Antibiotic susceptibility pattern and the indicator of decreased ciprofloxacin susceptibility of Salmonella enterica serovar Typhi isolated from Dhulikhel Hospital, Nepal.

Monitoring the antibiotic susceptibility pattern of Salmonella enterica serovar Typhi (S. Typhi) is important for efficiently managing cases of typhoid fever. In this study, the antimicrobial susceptibility patterns of 114 S. Typhi isolates, which were collected from a university hospital in Nepal during July 2009-December 2010, were investigated by disc diffusion assays. All of the S. Typhi isolates were sensitive to amoxycillin-clavulanic acid. More than 95% of the isolates were sensitive to chloramphenicol, ceftazidime, ceftriaxone, and cotrimoxazole. In addition, 1.7% of the studied isolates showed multiple drug resistance patterns. Of the 40 S. Typhi isolates, 32 strains (80%) showed nalidixic acid (NA) resistance with decreased susceptibility to ciprofloxacin (CIP). Importantly, we found the simultaneous presence of NA resistance and decreased susceptibility to CIP, suggesting that the resistance to NA is a reliable indicator of decreased CIP susceptibility (sensitivity, 97.5%; specificity, 100.0%). Furthermore, the sequencing of NA-resistant S. Typhi isolates showed a predominant amino acid alteration in the quinolone resistance-determining region (QRDR) of gyrA gene at position 83 from Ser→Phe. Two isolates with resistance to both CIP and NA had a double-mutation (Ser83→Phe and Asp87→Asn) in the QRDR of the gyrA gene, of which one had an additional amino acid mutation (Ser80→Ilu) in the QRDR of the parC gene.

Pulsed field gel electrophoresis analysis of Vibrio cholerae isolates in southern Thailand.

Forty isolates of V. cholorae O1, O139 and non-O1/non-O139 collected from outbreaks in Songkhla and Phuket Provinces of southern Thailand during 1999-2001 and sporadic cases from different regions of Thailand during 1993-2002 were characterized using pulsed field gel electrophoresis (PFGE). Digestion of chromosomal DNA of the V cholerae isolates with restriction endonuclease NotI, followed by PFGE, generated 10 distinct restriction endonuclease analysis patterns consisting of 8 to 13 bands, ranging in size from 78 to 394 kb. PFGE patterns of O1 Inaba strains from the outbreak in Songkhla were identical (P1) except one isolate (P3). The O1 Inaba outbreak strains from Phuket in the same period belonged to P2 pattern, whereas the O1 Ogawa strain from the outbreak in Phuket isolated in 1999 was of P7 pattern. These patterns of O1 Inaba and Ogawa strains were slightly different suggesting that the isolates were epidemiologically related and therefore the outbreaks were likely due to the same V cholerae clone. Isolates of V cholerae O1 Inaba from sporadic cases in the neighboring area (e.g., Pattani Province) in a similar period of time of the outbreak in Songkhla Province had very similar patterns, with only one single band different from those of the outbreak isolates. This indicates that the Inaba strains isolated from Songkhla Province during the 2001 cholera outbreak belonging to P1 pattern had not spread to other regions in 2001 and 2002. On the otherhand, the sporadic isolates collected from other regions of Thailand were quite distinct from the outbreak isolates in Songkhla Province, especially those from Chaiyaphum and Chaing Mai Provinces, which belonged to P5 and P6 pattern, respectively. Isolates of V cholerae O139 and non-O1/non-O139 gave different patterns from that of V. cholerae O1. This study shows that the PFGE technique is markedly advantageous in distinguishing strains of V cholerae isolates leading to insightful detailed charateristics of these isolates in Thailand.

In vitro activity of doripenem against Burkholderia pseudomallei.

The MIC(50) and MIC(90) values of doripenem, determined by Etest, for 110 isolates of Burkholderia pseudomallei were 0.5 and 0.75 microg/ml, respectively. There were significant correlations between MICs determined by Etest and MICs determined by agar dilution, MICs determined by Etest and inhibition zone size, and MICs determined by agar dilution and inhibition zone size.

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.

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.

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.

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.

Bioequivalence, antibacterial activity and therapeutic outcome of a generic meropenem (Mapenem).

BACKGROUND: The authors aimed to compare the bioequivalence and antibacterial activity of a generic meropenem with the original meropenem and studied its preliminary therapeutic outcome. MATERIAL AND METHOD: A randomized, open-label, crossover study was employed to assess the bioequivalence and antibacterial activity. Twenty-six healthy males were recruited at Siriraj Hospital, Thailand and randomized to firstly receive either a single intravenous 30-minute infusion of a generic (Mapenem) or original meropenem (Meronem) and vice versa for the second period. The washout period was one week. Ten milliliters of blood samples were collected before meropenem infusion and at 0, 10, 15, 30, 45, 60, 90, 120, 150, 180, 240, 360, 470 and 480 minutes after the beginning of the drug infusion. Blood samples were coded and separated into plasma and serum samples. Plasma samples were used to determine drug concentrations by HPLC-UV detector and the data were analyzed for Cmax, AUC0-t and AUC0-inf. Serum samples were assayed in triplicate for measuring generic and original meropenems' inhibitory activities of a meropenem-susceptible E. coli ATCC 25922 in the same agar plate. An open-label design was used to preliminarily study of the therapeutic outcome and adverse effects of the generic meropenem in 30 patients. RESULTS: All enrolled twenty-six volunteers completed the whole study. The statistical analysis of 90% confidence interval of Cmax, A UC0-t, and AUC0-inf of the generic and original meropenems were 87.7 to 101.7%, 96.3 to 102.4% and 96.3 to 102.3%, respectively. The results were within the standard range of bioequivalence acceptance criteria (80-125%) and the powers of the test were greater than 80%. Using E. coli ATCC 25922 in the blind assay of serum inhibition activity, the inhibitory zone sizes (mm) of the generic compared to original meropenems were not statistically different with respect to every time points of blood collections (p < 0.05). Correlation of mean values of serum meropenem levels and the widths of inhibitory zone sizes of the same samples collected at the same intervals showed good linear relationship with r = 0.891; R2 = 0.794 (p < 0.01) for the generic meropenem and r = 0.885; R2 = 0.784 (p < 0.01) for the original meropenem. The therapeutic result with the generic meropenem for various indications was successful or improved in 24 cases from 30 cases (80%) and the bacterial cure rate was 23 in 30 clinical isolates (76.7%). Adverse reactions probably related to the study medication were rash and elevated liver enzymes in 1 and 3 patients, respectively, and all resolved spontaneously. CONCLUSION: In the present study, the generic meropenem exhibited indifferent bioequivalence and antibacterial activity compared to the original meropenem. There was also a good correlation between serum levels and inhibitory zone sizes produced by the same serum samples in every periods of blood collection. Clinical efficacy of the generic meropenem was shown to be satisfactory without notable severe adverse reaction.

Antibacterial activities of four Thai medicinal plants.

Medicinal plants have long been used and prescribed in Thailand for centuries. Some of them have been used for treating various diseases including infectious diseases. Pouzolzia pentandra Benn., Gelonium multiflorum A. Juss., Erycibe elliptilimba Merr. and Chun., Balanophora abbreviate Bl. are Thai medicinal plants from the Thai pharmacopoeia that have been prescribed for treating unknown fevers including some specific infectious diseases. This investigation demonstrated the effects of these Thai medicinal plants for their antibacterial activities by using the macrodilution assay. Based on the present study, the water methanol fraction (fraction 2) of Balanophora abbreviate Bl. showed the antibacterial activity at the MIC level of 250 microg/ml but the activity was bacteriostatic in its effects. Therefore, the use of these medicinal plants in controlling fever and infectious diseases appears to be justified and further investigations may be required to obtain more information.

In vitro activity of tigecycline against Burkholderia pseudomallei and Burkholderia thailandensis.

Investigation of the in vitro activity of tigecycline against Burkholderia pseudomallei and Burkholderia thailandensis revealed that the inhibition zone diameters of tigecycline against all isolates were >or=20 mm and that the MIC50 values were 0.5 and 1 microg/ml and the MIC90 values were 2 and 1.5 microg/ml for B. pseudomallei and B. thailandensis, respectively.

Staphylococcal cassette chromosome mec (SCCmec) typing of methicillin-resistant Staphylococcus aureus strains isolated in 11 Asian countries: a proposal for a new nomenclature for SCCmec elements.

A description of staphylococcal cassette chromosome mec (SCCmec) elements carried by 615 methicillin-resistant Staphylococcus aureus (MRSA) strains isolated in 11 Asian countries is reported, and a novel nomenclatural system based on their structures is proposed. The 615 strains were classified as type 3A (370 strains), type 2A (207 strains), type 2B (32 strains), type 1B (1 strain), and nontypeable (5 strains). The previously reported type III SCCmec (DDBJ/EMBL/GenBank accession no. AB037671) carried by the MRSA strain 85/2082 was ascertained to be composed of two SCC elements, type 3A SCCmec and SCCmercury. PCR analysis indicated that 310 of 370 type 3A SCCmec strains carried both SCC elements. These strains were prevalent in eight countries: Thailand, Sri Lanka, Indonesia, Vietnam, Philippines, Saudi Arabia, India, and Singapore. The remaining 60 type 3A SCCmec strains differed with respect to the left extremity polymorphism or to the presence of ccrC. Among these, two were identified as carrying only type 3A SCCmec elements, but their left extremities differed. Type 2A SCCmec strains predominated in Korea and Japan, although the frequency of the presence of ant(4')-1 gene downstream of mecA varied (53% for Korean strains; 93% for Japanese strains). Various SCCmec elements were identified in the tested strains, and limited numbers were identified by their multilocus sequence typing genotypes. These data suggest that numerous MRSA clones are disseminated in Asian hospitals, and these consist of minor clones that are presumed to have arisen locally and major clones that are presumed to have been introduced from other countries.

The outbreak of Serratia marcescens bacteremia in a pediatric ward, Siriraj Hospital 1997.

Between October 20 and November 11, 1997, Serratia marcescens bacteremia was identified in 8 patients in a pediatric ward at Siriraj Hospital. The organism was isolated from 17 blood and 3 bone marrow specimens. The only common associated factor in these patients was that they all had received an intravenous fluid infusion. In the attempt to investigate the source of S. marcescens implicated in the outbreak, 108 specimens of intravenous fluid, 3 intravenous fluid bottle caps, 4 specimens from intravenous fluid tubing sets, 21 specimens of antiseptics used on the ward, 28 specimens of rectal swabs from patients on the ward, 1 sample of blood culture media prepared by the hospital for routine use, and 62 environmental specimens including hand swabs of the medical personnel, refrigerator, air conditioning, milk samples, room air, water sink, wooden splint and adhesive tape used to immobilize the intravenous access. Of 227 specimens sent for culture, S. marcescens was isolated from only one specimen collected from the in-use intravenous fluid given to a patient with Serratia bacteremia. S. marcescens was not found in any other surveillance culture. The 8 patients were placed under quarantine in the same room with an exclusive nursing team. With the investigation and intervention including monitoring for meticulous hand washing of the ward staff, the outbreak was stopped within 7 days. Although the investigation failed to discover the environmental reservoir of S. marcescens in this outbreak, the data suggested that intravenous fluid was probably the route of transmission and the medical personnel played an important role in spreading the infection.

Antiseptics for preventing omphalitis.

BACKGROUND: Omphalitis may cause serious complications and contribute to neonatal morbidity and mortality. From January 1997 to August 1998, the incidence of omphalitis in the Department of Obstetrics and Gynecology, Faculty of Medicine Siriraj Hospital had been increased from 0.9 to 17.4 per 1,000 live births. A prospective randomized trial using antiseptic applied directly to the umbilical stump was conducted aiming to reduce an epidemic outbreak of omphalitis in the newborn nursery. OBJECTIVE: To determine which antiseptic is appropriate for preventing omphalitis in the newborn infants. PATIENTS AND METHOD: Newborn infants delivered in the Department of Obstetrics and Gynecology, Faculty of Medicine Siriraj Hospital were randomized into group A (Triple dye) or group B (70% Alcohol). The infant with omphalitis was assessed by a pediatrician or a neonatology fellow. At home, the same antiseptic will be continually applied to the umbilical stump daily until a few days after cord detachment. Relative risk was calculated and statistical significance was tested by Chi-square test. RESULTS: Four hundred and twenty-seven infants were enrolled. Birth weight, gestational age and gender of the infants in both groups were not different. There were no known maternal risk factors for omphalitis. Omphalitis was observed in 9/213 (4.2%) infants in group A and 23/214 (10.7%) infants in group B. The relative incidence rate between each group was statistically significant (p<0.01). Triple dye group was 60 per cent less likely to develop omphalitis compared to 70 per cent Alcohol group (RR 0.39, 95% CI: 0.19-0.83). The mean duration for cord detachment were 13.6 and 11.5 days in group A and group B, respectively. CONCLUSION: During an epidemic outbreak of omphalitis, Triple dye was the most appropriate and effective antiseptic to prevent omphalitis but could delay cord separation.