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Carriage of antibiotic-resistant bacteria by healthy children
M R Millar1, T R Walsh, C J Linton
1Department of Microbiology, The Royal London Hospital, Barts and The London NHS Trust, Whitechapel Road, London E1 1BB, UK. M.R.Millar@mds.qmw.ac.uk
Insights
Antibiotic-resistant bacteria are common in healthy children, even before they are exposed to specific antibiotics. This resistance may be acquired from various sources, suggesting widespread dissemination of resistant strains.
Area of Science:
- Microbiology
- Public Health
- Pediatrics
Background:
- Antibiotic resistance is a growing global health concern.
- Understanding carriage rates in healthy populations is crucial for public health strategies.
- Children are a key demographic for studying the early acquisition of resistant bacteria.
Purpose of the Study:
- To determine the frequency of antibiotic-resistant bacteria carriage in healthy 7- and 8-year-old children.
- To investigate resistance patterns to various antibiotics, including those not commonly prescribed to children.
Main Methods:
- Study population: Healthy children born in Avon between April 1991 and December 1992, attending ALSPAC (Avon Longitudinal Study of Pregnancy and Childhood) 7-year follow-up.
- Sample collection: Mouthwash and stool samples were used to estimate bacterial carriage.
- Resistance testing: Isolates of Staphylococcus aureus, Haemophilus spp., Branhamella catarrhalis, Group A beta-haemolytic streptococci, and Gram-negative bacilli were tested for resistance to multiple antibiotics.
Main Results:
- Staphylococcus aureus: 37.1% carriage; 3% resistant to chloramphenicol/tetracycline, 2% methicillin-resistant.
- Haemophilus spp.: 72% carriage; significant resistance to ampicillin (17%), erythromycin (13.3%), and tetracycline (1.9%).
- Gram-negative bacilli in stool: 11% showed high-level chloramphenicol resistance, often co-resistant to ampicillin, spectinomycin, and streptomycin. 3.2% resistant to ceftazidime, with 35% of these possessing extended-spectrum beta-lactamases.
Conclusions:
- Healthy children carry a significant burden of antibiotic-resistant bacteria, including resistance to antibiotics they have not been prescribed.
- Resistance to certain antibiotics like ceftazidime, chloramphenicol, and tetracycline may be acquired through non-direct exposure routes.
- The findings indicate widespread dissemination of antibiotic-resistant bacteria, with potential acquisition occurring before specific selective pressures are applied in childhood.
Abstract:
The frequency of carriage of antibiotic-resistant bacteria in healthy 7- and 8-year-old children in Bristol was studied. Children born in Avon between 1 April 1991 and 31 December 1992, attending the Avon Longitudinal Study of Pregnancy and Childhood (ALSPAC) 7 year follow-up clinic, formed the study population. Carriage was estimated using mouth and stool samples. None of 105 children on whom information was available had received tetracycline, chloramphenicol, ciprofloxacin or an extended-spectrum cephalosporin in the previous year. Staphylococcus aureus was isolated from mouthwashes from 200 (37.1%) of 539 children sampled. Six (3%) of the isolates were resistant to chloramphenicol or tetracycline and four (2%) were methicillin resistant. Haemophilus spp. were isolated from 369 (72%) of 513 samples and 63 (17%) were ampicillin resistant, 49 (13.3%) were erythromycin resistant and seven (1.9%) were tetracycline resistant. Branhamella catarrhalis was isolated from 333 (74%) of 450 samples. Twenty-eight (8.4%) were erythromycin resistant and 14 (4.2%) strains were tetracycline resistant. Group A beta-haemolytic streptococci were isolated from 17 of 507 children sampled. One (5.9%) was tetracycline resistant. Stool samples were returned from 335 (62%) of 539 children from whom they were requested. Eleven per cent of samples yielded Gram-negative bacilli with high-level resistance to chloramphenicol, which was frequently linked to resistance to ampicillin, spectinomycin and streptomycin. Isolates demonstrating resistance to the third-generation cephalosporin ceftazidime were recovered from 17 subjects (3.2%). Six (35%) of 17 isolates possessed extended-spectrum beta-lactamases. Healthy children carry bacteria resistant to antibiotics to which children are not usually exposed. Resistance to ceftazidime, chloramphenicol and tetracycline may be co-selected by exposure to other antibiotics used in children or may be acquired from family members, pets, other children or food. These results suggest that antibiotic-resistant bacteria are widely disseminated and may be acquired by children before exposure to specific selection pressure.