Association of biofilm formation, antimicrobial resistance, clinical characteristics, and clinical outcomes among Acinetobacter baumannii isolates from patients with ventilator-associated pneumonia.

INTRODUCTION: Biofilm formation is an important virulence factor of Acinetobacter baumannii. Here, we examined the biofilm formation of archived A. baumannii causing ventilator-associated pneumonia (VAP). METHODS: Eighteen and twenty isolates of A. baumannii causing bacteremic pneumonia and non-bacteremic pneumonia were included, respectively. Antimicrobial susceptibility testing was performed by broth microdilution method, while biofilm formation was evaluated by microtiter dish biofilm formation assay. RESULTS: All 38 isolates were still susceptible to colistin and tigecycline, whereas almost all isolates were non-susceptible (intermediate to resistant) to several antimicrobial agents, especially ceftriaxone and cefotaxime. Approximately, 44% of bacteremic isolates and 50% of non-bacteremic isolates were classified as carbapenem-resistant A. baumannii (CRAB). Biofilm formation was detected in 42% of the studied isolates. Bacteremia among the patients infected with biofilm-producing isolates was significantly higher than in those infected with non-biofilm-producing isolates. The antimicrobial susceptibilities of A. baumannii with biofilm formation were lower than those without biofilm formation, but the differences did not have statistical significance. The patients infected with non-biofilm-producing isolates had good clinical and non-clinical outcomes than those infected with biofilm-producing isolates. The survival rate of patients diagnosed with VAP due to biofilm-producing A. baumannii was lower than in those patients diagnosed with VAP due to non-biofilm-producing isolates. CONCLUSION: Biofilm formation of A. baumannii causing VAP was associated with antimicrobial resistance and bacteremia as well as unfavorable clinical outcomes.

A randomized controlled study comparing the efficacy of soap versus soap-plus-microwave disinfection for irrigation device in children with acute rhinosinusitis.

BACKGROUND: Nasal irrigation is an effective component of sino-nasal disease management. Nonetheless, bacterial contamination is worrisome. OBJECTIVE: To study bacterial colonization incidence using squeeze-bottle nasal irrigation devices, after disinfection with soap or soap-plus-microwave technique, in pediatric acute rhinosinusitis. METHODS: A randomized, prospective, controlled study was conducted on acute rhinosinusitis children, aged 2-15 years. Each participant was randomized into a soap-cleaning or soap-plus- microwave group. For a two-week period, participants irrigated their nostrils with NSS twice daily and cleaned the bottle after each use. In the end, bottles were sent to a microbiological laboratory for bacterial identification. RESULTS: The mean 5S Score and satisfaction score gradually improved in both groups with no significant differences between groups. Bacterial identification frequency in the soap group was slightly higher than in the soap-plus-microwave one, without statistical significance. For safety and tolerability, all participants reported 100% adherence to nasal irrigation. The soap-plus-microwave group reported more minor adverse outcomes than the soap-cleaning one. No thermal deformation of irrigation bottles was observed. CONCLUSIONS: Regular cleaning of nasal irrigation devices is needed to minimize bacterial contamination. Only soap or soap plus microwave disinfection appeared simple and safe for disinfection. Both techniques can equally minimize the rate of bacterial contamination. Although no gross thermal deformation at optimal power and duration, chemical irritants after high power or long microwave durations may be a concern.

Molecular epidemiology of vancomycin-resistant Enterococcus faecium clinical isolates in a tertiary care hospital in southern Thailand: a retrospective study.

OBJECTIVE: Vancomycin-resistant enterococci are nosocomial pathogens that are responsible for commonly causing healthcare-associated infections, and they exhibit increased resistance to many antimicrobials, particularly to vancomycin. The epidemiological data available on vancomycin-resistant enterococci (VRE) in Thailand are inadequate. METHODS: Using enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR), this study investigated genes that encode antimicrobial resistance and genetic relatedness to further understand VRE prevalence. Ninety VRE isolates were collected between 2011 and 2019 from a tertiary care hospital in southern Thailand. Antimicrobial susceptibility was determined using the disk diffusion method and E-test methods. Multiplex PCR was performed to detect the van gene and virulence genes. RESULTS: The study showed a high prevalence of diverse multidrug-resistant VRE strains. The prevalence of VRE infection was the highest in 2014 (28 isolates, 39.4%). VRE were mostly found in the urogenital tract (26 isolates, 28.9%), followed by the digestive tract (20%), body fluid, i.e., pancreatic cyst fluid, peritoneal dialysis fluid, Jackson-Pratt (JP) drain (20%), and blood specimens (10%). Patients in medical and surgical wards had 71.1% multi-drug-resistant and 28.9% extensively drug-resistant (XDR) VRE strains, respectively. The most prevalent antibiotic resistance was to ampicillin (74.4%). Susceptibility to gentamicin and meropenem were similar (7% and 10%, respectively). Four isolates (4.4%) were resistant to colistin. Only vanA was detected among the strains. The virulence gene test showed that the detection rates of enterococcal surface protein (esp) and hyaluronidase (hyl) genes were 91.1% and 5.6%, respectively. According to ERIC-PCR analysis, 51 of 90 strains had clonality, with a similarity rate of 95%. CONCLUSIONS: We conclude that there is a need to implement infection control practices and active surveillance. Molecular techniques can effectively detect antibiotic-resistant genes, which would allow monitoring to control VRE infection in hospitals.

In vitro elution characteristics of gentamicin-impregnated Polymethylmethacrylate: premixed with a second powder vs. liquid Lyophilization.

BACKGROUND: Antibiotic-loaded bone cement, or antibiotic-impregnated polymethylmethacrylate (PMMA), were developed to prevent and treat bone and joint infections. Gentamicin is an antibiotic that is commonly used in combination with PMMA; however, gentamicin powder is hard to obtain in many countries. This study aimed to evaluate the elution characteristics of gentamicin-impregnated PMMA made with lyophilized liquid gentamicin, compared with PMMA; which is made from commercial gentamicin powder. METHODS: The experimental sample was divided into 2 groups: the gentamicin power group (PG-PMMA) and the lyophilized liquid gentamicin group (LG-PMMA). Ten cement spacers were prepared in each group. These were produced by mixing gentamicin powder, or lyophilized liquid gentamicin, with a powder polymer before adding the liquid monomer (2 g of gentamicin and 40 g of PMMA). The volume and surface area of the antibiotic-impregnated cement spacers were 50 cm3 and 110 cm2, respectively. Each spacer was immersed in phosphate-buffered saline, which was changed daily under sterile conditions. The solutions were collected to measure the level of gentamicin using the enzyme multiplied immunoassay technique (EMIT), at days 1, 2, 3, 4, 5, 6, 7, 14, 21, 28, 35 and 42. RESULTS: The collections from both groups had high concentrations of gentamicin on day 1 (113.63 ± 23.42 mg/dL in LG-PMMA and 61.7 ±8.37 mg/dL in PG-PMMA), but experienced a continuous decrease over time. The PMMA spacers from both groups could release gentamicin for up to 6 weeks (3.28 ± 1.17 mg/dL in LG-PMMA and 1.21 ± 0.28 mg/dL in PG-PMMA). However, there were significantly higher levels of gentamicin concentrations in the LG-PMMA group compared to the PG-PMMA group at all time points (P< 0.05). CONCLUSION: Gentamicin-impregnated PMMA made with lyophilized liquid gentamicin had approximately a two times higher rate of antibiotic elution in preliminary in vitro studies, as compared with PMMA made with premixed gentamicin powder.

Enterococcus faecalis Isolated From Infant Feces Inhibits Toxigenic Clostridioides (Clostridium) difficile.

Clostridioides (Clostridium) difficile infection is implicated as a major cause of antibiotic-associated diarrhea in hospitals worldwide. Probiotics, especially lactic acid bacteria, are the most frequently used alternative treatment. This study aims to identify potential probiotic enterococci strains that act against C. difficile strains and exert a protective effect on colon adenocarcinoma cells (HT-29 cells). To this end, nine Enterococcus strains isolated from the feces of breast-fed infants were investigated. They were identified as E. faecalis by 16s rRNA sequencing and MALDI-TOF. The probiotic properties including their viabilities in simulated gastrointestinal condition, cell adhesion ability, and their safety were evaluated. All strains exhibited more tolerance toward both pepsin and bile salts and adhered more tightly to HT-29 cells compared with the reference probiotic strain Lactobacillus plantarum ATCC 14917. Polymerase chain reaction (PCR) results exhibited that six of nine strains carried at least one virulence determinant gene; however, none exhibited virulence phenotypes or carried transferable antibiotic resistance genes. These strains did not infect Galleria mellonella when compared to pathogenic E. faecalis strain (p < 0.05). Moreover, their antibacterial activities against C. difficile were examined using agar well-diffusion, spore production, and germination tests. The six safe strains inhibited spore germination (100 - 98.20% ± 2.17%) and sporulation, particularly in C. difficile ATCC 630 treated with E. faecalis PK 1302. Furthermore, immunofluorescence assay showed that the cytopathic effects of C. difficile of HT-29 cells were reduced by the treatment with the cell-free supernatant of E. faecalis strains. These strains prevented rounding of HT-29 cells and preserved the F-actin microstructure and tight junctions between adjacent cells, which indicated their ability to reduce the clostridial cytopathic effects. Thus, the study identified six E. faecalis isolates that have anti-C. difficile activity. These could be promising probiotics with potential applications in the prevention of C. difficile colonization and treatment of C. difficile infection.

Population Pharmacokinetics and Pharmacodynamics Modeling To Optimize Dosage Regimens of Sulbactam in Critically Ill Patients with Severe Sepsis Caused by Acinetobacter baumannii.

Sulbactam is being considered as an alternative concomitant medication with other effective antibiotics for the treatment of multidrug-resistant (MDR) Acinetobacter baumannii infections. Pathophysiological changes in critically ill patients with severe sepsis, resulting in altered pharmacokinetic (PK) patterns for antibiotics, are important factors in determining therapeutic success. The aims of this study were (i) to examine the population PK parameters and (ii) to assess the probability of target attainment (PTA) for sulbactam in patients with severe sepsis caused by A. baumannii PK studies were carried out following administration of 2 g of sulbactam every 12 h on the 4th day of drug administration in 27 patients, and a Monte Carlo simulation was performed to determine the PTA of achieving 40% exposure time during which the plasma drug concentration remained above the MIC (T>MIC) and 60% T>MIC The central and peripheral volumes of distribution were 14.56 and 9.55 liters, respectively, and total clearances of sulbactam were 2.26 liters/h and 7.64 liters/h in patients aged >65 years and ≤65 years, respectively. The high PTAs (≥90%) for targets of 40% T>MIC and 60% T>MIC with a MIC of 4 µg/ml were observed when sulbactam was administered by a 4-h infusion of 1 g every 12 h and 1 g every 8 h, respectively. Sulbactam would be an alternative antibiotic option to coadminister with colistin for the treatment of infections caused by MDR A. baumannii However, for pathogens with MICs of >4 µg/ml, higher dosage regimens of sulbactam are required.

Resistance of Asian Cryptococcus neoformans serotype A is confined to few microsatellite genotypes.

BACKGROUND: Cryptococcus neoformans is a pathogenic yeast that causes cryptococcosis, a life threatening disease. The prevalence of cryptococcosis in Asia has been rising after the onset of the AIDS epidemic and estimates indicate more than 120 cases per 1,000 HIV-infected individuals per year. Almost all cryptococcal disease cases in both immunocompromised and immunocompetent patients in Asia are caused by C. neoformans var. grubii. Epidemiological studies on C. neoformans in pan-Asia have not been reported. The present work studies the genetic diversity of the fungus by microsatellite typing and susceptibility analysis of approximately 500 isolates from seven Asian countries. METHODOLOGY/PRINCIPAL FINDINGS: Genetic diversity of Asian isolates of C. neoformans was determined using microsatellite analysis with nine microsatellite markers. The analysis revealed eight microsatellite complexes (MCs) which showed different distributions among geographically defined populations. A correlation between MCs and HIV-status was observed. Microsatellite complex 2 was mainly associated with isolates from HIV-negative patients, whereas MC8 was associated with those from HIV-positive patients. Most isolates were susceptible to amphotericin B, itraconazole, voriconazole, posaconazole, and isavuconazole, but 17 (3.4%) and 10 (2%) were found to be resistant to 5-flucytosine and fluconazole, respectively. Importantly, five Indonesian isolates (approximately 12.5% from all Indonesian isolates investigated and 1% from the total studied isolates) were resistant to both antifungals. The majority of 5-flucytosine resistant isolates belonged to MC17. CONCLUSIONS: The findings showed a different distribution of genotypes of C. neoformans var. grubii isolates from various countries in Asia, as well as a correlation of the microsatellite genotypes with the original source of the strains and resistance to 5-flucytosine.

Pharmacodynamics of meropenem in critically ill patients with febrile neutropenia and bacteraemia.

The bactericidal activity of ß-lactams is determined by the time that concentrations in tissue and serum are above the minimum inhibitory concentration (T>MIC) for the pathogen. The aim of this study was to compare the probability of target attainment (PTA) and the cumulative fraction of response (CFR) for meropenem between administration by bolus injection and a 3-h infusion. The study was a randomised, three-way, cross-over design in eight febrile neutropenic patients with bacteraemia. Each subject received meropenem in three regimens consecutively: (i) a bolus injection of 1g every 8 h (q8h) for 24 h; (ii) a 3-h infusion of 1 g q8h for 24 h; and (iii) a 3-h infusion of 2 g q8h for 24h. For pathogens with an MIC of 4 µg/mL, the PTA of achieving 40% T>MIC following administration of meropenem by a bolus injection of 1g q8h, a 3-h infusion of 1 g q8h and a 3-h infusion of 2g q8h was 75.7%, 99.24% and 99.96%, respectively. Only the 3-h infusion of 2 g q8h achieved a PTA >99% for 40% T>MIC for a MIC of 8µg/mL. By referral to the European Committee on Antimicrobial Susceptibility Testing (EUCAST) MIC distributions, the three regimens of meropenem were predicted to achieve a CFR≥90% against Escherichia coli and Klebsiella spp. In conclusion, a 3-h infusion of 2 g of meropenem q8h resulted in the highest PTA rates. The three regimens of meropenem had high probabilities of achieving optimal impact against E. coli and Klebsiella spp.

Comparison of continuous infusion versus intermittent infusion of vancomycin in patients with methicillin-resistant Staphylococcus aureus.

OBJECTIVE: To compare the pharmacokinetics of vancomycin administration by continuous infusion and intermittent infusion. MATERIAL AND METHOD: A prospective, randomized, two-way crossover study of 12 patients with methicillin-resistant Staphylococcus aureus infections was conducted. All patients were randomized to receive vancomycin in both regimens consecutively: (i) infusion of 15 mg/kg of vancomycin as a loading dose for 1 h followed by 30 mg/kg of vancomycin as a continuous infusion over 24 h for 48 h; and (ii) intermittent infusion of 15 mg/kg of vancomycin for 1 h every 12 h for 48 h. Vancomycin pharmacokinetic studies were carried out during hours 24-48 after the start of both regimens. RESULTS: For the continuous infusion regimen, the mean highest steady-state concentration was 24.88 +/- 12.75 microg/ml and the mean lowest steady-state concentration was 19.89 +/- 10.15 microg/ml. For the intermittent infusion regimen, the mean peak and trough serum concentrations were 55.02 +/- 17.36 and 12.43 +/- 12.86 microg/ml, respectively. After 10 days of vancomycin treatment, the MRSA infections were eradicated in all patients. Moreover, during both methods of infusion, no adverse events related to the use of vancomycin were observed. CONCLUSION: Either continuous infusion or intermittent infusion can be used as an effective mode of vancomycin administration to achieve bactericidal activity.

The efficacy of hydroxyapatite composite impregnated with amphotericin B.

We investigated the efficacy of local biodegradable composites composed of hydroxyapatite-plaster of paris and either chitosan or alginate binder impregnated with amphotericin B. Antifungal activity was tested for Candida albicans using a modified disc diffusion technique for 6 weeks and compared with similarly impregnated polymethylmethacrylate. The physicochemical properties of each preparation were evaluated using scanning electron microscopy and Fourier transform infrared spectroscopy. The antifungal activity of amphotericin B eluted from the hydroxyapatite composites was significantly greater than the polymethylmethacrylate after 7 days. The hydroxyapatite composites and the polymethylmethacrylate system sustained their antifungal activity for at least 1 month. However, after 5 weeks, the antifungal activities of the polymethylmethacrylate systems rapidly lessened, while the hydroxyapatite composites sustained their activities at a much higher level. We found no difference in antifungal activity between the hydroxyapatite composite using either the chitosan or alginate binder. Scanning electron microscopy and Fourier transform infrared spectroscopy revealed the drug release profile. The hydroxyapatite composites impregnated with amphotericin B showed superior antifungal efficacy over those loaded in polymethylmethacrylate in an in vitro study, but additional in vivo research is needed to confirm this result.

Varidans streptococci in the oral flora of the patients at risk for infective endocarditis: species and penicillin susceptibilities.

This study examined viridans streptococci (SV) in oral flora of patients at risk of infective endocarditis (IE) by obtaining 57 isolates from gum-tooth margin swabs of 3 groups of patients. Penicillin minimal inhibitory concentrations (MICs) were determined by E test. Group 1 was from 30 patients with prosthetic heart valves who did not receive antimicrobial agents within 3 months prior to recruitment. Group 2 consisted of 21 patients with known rheumatic heart diseases who regularly received penicillin prophylaxis. Group 3 was 2 patients with IE caused by SV in whom dental swabs were performed before and on the third day of treatment. Streptococcus mitis was found most frequently (49% among 51 oral isolates of SV from patients in group 1 and 2) and in both blood cultures of IE patients. Ninety-four per cent of the isolates were penicillin-susceptible and the rest were intermediate-resistant (IR) equally distributed in both groups 1 and 2. In 2 patients with IE, oral SV obtained after 3 days of penicillin therapy had MICs rising 3 and 5 folds of the baselines. It is suggested that surveillance of susceptibilities of oral SV in patients at risk for IE should be kept up since this will affect the dose and type of antimicrobial agents in IE prophylaxis.

Continuous infusion versus intermittent administration of cefepime in patients with Gram-negative bacilli bacteraemia.

The objective of this study was to compare the pharmacokinetics of cefepime administered by continuous infusion and intermittent injection regimens. A prospective, randomized, cross-over study of ten patients with Gram-negative bacilli bacteraemia was conducted. All patients were randomized to receive cefepime either as a 4-g continuous infusion over 24 h for 48 h or a 2-g bolus administered intermittently intravenously every 12 h for 48 h. After 48 h the patients received the alternative dose regimen. Cefepime pharmacokinetic studies were carried out during hours 36-48 after the start of both regimens. All of the pathogens isolated from the blood in 7 patients had a minimum inhibitory concentration (MIC) < 1 microg mL(-1). In both regimens, the serum cefepime concentrations at all time points were higher than the MIC for the pathogens isolated from this study. For the continuous infusion arm, the highest steady-state concentration was 49.80+/-18.40 microg mL(-1) and the lowest steady-state concentration was 41.42+/-16.48 microg mL(-1). The steady-state concentrations were greater than 4 times the MIC of 8 microg mL(-1). For the intermittent injection regimen, the mean trough concentration was 4.74+/-3.99 microg mL(-1). The mean serum cefepime concentration was above 8 microg mL(-1) for 81.66% of the dosing interval. Therefore, we conclude that either continuous infusion or intermittent injection can be used as an effective mode of cefepime administration to achieve bactericidal activity.