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Background: Although pertussis has been considered a disease of childhood, it is also recognized as an important respiratory tract infection in adolescents and adults. However, in countries with routine vaccination against pertussis with high coverage, pertussis is not usually taken into consideration for the etiology of prolonged cough in adults. Previous studies in a variety of populations in developed countries have documented that pertussis is quite common, ranging from 2.9 to 32% of adolescents and adults with prolonged cough. The anticipation and early recognition of this change in the epidemiology is important because the affected adolescents and adults act as reservoirs of the disease and source of infection to the vulnerable population of infants, for whom the disease can be life threatening. We conducted a prospective study to determine the prevalence of pertussis in Thai adults with prolonged cough., Methods: Seventy-six adult patients with a cough lasting for more than 2 weeks (range, 14-180 days) were included in the present study. The data regarding medical history and physical examination were carefully analyzed. Nasopharyngeal swabs from all patients were obtained for the detection of deoxyribonucleic acid of Bordetella pertussis by the polymerase chain reaction (PCR) method. Paired serum samples were collected and tested for IgG antibody against pertussis toxin by using an ELISA method., Results: Of 76 adult patients, 14 patients (18.4%) with the mean age of 59 (range, 28-85) years and the mean duration of cough of 34 (range, 14-120) days had laboratory evidence of acute pertussis infection. One patient was diagnosed by the PCR method, while the rest had serological diagnosis. Whooping cough is a significantly associated symptom of patients with chronic cough who had laboratory evidence of pertussis. (p < .05, odds ratio 3.75, 95% confidence interval: 1.00, 14.06) CONCLUSION: Pertussis is being increasingly recognized as a cause of prolonged, distressing cough among adults in Thailand. This result addresses the need of pertussis vaccination in Thai adults for preventing transmission to a high risk group such as newborn infants.

A case of 6-week-old male infant with meningitis and concurrent bacteremia caused by Streptococcus gallolyticus subspecies pasteurianus (Streptococcus bovis biotype 11.2) is presented. The isolates were susceptible to all beta-lactam antibiotics. Nevertheless, delayed defervescence and lack of satisfactory clinical improvement after treatment with multiple beta-lactam antibiotics prompted the combination therapy of vancomycin and penicillin G. The patient completed a 2-week course of antibiotics and recovered uneventfully.

Objective: To describe the clinical course, serotype distribution and antimicrobial resistance patterns of invasive pneumococcal disease (IPD) cases in a public hospital., Material and Method: Retrospective review of IPD cases occurring from January 2004 through December 2008 was performed. Antibiotic susceptibility testing and serotyping were performed for available isolates., Results: Fifty one IPD cases occurred during the study period, of which 47 had medical records available for review. The majority of cases occurred among children under 5 years of age (23.4%) and adults over 60 years of age (36.1%). Underlying diseases were identified in 72.3% of patients. Fifty-three percent of cases were associated with pneumonia, while 17% had meningitis, and 15% had isolated bacteremia. Serotype could be determined for 15 (31.9%) isolates, and 6B was most common. Based on current antibiotic susceptibility breakpoints for meningitis, 4 of the 7 available isolates from meningitis cases were penicillin resistant and one had reduced susceptibility to cefotaxime. Among non-meningitis isolates, 96.7% were penicillin susceptible and 3.3% had intermediate susceptibility to penicillin. Overall case fatality proportion was 19%., Conclusion: At this tertiary care hospital in Bangkok, IPD has disproportionately affected young children and the elderly. High rates of penicillin resistance among meningitis cases, the most severe form of IPD, underscore the need of appropriate treatment strategies and vaccine usage.

Objective: To determine the prevalence, clinical epidemiology, and antimicrobial susceptibility of Pseudomonas aeruginosa in Thailand from 2000 to 2005., Material and Method: Using WHONET data from 28 hospitals participating in the National Antimicrobial Resistance Surveillance Thailand (NARST) program, all data were reviewed and analyzed for the prevalence, clinical epidemiology, and antimicrobial susceptibility of clinical isolates of P. aeruginosa from 2000 to 2005., Results: During the six-year surveillance, the prevalence of P. aeruginosa in clinical isolates was constant among 28 hospitals. The most common sites of isolation included sputum, pus, and urine. The most active antimicrobials were netilmicin (88% to 90.8%), cefoperazone/sulbactam (85.1% to 89.5%), imipenem (84.6% to 87.2%), and meropenem (84.5%). The resistance to ceftazidime was very high, ranging from 24.6-27.4%. The prevalence of multidrug-resistant (MDR) P. aeruginosa (resistance to amikacin, ciprofloxacin, and ceftazidime) was constant. Some hospitals in Central and Eastern regions had the prevalence of MDR up to 20% to 30% of the isolates., Conclusion: According to NARST data, the antimicrobial resistance rates of P. aeruginosa remains constant with the exception of relatively high rates in ceftazidime. The prevalence of MDR P. aeruginosa is generally low with a moderately high prevalence in some hospitals.

Objective: To determine the trends of antimicrobial susceptibility of enterococci in Thailand from 2000 to 2005., Material and Method: All enterococcal isolates from sterile site obtained from 28 hospitals in Thailand from 2000 to 2005 were tested for their susceptibility to ampicillin, high-level gentamicin, and vancomycin by the disk diffusion (Kirby Bauer) method. The relevant data were collected and analyzed by WHONET software program supported by the World Health Organization., Results: Enterococcus faecalis (47%) and E. faecium (23%) were the two most frequent enterococcal isolates. There was no trend of increasing resistance to ampicillin, high level gentamicin, and vancomycin among E. faecalis isolates during the study period. There was a trend of an increasing resistance to ampicillin and high-level gentamicin among E. faecium isolates. Among E. faecium, the rates of vancomycin resistance were very low, ranging from 0.5% to 1.9%, and there was no trend of increasing rates of resistance., Conclusion: In the present study, there is a trend of decreasing susceptibility to ampicillin and high-level gentamicin in E. faecium. In contrast, there is no trend of increasing resistance to vancomycin. This would have effects on selection of empirical antimicrobial treatment on enterococcal infections especially a decision to use ampicillin or gentamicin.

Objective: To determine the prevalence and antibiotic susceptibility patterns of Burkholderia pseudomallei isolates in Thailand from 2000 to 2004., Material and Method: the data on WHONET from 28 hospitals participated in the National Antimicrobial Resistance Surveillance Thailand (NARST) surveillance program, was reviewed and analyzed for the prevalence and antimicrobial susceptibility patterns., Results: During the five-year surveillance, the prevalence of B. pseudomallei in clinical isolates was 69% in the Northeast, 14% in the North, 11.8% in the Center, and 5% in the South. Compared to other regions, the prevalence rate in the Northeast had gradually increased from 2000 to 2004. Burirum Hospital had the highest prevalence rate in this area. The majority of isolates were obtained from blood (44.9%), pus (25.6%), respiratory tract (13.3%), and urinary tract (6.3%). The isolates from unusual sites including bone marrow, heart, and placenta were less commonly noted (< 1%). Based on in vitro susceptibility results, all isolates in each region expressed high susceptibility to ceftazidime (> 98.5%), amoxicillin/clavulanic acid (> 95%), cefoperazone/sulbactam (> 98%), imipenem (98.5%), and meropenem (98%), but express less susceptibility to trimethoprim-sulfamethoxazole (< 53%). However, the susceptibility of B. pseudomallei to trimethoprim/ sulfamethoxazole determined by the disk diffusion method is unreliable; it must be performed by the minimal inhibitory concentration method., Conclusion: With the exception of the Northeast, the prevalence rate of B. pseudomallei remains stable for all regions in Thailand. The isolates obtained from blood and pus represent more than two-thirds of all clinical isolates. Antimicrobial susceptibility patterns showed no evidence of increased resistance to antimicrobials most commonly prescribed for the treatment of melioidosis.

Objective: To determine the prevalence, clinical epidemiology, and antimicrobial susceptibilities of Acinetobacter baumannii in Thailand from 2000 to 2005., Material and Method: Twenty-eight hospitals participated in the National Antimicrobial Resistance Surveillance Thailand program. All data were reviewed and analyzed for the prevalence, clinical epidemiology, and antimicrobial susceptibilities of the clinical isolates of A. baumannii from 2000 to 2005., Results: The number of clinical isolates of Acinetobacter spp. increased from 8,699 isolates in 2000 to 14,071 isolates in 2005. The most common species, identified by biochemical and growth characteristics, was A. baumannii. More than 50% of all isolates were from the respiratory tract specimens. The percentage of resistance has been increasing, particularly multi-drug-resistant (MDR) or carbapenem-resistant phenotypes. Of carbapenem-resistant strains, the prevalence was 2.1% and 46.7% in 2000 and 2005, respectively. Most carbapenem-resistant strains were also MDR. The prevalence of MDR strains was highest in the Central region and Bangkok. Cefoperazone/sulbactam was the antimicrobial against largest proportion Acinetobacter spp., although the prevalence of resistance to this agent is on the upward trend., Conclusion: A standardized technique to identify the organisms to the species level should be determined to be used in the surveillance system. Because the prevalence of Acinetobacter spp. resistant to multiple classes of antimicrobials including carbapenems and cefoperazone/sulbactam are increasing, there is an urgent need for a more active surveillance system, more stringent infection control efforts, and powerful antimicrobial stewardship programs in all healthcare sectors to minimize the further spread of this MDR strain.

As part of the continuing national antimicrobial surveillance, the national antimicrobial resistance surveillance thailand (NARST), data of all clinical isolates of Streptococcus pneumoniae were collected from 28 hospitals in Thailand from 2000 to 2005. Epidemiological and microbiological data were obtained and analyzed using the WHONET software program. Among all isolates tested for antimicrobial susceptibility, the rates of penicillin resistance were constantly high, ranging from 42.4% in 2000 to 47.7% in 2005. The third-generation cephalosporin resistance rate, determined by Epsilon test (E-test) in 10% to 15% of all isolates each year, ranged from 2.1% to 8.4%. The rates of erythromycin resistance ranged from 24.2% to 30.3%. Surprisingly, one isolate in 2005 was resistant to levofloxacin. The rates of multi-drug resistance ranged from 14.8% to 34.3%. In conclusion; the present (NARST) study documents remarkable increase of penicillin, erythromycin, and multi-drug resistance rates in Thailand, especially among isolates from the North, the Center, the East, and Bangkok; from university hospitals; from young children; and from non-sterile specimens.

From 2000 to 2005, the data of all clinical isolates of Staphylococcus aureus including methicillin-susceptible S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA) from 28 hospitals in the National Antimicrobial Resistance Surveillance, Thailand (NARST) program were reviewed and analyzed for the prevalence and pattern of antimicrobial susceptibility by WHONET software program. Among all isolates, around 26% of MRSA have been noted in each year The rates of erythromycin-resistant MRSA were relatively high, ranging from 94.5% to 96.8%, followed by clindamycin resistant (37.4% to 68.9%), fosfomycin-resistant (7.7% to 17%), vancomycin-resistant (0.1% to 0.8%), and teicoplanin resistant (0.2% to 1.3%). The rates of antimicrobial resistance MSSA were constantly low, with erythromycin resistance ranging from 3.7% to 4.6%, clindamycin resistance ranging from 1.4% to 2.3%, fosfomycin resistance ranging from 0.7% to 1.4%, vancomycin resistance ranging from 0.1% to 1.2%, and teicoplanin resistance ranging from 0.1% to 1.1%. An increasing trend of vancomycin resistance in S. aureus determined by the disk diffusion method should be further confirmed by appropriate susceptibility methods. Molecular typing methods are needed to determine the epidemiological association between these resistant isolates.

Objective: To study the trends of antimicrobial resistance of Escherichia coli in Thailand during 2000 and 2005., Material and Method: All isolates of E. coli from 28 hospitals across Thailand from 2000 to 2005 were tested for their susceptibility to aminoglycosides, beta-lactams, fluoroquinolones, and trimethoprim-sulfamethoxazole by the disk diffusion method (Kirby Bauer). The relevant data were collected and analyzed by the WHONET software program supported by the World Health Organization., Results: The rate of resistance to ampicillin, ceftriaxone, ceftazidime gentamicin, and ciprofloxacin increased from 79.3% to 85.3%, 12.7% to 28.5%, 10.7% to 15.2%, 25% to 32.9%, and 45.1% to 51% during the 6-year period from 2000 to 2005 among isolates from catheterized urine, respectively. The rate of resistance to gentamicin and ceftriaxone increased from 23.2% to 28.9% and 6.8% to 24.2%, from 2000 to 2005 respectively among isolates in non-intensive care units (non-ICUs). The rate of resistance to gentamicin increased from 18% to 26.1%, and 24.2% to 29.6% among isolates in out-patient department (OPD) and non-OPD, respectively. The rate of resistance to ceftriaxone increased from 2.5% to 15.4%, and 7.9% to 25.9% among isolates in OPD and non-OPD, respectively. The rate of resistance to gentamicin and ceftriaxone increased from 23.2% to 28.9%, and 6.8% to 24.2% among isolates in non-ICU, respectively. The rate of resistance to trimethoprim-sulfamethoxazole decreased from 71.2% to 62.6% among isolates in non-ICUs. Isolates from catheterized urine were significantly associated with imipenem resistance (p > 0.05)., Conclusion: The present study shows a significant correlation between ciprofloxacin resistance and fluoroquinolone use, and indicates that prior fluoroquinolone use seems to be the most important risk factor for ciprofloxacin-resistant E. coli bacteremia. Isolates from catheterized urine were significantly associated with resistance to imipenem, and the ICU hospitalization and OPD attention during the previous year were significantly associated with ofloxacin resistant E. coli.

Objective: To evaluate the prevalence and susceptibility pattern of Escherichia coli and Klebsiella pneumoniae isolates producing extended-spectrum beta-lactamases (ESBLs) in Thailand from 2000 to 2005., Material and Method: Data on the WHONET, from 28 hospitals participated in the National Antimicrobial Resistance Surveillance, Thailand surveillance program, were reviewed and analyzed for the prevalence and susceptibility pattern., Results: During the five-year surveillance from 2000 to 2005, the prevalence of ESBL-producing E. coli detected by ceftazidime screening test was 17%, 21.3%, 23.2%, 20.4%, 23.1%, and 25.0%; as well as detected by cefotaxime screening test was 20.8%, 65.9%, 69.3%, 69.3%, 68.3%, and 33.8%, respectively. The prevalence of ESBL-producing K. pneumoniae detected by ceftazidime screening test was 30.9%, 34.7%, 32.5%, 34.4%, 372%, and 39.2%; as well as detected by cefotaxime screening test 38.4%, 39.3%, 40.1%, 41.0%, 42.8%, and 40.4%, respectively., Conclusion: From 2000 to 2005, the prevalence of ESBL-producing organisms in Thailand was high. ESBL-producing E. coli was most commonly isolated from sputum, followed by blood and urine specimens. ESBL-producing K. pneumoniae had not been increasingly isolated from sputum, blood and urine.

Four Enterobacter cloacae clinical isolates with reduced susceptibility to ceftazidime from two hospitals in Thailand were studied. Production of extended-spectrum beta-lactamase was confirmed by double disk synergy test and combination disk method. All isolates were highly resistant to ceftazidime but retained susceptibility to imipenem. One isolate was able to hydrolyze cefotaxime, ceftazidime and cefepime, the latter being one of the treatment choices for infection by Enterobacter spp. PCR analysis demonstrated the presence of bla(SHV12) in addition to bla(TEM-1) in all isolates suggesting that SHV-12 was associated with high-level resistance to ceftazidime in the E. cloacae isolates.

A collection of 307 pneumococcal isolates form 84 children and 223 adults admitted to Siriraj Hospital were separated into two groups, penicillin-susceptible (PSSP) and penicillin-nonsusceptible (PNSP). Each group was tested for susceptibilities to 12 drugs (cefuroxime, amoxicillin, chloramphenicol, tetracycline, cefotaxime, ceftriaxone, imipenem, meropenem, ciprofloxacin, ofloxacin, erythromycin and co-trimoxazole). PSSP were susceptible to cefuroxime (87.5%), amoxicillin (100%), chloramphenicol (84.7%), tetracycline (45.8%), cefotaxime (99%), ceftriaxone (99%), imipenem (99%), meropenem (100%), ciprofloxacin (76%), ofloxacin (99%), erythromycin (94.8%) and co-trimoxazole (61.5%). PNSP were resistant to most drugs, except for amoxicillin (99%), ofloxacin (99%) and ciprofloxacin (86.3%). Twenty-two pneumococcal isolates belonging to the three most common serotypes (6, 19, 23) were randomly selected for studies of the pbp2b gene with RFLP. There were 7 distinct pbp2b RFLP patterns. RFLP pattern 1 was the most predominant resistant pattern. The RFLP pattern 2 was found only in PSSP.

Detection of gamma-glutamyl transpeptidase (GGT; ggt ) activity is one of the useful methods for a specific identification of Neisseria meningitidis. However, we previously happened to isolate a ggt -deficient N. meningitidis strain (NIID113) from a healthy carrier. In this study, in order to re-examine the reliability of the marker, we again investigated the GGT activity of 245 N. meningitidis human isolates and identified two other GGT-defective N. meningitidis isolates besides NIID113. The isolation frequency (1.2%) of ggt mutants among human isolates strongly confirmed the 98.8% reliability of GGT activity as the identification marker for N. meningitidis.