• Journal of Microbiology
• /
• v.41 no.3
• /
• pp.202-206
• /
• 2003

A protein, exhibiting a high similarity to the major serine transporter of Escherichia coli, SstT, was found in Haemophilus influenzae Rd. A Na$\^$＋/-stimulated serine transport activity was also detected in the cells. The gene (sstT) for the Na$\^$＋//serine symporter from the chromosome of H. influenzae was cloned, and the properties of the transporter investigated. The serine transport activity was stimulated by Na$\^$＋/. The uptake of Na$\^$＋/ was elicited by the addition of serine or threonine into the cells, supporting the idea that these amino acids are transported by a mechanism of Na$\^$＋//substrate symport. No uptake of H$\^$＋/ was elicited by the influx of serine. The serine transport via the SstT of H. influenzae was inhibited by excess threonine, which was used as another substrate. The $K_{m}$ and the $V_{max}$ values for the serine transport were 2.5 ${\mu}$M and 14 nmol/min/mg protein, respectively.

• 한국생물공학회:학술대회논문집
• /
• 2000.11a
• /
• pp.575-578
• /
• 2000

The N-acetylneuraminate lyase(NALase) from Escherichia coli was cloned and it was compared to that from Haemophilus influenzae and Clostridium perfringens. NALase from E. coli was expressed in very high level(about 6U/mg). The ManNAc Km value of three enzymes was almost the same. Pyruvate inhibited from H. influenzae was inhibited by GlcNAc in lower level than the others. The crude extract has about 30 times more activity than the cell for the substrate and product diffusion limit problem. The pH stability of three enzymes at pH 11 was also checked for its importance in the direct synthesis of Neu5Ac from GlcNAc and pyruvate at high alkaline condition.

• Pediatric Infection and Vaccine
• /
• v.27 no.3
• /
• pp.147-157
• /
• 2020

Purpose: We investigated the trend of antibiotic susceptibility of Haemophilus influenzae over 5 consecutive years. Methods: We analyzed the antibiotic susceptibility of H. influenzae isolated from children aged <18 years, who were admitted to the Asan Medical Center Children's Hospital from March 2014 to April 2019. Antibiotic susceptibility of H. influenzae was determined by the disk diffusion test according to the European Committee on Antimicrobial Susceptibility Testing guidelines. Results: Excluding duplicates, 69 isolates were obtained over the past 5 years. The median age of the patients was 5 years (range, 2.8-8.6 years). The antibiotic susceptibility patterns were as follows: ampicillin (AMP)-susceptible/amoxicillin-clavulanate (AMC)-susceptible (AS/ACS; n=15 [21.7%]), AMP-resistant/AMC-susceptible (AR/ACS; n=21 [30.4%]), and AMP-resistant/AMC-resistant (AR/ACR; n=33 [47.8%]). The prevalence of isolates with AR/ACR phenotype tended to increase from 42.1% in 2014-2015 to 54.5% in 2018-2019 (P=0.342). Compared to 2014-2015, the resistance rates to cefuroxime and ceftriaxone in 2018-2019 increased from 31.6% to 77.3% and from 0.0% to 59.1%, respectively (P=0.003 and P<0.001, respectively). Conclusions: Over the last 5 years, H. influenzae isolates with AR/ACR phenotype and ceftriaxone resistance were frequently observed at our institute. The incidence of resistance to cefuroxime and ceftriaxone has increased significantly.

• Journal of Microbiology
• /
• v.41 no.2
• /
• pp.78-82
• /
• 2003

We identified two proteins in Haemophilus influenzae Rd that exhibited high similarity to two major serine transporters of Escherichia coli (SstT and SdaC). Then, we investigated serine transport in H. influenzae Rd and detected $Na^{+}$-stimulated L-serine transport activity. The optimum NaCl concentration for this stimulation was about 20 mM. The uptake of $Na^{+}$ by H. influenzae Rd was found to be elicited by L-serine influx, which supports the idea that L-serine is transported by a mechanism of $Na^{+}$/serine symport. No uptake of $H^{+}$ elicited by L-serine influx was detected. $Na^{+}$/serine symport activity was not inhibited by other amino acids such as L-threonine or D-serine. Two distinct Km values were obtained from the kinetic analysis of serine transport. Thus, two serine transport pathways may exist in H. influenzae Rd, and it appears that both systems are stimulated by $Na^{+}$.

• 대한예방의학회:학술대회논문집
• /
• 2005.10a
• /
• pp.353-353
• /
• 2005

• Clinical and Experimental Pediatrics
• /
• v.49 no.3
• /
• pp.242-250
• /
• 2006

Haemophilus influenzae type b(Hib) conjugate vaccines prevent Hib disease in individuals and reduce the carriage and transmission of the organism in the community. The incidence of Hib disease has been decreased dramatically in a diverse range of countries through the use of a variety of conjugate vaccines and vaccine schedules. In some countries, the vaccine has caused a near-disappearance of invasive Hib disease through a combination of direct protection and herd immunity. The effectiveness of the vaccine was not modified by the type of conjugate vaccine, the number of doses given(two, three or four), age at first vaccination(two months, 42 to 90 days, three months) and whether the vaccine was tested in an industrialized or developing country. Over 15 years of international experience with vaccines has also demonstrated that they are safe. In 2004, Hib vaccines were adapted in routine immunization in 92 countries in the world. Decisions regarding the use of the Hib vaccine in routine immunization schedules depend not only on the effectiveness and efficacy of the vaccine but also on factors such as burden of disease, vaccine cost, and competing priorities. In Korea, Hib disease burden seemed to be lower than other developed countries(~10/100,000). Moreover Hib vaccines showed excellent immunogenicity in Korean children in many studies. Therefore, a potential approach to economize the cost of Hib vaccines could be to explore the possibilities of using reduced vaccine doses for immunization as some other countries.

• Journal of Microbiology and Biotechnology
• /
• v.14 no.3
• /
• pp.520-524
• /
• 2004

A protein that exhibited a high similarity to a major serine transporter of Escherichia coli, SdaC, was found in Haemophilus injluenzae Rd. Also, $Na^+$-stimulated serine transport activity was detected in the cells. The sdaC of H. injluenzae was cloned and the properties of the transporter were investigated. The activity of serine transport was stimulated by $Na^+$. Uptake of $Na^+$ elicited by L-serine influx into cells was also observed, which supports the idea that L-serine is transported by a mechanism of $Na^+$serine symport. No uptake of $H^+$ elicited by L-serine influx was detected. This result was not consistent with that obtained with the homologous protein, SdaC of E. coli, which uses $H^+$as a coupling cation. The serine transport via the SdaC of H. influenzae was not inhibited by other amino acids such as threonine or D-serine like the SdaC of E. coli. Thus, the SdaC of H. influenzae is a $Na^+$-dependent L-serine specific symporter and an unusual natural mutant. The $K_m$ and the $V_{max}$, value for the serine transport in the SdaC of H. influenzae were $7.6\mu$M and 22.9 nmol/min/mg protein, respectively.

• Pediatric Infection and Vaccine
• /
• v.8 no.2
• /
• pp.234-240
• /
• 2001

Buccal cellulitis which presents with high fever and a swelling of the cheek with violaceous hue in young children is most often caused by H. influenzae. Bacteremia is common in buccal cellulitis caused by H. influenzae, and a culture of cerebrospinal fluid should be obtained because meningitis may be present despite the lack of meningeal irritation signs. Although buccal cellulitis is considered to be one of the important manifestations of H. influenzae infection, only two cases have been reported in Korea yet. We experienced a case of buccal cellulitis with H. influenzae bacteremia in an immunocompetent girl of 18-month-old. She was presented with high fever followed by rapidly progressive swelling and tenderness of both cheeks with violaceous hue in four hours. The blood culture revealed H. influenzae type b. There was no concurrent otitis media, sinusitis, or meningitis and no portal of entry was identified. Fever subsided two days after starting intravenous cefotaxime. Intravenous cefotaxime was subsequently changed to oral cefixime, and antibiotics were administered for a total of two weeks. We report this case with a review of related literature.

• Pediatric Infection and Vaccine
• /
• v.26 no.3
• /
• pp.188-193
• /
• 2019

Since the implementation of conjugate Haemophilus influenzae serotype b (Hib) vaccine, the rate of infections caused by Hib has dramatically decreased, and the proportion of infections caused by non-type b H. influenzae has increased. Cerebral venous sinus thrombosis (CVST) is rare; however, it should be considered as a potential complication of bacterial meningitis. Herein, we report about a child who developed CVST after being diagnosed with H. influenzae serotype f meningitis.

• Korean Journal of Microbiology
• /
• v.39 no.1
• /
• pp.36-39
• /
• 2003

The rapid and reliable 16S rDNA multiplex polymerase chain reaction (PCR) assay was established to characterize bacterial etiologies of middle ear effusion. These etiologies included Haemophilus influenzae, Moraxella catarrhalis and Streptococcus pneumonia, which were detected in middle-ear effusion (MEE) samples taken from patient with otitis media. A total of 39 MEE samples were aspirated from 26 patients. DNA was extracted from MEE samples, and PCR was done with DNA extracts by using the common primers, which is localized at C4 region in the 16S rDNA gene of all bacterial species, and species-specific primers: (i) Haemophilus-specific primer, (ii) Moraxella- specific primer, and (iii) Streptococcus-specific primer. Among 39 samples tested, 24 (61.5%) were positive for H. influenzae, 10 (25.6%) were positive for M. catarrhalis, 3(7.7%) were positive for S. pneumonia, and 11 (28%) were negative for 165 rDNA multiplex PCR reaction. Nine samples (28.6%) exhibited a mixed infection and were positive for both H. infuenzae and M. catarrhalis. We suggested that 16S rDNA multiplex PCR is a useful method to identify rapidly for rapid identification of the pathogenic bacteria and characterization of bacterial etiologies of middle ear effusion.