Effectiveness of the Air-Filled Technique to Reduce the Dead Space in Syringes and Needles during ChAdox1-n CoV Vaccine Administration.

In the current study, we calculated the vaccine volume and amount of dead space in a syringe and needle during ChAdox1-n CoV vaccine administration using the air-filled technique. The aim is to reduce the dead space in syringes and needles in order to administer up to 12 doses per vial. The hypothetical situation uses a vial with a similar size as the ChAdox1-n CoV vial. We used distilled water (6.5 mL) to fill the same volume as five vials of ChAdox1-n CoV. When 0.48 mL of distilled water is drawn according to the number on the side of the barrel, an additional 0.10 mL of air can be used in the dead space of the distilled water in the syringe and needle for 60 doses, which can be divided into an average of 0.5 mL per dose. ChAdox1-n CoV was administered using a 1-mL syringe and 25G needle into 12 doses using this air-filled technique. The volume of the recipient vaccine will increase by 20% and save on the budget for low dead space syringes (LDS).

SARS-CoV-2 Variants by Whole-Genome Sequencing in a University Hospital in Bangkok: First to Third COVID-19 Waves.

BACKGROUND: Multiple severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants emerged globally during the recent coronavirus disease (COVID-19) pandemic. From April 2020 to April 2021, Thailand experienced three COVID-19 waves, and each wave was driven by different variants. Therefore, we aimed to analyze the genetic diversity of circulating SARS-CoV-2 using whole-genome sequencing analysis. METHODS: A total of 33 SARS-CoV-2 positive samples from three consecutive COVID-19 waves were collected and sequenced by whole-genome sequencing, of which, 8, 10, and 15 samples were derived from the first, second, and third waves, respectively. The genetic diversity of variants in each wave and the correlation between mutations and disease severity were explored. RESULTS: During the first wave, A.6, B, B.1, and B.1.375 were found to be predominant. The occurrence of mutations in these lineages was associated with low asymptomatic and mild symptoms, providing no transmission advantage and resulting in extinction after a few months of circulation. B.1.36.16, the predominant lineage of the second wave, caused more symptomatic COVID-19 cases and contained a small number of key mutations. This variant was replaced by the VOC alpha variant, which later became dominant in the third wave. We found that B.1.1.7 lineage-specific mutations were crucial for increasing transmissibility and infectivity, but not likely associated with disease severity. There were six additional mutations found only in severe COVID-19 patients, which might have altered the virus phenotype with an inclination toward more highly pathogenic SARS-CoV-2. CONCLUSION: The findings of this study highlighted the importance of whole-genome analysis in tracking newly emerging variants, exploring the genetic determinants essential for transmissibility, infectivity, and pathogenicity, and helping better understand the evolutionary process in the adaptation of viruses in humans.

Comparison of antibody responses before and after booster doses with the Pfizer-BioNTech or Oxford-AstraZeneca vaccines in healthcare workers in Thailand.

The severe acute respiratory syndrome 2 (SARS-CoV-2) has spread rapidly worldwide, not only causing significant morbidity and mortality but also dramatically increasing health care spending. To manage this in Thailand, healthcare workers first received two doses of the CoronaVac vaccine followed by a booster vaccine with either BNT162b2 vaccine (Pfizer-BioNTech; PZ) or ChAdOx1 nCoV-19 vaccine (Oxford-AstraZeneca; AZ). Given that the difference in anti-SARS-CoV-2 levels following vaccination may vary depending on the vaccine and on demographic characteristics, we measured the antibody response after the second CoronaVac dose and after the booster with either the PZ or AZ vaccine. Our results in 473 healthcare workers show that the variation in antibody response to the full CoronaVac dose depends on demographic characteristics such as age, gender, body mass index, and underlying disease. After receiving a booster dose, anti-SARS-CoV-2 levels were significantly higher in participants who received the PZ vaccine than in people who received the AZ vaccine. Overall, however, receiving a booster dose of either the PZ or AZ vaccine promoted strong antibody responses, even in the old and those with obesity or diabetes mellitus. In conclusion, our results support the use of a booster vaccination program after full vaccination with the CoronaVac vaccine. This approach effectively enhances immunity against SARS-CoV-2, especially in clinically vulnerable groups and healthcare workers.

Molecular characterization and antibiotic resistance of Staphylococcus aureus isolated from clinical specimens in an urban university hospital in Bangkok, Thailand.

Little is known about the properties of the current strains of Staphylococcus aureus associated with human infections in Thailand. This study examined the rate of resistance to various antimicrobial agents, prevalence of virulence genes, and biofilm formation ability of 60 clinical S. aureus isolates from a single Thai hospital. Moreover, the Staphylococcus protein A gene (spa) type was determined among methicillin-resistant S. aureus (MRSA) isolates. Most methicillin-susceptible S. aureus isolates were susceptible to antimicrobials, whereas all MRSA isolates were resistant to erythromycin and clindamycin. The major virulence genes among the isolates were hla (100%), sec (26.7%), and hlb (20%). Meanwhile, 46.7% and 1.7% of the strains exhibited low-grade and high-grade biofilm formation, respectively. Our findings revealed the presence of spa types among MRSA isolates were: t032 (37.5%, 6/16), t088 (25%, 4/16), t001 (12.5%, 2/16), t008 (6.25%, 1/16), t034 (6.25%, 1/16), t439 (6.25%, 1/16), and t1928 (6.25%, 1/16). These findings will be useful for future research on anti-virulence therapies and the epidemiology of the strains circulating in our hospital.

Immune response after COVID-19 vaccination among patients with chronic kidney disease and kidney transplant.

BACKGROUND: Vaccination of patients with chronic kidney disease (CKD) and kidney transplants (KTs) may achieve a less robust immune response. Understanding such immune responses is crucial for guiding current and future vaccine dosing strategies. METHODS: This prospective, observational study estimated the immunogenicity of humoral and cellular responses of two SARS-CoV-2 vaccines in different patient groups with CKD compared with controls. Secondary outcomes included adverse events after vaccination and the incidence of COVID-19 breakthrough infection, including illness severity. RESULTS: In total, 212 patients received ChAdOx1 nCoV-19 (89.62 %) or inactivated vaccines (10.38 %).The antibody response against the S protein was analyzed at T0 (before the first injection), T1 (before the second injection), and T2 (12 weeks after the second injection). Seroconversion occurred in 92.31 % of controls at T2 and in 100 % of patients with CKD, 42.86 % undergoing KT, 80.18 % of hemodialysis (HD), and 0 % of patients undergoing continuous ambulatory peritoneal dialysis (CAPD) at T2 of the ChAdOx1 nCoV-19 vaccine. Neutralizing antibody levels by surrogate virus neutralization test were above the protective level at T2 in each group. The KT group exhibited the lowest neutralizing antibody and T cell response. Blood groups O and vaccine type were associated with good immunological responses. After the first dose, 14 individuals (6.6 out of the total population experienced COVID-19 breakthrough infection. CONCLUSION: Immunity among patients with CKD and HD after vaccination was strong and comparable with that of healthy controls. Our study suggested that a single dose of the vaccine is not efficacious and delays may result in breakthrough infection. Some blood groups and types of vaccine can affect the immune response.

Efficacy and safety of ivermectin in the treatment of mild to moderate COVID-19 infection: a randomized, double-blind, placebo-controlled trial.

BACKGROUND: The emergent outbreak of coronavirus disease (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has emphasized the requirement for therapeutic opportunities to overcome this pandemic. Ivermectin is an antiparasitic drug that has shown effectiveness against various agents, including SARS-CoV-2. This study aimed to assess the efficacy of ivermectin treatment compared with the standard of care (SOC) among people with mild to moderate COVID-19 symptoms. METHODS: In this randomized, double-blind, placebo-controlled, single-center, parallel-arm, superiority trial among adult hospitalized patients with mild to moderate COVID-19, 72 patients (mean age 48.57 ± 14.80 years) were randomly assigned to either the ivermectin (n=36) or placebo (n=36) group, along with receiving standard care. We aimed to compare the negativity of reverse transcription polymerase chain reaction (RT-PCR) result at days 7 and 14 of enrolment as the primary outcome. The secondary outcomes were duration of hospitalization, frequency of clinical worsening, survival on day 28, and adverse events. RESULTS: At days 7 and 14, no differences were observed in the proportion of PCR-positive patients (RR 0.97 at day 7 (p=0.759) and 0.95 at day 14 (p=0.813). No significant differences were found between the groups for any of the secondary endpoints, and no adverse events were reported. CONCLUSION: No difference was found in the proportion of PCR-positive cases after treatment with ivermectin compared with standard care among patients with mild to moderate COVID-19 symptoms. However, early symptomatic recovery was observed without side effects. TRIAL REGISTRATION: ClinicalTrials.gov NCT05076253. Registered on 8 October 2021, prospectively.

Performance of colorimetric reverse transcription loop-mediated isothermal amplification as a diagnostic tool for SARS-CoV-2 infection during the fourth wave of COVID-19 in Thailand.

BACKGROUND: COVID-19, which is caused by SARS-CoV-2 and its variants, poses an ongoing global threat, particularly in low-immunization coverage regions. Thus, rapid, accurate, and easy-to-perform diagnostic methods are in urgent demand to halt the spread of the virus. OBJECTIVES: We aimed to validate the clinical performance of the FastProof 30 min-TTR SARS-CoV-2 reverse transcription loop-mediated isothermal amplification (RT-LAMP) method using leftover RNA samples extracted from 315 nasopharyngeal swabs. The sensitivity and specificity of RT-LAMP were determined in comparison with reverse transcriptase-polymerase chain reaction (RT-PCR). RESULTS: Of 315 nasopharyngeal swabs, viral RNA was detected in 154 samples (48.9%) by RT-PCR assay. Compared with RT-PCR, overall sensitivity and specificity of RT-LAMP were 81.82% (95% CI: 74.81-87.57) and 100% (95% CI: 97.73-100), respectively. A 100% positivity rate was achieved in samples with cycle threshold (Ct) <31 for RT-PCR targeting the ORF1ab gene. However, samples with Ct >31 accounted for false-negative results by RT-LAMP in 28 samples. CONCLUSIONS: RT-LAMP reliably detected viral RNA with high sensitivity and specificity and has potential application for mass screening of patients with acute COVID-19 infection when viral load is high.

Immunogenicity of the ChAdOx1 nCoV-19 vaccine against SARS-CoV-2 with 12-dose vials: An interim analysis.

BACKGROUND: ChAdOx1 nCoV-19 (AZD 1222) is the main vaccine planned for general administration in Thailand. This vaccine is stored in multiple-dose vials meant to be administered to 10 recipients with a volume of 0.5 mL for each dose. However, the vaccine vials were overfilled, which allows the administration of more than 10 doses per vial. We have stipulated the preparation and use of ChAdOx1 nCoV-19 vaccine using traditional 21 or 25G needles and planned to investigate the immune responses of participants who were administered the ChAdOx1 nCoV-19 vaccine using this technique. METHODS: We measured anti-SARS-CoV-2 anti-spike RBD IgG and neutralising antibody using a surrogate virus neutralising test (sVNT) among adults aged 18-72 years on average of 8.57 weeks (IQR 6.85-8.93) after the first dose of ChAdOx1 nCoV-19 vaccine. The primary outcome was the antibody level. The secondary outcomes included adverse events, factors affecting antibody levels, and incidence of COVID-19 infection. FINDINGS: In all, 60 participants comprised 25 males and 35 females. The mean age was 53.70 ± 17.48 years. BMI was 23.45 ± 3.69 kg/m2. Tests for the neutralising antibody were positive in 60% of the participants (71.4% among males and 44% among females). The median anti-SARS-CoV-2 QuantiVac (anti-spike IgG) level among male and female samples was 111.83 BAU/mL (IQR 73.48-196.74 BAU/mL) and 159.65 BAU/mL (IQR 100.39-371.81), respectively. The positive QuantiVac value of male and female samples was 88.00% and 98.44%, respectively (p-value = 0.382) .A good correlation was observed between neutralising Ab and anti-spike RBD IgG. CONCLUSION: Patients receiving 12-dose per vial injections of ChAdOx1 nCoV-19 exhibited high levels of immunity without severe side effects. This technique can be adopted to maximise the number of doses per vial while preserving vaccine effectiveness.

Impact of ultraviolet germicidal irradiation on new silicone half-piece elastometric respirator (VJR-NMU) performance, structural integrity and sterility during the COVID-19 pandemic.

Since the innovation of our new half-piece elastometric respirator, this type of filtering facepiece respirator (FFR) has been used widely in Thailand. Decontamination methods including ultraviolet C (UVC) germicidal irradiation and 70% alcohol have been implemented to decontaminate these respirators. We then examined the inactivation potential of different decontamination processes on porcine epidemic diarrhea virus (PEDV) and numerous bacterial strains, most of which were skin-derived. To enable rigorous integrity of the masks after repeated decontamination processes, fit tests by the Bitrex test, tensile strength and elongation at break were also evaluated. Our results showed that UVC irradiation at a dose of 3 J/cm2 can eradicate bacteria after 60 min and viruses after 10 min. No fungi were found on the mask surface before decontamination. The good fit test results, tensile strength and elongation at break were still maintained after multiple cycles of decontamination. No evidence of physical degradation was found by gross visual inspection. Alcohol (70%) is also an easy and effective way to eradicate microorganisms on respirators. As the current pandemic is expected to continue for months to years, the need to supply adequate reserves of personnel protective equipment (PPE) and develop effective PPE reprocessing methods is crucial. Our studies demonstrated that the novel silicone mask can be safely reprocessed and decontaminated for many cycles by UVC irradiation, which will help ameliorate the shortage of important protective devices in the COVID-19 pandemic era.

Species Distribution, Antifungal Susceptibility, and Molecular Epidemiology of Candida Species Causing Candidemia in a Tertiary Care Hospital in Bangkok, Thailand.

Candida species represent a common cause of bloodstream infection (BSI). Given the emergence of non-albicans Candida (NAC) associated with treatment failure, investigations into the species distribution, fungal susceptibility profile, and molecular epidemiology of pathogens are necessary to optimize the treatment of candidemia and explore the transmission of drug resistance for control management. This study evaluated the prevalence, antifungal susceptibility, and molecular characteristics of Candida species causing BSI in a tertiary-level hospital in Bangkok, Thailand. In total, 54 Candida isolates were recovered from 49 patients with candidemia. C. tropicalis was the most prevalent species (33.3%), followed by C. albicans (29.6%). Most Candida species were susceptible to various antifungal agents, excluding C. glabrata and C. tropicalis, which had increased rates of non-susceptibility to azoles. Most C. glabrata isolates were non-susceptible to echinocandins, especially caspofungin. The population structure of C. albicans was highly diverse, with clade 17 predominance. GoeBURST analysis of C. tropicalis revealed associations between genotype and fluconazole resistance in a particular clonal complex. The population structure of C. glabrata appeared to have a low level of genetic diversity in MLST loci. Collectively, these data might provide a fundamental database contributing to the development of novel antifungal agents and diagnostic tests.

A Search for Anti-Naegleria fowleri Agents Based on Competitive Exclusion Behavior of Microorganisms in Natural Aquatic Environments.

Naegleria fowleri causes deadly primary amoebic meningoencephalitis (PAM) in humans. Humans obtain the infection by inhaling water or dust contaminated with amebae into the nostrils, wherefrom the pathogen migrates via the olfactory nerve to cause brain inflammation and necrosis. Current PAM treatment is ineffective and toxic. Seeking new effective and less toxic drugs for the environmental control of the amoeba population to reduce human exposure is logical for the management of N. fowleri infection. On the basis of the concept of competitive exclusion, where environmental microorganisms compete for resources by secreting factors detrimental to other organisms, we tested cell-free culture supernatants (CFSs) of three bacteria isolated from a fresh water canal, i.e., Pseudomonas aeruginosa, Pseudomonas otitidis, and Enterobacter cloacae, were tested against N. fowleri. The CFSs inhibited growth and caused morphological changes in N. fowleri. At low dose, N. fowleri trophozoites exposed to P. aeruginosa pyocyanin were seen to shrink and become rounded, while at high dose, the trophozoites were fragmented. While the precise molecular mechanisms of pyocyanin and products of P. otitidis and E. cloacae that also exert anti-N. fowleri activity await clarification. Our findings suggest that P. aeruginosa pyocyanin may have a role in the control of amphizoic N. fowleri in the environment.

A novel bacteriocin from Enterococcus faecalis 478 exhibits a potent activity against vancomycin-resistant enterococci.

The emergence of multidrug-resistant enterococci (MDRE) and particularly vancomycin-resistant enterococci (VRE) is considered a serious health problem worldwide, causing the need for new antimicrobials. The aim of this study was to discover and characterize bacteriocin against clinical isolates of MDRE and VRE. Over 10,000 bacterial isolates from water, environment and clinical samples were screened. E. faecalis strain 478 isolated from human feces produced the highest antibacterial activity against several MDRE and VRE strains. The optimum condition for bacteriocin production was cultivation in MRS broth at 37°C, pH 5-6 for 16 hours. The bacteriocin-like substance produced from E. faecalis strain EF478 was stable at 60°C for at least 1 hour and retained its antimicrobial activity after storage at -20°C for 1 year, at 4°C for 6 months, and at 25°C for 2 months. A nano-HPLC electrospray ionization multi-stage tandem mass spectrometry (nLC-ESI-MS/MS) analysis showed that the amino acid sequences of the bacteriocin-like substance was similar to serine protease of E. faecalis, gi|488296663 (NCBI database), which has never been reported as a bacteriocin. This study reported a novel bacteriocin with high antibacterial activity against VRE and MDRE.

Clonal spread of carbapenem resistant Acinetobacter baumannii in the patients and their environment at BMA Medical College and Vajira Hospital.

OBJECTIVE: To determine the clonal spread of carbapenem-resistant Acinetobacter baumannii (CRAB) in the patients and their environment at BMA Medical College and Vajira Hospital. MATERIAL AND METHOD: A prospective study on CRAB isolated from the clinical specimens of 30 patients and 300 from their environmental samples were carried out from September 1-15, 2008. The CRAB isolates were genotyped using PCR-based typing method. RESULTS: Twenty-six (86.7%) and 20 (66.7%) cases of 30 patients had their environment contaminated with A. baumannii and CRAB, respectively Environmental contamination rates of A. baumannii and CRAB were 18.0% (54/300) and 13.0% (39/300), respectively. The most contaminated sites with CRAB were bedside cupboards (26.7%), followed by bedrails and bed sheets (20%), BP cuffs (16.7%), over bed tables and nurse station counters (13.3% each) and push carts (10%). Four molecular types were classified among 65 CRAB isolates. Molecular type 1 was the most prevalent (90.7%) and found in all kinds of environmental samples except patient record folder and computer keyboard/mouse. About 37% of the patients had at least one of their environmental samples contaminated with CRAB clonally related with their own types. CONCLUSION: Clonal spread of CRAB was demonstrated to emphasize the important of hand hygiene, contact precaution and patient's environmental decontamination in controlling the spread of CRAB in the hospital.

Epidemiologic study of nosocomial bacterial infection of pediatric patients at BMA Medical College and Vajira Hospital.

BACKGROUND: Nosocomial infection is a global public health problem, particularly by multi-drug resistant bacteria, increasing morbidity, mortality, and health care costs. The distribution of pathogens and antimicrobial sensitivity patterns change with time and vary among hospitals. OBJECTIVE: To determine and compare the bacterial pathogens causing nosocomial infections in pediatric patients and their susceptibility patterns between January 2000-December 2002 and January 2003-December 2005. MATERIAL AND METHOD: The bacterial pathogens and antimicrobial susceptibilities of children diagnosed as nosocomial infections at BMA Medical College and Vajira Hospital between January 2000-December 2002 and January 2003-December 2005 were comparatively analyzed. RESULTS: 1,863 and 1,884 isolates were identified in 2000-2002 and 2003-2005, respectively. The common sites of infections were bloodstream (28.6%), lower respiratory tract (15.3%), skin and soft tissue (14.9%), and urinary tract (12.5%). The major isolated gram positive pathogens were S. aureus, coagulase negative Staphylococcus and Enterococus. The major gram negative pathogens were E. coli, P. aeruginosa, K. pneumoniae, Enterobacter spp. and Acinetobacter spp. Compared between 2000-2002 and 2003-2005, methicillin resistant S. aureus (MRSA) was decreased from 4.3% to 1.5% P. aeruginosa from 13.3% to 7.5%, Enterobacter spp. from 4.2% to 2.4%, Serratia spp. from 1.3% to 0.3%, but methicillin resistant coagulase negative Staphylococcus was increased from 5.6% to 10.5% and K. pneumoniae from 5.5% to 7.7%, (p < 0.05). All gram positive cocci remained sensitive to vancomycin and linezolid. In 2003-2005, gram negative rods were less sensitive to 3rd and 4th generation cephalosporins and aminoglycosides than in 2000-2002. Sensitivity of gram negative rods to 3rd and 4th generation cephalosporins were not significantly different except Enterobacter spp. and Serratia spp., which were more sensitive to 4th generation cephalosporin (p < 0.05). Most gram negative pathogens (80-100%) were sensitive to ciprofloxacin except Acinetobacter spp. (61%). Carbapenems sensitivity were 100% except 92-100% for Enterobacter and 67-86% for P. aeruginosa, Acinetobacter spp. and Serratia spp. CONCLUSION: The bacterial pathogens causing nosocomial infections and their susceptibility patterns change with time, so periodic surveillance are essential as a guide for more proper empirical therapy especially in serious or life threatening infections that need urgent appropriate antibiotics.