Keywords
tracheostomy - children - adolescents - infection - bacteria - tracheal aspirate
Introduction
People with tracheostomies are under a greater risk of respiratory infections because
the tracheostomy tube functions as a bypass that eliminates the protection provided
by the nasal cavity. In addition to suppressing functions involving filtration, humidification,
and warming of the air, the tracheostomy creates a direct entrance for viruses and
bacteria into the lower respiratory tract. The presence of the tube also causes a
local inflammatory reaction that increases the risk of infection.[1] Some studies show that it is virtually impossible to keep the lower respiratory
tract sterile in children; pathogens have been found to be present in up to 100% of
children 2 weeks after surgery.[2]
[3]
[4] It is common for tracheostomized children to have their trachea colonized by bacteria.
This colonization can increase the risk of infection, usually by the same agent present
in their respiratory tracts.[5]
[6] However, some authors suggest that lower respiratory tract infections in tracheostomized
children do not occur because of colonizing bacteria, but because of exposure to other
bacteria.[7]
Tracheal secretion cultures have been used to treat tracheostomized children with
irritation in the lower respiratory tract, as well as to guide therapy with antibiotics
after laryngotracheal surgery.[6]
[8]
[9]
Since the 1960's, the number of children hospitalized on mechanical ventilation in
intensive care units has increased; with this increase, the need for tracheostomies
in this age group has increased as well.[10]
[11] This movement was accompanied by an increase in the number of surgeries for laryngotracheal
reconstruction, particularly in the 1970's, because these children needed to be rehabilitated.[12]
[13] One of the key points for the success of the procedure is the prevention and treatment
of infection at the surgical site, since infection can lead to therapeutic failure,
loss of the graft, bacterial superinfection and sepsis. In these cases, the sensible
and guided use of antibiotics would be essential.[14]
[15]
[16]
There is a lack of data on tracheal secretion cultures in tracheostomized children
and adolescents in Brazil. As a result, the main pathogens responsible for colonizing
and/or infecting the patients' tracheae are not known. Some Brazilian hospitals may
perform routine research on the microorganisms present in their patients' tracheae,
but access to that data is limited, since published data are scarce. It is still impossible
to know if the treatment for lower respiratory tract infections in these patients
is handled empirically or if it is based on guidance from laboratory diagnosis. Considering
these facts, the evaluation of the tracheal secretion cultures of children and adolescents
from our hospital could provide information with immediate as well as future impacts
on the care provided to these patients.
Objective
To evaluate the microbiology of tracheal secretion aspirates from tracheostomized
patients under 18 years old treated in a tertiary referral hospital.
Materials and Methods
This is a cross-sectional prospective study. Tracheostomized patients up to 18 years
of age treated in the Otorhinolaryngology department of our tertiary referral hospital
between November 2014 and November 2015 were evaluated. All patients with tracheostomies
of our ear, nose and throat department were invited to participate in the research.
The study has been submitted on the Plataforma Brasil website, and has been approved
by the institution's ethics committee (CAAE Registry No.: 046819/2014). The patients'
guardians and the children themselves were invited to participate in this study, which
was developed after they signed the informed consent form.
Tracheal secretions were collected using sterile gloves and by aspirating the patients
using an aspiration tracheal probe recommended for the size of the tracheostomy tube.
Once the tracheal secretion filled the probe completely, a sterile syringe containing
2 mL of saline solution was attached to the probe, and the content was injected until
all of the content in the probe had been collected in a sterile vial appropriate for
microbiological cultures.
The specimens were seeded in blood agar, chocolate agar and MacConkey agar (BD, Franklin
Lakes, NJ, US) using the standard technique.[4]
[6] The plaques were incubated in 5–7% CO2 at temperatures between 35°C and 37°C for 48 hours. Bacterial growth was quantified
as the amount of colony forming units per mL (CFU/mL). All microorganisms identified
were reported. Counts of over 106 CFU/mL were considered positive.[4]
[6]
[8]
[16]
All children underwent laryngeal evaluations using a flexible nasal fiberscope, as
well as rigid laryngeal endoscopies using 0°, 30°, and 70° endoscopes to diagnose
laryngotracheal pathologies.
The data collected were organized in an Excel® (Microsoft, Redmond, WA, US) spreadsheet for analysis in the Statistical Package
for the Social Sciences (IBM SPSS®, Chicago, IL, US) software, version 20.0. All means are presented with standard deviation
(SD) values. Descriptive statistics, such as percentages, were used to describe the
cultured microorganisms in the full cohort of study subjects. Fisher's exact test
was used to determine if there was a nonrandom association between the categorical
variables. A value of p < 0.05 was considered statistically significant for all analyses.
Results
A total of 20 children under 18 years of age (7.5 ± 5 years) were evaluated, 13 (65%)
of whom were male. The average age at the time of the tracheostomy was 2.8 ± 3.6 years
of age. About half the procedures were made by the emergency care team, meaning the
patient presented severe respiratory distress without the possibility of endotracheal
intubation. The data are presented in [Table 1].
Table 1
General data on the patients who participated in the study
|
Clinical and epidemiological characteristics
|
|
|
Age (years)
|
7.5 ± 5
|
|
Male gender
|
13 (65%)
|
|
Age when tracheostomy was performed (years)
|
2.8 ± 3.66
|
|
Urgent tracheostomy
|
9 (45.0%)
|
The most common disease found in the endoscopic evaluation of the respiratory tract
was acquired subglottic stenosis, followed by neoplasia, including recurring laryngeal
papillomatosis and one case of giant cervical lymphangioma with laryngeal and tracheal
extensions, as shown in [Table 2].
Table 2
Causes of obstruction of the upper respiratory tract
|
n (%)
|
|
Acquired glottic stenosis
|
12 (60%)
|
|
Laryngeal neoplasia
|
3 (15%)
|
|
Tracheal stenosis
|
2 (10%)
|
|
Vocal cord immobility
|
1 (5%)
|
|
Craniofacial alterations
|
1 (5%)
|
|
Laryngeal membrane
|
1 (5%)
|
Among the children analyzed, 45% exhibited some sort of comorbidity, and 40% had been
born premature. Prematurity was found to have a statistically significant association
with the presence of comorbidities (p = 0.002). The most common comorbidities were pneumopathies, followed by neuropathies,
as shown in [Table 3]. Two children had respiratory distress syndrome, two had bronchopulmonary dysplasia,
and one had Lung-Kidney disease. Of the patients with neuropathy, all of them (n = 2) had cerebral palsy.
Table 3
Comorbidity found among patients with tracheostomies
|
Comorbidity
|
n (%)
|
|
Pneumopathy
|
6 (30%)
|
|
Neuropathy
|
2 (10%)
|
|
Genetic syndrome
|
2 (10%)
|
|
Cardiopathy
|
1 (5%)
|
|
Alterations in the gastrointestinal tract
|
1 (5%)
|
Only 10% of the patients had negative tracheal secretion cultures, and, in patients
with positive cultures, the most prevalent microorganism was Pseudomonas aeruginosa, followed by Staphylococcus aureus ([Table 4]). Among the children with positive cultures for P. aeruginosa, six (60%) had been born premature; among the children carried to term, only 30%
were colonized by the same microorganism. Two patients (10%) had positive cultures
for more than one microorganism. There was no statistically significant correlation
between the pathogen identified and age, gender, prematurity, or urgency of the procedure.
Table 4
Frequency of microorganisms found in tracheal secretions and antibiotics used to counter
them
|
Microorganism
|
n (%)
|
Sensitivity (%)
|
|
Staphylococcus aureus
|
5 (25%)
|
|
|
Benzylpenicillin
|
|
0
|
|
Sulfamethoxazole / Trimethoprim
|
|
40%
|
|
Vancomycin
|
|
100%
|
|
Tetracycline
|
|
100%
|
|
Clindamicyn
|
|
40%
|
|
Oxacylin
|
|
100%
|
|
Erytromycin
|
|
40%
|
|
Pseudomonas aeruginosa
|
10 (50%)
|
|
|
Imipenem
|
|
90%
|
|
Amycacin
|
|
80%
|
|
Aztreonan
|
|
80%
|
|
Ciproflaxacin
|
|
80%
|
|
Gentamicin
|
|
80%
|
|
Levofloxacin
|
|
80%
|
|
Meropenem
|
|
90%
|
|
Ceftazidime
|
|
90%
|
|
Morganella morganii
|
2 (10%)
|
|
|
Amicacin
|
|
100%
|
|
Ceftazidime
|
|
100%
|
|
Amoxicilin + clavulanate
|
|
0
|
|
Ceftriaxone
|
|
100%
|
|
Levofloxacin
|
|
100%
|
|
Meropenen
|
|
100%
|
|
Klebsiella pneumoniae
|
1 (5%)
|
|
|
Cefepime
|
|
100%
|
|
Ceftazidime
|
|
100%
|
|
Ciprofloxacin
|
|
100%
|
|
Amicacyn
|
|
100%
|
|
Imipenem
|
|
100%
|
|
Gentamicin
|
|
100%
|
|
Ampicilin
|
|
0
|
|
Stentotrophomonas sp.
|
1 (5%)
|
|
|
Cefepime
|
|
100%
|
|
Ceftazidime
|
|
100%
|
|
Ciprofloxacin
|
|
100%
|
|
Amicacyn
|
|
100%
|
|
Imipenem
|
|
100%
|
|
Gentamicin
|
|
100%
|
|
Sulfametoxazol + trimetropim
|
|
0
|
|
Proteus mirabilis
|
1 (5.5%)
|
|
|
Amicacin
|
|
100%
|
|
Amoxicilin + clavulanate
|
|
100%
|
|
Ampicilin
|
|
100%
|
|
Cefepime
|
|
100%
|
|
Ceftriaxon
|
|
100%
|
|
Gentamicyn
|
|
100%
|
Discussion
Most of the evaluated children were male, as found in other studies.[4]
[17]
[18]
This study confirms previous findings that most tracheostomized children experience
tracheal colonization by potentially pathogenic bacteria, similar to what occurs in
patients with chronic obstructive pulmonary disease and cystic fibrosis.[1]
[6]
[9]
[19] The most frequent microorganisms found in the literature were P. aeruginosa and S. aureus.
None of our cultures were positive for methicillin-resistant Staphylococcus aureus (MRSA), which differs from the literature,[4]
[7]
[18] and that suggests that MRSA grows in countries where the use of antibiotics has
grown and in children with tracheostomies in place for more than 5 years.[18] Thus, when a patient with a tracheostomy presents with signs and symptoms of respiratory
infection, suspicion of MRSA should be higher in those who have had a tracheostomy
in place longer. Colonization by more than one type of bacteria is not uncommon in
the literature, a finding which is consistent with the evidence found in our study.[17]
[18]
[19] Although we included children with a great variability of age and pathologies, microorganisms
similar to the ones found in other studies were found in our tracheal cultures.[7]
[9]
[17]
[18]
Tracheostomies increase the risk of infection by allowing the air to reach the respiratory
tract without having been humidified, warmed, or filtered in the nasal cavity. In
addition, the tube itself causes a local inflammatory reaction, and increases the
susceptibility to colonization of the mucous membrane by several pathogens, thus increasing
the predisposition to infection.[1]
[8] It is also known that local hygiene is not always performed as recommended. Respiratory
tract manipulation that occurs during the aspirations and tube changes cannot be underestimated.[9]
[20] Several studies have established that subjects with long-term tracheostomies become
chronically colonized with bacteria that may lead to serious illness and complications.[2]
[8]
[21] However, there are no studies describing the relationship between the length of
time with the tracheostomy and the spectrum of bacterial growth. Our sample is not
enough to infer anything related to that.
Some studies suggest that routine tracheal secretion cultures can direct antibiotic
therapy in cases of acute infections of the lower respiratory tract, similar to what
occurs in patients with cystic fibrosis.[2]
[16]
[21] However, some studies suggest that, although tracheal colonization is common, the
microorganisms involved differ from those found in routine cultures, and that the
change in potentially pathogenic bacteria occurs every two weeks among individuals
outside a hospital environment.[7]
[20] Nurture, the accuracy of the culture can be affected by the colonization of the
upper respiratory tract, as well as by contamination of the instruments used in the
procedure, factors that generate false positives in the results.[22]
[23]
[24]
In recent decades, improvements in upper respiratory tract surgery performed in the
form of endoscopies as well as through external access have allowed for a growing
number of children to be decannulated. Postoperative infections are known to decrease
the success rate of surgeries, to lead to the loss of the graft, and to cause sepsis.[25] Although the effects of bacterial colonization in the induction of tracheal subglottic
stenosis are still uncertain, some studies suggest these factors may be related.[14]
[26]
[27] The knowledge of which pathogens are present can direct preventive health care and
prevent infection while avoiding the use of antibiotics of an inadequate spectrum.
A careful evaluation of the literature shows that, although colonization of the respiratory
tract in tracheostomized children is certain, there are still many doubts involved
in this situation. Are potentially pathogenic bacteria responsible for exacerbating
upper respiratory tract infections? What is the influence of potentially pathogenic
bacteria on the occurrence of tracheal and laryngeal stenosis? Can potentially pathogenic
bacteria decrease the success rate of laryngeal and tracheal reconstruction? Can potentially
pathogenic bacteria be countered? If so, how can it be accomplished?
Studies are scarce, discordant, present low levels of evidence, low numbers of patients,
and are mainly retrospective.[2]
[8]
[20]
[21]
[28]
Our study presents several limitations. The sample size prevents adequate statistical
analysis and a generalization of the results found. Because the patient sample is
incongruous, the results cannot be adjusted by other factors, such as the amount of
time between the tracheostomy and the collection of the material, the presence of
comorbidities, and the presence of hospital environment pathogens. This information
is limited because some patients were admitted to the hospital at the time of the
exam. Anaerobic bacteria cultures were not performed because of the hospital's limited
infrastructure. This study, however, is one of the few prospective studies involving
children and adolescents, and is the only one published in indexed databases in Brazil.
Studies with a higher number of patients, with systematic logging of aggravating conditions,
and with laboratory exam results from children with tracheostomies must be performed
in order to improve the care provided to these patients.
Conclusion
This study found that positive bacterial cultures are common in children and adolescents
with tracheostomies, especially cultures of P. aeruginosa and S. aureus. The sample size prevents adequate statistical analysis and a generalization of the
results found. We suggest that the routine access to tracheal secretions of people
with tracheostomy cultures would help make a microbiological profile and guide the
use of antibiotics.
