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Background Serotype 24F is one of the emerging pneumococcal serotypes after the introduction of pneumococcal conjugate vaccine (PCV). We aimed to identify lineages driving the increase of serotype 24F in France and place these findings into a global context. Methods Whole-genome sequencing was performed on a collection of serotype 24F pneumococci from asymptomatic colonisation (n=229) and invasive disease (n=190) isolates among individuals younger than 18 years in France, from 2003 to 2018. To provide a global context, we included an additional collection of 24F isolates in the Global Pneumococcal Sequencing (GPS) project database for analysis. A Global Pneumococcal Sequence Cluster (GPSC) and a clonal complex (CC) were assigned to each genome. Phylogenetic, evolutionary, and spatiotemporal analysis were conducted using the same 24F collection and supplemented with a global collection of genomes belonging to the lineage of interest from the GPS project database (n=25 590). Findings Serotype 24F was identified in numerous countries mainly due to the clonal spread of three lineages: GPSC10 (CC230), GPSC16 (CC156), and GPSC206 (CC7701). GPSC10 was the only multidrug-resistant lineage. GPSC10 drove the increase in 24F in France and had high invasive disease potential. The international dataset of GPSC10 (n=888) revealed that this lineage expressed 16 other serotypes, with only six included in 13-valent PCV (PCV13). All serotype 24F isolates were clustered in a single clade within the GPSC10 phylogeny and long-range transmissions were detected from Europe to other continents. Spatiotemporal analysis showed GPSC10-24F took 3–5 years to spread across France and a rapid change of serotype composition from PCV13 serotype 19A to 24F during the introduction of PCV13 was observed in neighbouring country Spain. Interpretation Our work reveals that GPSC10 alone is a challenge for serotype-based vaccine strategy. More systematic investigation to identify lineages like GPSC10 will better inform and improve next-generation preventive strategies against pneumococcal diseases. Funding Bill & Melinda Gates Foundation, Wellcome Sanger Institute, and the US Centers for Disease Control and Prevention.

Pneumococcal serotype 35B is an important non-conjugate vaccine (non-PCV) serotype. Its continued emergence, post-PCV7 in the USA, was associated with expansion of a pre-existing 35B clone (clonal complex [CC] 558) along with post-PCV13 emergence of a non-35B clone previously associated with PCV serotypes (CC156). This study describes lineages circulating among 35B isolates in South Africa before and after PCV introduction. We also compared 35B isolates belonging to a predominant 35B lineage in South Africa (GPSC5), with isolates belonging to the same lineage in other parts of the world. Serotype 35B isolates that caused invasive pneumococcal disease in South Africa in 2005-2014 were characterized by whole-genome sequencing (WGS). Multi-locus sequence types and global pneumococcal sequence clusters (GPSCs) were derived from WGS data of 63 35B isolates obtained in 2005-2014. A total of 262 isolates that belong to GPSC5 (115 isolates from South Africa and 147 from other countries) that were sequenced as part of the global pneumococcal sequencing (GPS) project were included for comparison. Serotype 35B isolates from South Africa were differentiated into seven GPSCs and GPSC5 was most common (49 %, 31/63). While 35B was the most common serotype among GPSC5/CC172 isolates in South Africa during the PCV13 period (66 %, 29/44), 23F was the most common serotype during both the pre-PCV (80 %, 37/46) and PCV7 period (32 %, 8/25). Serotype 35B represented 15 % (40/262) of GPSC5 isolates within the global GPS database and 75 % (31/40) were from South Africa. The predominance of the GPSC5 lineage within non-vaccine serotype 35B, is possibly unique to South Africa and warrants further molecular surveillance of pneumococci.

A Neisseria gonorrhoeae multilocus sequence type (MLST) ST7363 strain was isolated from a patient at the Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand, in 2010 and completely sequenced. This strain is susceptible to ceftriaxone and cefixime. A complete circular chromosome and circular plasmids were assembled from combined Oxford Nanopore Technologies (ONT) and Illumina sequencing.

Background: Invasive pneumococcal disease remains an important health priority owing to increasing disease incidence caused by pneumococci expressing non-vaccine serotypes. We previously defined 621 Global Pneumococcal Sequence Clusters (GPSCs) by analysing 20 027 pneumococcal isolates collected worldwide and from previously published genomic data. In this study, we aimed to investigate the pneumococcal lineages behind the predominant serotypes, the mechanism of serotype replacement in disease, as well as the major pneumococcal lineages contributing to invasive pneumococcal disease in the post-vaccine era and their antibiotic resistant traits. Methods: We whole-genome sequenced 3233 invasive pneumococcal disease isolates from laboratory-based surveillance programmes in Hong Kong (n=78), Israel (n=701), Malawi (n=226), South Africa (n=1351), The Gambia (n=203), and the USA (n=674). The genomes represented pneumococci from before and after pneumococcal conjugate vaccine (PCV) introductions and were from children younger than 3 years. We identified predominant serotypes by prevalence and their major contributing lineages in each country, and assessed any serotype replacement by comparing the incidence rate between the pre-PCV and PCV periods for Israel, South Africa, and the USA. We defined the status of a lineage as vaccine-type GPSC (≥50% 13-valent PCV [PCV13] serotypes) or non-vaccine-type GPSC (>50% non-PCV13 serotypes) on the basis of its initial serotype composition detected in the earliest vaccine period to measure their individual contribution toward serotype replacement in each country. Major pneumococcal lineages in the PCV period were identified by pooled incidence rate using a random effects model. Findings: The five most prevalent serotypes in the PCV13 period varied between countries, with only serotypes 5, 12F, 15B/C, 19A, 33F, and 35B/D common to two or more countries. The five most prevalent serotypes in the PCV13 period varied between countries, with only serotypes 5, 12F, 15B/C, 19A, 33F, and 35B/D common to two or more countries. These serotypes were associated with more than one lineage, except for serotype 5 (GPSC8). Serotype replacement was mainly mediated by expansion of non-vaccine serotypes within vaccine-type GPSCs and, to a lesser extent, by increases in non-vaccine-type GPSCs. A globally spreading lineage, GPSC3, expressing invasive serotypes 8 in South Africa and 33F in the USA and Israel, was the most common lineage causing non-vaccine serotype invasive pneumococcal disease in the PCV13 period. We observed that same prevalent non-vaccine serotypes could be associated with distinctive lineages in different countries, which exhibited dissimilar antibiotic resistance profiles. In non-vaccine serotype isolates, we detected significant increases in the prevalence of resistance to penicillin (52 [21%] of 249 vs 169 [29%] of 575, p=0·0016) and erythromycin (three [1%] of 249 vs 65 [11%] of 575, p=0·0031) in the PCV13 period compared with the pre-PCV period. Interpretation: Globally spreading lineages expressing invasive serotypes have an important role in serotype replacement, and emerging non-vaccine serotypes associated with different pneumococcal lineages in different countries might be explained by local antibiotic-selective pressures. Continued genomic surveillance of the dynamics of the pneumococcal population with increased geographical representation in the post-vaccine period will generate further knowledge for optimising future vaccine design. Funding: Bill & Melinda Gates Foundation, Wellcome Sanger Institute, and the US Centers for Disease Control. Fil: Lo, Stephanie W.. Wellcome Sanger Institute; Reino Unido Fil: Gladstone, Rebecca A.. Wellcome Sanger Institute; Reino Unido Fil: van Tonder, Andries J.. Wellcome Sanger Institute; Reino Unido Fil: Lees, John A.. University Of New York. School Of Medicine; Estados Unidos Fil: du Plessis, Mignon. National Institute For Communicable Diseases; Sudáfrica Fil: Benisty, Rachel. Ben Gurion University of the Negev; Israel Fil: Givon Lavi, Noga. Ben Gurion University of the Negev; Israel Fil: Hawkins, Paulina A.. University of Emory. Rollins School of Public Health; Estados Unidos Fil: Cornick, Jennifer E.. Malawi liverpool wellcome trust; Malaui Fil: Kwambana Adams, Brenda. University College London; Estados Unidos Fil: Law, Pierra Y.. University of Hong Kong; China Fil: Ho, Pak Leung. University of Hong Kong; China Fil: Antonio, Martin. Medical Research Council Unit The Gambia; Gambia Fil: Everett, Dean B.. University of Edinburgh; Reino Unido Fil: Dagan, Ron. Ben Gurion University of the Negev; Israel Fil: Von Gottberg, Anne. National Institute For Communicable Diseases; Sudáfrica Fil: Klugman, Keith P.. University of Emory. Rollins School of Public Health; Estados Unidos Fil: McGee, Lesley. Centers for Disease Control and Prevention; Estados Unidos Fil: Breiman, Robert F.. University of Emory. Rollins School of Public Health; Estados Unidos Fil: Bentley, Stephen D.. Wellcome Sanger Institute; Reino Unido Fil: Brooks, Abdullah W.. The Global Pneumococcal Sequencing Consortium; Reino Unido Fil: Corso, Alejandra. The Global Pneumococcal Sequencing Consortium; Reino Unido. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Área de Antimicrobianos; Argentina Fil: Davydov, Alexander. The Global Pneumococcal Sequencing Consortium; Reino Unido Fil: Maguire, Alison. The Global Pneumococcal Sequencing Consortium; Reino Unido Fil: Pollard, Andrew. The Global Pneumococcal Sequencing Consortium; Reino Unido Fil: Kiran, Anmol. The Global Pneumococcal Sequencing Consortium; Reino Unido Fil: Skoczynska, Anna. The Global Pneumococcal Sequencing Consortium; Reino Unido Fil: Moiane, Benild. The Global Pneumococcal Sequencing Consortium; Reino Unido Fil: Beall, Bernard. The Global Pneumococcal Sequencing Consortium; Reino Unido Fil: Sigauque, Betuel. The Global Pneumococcal Sequencing Consortium; Reino Unido Fil: Aanensen, David. The Global Pneumococcal Sequencing Consortium; Reino Unido Fil: Lehmann, Deborah. The Global Pneumococcal Sequencing Consortium; Reino Unido Fil: Faccone, Diego Francisco. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Instituto Nacional de Enfermedades Infecciosas. Área de Antimicrobianos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

We surveyed group C and group G β-hemolytic streptococci for emm and emmL (emm -like) genes which encode the M protein, as well as determined their antimicrobial susceptibilities. A total of 97 isolates 79 GCS/GGS isolates and 18 isolates from other groups were tested for the M protein gene by PCR. Focusing on invasive infections with group A (GAS), group C (GCS), and group G (GGS) β-hemolytic streptococci isolated from blood, the M protein gene was found in 90.0%, 84.6%, and 78.3% of isolates, respectively. The hypervariable N terminal region of the emm was sequenced from 62 isolates, and 26 types of the emm gene were identified. Based on these results, type emm222.2 may be endemic to Thailand. The results of antimicrobial susceptibility testing of groups C, G, and non-groups A to G isolates indicated high susceptibility (range 82-100%) to penicillin, cefotaxime, chloramphenicol, clindamycin, erythromycin, linezolid, ofloxacin, and vancomycin, whereas the isolates showed low susceptibility (range 0-15.6%) to tetracycline.

We studied the antimicrobial susceptibility and prevalence of the blaTEM-1 and blaTEM-135 genes in Neisseria gonorrhoeae isolates obtained in Thailand. The isolates were tested using the disk diffusion method, and 100% of 370 isolates were found susceptible to cefixime, ceftriaxone, cefotaxime, ceftazidime, cefepime, spectinomycin, and azithromycin. Some of the isolates were resistant to penicillin (85.7%), ciprofloxacin (88.0%), ofloxacin (97.4%), or tetracycline (89.1%). Penicillinase-producing N. gonorrhoeae accounted for 83.8% of isolates, with 70.0% of these further identified as penicillinase-producing plus tetracycline resistant N. gonorrhoeae. Penicillin, tetracycline, and ciprofloxacin are not recommended for treatment because of the high prevalence (89.7%) of multidrug resistant gonococci. A study of genes controlling enzyme of beta-lactamase production (blaTEM-1 and blaTEM-135) was performed using mismatch amplification mutation assay PCR method and DNA sequencing. Beta-lactamase positive N. gonorrhoeae carried blaTEM-1 (69.6%) and blaTEM-135 (30.4%), indicating that there is a significant increase and spread of blaTEM-135 among gonococci in Thailand.

Haemophilus influenzae was isolated from 556 different patients, mostly 10 years or under, at a tertiary referral hospital in Bangkok, Thailand during 2012 - 2015. Peak period of detection was from January to March. Thirty-nine percent of the isolates were β-lactamase positive. β-Lactamase-negative ampicillin-resistant H. influenzae (BLNAR) constituted 2% of β-lactamase-negative cases. H. influenzae was susceptible to ampicillin (58%), amoxicillin/clavulanate (99%), cefotaxime (100%), ceftriaxone (100%), cefuroxime (99%), ciprofloxacin (99%), chloramphenicol (86%), tetracycline (75%), and trimethoprim-sulphamethoxazole (52%). β-Lactamase-producing isolates (72%) showed high minimal inhibitory concentration (MIC) to ampicillin (128-516 μg/ml) and all BLNAR isolates low ampicillin MIC (2-16 μg/ml). These findings indicate that the level of ampicillin resistance in H. influenzae depended on differences in resistance mechanism.

We studied the antimicrobial susceptibility and prevalence of the bla

BACKGROUND: Class 1 integron element is innate to most of the multidrug resistant Acinetobacter baumannii and its spread is common among international clones worldwide. The aim of this study was to document the presence of bla VEB-1 harboring class 1 integron element and its gene cassettes in Thai A. baumannii in relation to A. baumannii European clone I, AYE strain. MATERIALS AND METHODS: Thirty seven carbapenem resistant A. baumannii isolates identified in routine microbiology laboratory of Siriraj Hospital, Bangkok were studied. The dot blot hybridization was performed to detect class 1 integron element integrase gene. PCR was used to amplify bla VEB-1 , arr2 , cmlA , bla OXA-10 resistance cassettes, and variable region of class 1 integron element. bla VEB-1 gene was localized by southern blot hybridization. RESULTS: The prevalence of class 1 integron element was 86.48% in the isolates studied. The bla VEB-1 was present in 7 isolates however the location of bla VEB-1 gene was different in different isolate. Four isolates (Ab03-168, Ab04-28, Ab08-20, and Ab08-22) harbored calss 1 integron element variable region sized 5.5 kb as described in strain AYE. However, bla VEB-1 was only amplified from Ab03-168. The cassette organization in this isolate was 5’CS-aadB -bla VEB-1 - arr2 - cmlA-bla OXA- 10 -aadA1-3’CS. The class 1 integron element similar to the element identified in genomic resistance island, AbaRI of European clone I, AYE was identified in Thai A. baumannii . CONCLUSIONS: bla VEB-1 harboring class 1 integron element with minor cassette variation was identified in Thai A. baumanni isolate which might suggest the spread of this resistant cassette or the spread of the European clone I in Thailand. Monitoring of the global spread of multi-resistant A. baumannii is mandatory to control the spread of resistant genes and this multi-resistant pathogen. DOI: http://dx.doi.org/10.3126/ijim.v1i1.6715 Int J Infect Microbiol 2012;1(1):24-28

Background: Siderophore is an iron chelator produced by microorganism. Pseudomonas aeruginosa produces two siderophores (pyoverdin and pyochelin). Desferrioxamine is a siderophore used in thalassemia patients to treat an iron overload of vital organs. Objective: Compare the ability of pyoverdin, pyochelin, and desferrioxamine for iron mobilization from ferritin. Materials and Methods: In vitro experiment, the ability of P. aeruginosa siderophores and desferrioxamine for iron mobilization from ferritin was compared by using a dialysis membrane assay at pH values of 7.4 and 6.0. Stimulation of P. aeruginosa PAO1 growth by all siderophores was studied in glucose minimum medium. Results: All three compounds were capable of iron mobilization at both pHs. At pH 6.0, the most effectiveness compound was desferrioxamine (31.6%), followed by pyoverdin (21.5%) and pyochelin (13.7%) compared on weight basis, each at 10 μg/mL. At equimolar concentration, their activities were desferrioxamine (38.5±1.2%), followed by pyoverdin (32.0±4.8%) and pyochelin (26.7±1.9%), respectively. Conclusion: The most effective compound in iron mobilization from ferritin was desferrioxamine, followed by pyoverdin and pyochelin respectively.

Neisseria gonorrhoeae is a major public health problem globally, especially because the bacterium has developed resistance to most antimicrobials introduced for first-line treatment of gonorrhea. In the present study, 96 N. gonorrhoeae isolates with high-level resistance to penicillin from 121 clinical isolates in Thailand were examined to investigate changes related to their plasmid-mediated penicillin resistance and their molecular epidemiological relationships. A β-lactamase (TEM) gene variant, bla TEM-135 , that may be a precursor in the transitional stage of a traditional bla TEM-1 gene into an extended-spectrum β-lactamase (ESBL), possibly causing high resistance to all extended-spectrum cephalosporins in N. gonorrhoeae , was identified. Clonal analysis using multilocus sequence typing (MLST) and N. gonorrhoeae multiantigen sequence typing (NG-MAST) revealed the existence of a sexual network among patients from Japan and Thailand. Molecular analysis of the bla TEM-135 gene showed that the emergence of this allele might not be a rare genetic event and that the allele has evolved in different plasmid backgrounds, which results possibly indicate that it is selected due to antimicrobial pressure. The presence of the bla TEM-135 allele in the penicillinase-producing N. gonorrhoeae population may call for monitoring for the possible emergence of ESBL-producing N. gonorrhoeae in the future. This study identified a bla TEM variant ( bla TEM-135 ) that is a possible intermediate precursor for an ESBL, which warrants international awareness.

Streptococcus pneumoniae was isolated from 170 patient specimens at Siriraj Hospital during January-December 2008. Patients were 66% male and ranged in age from 3 months to 94 years (mean +/- SD = 38.2 +/- 31.7). The largest proportion (29.4%) of isolates were from patients older than 60 years, followed by patients aged 2-5 years (20%) and from patients less than 2 years (12.4%). Monthly isolation was highest in December (22 isolates in December compared to the average of 13 isolates of the other months). Antimicrobial susceptibility for eight drugs was determined by the disk diffusion method. Overall, susceptibility was generally high to chloramphenicol (71.8%), linezolid (100%), ofloxacin (93.5%) and vancomycin (100%), but less susceptible to erythromycin (35.3%), penicillin (31.1%), tetracycline (28.8%) and trimethoprim/ sulfamethoxazole (24.1%). Among the 105 (62%) isolates resistant to three or more drugs, the most common resistance pattern was erythromycin-penicillin-tetracycline-trimethoprim/sulfamethoxazole, accounting for 39% of such isolates, followed by chloramphenicol-erythromycin-penicillin-tetracycline- trimethoprim/sulfamethoxazole (29.5%). The minimal inhibitory concentrations (MIC) of penicillin and cefotaxime were determined by broth microdilution. By 2008 CLSI criteria, 92% and 90% of 51 sterile site isolates were penicillin and cefotaxime susceptible, including one of two meningitis cases. In contrast, of 26 non-sterile site isolates, only 26.9% and 76.9% were susceptible to penicillin and cefotaxime, respectively. The MICs of penicillin were higher for isolates from non-sterile sites than for those from sterile sites.

Penicillin resistance in Streptococcus pneumoniae isolates results from altered penicillin-binding proteins (PBPs), especially PBP2, which has a reduced affinity to penicillin. This study evaluated drug resistance and the gene sequence of the conserved motif pbp2b of penicillin-resistant isolates in Thailand.Penicillin-resistant pneumococci with minimum inhibitory concentrations (MIC) for penicillinor = microg/ ml and penicillin-susceptible strains were identified from clinical specimens. The pbp2b genes were amplified by polymerase chain reaction (PCR), and the purified PCR product was cloned into E. coli. The recombinant plasmid clones containing pbp2b were sequenced and evaluated for mutations corresponding to penicillin and cefotaxime resistance.Penicillin-susceptible S. pneumoniae isolates were susceptible to 12 other antibiotics tested (range 95-100%) while penicillin-nonsusceptible isolates were resistant to most antibiotics except amoxicillin/clavulanate and levofloxacin. Sequence analysis of pbp2b showed a substitution of A for T451 next to the region of the SSN triad in all six resistant isolates tested and mutations clustered around the KTG triad in two isolates. Using the ClustalW alignment program, Thai isolates differed from those of European countries, but were more similar to those from Japan than Korea.Penicillin or cefotaxime resistance in S. pneumoniae in Thailand was due to affinity reduction of PBP2b, similar to changes found in other Asian isolates.

The most frequent markers of fluoroquinolone resistance in S. pneumoniae are chromosomal mutations in the quinolone-resistance-determining regions of DNA gyrase and topoisomerase IV encoding for the gyrA, gyrB and parC, parE genes. In 2008, 6.5% of the Streptococcus pneumoniae isolates in a Bangkok university hospital were resistant to ofloxacin. Using PCR and DNA sequencing, we identified mutations in both the gyrA and parC genes of four ofloxacin- and ciprofloxacin-resistant S. pneumoniae isolates (minimum inhibitory concentrations32 microg/ml). Mutations were found in the gyrA gene at positions Ser81Phe, Glu85Gly, Glu85Lys and in the parC gene at position Ser79Tyr. Three isolates had mutations in both genes. Two of the isolates were serotype 6B and two were serotypes not contained in currently licensed pneumococcal vaccines. This is the first report of the mechanisms of fluoroquinolone resistance in S. pneumoniae in Thailand.

Rapid detection of bacterial pathogen causing meningitis is very important to guide antimicrobial therapy before the standard culture result is available. Other than gram stain, one of the most useful rapid methods is the detection of bacterial antigen in cerebrospinal fluid. This article reviewed the methods of bacterial antigen detection for diagnosis of meningitis as well as a microbiology aspect of this life-threatening disease.

Acinetobacter baumannii has emerged in health care settings as a pandrug-resistant pathogen. Carbapenems are ineffective for treatment of this pathogen. Here we explored the molecular epidemiology and mechanism of carbapenem resistance in clinical isolates of carbapenem-resistant A. baumannii (CRAB). Antibiotic susceptibility by disk diffusion test was performed using imipenem and meropenem disk on 200 different clinical CRAB isolates. All isolates were resistant and gave inhibition zones of both antibiotic disksor = 13 mm. Polymerase chain reaction (PCR) was carried out on 37 randomly selected isolates to amplify the common carbapenem hydrolyzing beta-lactamase genes (bla(OXA23)-like, bla(OXA-24/40)-like, bla(OXA-58), bla(IMP), and bla(VLM)). Clones were resolved by PCR-randomly amplified polymorphic DNA (PCR-RAPD) and plasmid profiling. PCR amplification and DNA sequencing revealed the existence of bla(OXA-23) downstream of the insertion element, ISAba1, in all 37 isolates tested. This segment was present in the carbapenem-resistant genomic resistant island AbaR4. These isolates were resolved into three RAPD types (Type I, 20 isolates; Type II, 16 isolates; and type III, 1 isolate) and 10 plasmid profiles. The CRAB isolates investigated here were oligoclonal and carbapenem resistance was conferred by the presence of bla(OXA-23). The presence of this beta-lactamase gene in many clonal isolates indicated its wide spread.

This is the first reported case of bacillary angiomatosis associated with Bartonella henselae in Thailand. The clinical, pathological, and microbiological findings are presented. The bacterium was isolated from a biopsy of skin lesions obtained on admission and identified by cellular morphology, characteristics of colonies on chocolate agar, extensive biochemical tests and 16S ribosomal DNA sequencing.

A total of 400 clinical Streptococcus pneumoniae strains from patients with respiratory diseases were collected from January 2002 to December 2005. In this study, an increased prevalence of penicillin-nonsusceptible S. pneumoniae (PNSP) from 63% in 2002-2003 to 69% in 2004-2005 was found. During 2004-2005, 56% were erythromycin-nonsusceptible S. pneumoniae (ENSP) and 54% were both PNSP and ENSP. The PNSP, ENSP and PNSP+ENSP groups showed similar trends, ie, sensitive to amoxicillin/clavulanate (range 97.2-98.5%), levofloxacin (range 90.7-92.4%), ceftriaxone (range 87.1-89.4%), and ofloxacin (range 64.8-66.1%). Lower levels of susceptibility were detected for azithromycin, clarithromycin, cefdinir, cefprozil, clindamycin, co-trimoxazole, chloramphenicol and tetracycline in penicillin and erythromycin-nonsusceptible strains. Of the macrolide-resistant S. pneumoniae, 55% of strains exhibited the M phenotype and 45% the constitutive MLS(B) phenotype. No pneumococci with the inducible MLS(B) phenotype were detected in Thailand.

Among 120 Escherichia coli isolates from Thai patients, 37 and 9 isolates were extended-spectrum beta-lactamase (ESBL) and suspected ESBL producers respectively while 5 E. coli isolates from 120 Thai healthy adults were suspected ESBL producers. Integrase (intl1) gene was detected in 99% of the clinical and 87% of the non-clinical isolates. Among 37 ESBL producers, percent recovery of bla(TEM), bla(CTX-M), bla(SHV) and bla(VEB) was 78%, 78%, 8% and 8%, respectively. Twenty-five isolates of ESBL producers carried both bla(TEM) and bla(CTX-M), 2 isolates carried 3 genes (bla(TEM), blac(CTX-M), and bla(SHV)) and 3 showed no detectable bla gene. Among the 14 suspected ESBL producers, intl1 and bla(TEM) were detected in 13 isolates. ESBL producers from clinical samples were resistant to most of the tested antimicrobial agents compared to non-ESBL producers and isolates from healthy adults with about half of the latter susceptible to all tested antimicrobial agents. Only one clinical isolate was resistant to imipenem. Susceptibility to trimethoprim/sulfamethoxazole among the clinical isolates in ESBL producer group (27%) and non-producer group (33%) were comparable, whereas the percent susceptibility of the non-clinical isolates was about twice that of the clinical isolates.

Extended-spectrum beta-lactamases (ESBLs) are most prevalent in Klebsiella pneumoniae. This organism is frequently isolated from clinical specimens and can cause septicemia, pneumonia or urinary tract infection. There were occasionally suspicious outbreaks of ESBL-producing K. pneumoniae in patients' wards. The objective is to determine whether the randomly amplified polymorphic DNA (RAPD), which is a polymerase chain reaction (PCR)-based typing technique, can be used as a typing method for studying the molecular epidemiology of ESBL-producing K. pneumoniae.The present study was carried out by using 30 ESBL-producing K. pneumoniae isolates obtained from different patients admitted to Siriraj Hospital between January and February 2004. RAPD was evaluated for three primers. All isolates were re-examined by using Southern blot hybridization.It was found that 29 DNA band patterns were generated individually by either AP4 or HLWL74 and R108 primers (30 patterns) for RAPD analysis and 30 patterns for Southern blot hybridization with class 1 integron (intI1) probe. Different patterns indicated that these 30 isolates could not be the cause of an outbreak in Siriraj Hospital.The RAPD typing is good and can be used as a screening, rapid and inexpensive'test for ESBL-producing K. pneumoniae during investigation of outbreaks.

We evaluated 582 Haemophilus influenzae isolates from patients between January 2000 and December 2004. Overall, 433 isolates were obtained from sputum and bronchial washings, 124 isolates were from pus, 19 isolates were from blood and 6 isolates form cerebrospinal fluid. H. influenzae was sensitive to amoxicillin/clavulanate, ampicillin/sulbactam, gentamicin, cefuroxime, ceftriaxone, cefotaxime, ciprofloxacin, ofloxacin, imipenem, meropenem (range 97-100%), chloramphenicol (75%), ampicillin/amoxicillin (52%), but resistant to trimethoprim-sulphamethoxazole. As for beta-lactamase production, 48.4% of the isolates tested were positive.

The CA-MRSA infections have emerged in many parts of the world over the past decade. To our knowledge, the prevalence of CA-MRSA infections in Thai patients is unknown.To determine an epidemiology of Staphylococcus aureus (S. aureus) infections in hospitalized patients in Siriraj Hospital and the prevalence of infections caused by community-acquired methicillin-resistant S. aureus (CA-MRSA).The study was carried out at Siriraj Hospital from January to May 2005. The eligible patients were hospitalized patients whom S. aureus were isolated from their clinical specimens submitted to Department of Microbiology. S. aureus isolate was classified into infection or colonization. S. aureus infections were further classified into methicillin-resistant S. aureus (MRSA) or methicillin-sensitive S. aureus (MSSA) infections, and hospital-acquired (HA) or community-acquired (CA) infections. CA-MRSA infection is defined as infection caused by MRSA isolated from the patient within 72-hour of hospitalization and has no features of HA MRSA infections.There were 669 S. aureus isolates from 448 patients. Two hundred and sixty two patients (58.5%) were MSSA whereas 186 (41.5%) were MRSA infections. CA-MRSA was found in three isolates (0.9% of total MRSA) from two patients.The prevalence of CA-MRSA infections in hospitalized patients in Siriraj Hospital was uncommon and these patients could probably be HA MRSA infections.

This study was undertaken from 1995-2000 to investigate the cause of respiratory tract infection among 481 patients with human immunodeficiency virus (HIV) at Siriraj Hospital, Bangkok, Thailand. The positive rate of bacterial pathogens was 38.46%. Pseudomonas aeruginosa appeared to be the most common pathogen (32.97%), followed by Staphylococcus aureus (18.92%), Klebsiella pneumoniae (10.81 %), Haemophilus influenzae (7.57%), and Acinetobacter baumannii (5.95%). P. aeruginosa was sensitive to netilmycin, amikacin, imipenem, meropenem, cefoperazone/sulbactam, piperacillin/tazobactam, and gentamicin (67-84%). S. aureus was sensitive to vancomycin and teicoplanin (100%).

Pseudomonas aeruginosa is a leading cause of nosocomial infections. One thousand two hundred and twenty strains of mucoid and non-mucoid types of P. aeruginosa isolated from different patients were examined at Siriraj Hospital from January 2001-October 2003. The prevalences of P. aeruginosa mucoid type and non-mucoid type were 3.6% and 96.4%, respectively. Susceptibility testing was performed by Kirby-Bauer disk diffusion method as recommended by NCCLS. The isolates with mucoid phenotypes were more susceptible than the non-mucoid isolates. The antimicrobial susceptibility pattern of both types should provide guidelines for the selection of appropriate drugs for treatment.

Bacterial infections in human immunodeficiency virus (HIV) infected patients may frequently develop into septicemia. Our study evaluated the bacterial pathogens isolated from hemocultures of HIV-infected patients at Siriraj Hospital and their antimicrobial susceptibility tests. The percentages of positive hemocultures were 24.64, 21.38, 23.88, and 28.46% in 1996, 1997, 1998, and 1999, respectively. Salmonella spp was the most pathogen isolated, followed by Escherichia coil (10.93%), Staphylococcus aureus (8.2%), coagulase-negative staphylococci (6.56%), nonfermentative gram-negative rods (6.01%), Pseudomonas aeruginosa (5.46%), Klebsiella pneumoniae (4.37%), and Enterobacter spp (4.37%). Salmonella, serogroup C was the most frequently isolated serogroup. It was sensitive to amoxicillin/clavulanate in 100%, ampicillin/sulbactam in 89%, cefazolin, cefuroxime, cefotaxime, ceftriaxone, ceftazidime, imipenem, gentamicin, amikacin, netilmycin, ofloxacin, and ciprofloxacin in 100%. The changing spectrum of bacteria and antimicrobial susceptibility patterns in HIV-1 infected patients may provide a guideline for the selection of appropriate drugs for treatment.

Infective endocarditis is life-threatening and urgent treatment is needed. We review here 6217 patients with infective endocarditis admitted to Siriraj Hospital during a 20 year period, 1982-2001. In this retrospective study, we obtained our data from hemoculture results. Bacterial pathogens were found in only 834 patients (13.41%). Of the five most common pathogens, nonfermentative gram-negative rods (N.F.) ranked first (20.94%), followed by coagulase-negative staphylococci (12.47%), viridans streptococci (10.23%), Staphylococcus aureus (9.29%), and Escherichia coli (8.59%). Of the N.F., the sensitivities were: cefoperazone/sulbactam (86%), piperacillin/tazobactam (86%), meropenem (84%), imipenem (83%), ceftazidime (78%), ofloxacin (85%), ciprofloxacin (71%), and co-trimoxazole (71%).

Meningitis caused by Salmonella species is not uncommon in many developing countries. Patients suspected of bacterial meningitis who were admitted to Siriraj Hospital were enrolled in this study during 1986-2001. There were only 19 cases of Salmonella meningitis. Salmonella serogroup D ranked first, followed by serogroup C, serogroup B and then serogroup H. Most patients were children under 1 year of age. The antimicrobial susceptibility pattern for Salmonella meningitis may provide a guideline for the selection of appropriate drug treatment.

The objective of the study was to compare the clinical efficacy and bacteriological response of levofloxacin and amoxicillin/clavulanic acid (co-amoxiclav) in the treatment of purulent maxillary sinusitis. Sixty patients randomly received either levofloxacin 300 mg orally once daily (LEV group) or co-amoxiclav 625 mg three times a day (COA group) for 14 days. Thirty four patients were in the LEV group and 26 patients were in the COA group. The mean total symptom score was significantly decreased after treatment and was comparable between both groups. Radiological improvement was 61.8% in the LEV group (41.2% resolution, 20.6% improvement) and 61.5% in the COA group (26.9% resolution, 34.6% improvement). Pretreatment maxillary antral aspiration cultures were positive in 28 patients (82.4%) in the LEV group and 20 patients (76.9%) in the COA group. Bacteriological eradication was 78.5% in the LEV group and 70.0% in the COA group, which was not significantly different. In the LEV group, the eradication rate for major pathogens of acute sinusitis was 100% for H. influenzae (both betalactamase +ve and -ve), 100% for S. pneumoniae and S. aureus, 100% for Neisseria species, and 66.7% for P. aeruginosa. The eradication rate in the COA group was 75% for H. influenzae (both betalactamase +ve and -ve), 100% for S. pnumoniae and S. aureus, 50% for Neisseria species, and 0% for P. aeruginosa. There were no significant changes in vital sign measurements or hemato-biochemical parameters at the end of treatment as compared to baseline values, in both groups. Adverse events were found in 8.8% of patient in the LEV group and in 7.7% of patients in the COA group. Adverse events included nausea, abdominal pain, and diarrhea. All the adverse events in both groups were mild and resolved spontaneously. This study demonstrated that levofloxacin 300 mg orally once daily was as effective and safe as amoxicillin/clavulanic acid 625 mg three times a day in the treatment of maxillary sinusitis, either acute or acute exacerbation. Both drugs showed bacteriological efficacy that was not significantly different. The once daily dosage regimen is more applicable, convenience and has better compliance.

Many essential oils have antibacterial activity with a potential use in medicine. Citrus hystrix DC, or makrut lime, contains two essential oils, makrut leaf oil and makrut (fruit peel) oil, of which we determined the inhibitory effect against respiratory pathogens and evaluated their active components. Gas chromatography-mass spectrometry was used to analyse the chemical composition of the essential oils. The antibacterial activities were tested by disc-diffusion and broth microdilution methods against 411 isolates of groups A, B, C, F, G streptococci, Streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus (methicillin-resistant and -sensitive S. aureus) and Acinetobacter baumannii, obtained from patients with respiratory tract infections. Makrut leaf oil and makrut oil were both effective against all the pathogens with minimal inhibitory concentration (MIC) ranges of 0.06-68 mg/ml and 0.03-17.40 mg/ml, respectively. Citronellal was found to be the major component (80.04%) in makrut leaf oil and had the lowest MIC. In contrast, makrut oil consisted of several components (limonene 40.65%, terpinene-4-ol 13.71%, -terpineol 13.20%), and the most active component was -terpineol, followed by terpinene-4-ol, and limonene. These results suggest that makrut leaf oil, makrut oil, and their components (citronellal, -terpineol, terpinene-4-ol) may be alternative natural source medicine to prevent and treat many bacterial diseases.