Keywords
anterior skull base surgery - nasal packing - bacterial culture
Introduction
Endoscopic endonasal corridor has emerged as the first choice among all the approaches
for pituitary adenoma, anterior skull base meningioma, majority of craniopharyngioma,
and many other skull base tumors. One of the crucial steps in the above approach involves
reconstruction of skull base after tumor excision. Various techniques, including pedicle
flap, reverse pedicle flap, mucosal flap, etc. have been described in literature.[1] Nonetheless, use of nasal packs to reinforce the above reconstructions is one of
the popular teachings practiced worldwide. However, as our insight in sinonasal physiology
grew, the opponents of the nasal packing step pointed out its subclinical and unaddressed
problems. One of the major issues related to the use of nasal packs is the possibility
of infection or meningitis. This study aims to study the infective potential of nasal
packs in postoperative period by analyzing bacterial growth over these packs.
The nasal cavity is known to harbor a natural nasal bacterial flora, and this cavity
acts as gateway to anterior skull base and cranial fossa. Staphylococcus aureus is
the commonest nasal commensal and the bacteria is implicated in many clinical infections.[1] This fact was reported by Danbolt (1931) in his report on furunculosis. The methicillin-resistant
Staphylococcus aureus (MRSA) is another potential pathogen implicated in wide range
of infections. Majumdar et al reported that even the healthy population harbor a nasal
carrier state of almost 25%.[2] In a similar study by Kuehert et al, the Western population was studied, and Staphylococcus
aureus and MRSA colonization was found to be present in nearly one-third of the population.[3] These nasal carriers are supposed to have the maximum load and disperse organisms
at the highest rate.[4] These facts are important for skull base surgeons, as there is a theoretical possibility
of introducing the above-mentioned nasal commensals into the cranial cavity during
endoscopic endonasal surgery (EES). Henceforth, the practice of using nasal packing
in EES became controversial, as it poses the potential risk of contracting meningitis.
Despite being an important clinical issue, there is lack of substantial recommendation
or large population-based studies guiding surgeons on the judicious use of nasal packing.
Materials and Methods
This is a prospective, observation, single institutional study, wherein the bacterial
culture from the secretions of the post-EES nasal packs were analyzed. The study included
the patients with central skull-based tumors irrespective of histopathology. Preoperative
nasal swab was taken for aerobic culture to identify the normal nasal carrier state
of the patient. The nasal packing was done with Merocel packs smeared with Betadine
ointment bilaterally. The intention of using nasal packs was both to provide pressure
over the nasal mucosa to achieve hemostasis and reinforce the skull base reconstruction.
We removed the nasal packs between the 3rd and 5th postoperative day, and all the
patients were administered empirical intravenous antibiotics for 48 hours. The pack
removal was done in an aseptic manner and those packs were preserved in sterile containers.
The containers were transferred immediately to our microbiology department. At the
laboratory, the packs were squeezed, and the secretions were analyzed for aerobic
and anaerobic culture in the BACTEC bottles. The growth was studied up to 72 hours
of initial sampling. The data obtained was tabulated and analyzed using SPSS 22.0,
IMB. Individual patient consent was taken to use clinical and radiological data for
publication as per our departmental protocol.
Statistical Analysis
Continuous and normally distributed variable was represented as mean ± standard deviation
(SD) and categorical variable in frequency (%). Association between two categorical
variables were assessed using Fisher exact test. Simple bar diagrams and pie charts
were used to present the categorical variables in terms of their frequency (%). A
two-tailed p value < 0.05 was considered as statistically significant. The statistical analysis
was performed using the Statistical Package for Social Sciences, Version–23 (SPSS-23,
IBM, and Chicago, USA
Results
Our study included 30 patients (M:F 15:15) with a mean age of 36.10 years (SD = 12.94,
range 9–61). Among these, 63.3% (n = 19) cases had pituitary macroadenoma, four cases had craniopharyngioma, and there
was one case each of clival chordoma, olfactory grove meningioma, pituitary apoplexy,
recurrent pituitary macroadenoma, right cavernous meningioma, right para clival mass
and traumatic cerebrospinal fluid (CSF) rhinorrhea (
[Fig. 1]
). The preoperative nasal swab of two patients showed a positive smear. One patient
had both E. fecium and MRCNS, while the other patient tested positive for MRSA. The
preoperative nasal swab of the rest of the 28 patients were found to be negative for
organisms (
[Fig. 2]
).
Fig. 1 Anterior skull base pathologies in the study group.
Fig. 2 Preoperative nasal swab in study patients. E. fecium, Escherichia fecium; MRSA, methicillin-resistant
Staphylococcus aureus.
Among the postoperative nasal packs secretions culture, two patients who were nasal
carriers (6.6%) had the same organism in postoperative nasal pack secretions, while
12 patients (40%) showed a new growth of organisms (p = 0.6). The most common organism was MSCNS (n = 3; 10.0%), followed by E. fecalis (n = 3; 10.0%), MRCNS (n = 2; 6.7%), and Acinetobacter baumanni with E. fecalis, Acinetobacter baumanni with
MRCNS, Citrobacter koseni, E. fecium with MRCNS and MRSA in one patient each (3.3%).
One patient showed MRCNS in anaerobic culture (
[Fig. 3]
). Of the patients in whom the pack was removed on and before 3 days, only three patients
(out of 5, 60%) developed growth of organism compared with 11 patients (out of 25,
44%) who developed growth of organism and among whom the nasal pack was removed on
and after fourth day. Duration of packing did not show any statistically significant
association with respect to development of new colonies of organism (p = 0.642).
Fig. 3 Postoperative nasal culture in study patients. E. fecalis, Escherichia fecalis; E.
fecium, Escherichia fecium; MRSA, methicillin-resistant Staphylococcus aureus; MSCNS,
methicillin-sensitive coagulase negative Streptococcus; MRCNS, methicillin-resistant
coagulase negative Streptococcus.
Discussion
Although there are many synthetic materials available for the nasal packing, but cotton
gauze smeared with antibiotic ointment is the most popular and conventional. The commercial
nasal packs (Merocel) are expandable porous material made of polyvinyl acetate, while
absorbable nasal packs made of esterified hyaluronic acid are also available. These
nasal packs expand and exert pressure on the nasal mucosa and its blood vessels, thereby
aiding in achieving hemostasis. In the last two decades, various authors focused on
the complications and discomfort from nasal packs and argued against their use in
skull base surgery.
In EES, these packs also support the skull base reconstruction. The nasal secretions
tend to soak the porous nasal pack and provide an excellent culture media for bacteria.
The nasal commensal can flourish in such a media, and pathogens can also grow in such
a supple environment. Thus, the postoperative nasal cavity is loaded with commensals
and pathogens, which are in close proximity to the skull base defect. Henceforth,
the local transmission of bacteria and further meningitis are matters of concern.
Several studies have evaluated meningitis after EES. Lai et al performed a systematic
review of 42 articles and found an overall risk of 1.8% following EES.[5] Further, some studies including patients with postoperative CSF leak showed much
higher incidence (nearly 10–15%).[6] Arbolay et al reported that not only did 20 to 30% of their cases develop meningitis
but their series also registered a mortality of 20%.[5]
[7]
[8] In a similar study by Gupta et al, the pattern of bacterial growth in nasal packs
used in packing epistaxis were analyzed, and they found that 86.6% nasal packs had
bacterial colonisation.[9] The quoted rate was much higher than ours, as they used loose cotton packs to pack
the nasal cavity. Another study from Nepal found prevalence of bacterial growth to
be 64.7%.[10]
In our study, we had packed the nasal cavity postoperatively, and the duration of
retaining the nasal packs was based on two important factors, 1) hemostasis of the
nasal mucosa at the end of surgery and 2) the size of anterior skull base defect repair.
If there was minimal nasal mucosal bleeding at the end of the surgery and a small
defect of the dura with a low-flow CSF leak, the nasal packs were removed in 2 days.
In case of substantial nasal mucosal ooze or diffuse bleeding with a larger defect
repair, the nasal packs were retained till 5 days.
In our study, the nasal bacteriological flora grew in 46.7% patients. Two of our patients,
who were nasal carriers, showed same organism in the postoperative nasal pack culture
also. Thus, 40% patients showed a nasal pack-induced change in the nasal flora. This
proportion was similar in both the groups, that is, in the group where the packs were
removed before 4 days and in second group, where pack was removed after that. Considering
the small sample size, the statistical effect of duration of nasal packing with bacterial
growth could not be ascertained. In spite of the fact that the nasal bacteriological
flora changed in 40% of our patients, none of them developed meningitis. By performing
the nasal swab preoperatively, we can ascertain the carrier state and hence get an
idea of the culture and antibiotic assay. Therefore, if at all the patient develops
meningitis in the postoperative period, we can start antibiotics accordingly.
Conclusion
Nasal packing increases the bacterial load in the nasal cavity, and these bacterial
flora may be a potential source of meningitis. We advise to avoid these nasal packs,
or if required, remove the packs within 48 hours. A larger randomized prospective
population-based study is further needed to substantiate the conclusion. Our study
is important in highlighting a critical step and lays the foundation for future research.
A routine practice of nasal swab culture in the preoperative period and the culture
on the packs can also provide information about the normal growth pattern and the
selection of appropriate antibiotic assay.
