Epidemiology of bacteremia caused by uncommon non-fermentative gram-negative bacteria.

BACKGROUND: Prevalence of bacteremia caused by non-fermentative gram-negative bacteria (NFGNB) has been increasing over the past decade. Although many studies have already investigated epidemiology of NFGNB bacteremia, most focused only on common NFGNB including Pseudomonas aeruginosa (PA) and Acinetobacter baumannii (AB). Knowledge of uncommon NFGNB bacteremia is very limited. Our study aimed to investigate epidemiology and identify factors associated with uncommon NFGNB bacteremia. METHODS: This observational study was conducted at a university hospital in Thailand during July 1, 2007-Dec 31, 2008. All patients who had at least one blood culture positive for NFGNB and met the criteria for systemic inflammatory response syndrome within 24 hours before/after obtaining the blood culture were enrolled. The NFGNB isolates that could not be satisfactorily identified by the standard biochemical assays were further characterized by molecular sequencing methods. To identify factors associated with uncommon NFGNB bacteremia, characteristics of patients in the uncommon NFGNB group were subsequently compared to patients in the common NFGNB group (AB and PA bacteremia). RESULTS: Our study detected 223 clinical isolates of NFGNB in 221 unique patients. The major causative pathogens were AB (32.7%), followed by PA (27.8%), Stenotrophomonas maltophilia (5.4%), Acinetobacter lwoffii (4.9%) and Burkholderia pseudomallei (2.7%). Infection-related mortality was 63.0% in the AB group, 40.3% in the PA group and 17.4% in the uncommon NFGNB group. Factors associated with uncommon NFGNB bacteremia (OR [95% CI]; p-value) were male sex (0.28 [0.14-0.53]; p < 0.001), hospital-acquired infection (0.23 [0.11-0.51]; p < 0.001), recent aminoglycosides exposure 0.23 [0.06-0.8]; p = 0.01), primary bacteremia (6.43 [2.89-14.2]; p < 0.001]), catheter related infection (4.48 [1.54-13.06]; p < 0.001) and recent vancomycin exposure (3.88 [1.35-11.1]; p = 0.02). CONCLUSIONS: Our distribution of causative pathogens was slightly different from other studies. The common NFGNB group had a remarkably higher ID-mortality than the uncommon NFGNB group. Knowledge of factors associated with uncommon NFGNB bacteremia would help physicians to distinguish between low vs. high risk patients.

Molecular characterization of extended-spectrum beta-lactamases and its correlation with clinical laboratory standards institute interpretive criteria for disk diffusion susceptibility testing in enterobacteriaceae isolates in Thaialnd.

We performed extended-spectrum beta-lactamase (ESBL) phenotypic testing and molecular characterization of three ESBL genes (TEM, SHV and CTX-M) and susceptibility testing by Clinical Laboratory Standards Institute (CLSI) disk diffusion method against three cephalosporins (ceftriaxone, ceftazidime, cefepime) and a cephamycin (cefoxitin) among 128 Thai Escherichia coli and 84 Thai Klebsiella pneumoniae clinical isolates. ESBL production was discovered in 62% of E. coli and 43% of K. pneumoniae isolates. All isolates susceptible to ceftriaxone were ESBL-negative. Nearly all isolates non-susceptible to ceftriaxone, ceftazidime and cefepime produced ESBL; the presence of CTX-M genes in the isolates correlated with a ceftriaxone non-susceptible phenotype. Thirty-nine of 83 isolates (47%) of ceftazidime-susceptible E. coli and 50 of 99 isolates (50.5%) of cefepime-susceptible E. coli were ESBL-producing. SHV-type beta-lactamase genes were more prevalent among K. pneumoniae than E. coli isolates. CTX-M was the major ESBL gene harbored by ESBL-producers in both E. coli and K. pneumoniae isolates. Non-CTX-M ESBL-producers were found only among K. pneumoniae isolates. This study reveals an increase in ESBL-producing Enterobacteriaceae among Thai isolates and demonstrates gaps in the current CLSI disk diffusion susceptibility guidelines; it indicates the results of ceftazidime and cefepime disk diffusion susceptibility testing using CLSI criteria should be interpreted with caution.

Antimicrobial resistance of Acinetobacter baumannii: six years of National Antimicrobial Resistance Surveillance Thailand (NARST) surveillance.

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.

Long-term study of Escherichia coli and Klebsiella pneumoniae isolates producing extended-spectrum beta-lactamases.

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.

Antimicrobial resistance surveillance of Vibrio cholerae in Thailand from 2000 to 2004.

OBJECTIVE: To study the trends of antimicrobial resistance pattern of Vibrio cholerae in Thailand between 2000 and 2004. MATERIAL AND METHOD: All isolates of Vibrio cholerae from 28 hospitals across Thailand between 2000 and 2004 were tested for their susceptibility to ampicillin, chloramphenicol, norfloxacin, tetracycline 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 (WHO). RESULTS: V. cholerae O1, serotype Inaba was much more common than serotype Ogawa. The most frequent type of clinical specimens that V. cholerae isolated was the stool. There was no trend of increasing resistance of all V. cholerae both O1 and non O1. Over all average rates of tetracycline resistance of V. cholerae O1, Inaba and Ogawa were 0.9% and 16.3% respectively and trimethoprim/sulfamethoxazole resistance were 0.4% and 60.5% respectively. The strains were not resistant to norfloxacin. CONCLUSION: In Thailand, V. cholerae O1 were still susceptible to tetracycline and norfloxacin which were the most frequently antimicrobial used for the treatment of cholera. The trend of increasing resistance during the study period was not detected.

An overview of antimicrobial susceptibility patterns of gram-positive bacteria from National Antimicrobial Resistance Surveillance Thailand (NARST) program from 2000 to 2005.

In this overview, the authors summarize the antimicrobial susceptibility patterns of important Gram-positive bacteria from the National Antimicrobial Resistance Surveillance Thailand (NARST) program between 2000 and 2005 as well as the clinical implications. This collaborative network program was funded by the World Health Organization, and involved 33 hospitals throughout Thailand. There are rising trends of drug-resistant S. pneumoniae (DRSP), ampicillin-resistant enterococci, but a constant occurrence of methicillin-resistant S. aureus (MRSA) was noted during this period. The rates of penicillin and erythromycin resistances of S. pneumoniae were constantly high, ranging from 42.5% to 47.7% and 24.6% to 31.1%, respectively, whereas the rates of cefotaxime resistance were quite low, ranging from 2.1% to 8.4%. The rates of multidrug-resistant (MDR) S. pneumoniae ranged from 14.8% to 34.3%. Of all S. aureus isolates, MRSA comprised 24% to 27%, and vancomycin resistance rates of these MRSA isolates ranged from 0.1% to 0.8%. The antimicrobial resistance rates of methicillin-susceptible S. aureus isolates were very low. The rates of ampicillin and high-level gentamicin resistances of E. faecium from 2000 to 2005 have been significantly increasing from 52% to 84.1%, and from 46.9% to 75%, respectively, but vancomycin resistance was stable at the rates between 0.4% and 1.9%. In conclusions, antimicrobial resistance rates of important Gram-positive bacteria have been increasing in Thailand. All local, national, and international surveillance data will help to set the strategic plan for control and treatment of these resistant organisms. Appropriate and accurate microbiological procedures regarding the collection and transportation of clinical specimens as well as the identification of these emerging resistant organisms are urgently needed, in collaboration with other concerned sectors.

Antimicrobial resistance among clinical isolates of Staphylococcus aureus in Thailand from 2000 to 2005.

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.

Antimicrobial susceptibility of enterococci in Thailand from 2000 to 2005.

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.

National antimicrobial resistance surveillance among clinical isolates of Streptococcus pneumoniae in Thailand.

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.

Five-year surveillance for Burkholderia pseudomallei in Thailand from 2000 to 2004: prevalence and antimicrobial susceptibility.

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.

Antimicrobial resistance of Escherichia coli isolated from urine in Thailand from 2000 to 2005.

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.

Shigella species and serotypes among clinical isolates in Thailand from 2001 to 2005.

OBJECTIVE: To study the species and the serotypes of the clinical isolates of Shigella obtained from patients in Thailand. MATERIAL AND METHOD: The World Health Organization National Salmonella and Shigella Center Thailand, had confirmed the species and performed serotype identification of 1,913 clinical isolates of Shigella collected from the laboratory network of Department of Medical Sciences and the collaborated hospitals across Thailand from 2001 to 2005. RESULTS: Between the year 2001 and 2005, 728, 481, 160, 247, 297 clinical isolates were tested, respectively. There were 5 isolates of S. dysenteriae (group A), 416 isolates of S. flexneri (group B), 4 isolates of S. boydii (group C) and 1,488 isolates of S. sonnei (group D). A total of 21 Shigella serotypes were identified and there were 3 serotypes in group A, 11 serotypes in group B, 4 serotypes in group C, and 3 serotypes in group D. Throughout these five years, the five common serotypes were S. sonnei Phases I and II, 28.6% (548 isolates); S. sonnei Phase I, 24.6% (470 isolates); S. sonnei Phase II, 24.6% (470 isolates); S. flexneri Type 2a, 10.9% (208 isolates), and S. flexneri Type 3a, 6.3% (121 isolates), respectively. CONCLUSION: At the national scale in Thailand from 2001 to 2005, S. sonnei was the most frequent Shigella spp. isolated from patients in Thailand. In addition, S. dysenteriae and S. boydii were extremely uncommon. These findings are important in future vaccine development.

National Antimicrobial Resistance Surveillance, Thailand (NARST) data among clinical isolates of Pseudomonas aeruginosa in Thailand from 2000 to 2005.

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.

An overview of antimicrobial susceptibility patterns for gram-negative bacteria from the National Antimicrobial Resistance Surveillance Thailand (NARST) program from 2000 to 2005.

The National Antimicrobial Resistance Surveillance Thailand (NARST) has been initiated since 1998 to strengthen the surveillance program for antimicrobial-resistant pathogens as well as to standardize the laboratory practices in Thailand. This collaborative network was funded by the World Health Organization, and involved 33 hospitals throughout Thailand at the first phase. Nevertheless, no prior effort has been made to share the antimicrobial resistance data in the national level. In this overview, the authors provide an update on the status of antimicrobial resistance from 2000 to 2005 among important Gram-negative pathogens as well as the implication of these findings. The most striking finding appears to be the emergence of pandrug-resistant (PDR) Acinetobacter baumannii. Carbapenem-resistant A. baumannii has been dramatically increasing from 2.1% in 2000 to 46.7% in 2005. There is a trend towards the increasing incidence rates of ESBL-producing Escherichia coli from 2000 to 2005, but the incidence rates of ESBL-producing Klebseilla pneumoniae remain constant during the same period. The susceptibility of Burkholderia pseudomallei to various antibiotics, particularly ceftazidime and carbapenems, approached 100%. In conclusions, to help strengthen the future surveillance system, NARST needs to develop the data collection tools that include some important patient characteristics and the information that can help distinguish colonizations and infections as well as community-acquired infections and hospital-acquired infections. In addition, an appropriate test for antimicrobial susceptibility including the minimal inhibitory concentration determination should be implemented and carried out for all important pathogens. The NARST data emphasized a need to strengthen the antimicrobial stewardship as well as the infection control measures at the hospital level to help reduce the transmission of antimicrobial-resistant Gram-negative bacteria in Thailand.

Early-onset prosthetic valve endocarditis caused by Inquilinus sp.

Inquilinus is the newly described genus and has never been recognized as a cause of infective endocarditis. We report a case of early-onset prosthetic valve endocarditis caused by Inquilinus sp. in a tetralogy of Fallot patient who presented with heart failure. The bacterium was recovered from 11 consecutive blood cultures and identified by 16S rRNA gene sequencing.

Vancomycin overuse in Siriraj Hospital.

OBJECTIVE: An emergence of vancomycin resistant organisms particularly vancomycin-resistant enterococci (VRE) has become a serious public health concern. To prevent and control the spread of vancomycin resistant organisms, the prudent use of vancomycin is strongly recommended by the Hospital Infection Control Practices Advisory Committee (HICPAC). MATERIAL AND METHOD: A 6-week prospective observational study of vancomycin use was conducted in hospitalized patients at Siriraj Hospital from February to March 2005. Indications of initiating and continuing vancomycin were categorized according to HICPAC recommendations. Factors related to the appropriateness of vancomycin use were also evaluated. RESULTS: At initiation, vancomycin was inappropriately and empirically prescribed 19/222 times (8.6%) and 166/222 times (74.8%), respectively. After microbiological results were obtained, the rate of inappropriate prescription continued 132/222 times (59.5%). Furthermore, inappropriate use was significantly correlated with the type of department. There was a higher rate in the Department of Pediatrics, Surgery and Ophthalmology when compared with that of the Department of Medicine (p = 0.001). The inappropriate use also correlated with topical use (p < 0.001), intravenous administration (p = 0.012) and no consultation with an infectious disease specialist (p = 0.001). The overuse did not improve the clinical outcome. CONCLUSION: A substantial rate of inappropriate use of vancomycin was found in Siriraj Hospital. Intervention to improve appropriateness of vancomycin use should be urgently implemented to prevent and control the emergence of vancomycin resistant organisms.

Macrolide resistance and genotypic characterization of Streptococcus pneumoniae in Asian countries: a study of the Asian Network for Surveillance of Resistant Pathogens (ANSORP).

OBJECTIVES: To characterize mechanisms of macrolide resistance among Streptococcus pneumoniae from 10 Asian countries during 1998-2001. METHODS: Phenotypic and genotypic characterization of the isolates and their resistance mechanisms. RESULTS: Of 555 isolates studied, 216 (38.9%) were susceptible, 10 (1.8%) were intermediate and 329 (59.3%) were resistant to erythromycin. Vietnam had the highest prevalence of erythromycin resistance (88.3%), followed by Taiwan (87.2%), Korea (85.1%), Hong Kong (76.5%) and China (75.6%). Ribosomal methylation encoded by erm(B) was the most common mechanism of erythromycin resistance in China, Taiwan, Sri Lanka and Korea. In Hong Kong, Singapore, Thailand and Malaysia, efflux encoded by mef(A) was the more common in erythromycin-resistant isolates. In most Asian countries except Hong Kong, Malaysia and Singapore, erm(B) was found in >50% of pneumococcal isolates either alone or in combination with mef(A). The level of erythromycin resistance among pneumococcal isolates in most Asian countries except Thailand and India was very high with MIC(90)s of >128 mg/L. Molecular epidemiological studies suggest the horizontal transfer of the erm(B) gene and clonal dissemination of resistant strains in the Asian region. CONCLUSION: Data confirm that macrolide resistance in pneumococci is a serious problem in many Asian countries.

Mycobacterium tuberculosis infection among HIV/AIDS patients in Thailand: clinical manifestations and outcomes.

A one year retrospective study, was conducted at Bamrasnaradura Hospital, Nonthaburi Province, Bangkok, Thailand, of 271 subjects with both TB and HIV/AIDS. Single males (median age group 31 to 40 years) were most likely to develop co-infection. The commonest clinical manifestations on initial presentation included a low grade fever, cough, weight loss, lymphadenopathy with pancytopenia, and lung infiltrates. Multi-drug resistant TB (MDR-TB) was found in 26.6% of the subjects which was significantly associated with a past history of anti-TB treatment (p = 0.005; OR=2.5); it was also significantly associated with disseminated TB (p = 0.022; OR=1.9) and mortality (p= 0.013; OR=2.8). Analysis of clinical outcomes showed that 46.7% were lost to follow-up and 13.3% had died by the time of follow-up. Among those who survived, only 11.4% had been successfully treated; the rest had not improved due to relapse (2.9%), therapeutic failure (8.8%), treatment in progress (5.9%), and failure to complete treatment (10.7%).