Microbial isolates and resistance profiles in cerebrospinal fluid cultures: a five-year experience at a tertiary center

Central nervous system infections are a significant global health concern that results in morbidity and mortality. In case of these infections, empirical antibiotic treatment should be initiated according to the microbiological findings of the cerebrospinal fluid (CSF), and the treatment should be rearranged according to the antibiogram results.The study aimed to determine the distribution of meningitis agents and antimicrobial resistance patterns in our hospital. A total of 17,594 CSF culture samples collected from January 2020 to December 2024 were analyzed retrospectively. The study assessed demographic data, causative microorganisms, and antimicrobial resistance rates. Positive results were found in 7.3% of CSF culture samples, with 69.1% being gram-positive bacteria and 30.9% gram-negative bacteria. The highest positivity rate was detected in the palliative inpatient clinic (14.8%) despite most cultures being from the neonatal intensive care unit (23.5%). The most common microorganisms were coagulase-negative staphylococci(CoNS) (47.9%) and <i>Klebsiella pneumoniae</i> (<i>K.pneumoniae</i>) (9.1%). Methicillin resistance was present in 89.7% of CoNS, and the rate of extended-spectrum β-lactamase-producing strains in <i>K.pneumoniae</i> was 32.4%. Analysis of five-year data revealed the types of microorganisms and their antimicrobial resistance in positive CSF cultures. These findings will guide clinicians in promptly choosing the most effective empirical treatment. Infections of the brain and spinal cord can be very serious and even life-threatening. To treat these infections effectively, doctors often begin treatment with broad antibiotics and then adjust the medications once test results are available. One of the most important tests involves analyzing the clear fluid that surrounds the brain and spinal cord, called cerebrospinal fluid (CSF).In this study, we looked at 17,594 CSF samples collected at our hospital between 2020 and 2024. We wanted to find out which bacteria were most commonly responsible for these infections and how resistant they were to antibiotics. Only 7.3% of the samples showed bacterial growth, but these results provided important insights.We found that most infections were caused by gram-positive bacteria, a group of bacteria that are identified by a special laboratory stain, and the most common type was coagulase-negative staphylococci (CoNS), which are bacteria often linked to infections in people with medical devices. Among gram-negative bacteria, the most common was <i>Klebsiella pneumonia</i>e, which is known for being resistant to many antibiotics.We also observed that infections were more common in certain hospital areas, especially among patients with serious or long-term illnesses. By understanding which bacteria are most likely to cause infection and how resistant they are to treatment, doctors can make better decisions when choosing antibiotics, especially before lab results are ready.