In vitro activity of colistin plus sulbactam against extensive-drug-resistant Acinetobacter baumannii by checkerboard method.

OBJECTIVE: To determine in vitro activity of colistin plus sulbactam against extensive-drug-resistant (XDR) Acinetobacter baumannii. MATERIAL AND METHOD: Checkerboard method was used to determine in vitro activity of colistin plus sulbactam against 11 clinical isolates of XDR A. baumannii. The concentrations of colistin and sulbactam used in the study were 0.025 to 128 mg/ 1 and 4 to 256 mg/l, respectively. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of colistin, sulbactam and colistin plus sulbactam at various concentrations were determined. Fractional inhibitory concentration index (FICI) was calculated. The antibiotic combination is considered synergistic if FICI < 0.5, indifferent if FICI 0.5 to 4.0, and antagonistic if FICI > 4.0. RESULTS: Ten isolates of XDR A. baumannii were susceptible to colistin (MIC < 2 mg/l) and one isolate was resistant to colistin (MIC 8 mg/l). There were no antagonistic effects of colistin plus sulbactam against all study isolates. For 10 isolates of colistin-susceptible XDR A. baumannii, some MIC values of the combinations were lower than those of single antibiotics. However no synergistic effect of colistin and sulbactam was observed in colistin-susceptible XDR A. baumannii isolates. The synergistic effect of colistin and sulbactam was detected in some concentrations of colistin and sulbactam against colistin-resistant XDR A. baumannii isolate. CONCLUSION: The combination of colistin and sulbactam showed an indifferent effect against colistin-susceptible XDR A. baumannii. The combination of colistin and sulbactam showed synergistic effect at some concentrations of colistin and sulbactam against a clinical isolate of colistin-resistant XDR A. baumannii. In vitro time-kill method should be performed to confirm the aforementioned observations.

In vitro susceptibility test of sitafloxacin against resistant gram-negative bacilli isolated from Thai patients by disk diffusion method.

OBJECTIVE: To determine a correlation of minimum inhibitory concentration (MIC) of sitafloxacin determined by agar dilution method with inhibition zone diameter of sitafloxacin determined by disk diffusion method, and to determine inhibition zone, diameter breakpoints of sitafloxacin against resistant gram-negative bacilli isolated from Thai patients. MATERIAL AND METHOD: The study bacteria were 332 clinical isolates of gram-negative bacilli including ESBL-producing E. coli, ESBL-producing K. pneumoniae, P. aeruginosa andA. baumannii. Each isolate of the present study bacteria was tested for minimum inhibitory concentration (MIC) of sitafloxacin by agar dilution method and inhibition zone diameter of sitafloxacin by disk diffusion method. RESULTS: The MICs and inhibition zone diameters of sitafloxacin against gram-negative bacilli were well correlated (correlation coefficient -0.926, p-value < 0.001). The inhibition zone diameter > or = 15 mm had the least total error for determining susceptibility to sitafloxacin based on MIC value of sitafloxacin but the inhibition zone diameter > or = 16 mm had less false susceptibility than that of > or = 15 mm when compared with sitafloxacin MIC < or = 2 mg/l that was considered susceptible. The inhibition zone diameter > or = 19 mm had the least total error for determining susceptibility to sitafloxacin based on MIC value of sitafloxacin but the inhibition zone diameter > or = 18 mm had less false susceptibility than that of > or = 19 mm when compared with sitafloxacin MIC < or = 1 mg/l that was considered susceptible. CONCLUSION: For the susceptibility test of sitafloxacin against resistant gram-negative bacilli by disk diffusion method, the inhibition zone diameter > or = 16 mm and > or = 18 mm seem to be the appropriate breakpoints for susceptibility for resistant gram-negative bacilli isolated from urine and blood, respectively, since the serum concentration of sitafloxacin is rather low whereas the urinary concentration of sitafloxacin is much higher.

In vitro and in vivo activity of tebipenem against ESBL-producing E. coli.

OBJECTIVE: To determine in vitro and in vivo activity of tebipenem against ESBL-producing E. coli. MATERIAL AND METHOD: Minimum inhibitory concentration (MIC) of tebipenem against 100 clinical isolates of ESBL-producing E. coli was performed by broth micro-dilution technique. Blood and urine samples from 10 healthy male subjects before and after receiving 300 mg of tebipenem pivoxil 3 times a day for 2 consecutive days were determined for inhibitory and bactericidal titers against a clinical urinary isolate of ESBL-producing E. coli by disk diffusion method and broth micro- dilution method. RESULTS: MIC50 and MC90 of tebipenem against ESBL-producing E. coli were both 0.06 mg/L with MIC range from ≤ 0.06 to 0.25 mg/L. The inhibition zones were observed around the disks inoculated with serum samples and urine samples collected from all study subjects after receiving tebipenem pivoxil for at least 1 hour and 5 hours, respectively. The inhibitory titer of 1:160 and bactericidal titer of 1:160 of serum samples were observed for at least one hour after ingestion of tebipenem pivoxil. Inhibitory titer of 1:640 and bactericidal titer of 1:640 of urine samples were observed after at least 14 hours after ingestion of tebipenem pivoxil. No subjects experienced side effects related to receiving tebipenem pivoxil. CONCLUSION: Tebipenem is very active against ESBL-producing E. coli. Oral administration of tebipenem pivoxil 300 mg 3 times a day for two days was well tolerated, safe and induced high inhibitory and bactericidal activity in serum and urine. Tebipenem pivoxil could be an oral agent for effective therapy of ESBL-producing E. coli infections.

In vitro activity of polymyxin B against carbapenem-resistant Acinetobacter baumannii.

OBJECTIVE: To determine in vitro activity of polymyxin B against carbapenem-resistant Acinetobacter baumannii. MATERIAL AND METHOD: The activity of polymyxin B was determined against 217 strains of carbapenem-resistant A. baumannii collected from different patients by standard agar dilution method and disk diffusion test using polymyxin B disk (300 units). The control strains were E. coli ATCC 25922 and P. aeruginosa ATCC 27853. RESULTS: The MIC values and inhibition zone diameters of polymyxin B against the quality control bacteria were within the acceptable range. The MIC50 and MIC90 values of polymyxin B against 217 strains of carbapenem-resistant A. baumannii were 0.5 and 1 mg/l, respectively. If the susceptible MIC breakpoint of polymyxin B was ≤ 2 mg/l, 98.2% of carbapenem-resistant A. baumannii strains were susceptible to polymyxin B. If the susceptible MIC breakpoint of polymyxin B was ≤ 2 mg/l, the sensitivity and the specificity ofthe inhibition zone diameter of > 12 mm were 100% and 75%, respectively. The aforementioned diagnostic parameters gave positive predictive value of 99.5% and negative predictive value of 100% for predicting susceptibility of carbapenem-resistant A. baumannii to polymyxin B by disk diffusion test. CONCLUSION: Polymyxin B was very active against carbapenem-resistant A. baumannii. The inhibition zone diameters of >12 mm was accurate enough to determine susceptibility of carbapenem-resistant A. baumannii topolymyxin B. Polymyxin B can be an alternative to or more preferable than colistin for therapy ofcarbapenem-resistant A. baumannii infections.

The risk of pig and chicken farming for carriage and transmission of Escherichia coli containing extended-spectrum beta-lactamase (ESBL) and mobile colistin resistance (mcr) genes in Thailand.

South-East Asian countries report a high prevalence of extended-spectrum cephalosporin- (ESC-) and colistin-resistant Escherichia coli (Col-R-Ec). However, there are still few studies describing the molecular mechanisms and transmission dynamics of ESC-R-Ec and, especially, Col-R-Ec. This study aimed to evaluate the prevalence and transmission dynamics of Ec containing extended spectrum beta-lactamases (ESBL) and mobile colistin resistance (mcr) genes using a 'One Health' design in Thailand. The ESC-R-Ec and Col-R-Ec isolates of human stool samples (69 pig farmers, 155 chicken farmers, and 61 non-farmers), rectal swabs from animals (269 pigs and 318 chickens), and the intestinal contents of 196 rodents were investigated. Resistance mechanisms and transmission dynamics of Ec isolates (n=638) were studied using short and long read sequencing. We found higher rates of ESBL-Ec isolates among pig farmers (n=36; 52.2%) than among chicken farmers (n=58; 37.4 %; P<0.05) and the control group (n=61; 31.1 %; P<0.05). Ec with co-occurring ESBL and mcr genes were found in 17 (6.0 %), 50 (18.6 %) and 15 (4.7 %) samples from humans, pigs and chickens, respectively. We also identified 39 (13.7 %) human samples with non-identical Ec containing ESBL and mcr. We found higher rates of ESBL-Ec, in particular CTX-M-55, isolates among pig farmers than among non-pig farmers (P<0.01). 'Clonal' animal-human transmission of ESBL-Ec and Ec with mcr genes was identified but rare as we overall found a heterogenous population structure of Ec. The Col-R-Ec from human and animal samples often carried mcr-1.1 on conjugative IncX4 plasmids. The latter has been identified in Ec of many different clonal backgrounds.

Prevalence of antibiotic resistance in fecal flora of patients undergoing transrectal ultrasound-guided prostate biopsy in Thailand.

OBJECTIVE: The objective of this study was to determine the prevalence of antibiotic resistance in fecal flora of patients undergoing transrectal ultrasound-guided needle biopsy of the prostate (TRUSB) and the factors associated with such antibiotic resistance. METHODS: A prospective study of patients undergoing TRUSB was conducted. Rectal swabs were performed and sent for cultures and antibiotic susceptibility testing before TRUSB. Clinical characteristics were determined. RESULTS: 287 Gram-negative isolates from 144 patients were identified, 80.1% were Escherichia coli and 13.9% were Klebsiella pneumoniae. 27 patients who received antibiotics within 3 months exhibited higher prevalence of organisms with extended-spectrum beta-lactamases (ESBL) production (40.7 vs. 22.2%) and ceftriaxone-resistance (48.1 vs. 28.2%). 134 patients received a short-course antibiotic prophylaxis in which fluoroquinolone (FQ) contributed to 89.6% of cases. Patients who received antibiotic prophylaxis showed a higher prevalence of organisms resistant to ceftriaxone (34.3 vs. 0%), ciprofloxacin (90.3 vs. 30%) and FQ (95.5 vs. 50%) and a trend of more ESBL production (27.6 vs. 0%). CONCLUSIONS: Previous antimicrobial use and prophylaxis with FQ are correlated with a higher prevalence of FQ and ceftriaxone resistance and ESBL production. A single dose of ceftriaxone without short-course FQ use is recommended as antibiotic prophylaxis in TRUSB.

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.

Inhibitory activity of fermented milk with Lactobacillus casei strain Shirota against common multidrug-resistant bacteria causing hospital-acquired infections.

OBJECTIVE: To determine inhibitory activity of fermented milk with Lactobacillus casei strain Shirota (FMLC) against common multi-drug-resistant (MDR) bacteria causing hospital-acquired infections. MATERIAL AND METHOD: Time-kill methods of FMLC and cell-free filtered fluid of FMLC (CF-FMLC) against Acinetobacter baumannii, Pseudomonas aeruginosa, ESBL-producing Escherichia coli & Klebsiella pneumoniae and methicillin-resistant Staphylococcus aureus were conducted. The control solutions were Mueller Hinton broth (MHB) and distilled water. The mixtures of FMLC, CF-FMLC, MHB and DW with 10(5) to 10(6) CFU/ml of each bacterium were prepared and incubated at 35 degrees C. Each mixture was quantified for viable bacteria at 0, 1, 3, 6 and 24 hr after incubation onto brain heart infusion agar plates. The inoculated agar plates were incubated at 35 degrees C for 24-48 hr. Bacterial colonies on agar plates were counted and compared among the mixtures. RESULTS: Log CFUs of each organism in MHB and distilled water after incubation were increased from 5.1-6.3 at 0 h to 6.4- > 11 at 24 hr. Log CFUs of each organism in FMLC and CF-FMLC after incubation with study bacteria for 0, 1, 3, 6 and 24 hr were decreased to undetectable amounts at 24 hr. CONCLUSION: FMLC and CF-FMLC exerted slow inhibitory activity against MDR bacteria resulting in eradication of all study bacteria at 24 hr. Such inhibitory effects were probably due to the products of the milk fermented by Lactobacillus casei strain Shirota. Clinical study is needed to determine if consumption of FMLC can prevent and treat colonization and infection with MDR bacteria in hospitalized patients.

Viability of Lactobacillus casei strain Shirota (LcS) from feces of Thai healthy subjects regularly taking milk product containing LcS.

OBJECTIVE: To demonstrate the recovery of Lactobacillus casei strain Shirota (LcS) from feces of Thai subjects who regularly took LcS containing milk product for 1 week and demonstrate the disappearance of LcS after stopped taking milk product. MATERIAL AND METHOD: First fecal samples were collected from 20 healthy adults at 10 days after they abstained from all lactobacillus containing milk products. Second specimens taken after the subjects ingested LcS containing milk product for 7 days and third specimens at 7 days after they stopped taking LcS containing milk product. All the fecal specimens were culture for LcS using LLV-FOS culture medium and enumeration of LcS was calculated. All stool samples were also tested for the presence of LcS by using nested PCR to confirm the presence of LcS obtained from culture method. RESULTS: Both culture and nested PCR method showed that all the stools samples obtained from subjects prior to the administration of LcS containing milk product were devoid of LcS, except for 3 specimens which showed weakly positive test for PCR. At 7 days after ingesting LcS containing milk product, all stool specimens were positive for LcS on both culture and PCR method. At 7 days after stopped taking LcS containing milk product, 1/19 specimens were positive from culture and 6/ 19 specimens were positive for PCR method. CONCLUSION: LcS could survive in the gastrointestinal tract of Thai subjects and could be recovered from the feces after ingestion.

Comparative in vitro activity of sitafloxacin against bacteria isolated from Thai patients with urinary tract infections and lower respiratory tract infections.

OBJECTIVE: To determine comparative in vitro activity of sitafloxacin against clinical isolates of bacteria from Thai patients with urinary tract infection and those with lower respiratory tract infection. MATERIAL AND METHOD: 1,255 clinical isolates of Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa, Acinetobacter baumannii, Enterococcus spp, Streptococcus pneumoniae, Staphylococcus aureus, Haemophilus influenzae and Moraxella catarrhalis isolated from different Thai patients with urinary tract infection and those with lower respiratory tract infection in 2010 were included. The minimum inhibitory concentrations (MICs) of sitafloxacin, ciprofloxacin, levofloxacin, moxifloxacin, imipenem, amikacin, ampicillin, ceftazidime, ceftriaxone, penicillin, piperacillin/tazobactam, vancomycin, azithromycin and trimethoprim/sulfamethoxazole were determined by standard agar dilution method. RESULTS: The MIC50 and MIC90 values of sitafloxacin against all tested bacteria were lowest when compared with those of levofloxacin, ciprofloxacin and moxifloxacin. Sitafloxacin was active against 51% of methicillin-resistant S. aureus (MRSA) isolates. The activity of sitafloxacin against multidrug-resistant (MDR) Gram-negative bacteria, such as, extended spectrum beta-lactamase (ESBL)-producing E. coli and K. pneumomiae, P. aeruginosa and A. baumannii was comparable to or more than that of some beta-lactam/beta-lactamase inhibitors, cephalosporins or carbapenems. CONCLUSION: Sitafloxacin is more active than levofloxacin, ciprofloxacin and moxifloxacin against isolated bacteria from Thai patients with urinary tract and lower respiratory infections including antibiotic resistant bacteria, such as MRSA, ESBL-producing Gram-negatives, carbapenem-resistant A. baumannii.

One Health Surveillance of Antimicrobial Resistance Phenotypes in Selected Communities in Thailand.

Integrated surveillance of antimicrobial resistance (AMR) using the One Health approach that includes humans, animals, food, and the environment has been recommended by responsible international organizations. The objective of this study was to determine the prevalence of AMR phenotypes in Escherichia coli and Klebsiella species isolated from humans, pigs, chickens, and wild rodents in five communities in northern Thailand. Rectal swabs from 269 pigs and 318 chickens; intestinal contents of 196 wild rodents; and stool samples from 69 pig farmers, 155 chicken farmers, and 61 non-farmers were cultured for E. coli and Klebsiella species, which were then tested for resistance to ceftriaxone, colistin, and meropenem. The prevalence of ceftriaxone-resistant E. coli and Klebsiella species in pigs, chickens, rodents, pig farmers, chicken farmers, and non-farmers was 64.3%, 12.9%, 4.1%, 55.1%, 38.7%, and 36.1%, respectively. Colistin resistance in pigs, chickens, rodents, pig farmers, chicken farmers, and non-farmers was 41.3%, 9.8%, 4.6%, 34.8%, 31.6%, and 24.6%, respectively. Meropenem resistance was not detected. The observed high prevalence of AMR, especially colistin resistance, in study food animals/humans is worrisome. Further studies to identify factors that contribute to AMR, strengthened reinforcement of existing regulations on antimicrobial use, and more appropriate interventions to minimize AMR in communities are urgently needed.

Feasibility, Challenges, and Benefits of Global Antimicrobial Resistance Surveillance System Implementation: Results from a Multicenter Quasi-Experimental Study.

The Global Antimicrobial Resistance Surveillance System (GLASS) is one of the pillars of the global action plan on antimicrobial resistance launched by the World Health Organization in 2015. This study was conducted to determine the feasibility and benefits of GLASS as a component of antimicrobial stewardship strategies in three provincial hospitals in Thailand. Data on the types of bacteria isolated and their antibiotic susceptibility during January-December 2019 and January-April 2020 were retrieved from the microbiology laboratory of each participating hospital. Laboratory-based antibiograms from 2019 and GLASS-based antibiograms from 2020 were created and compared. A total of 14,877 and 3580 bacterial isolates were obtained during January-December 2019 and January-April 2020, respectively. The common bacteria isolated in both periods were Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Staphylococcus aureus. Hospital-acquired infection (HAI)-related bacteria were observed in 59.0%, whereas community-acquired infection (CAI)-related bacteria were observed in 41.0% of isolates. Antibiotic resistance in CAIs was high and may have been related to the misclassification of colonized bacteria as true pathogens and HAIs as CAIs. The results of this study on AMR surveillance using GLASS methodology may not be valid owing to several inadequate data collections and the problem of specimen contamination. Given these considerations, related personnel should receive additional training on the best practices in specimen collection and the management of AMR surveillance data using the GLASS approach.

Microbiological equivalence of bacteriostatic and bactericidal activities of the sera from healthy volunteers receiving generic piperacillin/tazobactam (Pipertaz) and original piperacillin/tazobactam (Tazocin).

BACKGROUND: Several generic piperacillin/ tazobactam formulations have been approved by Thai Food andDrugAdministration, Ministry of Public Health. Piperacillin/ tazobactam is a parenteral drug. Therefore, a study demonstrating a biological equivalence of generic piperacillin/ tazobactam is not required for drug registration in Thailand. OBJECTIVE: The study was to determine microbiological equivalence of serum bacteriostatic and bactericidal activities of the sera from healthy volunteers receiving generic piperacillin/ tazobactam (PipertazA) and original piperacillin/tazobactam (Tazocin). MATERIAL AND METHOD: This was a randomized crossover study in 16 adult healthy volunteers. Each subject received 4.5 grams of Pipertaz and Tazocin in 50 ml of normal saline via intravenous infusion for 30 minutes. The blood samples were drawn at baseline prior to receiving the study drug, at 30 minutes after initiating infusion, and at 8 hours after initiating infusion. The serum bacteriostatic activity against E. coli ATCC 25922, K. pneumoniae, P aeruginosa ATCC 27853 and A. baumannii was performed by disk diffusion The serum bactericidal activity against E. coli ATCC 25922 was performed by Serum Bactericidal Titre. RESULTS: The average inhibition zone diameter of the serum samples from the subjects while receiving Pipertaz against each tested organisms was <1 mm smaller than that while receiving Tazocin and such difference was not significantly different. All serum samples collected at 30 minutes after initiating Tazocin and Pipertaz had bactericidal titres 1:64 to 1:256 against E. coli ATCC 25922. All serum samples collected at 8 hours after initiating Tazocin and Pipertaz had bactericidal titres < 1:2 against E. coli ATCC 25922. The differences of serum bactericidal titres of the serum samples collected at 30 minutes (p = 0.7) and 8 hours (p = 1.0) after initiating Tazocin and Pipertaz were not statistically significant. CONCLUSION: The sera from healthy volunteers receiving Pipertaz contain bacteriostatic and bactericidal activities not significantly different from those receiving Tazocin.

A One Health approach to assessing occupational exposure to antimicrobial resistance in Thailand: The FarmResist project.

This Southeast Asia-Europe research project will use a One Health approach to identify the major parameters responsible for the presence of animal-associated antimicrobial resistant bacteria in animal production facilities in Thailand and the risk of their transmission from animals to humans. We will focus on traditional, small, extensive pig and poultry farms where information on antibiotic use is scarce and animals live in close contact with humans. This cross-sectional study will be based on the epidemiological analysis of the antimicrobial resistance (AMR) present in fecal samples from animals and humans. Extended spectrum beta-lactamase producing Enterobacteriaceae (ESBL-E) and Enterobacteriaceae resistant to colistin will be actively searched in the feces of farm animals (pigs and poultry), small wild rodents and farmers. Phenotypic (selective plating) and genotypic (multilocus seuquence typing and sequencing) methods will be used for the detection of AMR, the identification of antibiotic resistance genes (ARGs) and the characterization of strains carrying resistance genes. Questionnaires will be administered to investigate the effects of antibiotic use, farm characteristics and biosecurity measures on the occurrence of AMR in animals. Subsequently, the fecal carriage of AMR and ARGs in farmers will be compared to a control population with no occupational contacts with animals, thus enabling an estimation of the risk of transmission of AMR/ARGs from animals to farmers.

Microbiological equivalence of serum bacteriostatic and bactericidal activities of the sera from healthy volunteers receiving original meropenem (Meronem) and generic meropenem (Mero).

BACKGROUND: Several generic meropenem formulations have been approved by Thai Food and Drug Administration, Ministry of Public Health since 2008. Meropenem is a parenteral drug. Therefore, a study demonstrating a biological equivalence of generic meropenem is not required for drug registration in Thailand. The objective of the study was to determine microbiological equivalence of serum bacteriostatic and bactericidal activities of the sera from healthy volunteers receiving original meropenem (Meronem) and generic meropenem (Mero). MATERIAL AND METHOD: This was a randomized crossover study in 16 adult healthy volunteers. Each subject received one gram of Meronem and Mero in 50 ml of normal saline via intravenous infusion for 30 minutes. The blood samples were drawn at baseline prior to receiving the study drug, at 30 minutes after initiating infusion, and at 8 hours after initiating infusion. The serum bacteriostatic activity against E. coli ATCC 25922, K. pneumoniae, P. aeruginosa ATCC 27853 and A. baumannii was performed by disk diffusion. The serum bactericidal activity against E. coli ATCC 25922 was performed by Serum Bactericidal Titre. RESULTS: The average inhibition zone diameter of the serum samples from the subjects while receiving Mero against each tested organisms was < 1 mm smaller than that while receiving Meronem and such difference was not significantly different. All serum samples taken at 30 minutes after initiating Meronem and Mero had bactericidal titres against E. coli ATCC 25922 > or = 1:256. Only 3 serum samples taken from the subjects while receiving Mero at 8 hours had less bactericidal titre for 1-fold dilution when compared with that of Meronem. CONCLUSION: The sera from healthy volunteers receiving Meronem and Mero had microbiological equivalence in terms of serum bacteriostatic and bactericidal activities.

Case Report: Recovery of Pathogenic Leptospira spp. from Routine Aerobic Blood Culture Bottles.

Leptospira spp. are fastidious and slow-growing bacteria, making recovery difficult and diagnostic sensitivity in the clinical setting low. However, collection of Leptospira isolates is valuable for epidemiological and laboratory research. Severe leptospirosis cases may present as septic shock, and the differential diagnosis often includes bacterial septicemia, leading clinicians to collect blood cultures. Here, we report the successful isolation of pathogenic Leptospira spp. from blood culture bottles (targeting aerobic bacteria incubated at 37°C) from a 64-year-old man admitted with septic shock. The patient presented with 4 days of fever, severe hypotension, transient atrial fibrillation, jaundice, and oliguric renal failure. After admission, intravenous ceftriaxone plus azithromycin was given with fluid resuscitation, norepinephrine infusion, invasive mechanical ventilation, and renal replacement therapy. He was discharged from the hospital 16 days after admission. Using the blood sample obtained on admission, the diagnosis of leptospirosis was confirmed by multiplex real-time PCR (targeting bacterial 16S rRNA and LipL32 gene). We collected 200 µL from the blood culture bottle to inoculate a 5-mL Ellinghausen, McCullough, Johnson, and Harris media supplemented with 5% fetal bovine serum. After 2 weeks of incubation at 30°C, Leptospira strains were identified and confirmed by real-time PCR. Genotyping was undertaken using the multi-locus sequence typing (MLST) scheme#1. The isolate matched with ST50 isolates in the PUbMLST database. This case provides evidence that in tropical countries, severe leptospirosis should be considered in patients who present with symptoms of sepsis. Pathogenic Leptospira may be successfully isolated from aerobic blood cultures in routine clinical settings.

Serum procalcitonin in diagnosis of bacteremia.

OBJECTIVE: To (a) determine the diagnostic value of procalcitonin (PCT) in differentiating sepsis with or without bacteremia, (b) evaluate the correlation of PCT levels to severity of sepsis, (c) establish the prognostic value in predicting the outcome of sepsis and (d) evaluate the correlation among different assays. MATERIAL AND METHOD: A prospective study was carried out from August through November 2007. Blood for PCT levels and culture were drawn simultaneously. RESULTS: Fifty-six patients with clinical suspicious of sepsis were enrolled in the study; bacteremia (n = 30) and non-bacteremia (n = 26). There were good correlations between the PCT levels measured by three assays (p < 0.001). At the threshold of 0.5 ng/mL, PCT had > 90% sensitivity for diagnosis of bacteremia. Of the bacteremic group, median PCT levels measured by Kryptor and VIDAS assays were 12.4 and 16.6 ng/mL respectively. In the non-bacteremic group, median PCT levels measured by Kryptor and VIDAS were 4.2 and 4.9 ng/mL respectively. PCT levels were significantly higher in the bacteremic group (p = 0.04). The optimum thresholds to discriminate between these two groups were found to be 5, 6.5 and 2 ng/mL for Kryptor, VIDAS and PCT-Q, respectively. In addition, correlations of PCT and increasing values of the APACHE II score were observed. PCT levels in the severe sepsis and MOD group were also found to be significantly higher CONCLUSION: PCT was highly sensitive in detecting bacteremia, although not very accurate in differentiating bacteremic from non-bacteremic SIRS in adult patients.

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.

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.

Contamination by Antibiotic-Resistant Bacteria in Selected Environments in Thailand.

This study determined the presence of important antibiotic-resistant bacteria in selected environments in Thailand, including wastewater samples from 60 hospitals; washed fluid, leachate, flies, cockroaches, and rats collected from five open markets; washed fluid from garbage trucks; and stabilized leachate from a landfill facility. At least one type of antibiotic-resistant bacteria was isolated from all samples of influent fluid before treatment in hospitals, from wastewater treatment tank content in hospitals, and from 15% of effluent fluid samples after treatment with chlorine prior to draining it into a public water source. Antibiotic-resistant bacteria were recovered from 80% of washed market fluid samples, 60% of market leachate samples, all fly samples, 80% of cockroach samples, and all samples of intestinal content of rats collected from the open markets. Antibiotic-resistant bacteria were recovered from all samples from the landfill. Extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli and/or Klebsiella pneumoniae were the most common antibiotic-resistant bacteria recovered from all types of samples, followed by carbapenem-resistant E. coli and/or K. pneumoniae. Colistin-resistant Enterobacteriaceae, carbapenem-resistant Psuedomonas aeruginosa, carbapenem-resistant Acinetobacter baumannii, colistin-resistant Enterobacteriaceae, vancomycin-resistant Enterococci, and methicillin-resistant S. aureus were less common. These findings suggest extensive contamination by antibiotic-resistant bacteria in hospital and community environment in Thailand.