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.