Acute Bacterial Meningitis - Diagnostic

Diagnostic LaboratoryCertainty of diagnosis is to identify the pathogen of bacterial meningitis in cerebrospinal fluid obtained by lumbar puncture.Whenever meningitis is suspected should be made mandatory for performing a lumbar puncture cultures but also to determine cytology. Because the result is obtained later cultures, after 3-4 weeks, early diagnosis will be made on behalf of cerebrospinal fluid cytology. Cytology and chemical composition of cerebrospinal fluid will not only confirm the diagnosis of meningitis, but it will give directions and the causal agent. After the lumbar puncture will investigate the macroscopic appearance of cerebrospinal fluid and will be sent to the laboratory for analysis and culture. Normal cerebrospinal fluid looks clear, like "water stone." The liquid is cloudy appearance of bacterial meningitis, yellow, possibly flakes, a sign that has an increased content of leukocytes. Blood in lumbar puncture fluid can mean two things: vessel injury by the needle examiner or subarachnoid bleeding. If a vessel is damaged by accident, this has no importance, the bleeding stops spontaneously in the first few seconds clatifica liquid as it flows from the needle. If the bleeding does not stop bleeding and fluid looks throughout the harvesting, then there is a subarachnoid hemorrhage as dark prognosis.Microscopic examination of cerebrospinal fluid in bacterial meningitis reveals a higher concentration of leukocytes, from 50.000 and 100. 000/dl and even more, with neutrophil predominance. If leukocytes are in low concentrations, it means that the patient is immunocompromised, and the prognosis is grim.Proteinorahia (cerebrospinal fluid protein concentration) is increased in most patients. Glicorahia has values ​​below 40 mg / dL in bacterial meningitis.
Summarizing, the microscopic appearance of cerebrospinal fluid in bacterial meningitis is as follows: WBC> 100. 000/dl (of which 80% neutrophils), proteinorahia> 220 mg / dl, glicorahia <40 mg / dl, the report glicorahie / serum glucose <0. 23.
It is also performed blood cultures, preferably made from blood collected during febrile, to identify the pathogen, counts with the determination of C-reactive protein (low values ​​of the diagnosis of bacterial meningitis this rule), evaluation of electrolytes and clotting factors, summary urine and urine to detect a possible urinary tract infection. Equipped hospitals can test polymerase chain reaction used to amplify bacterial DNA, useful for rapid detection of the etiologic agent. They also recommend a biopsy of the rash to identify opportunistic or making smears of material collected from petechial lesions (which reveals intracellular cocci).
Among imaging examinations, the most used are computed tomography (CT) and simple chest radiography. Chest radiograph is performed to detect a lung infection and to observe the lung condition, whether or not effusions. Usually is performed cranial CT and is helpful in assessing the state of the brain, to detect cerebral edema and cerebral lesions. MRI (magnetic resonance imaging) reveal subdural effusions better than CT, and cerebral cortical infarcts.
Differential Diagnosis
Bacterial meningitis must be differentiated from diseases that evolve with outbreaks of infection and brain abscess parameningeala as subdural, subdural MPM's. Also, bacterial meningitis can lend itself to confusion with viral meningitis or toxic etiology (caused by radiocontrast agents, anesthetics or other drugs) with tuberculous or fungal meningitis, central nervous system syphilis, Lyme disease, infection with rickettsiae. Other diseases with differential diagnosis is made are: bacterial endocarditis, central nervous system neoplasms, cerebral vasculitis, granulomatous angeitele, sarcoidosis, subarachnoid hemorrhage, neuroleptic malignant syndrome, Rocky Mountains spotted fever (for those who travel or are resident in the U.S.).