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β-Lactam Resistance in Upper Respiratory Tract Pathogens Isolated from a Tertiary Hospital in Malaysia
Soo Tein Ngoi1, Anis Najwa Muhamad1, Cindy Shuan Ju Teh1
1Department of Medical Microbiology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur 50603, Malaysia.
Abstract:
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 β-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 β-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, β-lactam antibiotics except penicillins remained largely effective against URTI pathogens in this region.
Insights
Antimicrobial resistance is rising in respiratory pathogens. While some bacteria show high resistance to certain beta-lactams, newer agents like cefcapene remain effective against common upper respiratory tract infection (URTI) strains.
Area of Science:
- Medical Microbiology
- Infectious Diseases
- Antimicrobial Resistance
Background:
- Antimicrobial resistance (AMR) in respiratory pathogens poses a significant global public health threat.
- Common upper respiratory tract infections (URTIs) are caused by bacteria such as Streptococcus pneumoniae, Haemophilus influenzae, and Staphylococcus aureus.
Purpose of the Study:
- To investigate the trends and resistance mechanisms of beta-lactam antibiotics against URTI pathogens.
- To assess the susceptibility patterns of key respiratory pathogens in Kuala Lumpur, Malaysia.
Main Methods:
- Analysis of 150 URTI bacterial strains isolated from a tertiary care hospital.
- Phenotypic susceptibility testing for various beta-lactam antibiotics.
- Molecular analysis of resistance mechanisms, including PBP mutations and beta-lactamase detection.
Main Results:
- Streptococcus pneumoniae exhibited high non-susceptibility to penicillin G, amoxicillin-clavulanate, imipenem, and meropenem, linked to PBP mutations.
- Haemophilus influenzae showed high susceptibility, with ampicillin resistance associated with PBP3 mutations and blaTEM presence.
- Methicillin-susceptible Staphylococcus aureus (MSSA) strains were largely resistant to penicillin G.
- Cefcapene and flomoxef demonstrated high efficacy against nearly all tested URTI strains.
Conclusions:
- Beta-lactam antibiotics, excluding penicillins, generally maintain effectiveness against URTI pathogens in the studied region.
- Understanding resistance trends and mechanisms is crucial for guiding appropriate antimicrobial therapy for URTIs.
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