Tigecycline resistance may be associated with dysregulated response to stress in Mycobacterium abscessus.

Previously, we characterized 7C, a laboratory-derived tigecycline-resistant mutant of Mycobacterium abscessus ATCC 19977, and found that the resistance was conferred by a mutation in MAB_3542c, which encodes an RshA-like protein. In M. tuberculosis, RshA is an anti-sigma factor that negatively regulates the SigH-dependent heat/oxidative stress response. We hypothesized that this mutation in 7C might dysregulate the stress response which has been generally linked to antibiotic resistance. In this study, we tested this hypothesis by subjecting 7C to transcriptomic dissection using RNA sequencing. We found an over-expression of genes encoding the SigH ortholog, chaperones and oxidoreductases. In line with these findings, 7C demonstrated better survival against heat shock when compared to the wild-type ATCC 19977. Another interesting observation from the RNA-Seq analysis was the down-regulation of ribosomal protein-encoding genes. This highlights the possibility of ribosomal conformation changes which could negatively affect the binding of tigecycline to its target, leading to phenotypic resistance. We also demonstrated that transient resistance to tigecycline could be induced in the ATCC 19977 by elevated temperature. Taken together, these findings suggest that dysregulated stress response may be associated with tigecycline resistance in M. abscessus.

Five-year species distribution and antimicrobial susceptibility of non-tuberculous mycobacteria in Malaysia, 2018-2022.

Introduction. Non-tuberculous Mycobacteria (NTM) is a group of mycobacteria distinct from the Mycobacterium tuberculosis complex. They can cause opportunistic infections, especially in immunocompromised individuals.Gap Statement. Over the last few years, there has been a growing concern regarding the distribution and antimicrobial resistance of NTM in Malaysia. however, a comprehensive study to fully grasp the NTM situation has yet to be conducted.Aim. This study aimed to investigate the species distribution and antimicrobial susceptibility patterns of NTM isolated from clinical samples in Malaysia from 2018 to 2022.Methodology. A retrospective analysis was conducted on NTM isolates obtained from various clinical specimens over a span of five years. The isolates were identified using phenotypic and molecular techniques, and antimicrobial susceptibility profiles for clinically significant isolates were determined using minimum inhibitory concentration.Results. The study revealed a diverse distribution of NTM species in Malaysia, with Mycobacteroides abscessus complex and Mycobacterium avium complex emerging as the most predominant. Furthermore, the antimicrobial susceptibility patterns showed varying degrees of resistance to commonly used antibiotics, highlighting the significance of treatment tailored to susceptibility testing results.Conclusion. This study provides valuable perspective into the epidemiology of NTM in Malaysia. The information gained from this study should prove useful for empirically treating serious NTM infections prior to species identification and the availability of antimicrobial susceptibility testing results.

The association between VSX1 exon3 gene variants and keratoconus in Malaysian patients.

Purpose: This case-control study aims to examine possible associations of VSX1 exon3 gene variants with the development of keratoconus (KC) in Malaysian patients. Methods: A case-control study was done on 42 keratoconus cases, 127 family member controls, and 96 normal controls. Results: Three gene variants, p.A182A, p.P237P, and p.R217H showed significant associations with keratoconus (P < 0.05). While p.A182A and p.P227P were more prevalent than in the family and normal controls (OR 3.14-4.05), the reverse was observed with p.R217H (OR 0.086-1.59). With Haploview analysis, p.A182A and p.P237P were shown to be in linkage disequilibrium (LD) (LOD (logarithm of the odds score) score of 2.0, r2 of 0.957, and 95% confidence interval (CI) of 0.96-1.00). Conclusion: The study results suggest that the p.A182A and p.P237P variants could have contributed to the development of keratoconus in some Malaysians and that these two variants are likely to be co-inherited. In contrast, the p.R217H variant appeared to confer some protection against the development of keratoconus.

RshA mutations contributing to tigecycline resistance in Mycobacteroides abscessus.

Tigecycline is an important rescue antibiotic for many bacterial infections. In Mycobacteroides abscessus, tigecycline resistance has been associated with dysregulated stress response caused by aberrations in the interaction of the SigH and RshA factors. In this study, two tigecycline-resistant mutants of M. abscessus (CL5A and CL6A) with mutations in the rshA gene were studied using gene complementation, RT-qPCR and the bacterial adenylate cyclase two-hybrid (BACTH) system. The results supported the premise that mutations in the rshA interrupt the RshA-SigH interaction to cause the overexpression of the sigH gene that leads to tigecycline resistance or reduced susceptibility.

Mutations in atpG2 may confer resistance to gentamicin in Listeria monocytogenes.

Introduction Listeriosis, a foodborne infection caused by Listeria monocytogenes, could lead to febrile listerial gastroenteritis and a more invasive form which is often associated with a high mortality and hospitalisation rate. Gentamicin, used as an adjunct therapy with ampicillin, remains the treatment of choice for this life-threatening and invasive infection.Gap statement Nevertheless, there is little data on gentamicin resistance determinants in L. monocytogenes.Aim In this study, we selected and characterised B2b, a gentamicin-resistant mutant derived from L. monocytogenes ATCC 19115 to determine the target(s) of resistance in L. monocytogenes after exposure to gentamicin.Methodology Whole-genome sequencing was carried out to identify the mutation site(s) and possible mechanism(s) of resistance. The mutant was characterised using antimicrobial susceptibility testing and PCR. For biological verifications, complementation and allelic exchange mutagenesis were carried out.Results We found that the gentamicin resistance in B2b was caused by a 10 bp deletion in atpG2 which encodes a gamma subunit of the ATP synthase in L. monocytogenes. Using atpG2 PCR, various other mutations were identified in other gentamicin resistant mutants derived from ATCC 19115. In addition, the mutation from B2b, when introduced into L. ivanovii, also caused gentamicin resistance in this Listeria species.Conclusion Hence, atpG2 mutations appear to be important determinants of gentamicin resistance not only in L. monocytogenes but possibly also in other Listeria species.

A mutation in anti-sigma factor MAB_3542c may be responsible for tigecycline resistance in Mycobacterium abscessus.

In this study, we characterized 7C, a spontaneous mutant selected from tigecycline-susceptible Mycobacterium abscessus ATCC 19977. Whole-genome sequencing (WGS) was used to identify possible resistance determinants in this mutant. Compared to the wild-type, 7C demonstrated resistance to tigecycline as well as cross-resistance to imipenem, and had a slightly retarded growth rate. WGS and subsequent biological verifications showed that these phenotypes were caused by a point mutation in MAB_3542c, which encodes an RshA-like protein. In Mycobacterium tuberculosis, RshA is an anti-sigma factor that negatively regulates the heat/oxidative stress response mechanisms. The MAB_3542c mutation may represent a novel determinant of tigecycline resistance. We hypothesize that this mutation may dysregulate the stress-response pathways which have been shown to be linked to antibiotic resistance in previous studies.

The predictive and diagnostic accuracy of vascular endothelial growth factor and pentraxin-3 in severe dengue.

This study aimed to evaluate vascular endothelial growth factor (VEGF) and pentraxin 3 (PTX-3) as predictive and diagnostic markers in differentiating severe dengue from non-severe dengue. The study was conducted in Ampang Health Clinic, Ampang Hospital and Serdang Hospital. The plasma levels of VEGF and PTX-3 were compared between severe dengue and non-severe dengue by ELISA from the day of presentation until discharged. Multiple logistic regression was used to develop predictive and diagnostic models by incorporating other clinical parameters. The receiver operating characteristics (ROC) analysis was used to assess the accuracy of the biomarkers and the developed models. Eighty-two patients were recruited, 29 with severe dengue and four died. The Area Under the Curve (AUC) was statistically significant in VEGF as diagnostic marker at Day 2 and 3 of illness with sensitivity of 80.00%-100.00% and specificity of 76.47%-80.00%. The predictive model with AUC of 0.84 (p < 0.01) has a sensitivity of 100.00% and specificity of 79.25% for predicting severe dengue. The diagnostic model with AUC of 0.71 (p < 0.01) has a sensitivity of 76.19% and specificity of 73.58% for diagnosing severe dengue. The AUC for PTX-3 was not statistically significant. VEGF may be used in combination with other clinical parameters to predict the severity of the disease. As a single biomarker, it may be used as an adjunct investigation to support the diagnosis of severe dengue. PTX-3 was not able to differentiate severe dengue from non-severe dengue.

Antibiotic resistance in Mycobacterium Abscessus and Mycobacterium Fortuitum isolates from Malaysian patients.

BACKGROUND: Rapidly growing mycobacterial species (RGM) are increasingly being recognized as the cause of various superficial and deep infections in humans. Two of the species most frequently isolated from clinical specimens are Mycobacterium abscessus and Mycobacterium fortuitum. Both species are associated with antibiotic resistances that may complicate therapy. This paper describes the pattern of resistance to five antibiotics commonly prescribed for RGM infections, in M. abscessus and M. fortuitum isolated from Malaysian patients. METHODS: The bacterial strains studied were examined with Etest strips to determine their minimum inhibitory concentrations (MICs) toward amikacin, ciprofloxacin, clarithromycin, imipenem, and linezolid. RESULTS: Among 51 M. abscessus isolates examined by the Etest, the overall MICs of ciprofloxacin, imipenem, amikacin, clarithromycin, and linezolid showed resistance rates of 33.3%, 31.4%, 2.0%, 5.9%, and 21.6%, to the five antibiotics, respectively. M. abscessus subspecies abscessus was more resistant than M. abscessus subsp. massilience to ciprofloxacin, imipenem, and linezolid but was more susceptible to clarithromycin and amikacin. M. fortuitum isolates were significantly less resistant than M. abscessus to ciprofloxacin (3.6%) and imipenem (7.1%) but more resistant to clarithromycin (42.9%) and linezolid (39.3%). CONCLUSION: A suitable combination therapy for Malaysian patients would be amikacin plus clarithromycin and ciprofloxacin, to cover infections by all three M. abscessus subspecies and M. fortuitum.

A new species of Mud Snake (Serpentes, Homalopsidae, Gyiophis Murphy & Voris, 2014) from Myanmar with a first molecular phylogenetic assessment of the genus.

A newly discovered species of homalopsid snake from the genus Gyiophis Murphy & Voris is described from the lowlands of Mawlamyine District in Mon state, southeastern Myanmar. Gyiophis salweenensis sp. nov. is presumed to be closely related to G. maculosa Blanford and G. vorisi Murphy based on the similarities in pholidosis and patterning but can be separated from G. maculosa by the shape of its first three dorsal scale rows that are square, ventral scale pattern that lacks a central spot, and a faint stripe on dorsal scale rows 1-4. It can be further distinguished from G. vorisi by its lower number of ventral scales (129 vs. 142-152), lower number of subcaudals (30/29 vs. 41-58), narrow rostral scale, and having more rows of spots on the dorsum (four vs. three). A preliminary molecular analysis using 1050 base pairs of cytochrome b (cytb) recovered G. salweenensis sp. nov. as the sister species to the Chinese Mud Snake (Myrrophis chinensis). G. maculosa and G. vorisi were unavailable for the analysis. The discovery of G. salweenensis sp. nov. highlights the need for more surveys into the herpetological diversity of eastern Myanmar which remains very much underestimated.

Prevalence of obesity and its associated risk factors among Chinese adults in a Malaysian suburban village.

INTRODUCTION: Obesity is a major modifiable risk factor associated with most chronic diseases. The aim of this study was to determine the prevalence of obesity, and its associated risk factors, among apparently healthy Chinese adults in a Malaysian suburban village. METHODS: This was a cross-sectional study conducted among the Chinese residents in Seri Kembangan New Village, Klang Valley, Selangor, Malaysia. Convenience sampling was used for the selection of participants. Body weight, height, waist and hip circumferences, and blood pressure were measured. Fasting venous plasma was drawn for the measurement of fasting glucose level and lipid profile. Data on sociodemographic factors, dietary habits, physical activity, perceived stress level and sleep duration were collected using interviewer-administered, pretested and validated questionnaires. RESULTS: Among the 258 Chinese residents (mean age 41.4 ± 10.0 years) recruited, the prevalence of obesity was 40%. The obese participants had significantly higher mean blood pressure, and triglyceride and fasting plasma glucose levels than the non-obese participants (p < 0.05). The obese participants also had a significantly lower high-density lipoprotein cholesterol level than the non-obese participants. Logistic regression analysis showed that drinking soy milk (adjusted odds ratio [OR] 0.447; 95% confidence interval [CI] 0.253-0.787; p < 0.05) and the perception that a balanced diet consists mainly of vegetables (adjusted OR 0.440; 95% CI 0.215-0.900; p < 0.05) were associated with a reduced risk of obesity. The risk of obesity was higher in younger participants (adjusted OR 2.714; 95% CI 1.225-6.011; p < 0.05). CONCLUSION: The prevalence of obesity was high among the apparently healthy suburban Chinese. Our findings suggest that soy milk consumption and the perception that a balanced diet consists mainly of vegetables are associated with a lower risk of developing obesity in this population.