title: Antibiotic susceptibility profile of Haemophilus influenzae and transfer of co-trimoxazole resistance determinants.
abstract: Prior to the implementation of Haemophilus influenzae type b vaccination   worldwide, H. influenzae has been one of the main causative agents of community acquired   pneumonia and meningitis in children. Due to the lack of information on the characteristics of   the H. influenzae isolates that have previously been collected in Malaysia, the H. influenzae   were assessed of their microbial susceptibility to commonly used antibiotics. Emphasis was   made on strains that were resistance to co-trimoxazole (SXT) and their mode of transfer of   the antibiotic resistance determinants were examined. A collection of 34 H. influenzae   isolates was serotyped and antimicrobial susceptibility tests were performed to 11 antibiotics.   To the isolates that were found to be resistant to co-trimoxazole, minimum inhibition   concentration (MIC) to SXT was performed using Etest while agar dilution method was used   to measure the individual MICs of trimethoprim (TMP) and sulfamethoxazole (SUL). These   isolates were also examined for presence of plasmid by PCR and isolation method. Conjugal   transfers of SXT-resistant genes to SXT-susceptible hosts were performed to determine their   rate of transfer. Result showed that 20.6% of the total number of isolates was serotype B   while the remaining was non-typeable. Antimicrobial susceptibility profile of all the isolates   revealed that 58.8% was resistant to at least one antibiotic. Majority of these isolates were   equally resistant to ampicillin and tetracycline (29.4% each), followed by resistance to SXT   (26.5%). From nine isolates that were found to be SXT-resistant, five contained plasmid/s.   Conjugal transfer experiment showed that these five isolates with plasmid transferred SXT-resistance   determinants at a higher frequency than those without. From these observations,   it is postulated that plasmid is not involved in the transfer of SXT-resistance genes but   presence of plasmid facilitates their transfer. The information obtained from this study provides   some basic knowledge on the antimicrobial susceptibility pattern of the H. influenzae isolates   and their mode of transfer of SXT-resistance genes.
authors.affiliation: Faculty of Medicine, Institute of Medical Molecular Biotechnology, Universiti Teknologi MARA, Sungai Buloh, Selangor. zainimz@salam.uitm.edu.my
authors.forename: Z
authors.initials: Z
authors.lastname: Mohd-Zain
authors.forename: N H
authors.initials: NH
authors.lastname: Kamsani
authors.forename: I S
authors.initials: IS
authors.lastname: Ismail
authors.forename: N
authors.initials: N
authors.lastname: Ahmad
mesh_terms: D000667:Ampicillin / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002648:Child; D017714:Community-Acquired Infections / Q000188:drug therapy / Q000382:microbiology; D004269:DNA, Bacterial / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial; D006192:Haemophilus Infections / Q000188:drug therapy / Q000382:microbiology*; D006193:Haemophilus influenzae / Q000187:drug effects* / Q000235:genetics* / Q000276:immunology / Q000302:isolation & purification; D006801:Humans; D008296:Malaysia; D008826:Microbial Sensitivity Tests; D010641:Phenotype; D010957:Plasmids / Q000235:genetics; D018410:Pneumonia, Bacterial / Q000188:drug therapy / Q000382:microbiology; D012703:Serotyping; D013752:Tetracycline / Q000494:pharmacology; D015662:Trimethoprim, Sulfamethoxazole Drug Combination / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D000667:Ampicillin; D015662:Trimethoprim, Sulfamethoxazole Drug Combination; D013752:Tetracycline