Early detection and treatment of bacterial infection is effective in slowing the progression of lung disease in cystic fibrosis (CF).1 It is recommended that a minimum of 4 samples are collected for bacterial culture annually.2 Approximately two-thirds of children with CF cannot routinely expectorate sputum3 ; therefore, samples, such as oropharyngeal swab (OPS), are used. With reduced hospital visits and increased telehealth consultations secondary to the severe acute respiratory syndrome coronavirus 2 pandemic, the number of samples available for analysis has been severely impacted.4 Therefore, alternative methods of obtaining OPS are needed. One option is parental collection of OPS.
Methods
Two OPS samples, by using standardized technique,5 were obtained from children with CF. Ethical approval was granted by the Sydney Children’s Hospitals Network (Ref:2019/ETH10536). The first OPS was collected by an experienced health care worker (HCW) (MD). The parent or caregiver observed the technique, were given standardized instructions, and then proceeded to obtain the second OPS.
Additionally, the test-retest reliability of OPS obtained by a HCW was investigated. On a separate visit, 2 OPS samples were collected by the same experienced HCW. Distress experienced during OPS was rated by using the Groningen Distress Rating Scale.6 Swabs were sent for bacterial culture by using standard microbiologic techniques. Positive culture results were identified as organism growth at any density.
Agreement was determined by using Cohen’s unweighted κ and reported with a 95% confidence interval. It was predetermined that at least 62 paired samples would be needed to show 80% agreement with an acceptable 95% confidence interval width of 0.3.
Results
Paired HCW-parent samples were obtained in 71 children (39 male; mean age: 7.2 years) (Table 1). Agreement was found in 58 of 71 paired swabs, with 26 of 71 positive for the same bacteria and 32 of 71 sample results both negative. A total of 8 HCW samples were positive when the parent sample result was negative; 5 parent samples were positive when the HCW sample was negative (Table 2).
Demographic data
| . | HCW-Parent (n = 71) . | HCW-HCW (n = 30) . |
|---|---|---|
| Age, mean (SD), y | 7.1 (3.2) | 7.3 (3.4) |
| Sex, male; female | 39; 32 | 17; 13 |
| Genotype | ||
| Homozygous F508del, n | 45 | 21 |
| Heterozygous F508del, n | 24 | 9 |
| Other, n | 2 | 0 |
| FEV1%pred, mean (SD) | 92 (13)a | 94 (19)b |
| . | HCW-Parent (n = 71) . | HCW-HCW (n = 30) . |
|---|---|---|
| Age, mean (SD), y | 7.1 (3.2) | 7.3 (3.4) |
| Sex, male; female | 39; 32 | 17; 13 |
| Genotype | ||
| Homozygous F508del, n | 45 | 21 |
| Heterozygous F508del, n | 24 | 9 |
| Other, n | 2 | 0 |
| FEV1%pred, mean (SD) | 92 (13)a | 94 (19)b |
FEV1%pred, forced expiratory volume in 1 second percent predicted.
n = 34.
n = 14.
Agreement Between Oropharyngeal Swabs Collected by an HCW and Parent
| Bacteria . | HCW +ve Parent −ve . | HCW −ve Parent +ve . | HCW +ve Parent +ve . | HCW −ve Parent −ve . | κ . | 95% Confidence Interval . |
|---|---|---|---|---|---|---|
| Staphylococcus aureus | 4 | 1 | 22 | 44 | 0.84 | 0.71–0.98 |
| Haemophilus influenzae | 3 | 4 | 1 | 63 | 0.17 | 0.0–0.75 |
| Pseudomonas aeruginosa | 1 | 0 | 3 | 67 | 0.85 | 0.56–1 |
| Bacteria . | HCW +ve Parent −ve . | HCW −ve Parent +ve . | HCW +ve Parent +ve . | HCW −ve Parent −ve . | κ . | 95% Confidence Interval . |
|---|---|---|---|---|---|---|
| Staphylococcus aureus | 4 | 1 | 22 | 44 | 0.84 | 0.71–0.98 |
| Haemophilus influenzae | 3 | 4 | 1 | 63 | 0.17 | 0.0–0.75 |
| Pseudomonas aeruginosa | 1 | 0 | 3 | 67 | 0.85 | 0.56–1 |
HCW, Healthcare Worker; +ve, positive; −ve, negative.
Paired HCW-HCW samples were obtained in 30 children (17 male; mean age: 7.3 years). Overall, 25 of 30 (83%) paired HCW–HCW samples were in agreeance, with 15 of 30 positive for the same bacteria and 10 of 30 samples both negative for any growth. A total of 5 of 30 (17%) paired HCW-HCW samples showed discrepant results (Table 3).
Agreement Between 2 Oropharyngeal Swabs Collected by an HCW
| Bacteria . | HCW1 +ve HCW2 −ve . | HCW1 −ve HCW2 +ve . | HCW1 +ve HCW2 +ve . | HCW1 −ve HCW2 −ve . | κ . | 95% Confidence Interval . |
|---|---|---|---|---|---|---|
| Staphylococcus aureus | 0 | 1 | 12 | 17 | 0.93 | 0.8–1 |
| Haemophilus influenzae | 1 | 0 | 2 | 27 | 0.78 | 0.36–1 |
| Pseudomonas aeruginosa | 0 | 3 | 4 | 23 | 0.67 | 0.32–1 |
| Bacteria . | HCW1 +ve HCW2 −ve . | HCW1 −ve HCW2 +ve . | HCW1 +ve HCW2 +ve . | HCW1 −ve HCW2 −ve . | κ . | 95% Confidence Interval . |
|---|---|---|---|---|---|---|
| Staphylococcus aureus | 0 | 1 | 12 | 17 | 0.93 | 0.8–1 |
| Haemophilus influenzae | 1 | 0 | 2 | 27 | 0.78 | 0.36–1 |
| Pseudomonas aeruginosa | 0 | 3 | 4 | 23 | 0.67 | 0.32–1 |
HCW1, Health care worker first sample; HCW2, Health care worker second sample; +ve, positive; −ve, negative.
The age of the child did not appear to influence results. Across all 101 paired samples, the mean age of children with concordant and discrepant results was 7.7 (SD: 5.4) and 7.2 (SD: 4.6) years, respectively. Distress experienced during the HCW and parent samples was low, with no difference between procedures (Table 4).
Distress Ratings During OPSs
| Sample Obtained . | Median Groningen Distress Rating Scale (IQR) . |
|---|---|
| Part A: HCW-Parent OPS | |
| HCW | 1 (1–2) |
| Parent | 1 (1–2) |
| Part B: HCW-HCW OPS | |
| HCW sample 1 | 1 (1–2) |
| HCW sample 2 | 1 (1–2) |
| Sample Obtained . | Median Groningen Distress Rating Scale (IQR) . |
|---|---|
| Part A: HCW-Parent OPS | |
| HCW | 1 (1–2) |
| Parent | 1 (1–2) |
| Part B: HCW-HCW OPS | |
| HCW sample 1 | 1 (1–2) |
| HCW sample 2 | 1 (1–2) |
Discussion
The findings of comparable agreement between HCW-parent swabs and HCW-HCW swabs are reassuring if parents are to obtain OPS from their child at home as part of remote health care delivery. Lenhart-Pendergrass et al7 reported the results of parents performing OPS in children at home and mailing samples to a laboratory. Common CF bacterial pathogens were detected; however, comparison was only made to the most recent HCW-taken sample, a mean of 4.8 months previous.
Agreement between parent and HCW nasal samples has been studied for virus and bacterial detection in children without CF. A recent systematic review concluded that parent-taken nasal swabs are appropriate for influenza research and surveillance.8 In the limited literature investigating parent-taken bacterial swabs, researchers found agreement in bacteria isolated in 50 of 69 (72%) paired parent-HCW nasal samples.9
Test-retest reliability of OPS has not previously been reported. In a single study, agreement of ∼80% was found between paired nasopharyngeal samples in children under general anesthetic.10 Because the technique was performed under general anaesthetic, technical difficulties were unlikely, indicating that lack of perfect agreement in the current study may not simply be because of technical differences in obtaining the swab but rather may indicate bacterial colonization occurring in patches.10
This study had limitations. Firstly, children had experience with having OPS obtained and parents had previously witnessed OPS; therefore, the results may not apply to settings where the child and/or parent are unsupervised or untrained. Another limitation was lack of randomization in order of obtaining OPS. Demonstration of OPS by the HCW was deemed important for parental training; therefore, randomization was not possible. Given low distress ratings throughout, it seems unlikely that lack of randomization impacted ability to collect OPS by either parent or HCW. Finally, while this study provides information on the accuracy of parent-taken samples, issues such as sample collection in the home environment itself, sample storage, and transport to a laboratory, would ideally be investigated to truly establish the suitability of parent-taken samples as part of a model of remote health care.
In conclusion, OPS samples obtained by trained parents are well tolerated by children and appear to be a promising alternative to attending clinic for HCW obtained samples.
FUNDING: Supported by research grants from the Sydney Children’s Hospitals Network Foundation and the HCF Foundation. The Sydney Children’s Hospitals Foundation and HCF Foundation had no role in the design and conduct of this study.
Mr Doumit conceptualized and designed the study, acquired the data, analyzed and interpreted the data, drafted the initial manuscript, and reviewed and revised the manuscript; Mr Cox acquired data, analyzed and interpreted data, and reviewed and revised the manuscript; Dr Chuang and Prof Jaffe conceptualized and designed the study, assisted with data interpretation, and critically reviewed the manuscript for important intellectual content; Drs Luxton and Butler coordinated and supervised data collection, analyzed and interpreted data and reviewed and revised the manuscript; and all authors approved the final manuscript as submitted and agree to be accountable for all aspects of the work.
References
Competing Interests
POTENTIAL CONFLICT OF INTEREST: The authors have indicated they have no potential conflicts of interest to disclose.
FINANCIAL DISCLOSURE: The authors have indicated they have no financial relationships relevant to this article to disclose.
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