3.3 Systemic (intravenous or enteral) antibiotics
Six retrospective cohort studies looked at the use of systemic
antimicrobials; these are summarised on table 1. Of these studies, one
covered initiation of antimicrobials in outpatient clinics27, four
looked at choice of inpatient antimicrobials28–31,
and one assessed impact of duration of antimicrobial therapy for airway
infections16.
Majmudar et al. compared antimicrobial prescription (enteral or inhaled)
versus increased airway clearance therapies (chest physiotherapy and the
use of nebulisers to assist coughing) alone for the management of LRTI
in tracheostomy dependent children. In their retrospective cohort of 283
episodes of LRTI in 82 children, they found that conservative management
with airway clearance alone did not result in significantly more
hospitalisations within 28 days of treatment, compared to those who
received an antimicrobial: adjusted OR 1.47 (95% CI: 0.75, 2.86);
p=0.2627.
However, clinician choice of whether to initiate antimicrobials or
airway clearance was likely based upon a clinical assessment of LRTI
severity with no form of randomisation, biassing the study results. In
part, this may reflect the difficulties clinicians have in
differentiating bacterial and non-bacterial LRTI leading to excessive
antimicrobial prescribing. This challenge is highlighted by a
retrospective cohort study of 90 patients who received a tracheostomy
over a 14 year period32.
During this time, there were 137 hospital admissions with LRTIs
affecting 46.7% (n=42) of the cohort, of which over a third were
treated with antimicrobials despite only 8.5% being defined as definite
bacterial pneumonia. In this study, definite bacterial pneumonia was
defined as a fever plus one or more of the following signs/symptoms: i)
new onset of purulent sputum or change in character of sputum, or
increased respiratory secretions, or increased suctioning requirements;
ii) new onset or worsening cough, or dyspnoea, or tachypnoea; iii) rales
or bronchial breath sounds; iv) worsening gas exchange.
Anti-pseudomonal antimicrobials were the predominant choice for the
treatment of tracheostomy associated airway infections in the available
literature. A retrospective review of 76 episodes of
ventilator-associated tracheobronchitis in 60 children reported that
enteral fluoroquinolones effectively treated the majority of infections
(65/76, 86%)30.
Interestingly, two large retrospective cohort studies using the
Paediatric Health Information System database in the United States
between 2007 and 2014 reported that use of empirical anti-pseudomonal
antibiotics on an individual level, or higher use on a hospital level
was associated with longer hospital admissions, but not 30-day
readmission rate28,29.
However, the longer length of hospital admissions observed here may have
been attributable to infection severity, antimicrobial resistance
limiting enteral treatment options, difficulty obtaining home
intravenous antimicrobial therapy, hesitance to transition from the
intravenous to enteral route, or other unmeasured confounders28.
Only one study investigated the optimal duration of antimicrobial
therapy in tracheostomy dependent children. In their retrospective
cohort study of 118 children diagnosed with ventilator-associated
tracheobronchitis, fewer patients who received a short-courses of
antimicrobials (<6 days) developed a hospital or ventilator
acquired pneumonia within 10 days of completing antimicrobials.
Additionally, prolonged courses of antimicrobials did significantly
increase the risk of multidrug resistant organisms being identified in
patients’ subsequent cultures16.