Risk factors for respiratory tract bacterial colonization in adults with neuromuscular or neurological disorders and chronic tracheostomy

The Frequency of Occurrence of Resistance and Genes Involved in the Process of Adhesion and Accumulation of Biofilm in Staphylococcus aureus Strains Isolated from Tracheostomy Tubes

Background: Bacterial biofilm on the surface of tracheostomy tubes (TTs) is a potential reservoir of potentially pathogenic bacteria, including S. aureus. For this reason, our study aimed to investigate biofilm production in vitro and the presence of icaAD and MSCRAMM genes in clinical S. aureus strains derived from TTs, with respect to antibiotic resistance and genetic variability. Methods: The clonality of the S. aureus strains was analyzed by the PFGE method. The assessment of drug resistance was based on the EUCAST recommendations. The isolates were evaluated for biofilm production by the microtiter plate method and the slime-forming ability was tested on Congo red agar (CRA). The presence of icaAD genes was investigated by PCR and MSCRAMM genes were detected by multiplex PCR. Results: A total of 60 patients were enrolled in the study. One TT was obtained from each patient (n = 60). Twenty-one TTs (35%) were colonized with S. aureus. A total of 24 strains were isolated as 3 patients showed colonization with 2 SA clones (as confirmed by PFGE). PFGE showed twenty-two unique molecular profiles. Two isolates (8%) turned out to be MRSA, but 50% were resistant to chloramphenicol, 25% to erythromycin and 8% to clindamycin (two cMLS_B and four iMLS_B phenotypes were detected). The microtiter plate method with crystal violet confirmed that 96% of the strains were biofilm formers. Representative strains were visualized by SEM. All isolates had clfAB, fnbA, ebpS and icaAD. Different MSCRAMM gene combinations were observed. Conclusions: the present study showed that the S. aureus isolated from the TTs has a high diversity of genotypes, a high level of antibiotic resistance and ability to produce biofilm.

Rethinking the ‘Pan-culture’: Clinical Impact of Respiratory Culturing in Patients with Low Pretest Probability of Ventilator-associated Pneumonia

Background

Respiratory cultures are often obtained as part of a “pan-culture” in mechanically ventilated patients in response to new fevers or leukocytosis, despite an absence of clinical or radiographic evidence suggestive of pneumonia.

Methods

This was a propensity score–stratified cohort study of hospitalized mechanically ventilated adult patients between 2014 and 2019, with a new abnormal temperature or serum white blood cell count (NATW), but without radiographic evidence of pneumonia, change in ventilator requirements, or documentation of purulent secretions. Two patient groups were compared: those with respiratory cultures performed within 36 hours after NATW and those without respiratory cultures performed. The co-primary outcomes were the proportion of patients receiving >2 days of total antibiotic therapy and >2 days of broad-spectrum antibiotic therapy within 1 week after NATW.

Results

Of 534 included patients, 113 (21.2%) had respiratory cultures obtained and 421 (78.8%) did not. Patients with respiratory cultures performed were significantly more likely to receive antibiotics for >2 days within 1 week after NATW than those without respiratory cultures performed (total antibiotic: adjusted odds ratio [OR], 2.57; 95% CI, 1.39–4.75; broad-spectrum antibiotic: adjusted OR, 2.47, 95% CI, 1.46–4.20).

Conclusions

Performance of respiratory cultures for fever/leukocytosis in mechanically ventilated patients without increasing ventilator requirements, secretion burden, or radiographic evidence of pneumonia was associated with increased antibiotic use within 1 week after incident abnormal temperature and/or white blood cell count. Diagnostic stewardship interventions targeting performance of unnecessary respiratory cultures in mechanically ventilated patients may reduce antibiotic overuse within intensive care units.

Biofilm Formation of Clinical Klebsiella pneumoniae Strains Isolated from Tracheostomy Tubes and Their Association with Antimicrobial Resistance, Virulence and Genetic Diversity

(1) Background: Due to the commonness of tracheotomy procedures and the wide use of biomaterials in the form of tracheostomy tubes (TTs), the problem of biomaterial-associated infections (BAIs) is growing. Bacterial colonization of TTs results in the development of biofilms on the surface of biomaterials, which may contribute to the development of invasive infections in tracheostomized patients. (2) Methods: Clinical strains of K. pneumoniae, isolated from TTs, were characterized according to their ability to form biofilms, as well as their resistance to antibiotics, whether they harbored ESβL genes, the presence of selected virulence factors and genetic diversity. (3) Results: From 53 patients, K. pneumoniae were detected in 18 of the TTs examined, which constituted 34% of all analyzed biomaterials. Three of the strains (11%) were ESβL producers and all had genes encoding CTX-M-1, SHV and TEM enzymes. 44.4% of isolates were biofilm formers, SEM demonstrating that K. pneumoniae formed differential biofilms on the surface of polyethylene (PE) and polyvinyl chloride (PVC) TTs in vitro. A large range of variation in the share of fimbrial genes was observed. PFGE revealed sixteen genetically distinct profiles. (4) Conclusions: Proven susceptibility of TT biomaterials to colonization by K. pneumoniae means that the attention of research groups should be focused on achieving a better understanding of the bacterial pathogens that form biofilms on the surfaces of TTs. In addition, research efforts should be directed at the development of new biomaterials or the modification of existing materials, in order to prevent bacterial adhesion to their surfaces.

The effect of nebulized antibiotics in children with tracheostomy

INTRODUCTION

Children with tracheostomy have an increased risk of bacterial colonization and infection of the lower respiratory tracts. This study aimed to investigate the effects of nebulized antibiotics on the bacterial load, the need for oral antibiotics, the number of hospitalizations, and the length of stay in the intensive care unit in tracheotomised children with persistent colonization.

METHODS

Children with tracheostomy and persistent bacterial colonization who were started on nebulized antibiotic therapy after a lower respiratory tract infection were included in the study. Nebulized gentamicin or colistin were used according to the results of the tracheal aspirate cultures. Demographic and clinic characteristics were recorded from one year prior until one year after initiation of nebulized antibiotic treatment.

RESULTS

Nebulized antibiotic treatment was initiated in 22 patients. Nebulized gentamicin was administered to 14 patients (63.6%) and colistin to 8 patients (36.4%). The median duration of treatment was 3 months (range 2-5 months). Following nebulized antibiotic treatment, median number of hospitalizations decreased from 2 (range 1.0-3.5) to 1 (range 0.0-1.5) (p = 0.04). The median length of stay in the intensive care unit reduced significantly from 89.5 days (range 43.0-82.5) to 25 days (range 7.75-62.75) after starting nebulized antibiotics (p = 0.028). Following nebulized antibiotic treatment median bacterial colony count also decreased (from 10⁵ CFU/ml (range 10⁵-10⁶) to 6 × 10⁴ CFU/ml (range 10⁴-10⁵); p = 0.003). There were no significant side effects during nebulized antibiotic therapy.

CONCLUSIONS

The use of nebulized antibiotics reduced the number of hospitalizations, length of stay in the intensive care unit, and bacterial load in tracheotomised children with persistent airway colonization without significant side effects. The use of nebulized antibiotics showed a statistically significant decrease in the measures studied. Use of nebulized antibiotics may help to decrease the health care burden of these children, families and health care system. Further studies are needed to determine the indications and optimal duration of long-term nebulized antibiotic treatment in children with tracheostomy.

Microbiological profiles of tracheostomy patients: a single-center experience

Background

This study compared the prevalence of common microorganisms in obstructed and non-obstructed cases across the four quarters on the first post-tracheostomy year.

Methods

A retrospective chart review of the microbiological profiles of all adult patients who underwent a tracheostomy was conducted between June 2015 and September 2019 at our hospital. Based on the tracheostomy indications, patients were allocated to obstructed or non-obstructed group. Any patient with at least one positive sample was followed up quarterly for a year. The first culture result obtained was recorded at least one month following the last antibiotic dose in each quarter.

Results

Out of the 65 tracheal aspirate results obtained from 58 patients (mean age, 57.5±16.48 years), the most common procedure and indications were surgical tracheostomy (72.4%) and non-obstructed causes (74.1%), respectively. Moreover, 47.7% of the culture results indicated Pseudomonas aeruginosa, which showed significantly different proportions across the quarters (p=0.006). Among obstructed patients, P. aeruginosa was the most common (35%), followed by methicillin-resistant Staphylococcus aureus (MRSA; 23.5%).

Conclusions

The most common post-tracheostomy microorganism was P. aeruginosa. MRSA showed a strong association with tracheostomy for obstructive indications.

Pseudomonas aeruginosa infection in respiratory samples in children with neurodisability-to treat or not to treat?

The objective was to investigate the prevalence of Pseudomonas aeruginosa (PA) in patients with complex neurodisability and current treatment practice in our centre in order to inform future guidelines. A retrospective case note review was undertaken at a tertiary children's hospital. One hundred sixty-two patients (mean age 11.7 years) with a primary diagnosis of neuromuscular disease (NMD) or severe cerebral palsy (CP) and a respiratory sample sent for analysis during the study period were studied. Associations between PA in respiratory samples and diagnosis, long-term ventilation, presence of a gastrostomy or a tracheostomy, antibiotic choice, clinical deterioration and adverse events were analysed. Twenty-five (15%) had one or more PA isolate in respiratory samples. There was a significant association between PA in respiratory samples and tracheostomy (p<0.05). In 52% samples, multiple pathogens co-existed. There was no significant association between choice of antibiotic and clinical outcome but when antibiotics were changed to specific PA antibiotics during the course of the illness, all resulted in clinical improvement. Twenty-six episodes involving 8 patients with recurrent admissions involved PA organisms that were resistant to one or more antibiotics.Conclusions: A larger prospective study may establish clearer criteria for guideline development. Techniques such as point-of-care testing to identify virulent strains of PA may improve patient outcomes and prevent the development of antibiotic resistance in the future. What is Known: •Children with complex neurodisability are at increased risk of respiratory morbidity and of infection with gram-negative organisms such as Pseudomonas aeruginosa. •There are currently no guidelines to inform treatment choices in this group of vulnerable children. What is New: •15% children in this study population had Pseudomonas aeruginosa in respiratory samples during a 12-month period, the majority of whom did not require critical care treatment. Thirteen of these children had a tracheostomy in situ and 12 did not.  •In those that deteriorated clinically or developed antibiotic resistant organisms, earlier detection and targeted treatment of Pseudomonas aeruginosa may have prevented deterioration.

Effect of probiotics on multi-resistant organism colonisation in persons with spinal cord injury: secondary outcome of ProSCIUTTU, a randomised placebo-controlled trial

STUDY DESIGN

Randomised double-blind placebo-controlled trial.

OBJECTIVES

Multi-resistant organism (MRO) colonisation is common in people with SCI. We aimed to determine whether Lactobacillus reuteri RC-14 + Lactobacillus GR-1 (RC14-GR1) and/or Lactobacillus rhamnosus GG + Bifidobacterium BB-12 (LGG-BB12) are effective in preventing or clearing MRO colonisation.

SETTING

New South Wales, Australia.

METHODS

The 207 SCI participants were randomised to one of four arms: (i) RC14-GR1 + LGG-BB12, (ii) RC14-GR1 + placebo, (iii) LGG-BB12 + placebo or (iv) double placebos for 6 months. Microbiological samples of nose, groin, urine and bowel were taken at baseline, 3 and 6 months. Analysis was conducted for the presence of methicillin-resistant Staphylococcus aureus (MRSA), multi-resistant gram-negative organisms (MRGNs) and vancomycin-resistant enterococcus (VRE). The outcomes were clearance of, or new colonisation with MRSA, MRGN, VRE or MROs and whether participants remained free of MRSA, MRGN, VRE or MROs throughout the study. Risk factors associated with an outcome were adjusted for using nominal or binary logistic regression.

RESULTS

There was a significant reduction in new MRGN colonisation compared with placebo for participants treated with RC14-GR1 (OR 0.10, 95% CI, 0.01-0.88, P = 0.04), after allowing that inpatients were more likely to be newly colonised (OR 21.41, 95% CI, 3.98-115.13, P < 0.0001). Participants who intermittent self-catheterised (IMC) were more likely to remain MRO-free than those utilising SPC or IDCs (OR 2.80, 95% CI, 1.41-5.54, P = 0.009).

CONCLUSIONS

Probiotics are ineffective at clearing MROs in people with SCI. However, RC14-GR1 is effective at preventing new colonisation with MRGNs. The use of IMC significantly improves the chance of remaining MRO-free.