Prevalence of Bordetella pertussis among children aged 4 years and above presenting with acute respiratory tract infection: a cross-sectional study.

INTRODUCTION AND AIM: In Malaysia, pertussis in children beyond infancy is underreported. This study aimed to determine the prevalence of Bordetella pertussis and the prevalence of pertussis-susceptible children aged ≥4 years who presented with acute respiratory infections. METHODS: This single-center, cross-sectional study conducted at the Paediatric Emergency Department from 1 October 2022, to 31 January 2023, included children aged 4 years and older with ARTIs symptoms and excluded those who were COVID-19 positive. B. pertussis was detected via quantitative Polymerase Chain Reaction on nasopharyngeal swabs and pertussis toxin (PT) IgG enzyme-linked immunosorbent assay. RESULTS: Children (n = 298) with a median (Interquartile range, [IQR]) age of 6.0 (5.0, 8.0) years old were recruited, and 98% were vaccinated adequately. Two cases of B. pertussis (n = 2/298, 0.67%) were detected. Both children were also co-infected with Bordetella spp. The majority of the patients (n = 246/296, 83.1%) had low protective antibodies against pertussis (anti-PT IgG <5 IU/ml), and children 5 years and older were more likely to have lower anti-PT Ig G levels of <5 IU/ml (odds ratio 2.02 [95% CI 1.04,3.90]) compared to children 4 years old. CONCLUSION: The prevalence of pertussis was low. However, there is significant waning immunity. Booster doses of pertussis vaccine should be given to all school-aged children.

Colonization of the newborn respiratory tract and its association with respiratory morbidity in the first 6 months of life: A prospective cohort study.

OBJECTIVES: We aimed to determine the association between newborn bacterial colonization and infant respiratory morbidity in the first 6 months of life. METHODS: This prospective study included healthy newborn infants. Nasopharyngeal swabs performed within 72 hours of delivery were analyzed using polymerase chain reaction. We assessed cumulative respiratory morbidity of infants at 6 months. RESULTS: A total of 426 mother-infant pairs were recruited. In 53.3% (n = 225) of newborns, Streptococcus pneumoniae (46%) and Staphylococcus aureus (7.3%) were isolated. None had Haemophilus influenzae nor Moraxella catarrhalis. At the age of 6 months, 50.7% of infants had experienced respiratory symptoms, 25% had unscheduled doctor visits, and 10% were treated with nebulizers. Colonization with S. pneumoniae was associated with reduced risk of any respiratory symptom (adjusted odds ratio [aOR] 0.39, 95% confidence interval [CI] 0.16, 0.50), unscheduled doctor visits (aOR 0.35; 95% CI 0.18, 0.67), and nebulizer treatment (aOR 0.23, 95% CI 0.07, 0.72) at 6 months. Pregnancy-induced hypertension was also associated with increased need for nebulizer treatment (aOR 9.11, 95% CI 1.43, 58.1). CONCLUSION: Colonization of the newborn respiratory tract occurred in 53% of infants. S. pneumoniae was the most common organism, and this was associated with a reduced risk for respiratory morbidity at 6 months of life.

ß-Lactam Resistance in Upper Respiratory Tract Pathogens Isolated from a Tertiary Hospital in Malaysia.

The rise of antimicrobial resistance (AMR) among clinically important bacteria, including respiratory pathogens, is a growing concern for public health worldwide. Common causative bacteria for upper respiratory tract infections (URTIs) include Streptococcus pneumoniae and Haemophilus influenzae, and sometimes Staphylococcus aureus. We assessed the ß-lactam resistant trends and mechanisms of 150 URTI strains isolated in a tertiary care hospital in Kuala Lumpur Malaysia. High rates of non-susceptibility to penicillin G (38%), amoxicillin-clavulanate (48%), imipenem (60%), and meropenem (56%) were observed in S. pneumoniae. Frequent mutations at STMK and SRNVP motifs in PBP1a (41%), SSNT motif in PBP2b (32%), and STMK and LKSG motifs in PBP2x (41%) were observed in S. pneumoniae. H. influenzae remained highly susceptible to most ß-lactams, except for ampicillin. Approximately half of the ampicillin non-susceptible H. influenzae harboured PBP3 mutations (56%) and only blaTEM was detected in the ampicillin-resistant strains (47%). Methicillin-susceptible S. aureus (MSSA) strains were mostly resistant to penicillin G (92%), with at least two-fold higher median minimum inhibitory concentrations (MIC) for all penicillin antibiotics (except ticarcillin) compared to S. pneumoniae and H. influenzae. Almost all URTI strains (88-100%) were susceptible to cefcapene and flomoxef. Overall, ß-lactam antibiotics except penicillins remained largely effective against URTI pathogens in this region.