The spread of chloramphenicol-resistant Neisseria meningitidis in Southeast Asia.

OBJECTIVES: Invasive disease caused by Neisseria meningitidis is a significant health concern globally, but our knowledge of the prevailing serogroups, antimicrobial susceptibility patterns, and genetics of N. meningitidis in Southeast Asia is limited. Chloramphenicol resistance in N. meningitidis has rarely been reported, but was first described in isolates from Vietnam in 1998. We aimed to characterise eight chloramphenicol resistant meningococcal isolates collected between 2007 and 2018 from diagnostic microbiology laboratories in Cambodia, Thailand and the Lao People's Democratic Republic (Laos). METHODS: Whole-genome sequencing was used to generate genome sequences from 18 meningococcal isolates including the eight chloramphenicol resistant isolates. We identified antimicrobial resistance genes present in these strains, and examined the phylogenetic relationships between strains. RESULTS: The eight resistant strains all contain the same chloramphenicol resistance gene first described in 1998, and are closely related to each other. Strains resistant to penicillin, tetracycline, and ciprofloxacin were also observed, including a chloramphenicol-resistant strain which has acquired penicillin and ciprofloxacin resistance. CONCLUSIONS: This study suggests that chloramphenicol-resistant N. meningitidis is more widespread than previously thought, and that the previously-identified resistant lineage is now found in multiple countries in Southeast Asia

A one-health sampling strategy to explore the dissemination and relationship between colistin resistance in human, animal, and environmental sectors in Laos

This study was designed to investigate the molecular epidemiology of mobile colistin resistance (mcr) using a “one-health” approach in Laos and to predict whether any dominant plasmid backbone and/or strain type influences the dissemination of mcr. We collected 673 samples from humans (rectal normal flora), poultry, and the environment (water, flies, birds, etc.) in Vientiane, Laos, from May to September 2018. A total of 238 Escherichia coli (E. coli) isolated from non-duplicative samples, consisting of 98 MCR-positive E. coli (MCRPEC) (“mcr” denotes the gene encoding mobile colistin resistance, and “MCR” denotes the subsequent protein encoded by mcr) and 140 MCR-negative E. coli (MCRNEC), were characterized by phenotype and Illumina sequencing. A subset of MCRPEC was selected for MinION sequencing, conjugation assay, plasmid stability, and growth kinetics in vitro. The prevalence of MCRPEC was found to be 14.6% (98/673), with the highest prevalence in human rectal swabs (45.9% (45/98), p < 0.0001, odds ratio (OR): 0.125, 95% CI: 0.077–0.202). The percentages of MCRPEC from other samples were 14.3% (2/14) in dog feces, 12.0% (24/200) in flies, 11.0% (11/100) in chicken meat, 8.9% (8/90) in chicken cloacal, 8.0% (4/50) in chicken caeca, and 7.5% (4/53) in wastewater. MCRPEC was significantly more resistant to co-amoxiclav, sulfamethoxazole-trimethoprim, levofloxacin, ciprofloxacin, and gentamicin than MCRNEC (p < 0.05). Genomic analysis revealed the distribution of MCRPEC among diverse clonal types. The putative plasmid Inc types associated with mcr-1 were IncX4, IncHI2, IncP1, IncI2, and IncFIA, and those associated with mcr-3 were IncFII, IncFIA, IncFIB, IncP1, and IncR. Recovery of highly similar plasmids from both flies and other sampling sectors implied the role of flies in the dissemination of mcr-1. mcr-positive plasmids were shown to be conjugative, and a significantly high transfer rate into a hypervirulent clone ST1193 was observed. Plasmids containing mcr irrespective of Inc type were highly stable and invariably did not exert a fitness effect upon introduction into a new host. These findings signify the urgent need for a standard infection control program to radically decontaminate the source of resistance

Impact of delays to incubation and storage temperature on blood culture results: a multi-centre study.

BACKGROUND: Blood cultures are one of the most important tests performed by microbiology laboratories. Many hospitals, particularly in low and middle-income countries, lack either microbiology services or staff to provide 24 h services resulting in delays to blood culture incubation. There is insufficient guidance on how to transport/store blood cultures if delays before incubation are unavoidable, particularly if ambient temperatures are high. This study set out to address this knowledge gap. METHODS: In three South East Asian countries, four different blood culture systems (two manual and two automated) were used to test blood cultures spiked with five common bacterial pathogens. Prior to incubation the spiked blood culture bottles were stored at different temperatures (25 °C, in a cool-box at ambient temperature, or at 40 °C) for different lengths of time (0 h, 6 h, 12 h or 24 h). The impacts of these different storage conditions on positive blood culture yield and on time to positivity were examined. RESULTS: There was no significant loss in yield when blood cultures were stored < 24 h at 25 °C, however, storage for 24 h at 40 °C decreased yields and longer storage times increased times to detection. CONCLUSION: Blood cultures should be incubated with minimal delay to maximize pathogen recovery and timely result reporting, however, this study provides some reassurance that unavoidable delays can be managed to minimize negative impacts. If delays to incubation ≥ 12 h are unavoidable, transportation at a temperature not exceeding 25 °C, and blind sub-cultures prior to incubation should be considered

The cost-effectiveness of the use of selective media for the diagnosis of melioidosis in different settings

Melioidosis is a frequently fatal disease requiring specific treatment. The yield of Burkholderia pseudomallei from sites with a normal flora is increased by culture using selective, differential media such as Ashdown’s agar and selective broth. However, since melioidosis mainly affects people in resource-poor countries, the cost effectiveness of selective culture has been questioned. We therefore retrospectively evaluated this in two laboratories in southeast Asia