[Study on serotyping of Haemophilus influenzae and the positive rates of beta-lactamase].
OBJECTIVE
To investigate the serotypes of both infectious and carriage strains of Haemophilus influenzae (Hi) and to evaluate the prevalence of beta-lactamase of major serotypes in Shanghai.


METHODS
The 534 specimens of sputum and swabs from patients with acute upper or lower respiratory tract infection and 255 cases of control group were collected and incubated on improved Collumbia chocolate medium. All isolated Haemophilus influenzae strains were serotyped by slide agglutinating assay or reverse indirect blood agglutinating method. beta-lactamase were measured by iodine test and paper disc method.


RESULTS
In the patient group, of the 164 Hi strains there were 69 Hib strains (42%, 69/164) and 91 NTHi(56%, 91/164). In the control group, there were 14 strains of Hib and 49 strains of NTHi among 66 strains of Hi, which were isolated from 255 specimens(26%, 66/255). 24%(38/160) of Hi in the patient group produced beta-lactamase. In this group, the positive rate of beta-lactamase was 29%(20/69) for Hib strains and 20%(18/91) for NTHi strains. Sixteen strains resisting to ampicillin were beta-lactamase negative.


CONCLUSIONS
These results indicate that Hib and NTHi are the major serotypes of Hi in both the patient and control group. The prevalence of Hib is higher in patients than in the control. Hib strains are more likely to produce beta-lactamase than NTHi.
Wang
G
G
Department of Respiratory Diseases, Changzheng Hospital, Second Military Medical University, Shanghai 200433.
Luo
W
W
Xiu
Q
Q
D000367:Age Factors; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D006192:Haemophilus Infections / Q000382:microbiology; D006193:Haemophilus influenzae / Q000187:drug effects / Q000201:enzymology* / Q000276:immunology; D006801:Humans; D008826:Microbial Sensitivity Tests; D012703:Serotyping; D001618:beta-Lactamases / Q000378:metabolism*
D000900:Anti-Bacterial Agents; D001618:beta-Lactamases