The second mechanism is amino acid substitution of the transpeptidase enzyme, PBP3, encoded by the ftsI gene ( 7). Strains that are resistant to ampicillin due to producing β-lactamase are termed β-lactamase positive, ampicillin resistant (BLPAR). β-lactamase production is the dominant mechanism, which is encoded most often by bla TEM−1 and rare bla ROB−1 ( 6). influenzae can utilize two mechanisms of action. Β-lactam antibiotics are the first choice of H. It is more likely that NTHi strains, like many other opportunists, are increasing due to increased numbers of individual with coexisting conditions and intensified diagnostics among them. In addition, invasive diseases caused by NTHi are emerging globally and is predisposed by age and coexisting conditions ( 5). NTHi has been the most prevalent cause of community-acquired pneumonia and exacerbation of chronic obstructive pulmonary disease (COPD) ( 3, 4). It is characterized as serotype a to f based on polysaccharide capsule antigens and lack of a capsule are identified as nontypeable (NTHi). influenzae is considered a priority pathogen by WHO ( 2). Haemophilus influenzae is a commensal bacteria colonizing mostly the upper respiratory tract causing mucosal and severe invasive infections such as meningitis and septicemia ( 1). The prevalence of both β-lactamase production and PBP3 mutation may contribute to high ampicillin resistance rate in Shanghai. influenzae infections among adults in Shanghai are predominately caused by NTHi with genetic diversity among adult patients. Four isolates of ST103 (7.84%) all produced β-lactamase without mutation of PBP3.Ĭonclusion: H.
A total of 36 sequence types (STs) were identified among all isolates. The PBP3 mutation was detected in 74.51% of the isolates, of which 12 belonged to group III. One third of these isolates produced TEM-1 type β-lactamase and 11.76% were β-lactamase negative ampicillin resistant strains (BLNAR).
The resistant rates of ampicillin and trimethoprim/sulfamethoxazole were both 45.10%. influenzae (NTHi) and three of them (5.88%) caused invasive infection.
Results: All isolates studied were nontypeable H. Molecular epidemiology was performed by MLST analyses. β-lactamase production was detected by cefinase disk and the ftsI gene were amplified and sequenced to determine the penicillin binding protein 3 (PBP3) mutation. Antimicrobial susceptibility test was carried out by the broth microdilution method.
Serotypes were determined according to specific capsule gene, bexA, amplified by PCR. Methods: A total of 51 clinical isolates from adult patients were consecutively collected. influenzae in adult patients in Shanghai. Objective: To determine the serotype distribution, antimicrobial resistance and multilocus sequence type (MLST) of H. influenzae in Shanghai are still unavailable. However, the epidemiologic characteristics of H. influenzae type b (Hib) vaccine worldwide. Department of Clinical Microbiology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, Chinaīackground: The serotype and antimicrobial resistance of Haemophilus influenzae in adult patients have changed due to the application of antimicrobials and H.Xin-Xin Li †, Shu-Zhen Xiao †, Fei-Fei Gu, Wei-Ping He, Yu-Xing Ni and Li-Zhong Han *