- To assess the diagnostic utility of CSF D-lactate levels in differentiating bacterial meningitis.
Main Methods:
- Measured D- and L-lactate production of Streptococcus pneumoniae, Staphylococcus aureus, Neisseria meningitidis, and Escherichia coli in vitro.
- Analyzed lactate levels in rabbit experimental meningitis models (S. pneumoniae, E. coli).
- Quantified D- and L-lactate in CSF samples from patients with bacterial meningitis.
Main Results:
- Despite significant in vitro D-lactate production by S. aureus, N. meningitidis, and E. coli, minimal D-lactate was detected in human CSF samples from patients with S. aureus, N. meningitidis, or E. coli meningitis.
- S. pneumoniae showed negligible D-lactate production in all experimental settings.
- In only 9 out of 54 human CSF samples did D-lactate levels exceed 0.15 mmol/l.
Conclusions:
- Increased total CSF lactate in meningitis primarily consists of L-lactate, predominantly originating from host cells.
- CSF D-lactate levels are of limited diagnostic value for differentiating bacterial meningitis.