Neurology India Medknow Publications on behalf of the Neurological Society of India ISSN: 0028-3886 EISSN: 1998-4022 Vol. 59, Num. 2, 2011, pp. 195-198

Neurology India, Vol. 59, No. 2, March-April, 2011, pp. 195-198

Original Article

The incidence of postoperative meningitis in neurosurgery: An institutional experience

Dwarakanath Srinivas¹, HB Veena Kumari², Sampath Somanna¹, Indiradevi Bhagavatula¹, Chandramouli Bangalore Anandappa¹

¹ Department of Neurosurgery, National Institute for Mental Health and Neurosciences (NIMHANS), Bangalore, India
² Department of Neuromicrobiology, National Institute for Mental Health and Neurosciences (NIMHANS), Bangalore, India

Correspondence Address: Dwarakanath Srinivas, Associate Professor, Neurosurgery, Neurosciences Faculty Block, NIMHANS, Hosur Road, Bangalore - 560 029, India, dwarakaneuro@yahoo.com

Date of Submission: 27-May-2010
Date of Decision: 25-Jun-2010
Date of Acceptance: 08-Nov-2010

Code Number: ni11057

PMID: 21483116

DOI: 10.4103/0028-3886.79136

Abstract

Keywords: Meningitis, neurosurgery, nosocomial infection antibiotic prophylaxis, postoperative, bacterial

Introduction

Nosocomial infections are the most common causes of morbidity and mortality in neurosurgical patients. Among the nosocomial infections, meningitis is the most dreaded infection and can lead to a variety of complications, including death. The diagnosis requires a high degree of clinical suspicion and cerebrospinal fluid (CSF) examination. Postoperative meningitis is associated with increase in the hospital stay and also increase in total cost of illness. The reported incidence of postoperative meningitis is quite variable. 0.5 - 8%). ^{[1],[2],[3],[4],[5]} In this article we report the incidence, clinical and bacteriological profile of postoperative meningitis at our institution.

Material and Methods

This was a retrospective study and study cohort included all patients who underwent various neurosurgical procedures at the department of neurosurgery, National Institute of Mental Health and Neurological Sciences, Bangalore, India over a period of seven years (2001 - 2007). Case records, computerized log containing records of all the infections (culture reports) occurring in the Institute, Hospital Infection Control Department, Department of Neuromicrobiology, were reviewed. CSF analysis was performed, unless contraindicated, in all the patients with clinical features of meningism. Patients with only culture-positive meningitis were included in this study for analysis. The demographic characters, nature of surgery, and the causative organism, along with its antibiotic sensitivity profile were analyzed. The antibiotic sensitivity pattern of the organism was also analyzed with special emphasis on the multidrug-resistant (MDR) strains. MDR strain was defined as those that is resistant to three or more classes of antibiotics.

Perioperative patient management protocol: All the patients scheduled for elective surgery are first examined for any condition that precludes surgery. This involves a preoperative fitness clearance from the anesthetists. The night before surgery patients takes a head bath with shampoo. The Institute has a protocol for antibiotics prophylaxis [Appendix]. The antibiotics used are dependant on the prevalent pattern of antibiotic sensitivity. Strict precaution is taken throughout, to ensure that there is no breach in sterility perioperatively. As a rule, we follow a policy of CSF analysis (unless contraindicated), before starting empirical antibiotics. Once the culture-sensitivity report is ready, the antibiotic is changed. The antibiotics are continued till the patient becomes clinically afebrile, for a period of 14 days or till the cultures become sterile, whichever is later.

Results

During the study period, 18,092 patients were operated and the breakup of the cases and the incidence of meningitis are given in [Table - 1]. There were a total of 415 patients who developed infection. The overall incidence of meningitis in patient with cranial surgeries was 2.1%. In elective cranial surgeries it was 2.2% and in emergency cranial surgery 2.1%. Patients who had a pre-existing infection like post-pyogenic meningitis or tuberculosis with hydrocephalous had a higher incidence of meningitis (P <0.05). This was followed by surgeries for intracranial tumors and surgery for various kinds of trauma and shunt-related surgeries.

The profile of the causative organisms is given in [Table - 2]. The most common organisms causing meningitis were non-fermentative Gram-negative bacteria (NFGNB) (27.3%) followed by Pseudomonas aeruginosa (15.6%) and Klebsiella species (12.6%). The overall mortality in patients with meningitis was 5%. This included all the patients who developed postoperative meningitis and expired, regardless of the final cause of death.

Among the 415 different organisms isolated (in patients who had various isolates, only the predominant isolate or the mutidrug-resistant strain among the various species isolated were included), four strains were resistant to all the drugs while 87 strains were sensitive to a single antibiotic [Table - 3]. Analysing the antibiotic sensitivity profile, imipenem (31%) and aminoglycoside (32%) were the most active against the MDR strains. The results are summarized in [Table - 4].

Discussion

Prevention of bacterial infections is one of the most important aspects in surgery, especially in neurosurgery, where a highly sterile environment is of utmost importance. In addition to the mortality and morbidity, infections are associated with enormous economic burden to the patients and also to the hospital. In India, in cases of multidrug-resistant infections, patient may have to spend up to $100 to 200 per day on antibiotics alone. These cost considerations are of relevance as most of the patients to which our Institute caters are from low economic strata. In our country, most often the patients bear the medical expenses from their own pocket.

The importance and efficacy of antibiotic prophylaxis has been conclusively established in various studies. ^[6],[7],[8] Different centers have used different antibiotic regimens and the reported incidence of postoperative central nervous infection (PCNSI) has varied from 0.5% to 7. ^{[1],[2],[3],[4],[5]} In the study by McClelland et al. ^[3] , the incidence of PCNSI was 0.8% and 0.4% in spinal surgeries. The most common organism was Staphylococcus aureus followed by Propionibacterium acnes. In the series by Kourbeti et al. ^[5] , the incidence of meningitis was 5.5% and in the majority it was caused by Gram-positive cocci. In the study by Blomstedt et al., ^[9] the incidence of infection was 7%. In our study the overall rate of meningitis was 2.1%, with an overall mortality rate of 5%, which compared favorably with other studies. ^{[1],[2],[3],[4],[5]} The most common organism in our series was NFGNB followed by Pseudomonas. This is in variance with the other studies. In the study by Dashti et al., ^[1] the most common organism was S. aureus (36%), while in others the reported rate varied upto 50%. ^[1],[10]

In a large prospective multicenter study of 2944 adults who underwent craniotomy, the independent risk factors for infection were CSF leakage and a subsequent operation while the independant predictive risk factors were non-elective surgery, clean-contaminated and dirty wounds, operative time > 4 hours, and more recent neurosurgery. Usage of antibiotic prophylaxis was not a factor. ^[11] In the study by Patir et al., ^[12] the risk factors for postoperative infection were altered sensorium, multiple operations, pre-existing infection, emergency surgery, duration of surgery for more than four hours, urinary catheterization, cerebrospinal fluid leak, and ventilatory support.

The other aspect that needs discussion is whether antibiotic prophylaxis is necessary or is there a need to shift to the newer generation antibiotics which are more expensive. In a large multicenter prospective study Korinek et al. ^[11] did not find the non-usage of antibiotic prophylaxis to be a risk factor for postoperative infections. The data of the metaanalysis of 1729 patients from six randomized studies suggests that prophylactic antibiotics administered before craniotomy reduces the rates of postoperative meningitis by approximately one-half. ^[6] Pons et al. ^[12] compared the use of ceftizoxime vs. vancomycin and gentamicin in neurosurgical prophylaxis and found that ceftizoxime was effective and less toxic with good cerebrospinal fluid penetration. Our antibiotic protocol includes cefotaxim and we have found it to be effective for the existing flora at our center. In our study Gram-negative bacteria were the predominant organisms. This is in contrast to the western studies where Gram-positive bacteria are the predominant organisms. ^{[11],[13],[14]} In the study by Erdem et al. ^[15] , the incidence of postoperative meningitis was 2.7% and the most common organisms isolated were S. aureus and Acinetobacter species.

The limitation of this study is that it is a retrospective one. We have included only patients with culture positive meningitis. Since CSF examination was performed only in those patients with clinical features of meningitis, it is quite possible that we could have missed come cases of meningitis by this inclusion criteria. In our study the mortality was only 5%. This was in spite of NFGNB (27.3%) being the common pathogen and a significant proportion of the pathogens being MDR strains.

Conclusion

In this article we have reviewed our experience with post operative meningitis. We recommend the use of affordable antibiotics depending on the prevalent bacterial flora and their sensitivity pattern

References

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