- Volume 70, Issue 10, 2021

The emergence of metallo-β-lactamase (MBL)-producing Enterobacterales , mainly New Delhi metallo-β-lactamase (NDM), represents a clinical threat due to the limited therapeutic alternatives. Aztreonam (AZT) is stable to MBLs, but most MBL-producing Enterobacterales isolates usually co-harbour other β-lactamases that confer resistance to AZT and, consequently, its use is restricted in these isolates. We compared the ability of sulbactam (SUL), tazobactam (TAZ), clavulanic acid (CLA) and avibactam (AVI) to restore the AZT activity in MBL-producing AZT-resistant Enterobacterales isolates. A collection of 64 NDM-producing AZT-resistant Enterobacterales from five hospitals in Buenos Aires city, Argentina, were studied during the period July–December 2020. MICs were determined using the agar dilution method with Mueller–Hinton agar according to Clinical and Laboratory Standards Institute (CLSI) recommendations. AVI, SUL and TAZ were used at a fixed concentration of 4 mg l−1, whereas CLA was used at a fixed concentration of 2 mg l−1. A screening method based on disc diffusion to evaluate this synergy was also conducted. Detection of bla KPC, bla OXA, bla NDM, bla VIM, bla CTXM-1, bla PER-2 and bla CIT was performed by PCR. The AZT-AVI combination restored the AZT activity in 98.4 % of AZT-resistant strains, whereas CLA, TAZ and SUL did so in 70.3, 15.6 and 12.5 %, respectively, in isolates co-harbouring extended-spectrum β-lactamases, but were inactive in isolates harbouring AmpC-type enzymes and/or KPC. The synergy screening test showed an excellent negative predictive value to confirm the absence of synergy, but positive results should be confirmed by a quantitative method. The excellent in vitro performance of the AZT-CLA combination represents a much more economical alternative to AZT-AVI, which could be of use in the treatment of MBL-producing, AZT-resistant Enterobacterales .

The options available for treating infections with carbapenemase-producing Enterobacteriaceae (CPE) are limited; with the increasing threat of these infections, new treatments are urgently needed. Biapenem (BIPM) is a carbapenem, and limited data confirming its in vitro killing effect against CPE are available. In this study, we examined the minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of BIPM for 14 IMP-1-producing Enterobacteriaceae strains isolated from the Okayama region in Japan. The MICs against almost all the isolates were lower than 0.5 µg ml−1, indicating susceptibility to BIPM, while approximately half of the isolates were confirmed to be bacteriostatic to BIPM. However, initial killing to a 99.9 % reduction was observed in seven out of eight strains in a time–kill assay. Despite the small data set, we concluded that the in vitro efficacy of BIPM suggests that the drug could be a new therapeutic option against infection with IMP-producing CPE.

Introduction. The resistance to quinolone reported in uropathogenic Escherichia coli (UPEC) is commonly caused by mutations in the target site encoding genes such as the gyrA gene. Bacterial plasmids carrying resistance genes such as qnr genes can also transfer resistance. Biofilms produced by UPEC can further aid the development of resistant urinary tract infections (UTIs).

Hypothesis. Biofilm production is associated with higher prevalence of quinolones resistance genetic determinants.

Aim. To detect the prevalence of qnr genes and gyrA gene mutation among quinolone-resistant UPEC and to investigate the relation between these genetic resistance determinants and biofilm production.

Methodology. Catheterized urine samples were collected from 420 patients with evidence of UTIs and processed using standard techniques. Isolated UPEC were screened for quinolone resistance using an antimicrobial susceptibility test. Biofilm production among quinolone-resistant isolates was detected using the tissue culture plate method. All quinolone-resistant isolates were screened for qnr genes (qnrA, qnrB and qnrS) by multiplex PCR and for gyrA gene mutation by PCR-RFLP.

Results. Two hundred and sixty-four UPEC isolates were detected from 420 processed urine samples. Out of the identified 264 UPEC, 123 (46.6 %) isolates were found to be quinolone-resistant, showing resistance to 1 or more of the tested quinolones. Of the 123 quinolone-resistant UPEC detected, 71(57.7 %) were biofilm producers. The qnr genes were detected among 62.6 % of the quinolone-resistant UPEC, with an estimated prevalence of 22.8, 32.5 and 37.4 % for qnrA, qnrB and qnrS genes, respectively. Additionally, the gyrA gene mutation was identified among 53.7 % of the quinolone-resistant isolates. We reported a significant association between biofilm production and the presence of qnrA, qnrB and qnrS genes. Furthermore, the gyrA gene mutation was significantly associated with biofilm-producing isolates. The coexistence of qnr genes, gyrA gene mutation and biofilm production was demonstrated in almost 40 % of the quinolone-resistant isolates.

Conclusions. A significantly higher prevalence of qnr genes (qnrA, qnrB and qnrS) as well as the gyrA gene mutation was found among biofilm-forming UPEC. The reported coexistence of these different resistance mechanisms could aggravate quinolone resistance. Therefore, monitoring of resistance mechanisms and a proper stewardship programme are necessary.

Introduction. Nontuberculous mycobacteria (NTM) are widespread in the environment and can cause various diseases in humans, especially immunocompromised patients.

Hypothesis. Treatment of diseases caused by NTM is a complicated issue, mainly due to the resistance of the pathogen to most antimicrobial agents. Bedaquiline (Bdq) is now widely used for the treatment of multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis (TB).

Aim. The main goal of our study was to evaluate the activity of Bdq against Mycobacterium avium complex (MAC), the most common species among NTM.

Methodology. A total of 166 MAC cultures (124 Mycobacterium avium and 42 Mycobacterium intracellulare ) were studied. The minimum inhibitory concentrations (MICs) of Bdq for M. avium and M. intracellulare were obtained by twofold serial dilutions in the Middlebrook 7H9 medium. MIC ranges were determined and the MIC50, MIC90 and ECOFF values were obtained.

Results. The MICs in respect of M. avium ranged from 0.003 to 1.0 µg ml−1; those for M. intracellulare ranged from 0.003 to 0.5 µg ml−1. The Bdq MIC50 and MIC90 values were found to be 0.015 and 0.12 µg ml−1 , respectively, for M. avium and 0.007 and 0.06 µg ml−1, respectively, for M. intracellulare . The tentative ECOFF values for M. avium and M. intracellulare were 0.12 and 0.06 µg ml−1, respectively.

Conclusion. The main bedaquiline susceptibility parameters for MAC strains isolated in the Moscow region were determined.

Introduction. Antibiotic use, particularly amoxicillin-clavulanic acid in dairy farming, has been associated with an increased incidence of AmpC-hyperproducing Escherichia coli .

Gap statement. There is limited information on the incidence of AmpC-hyperproducing E. coli from seasonal pasture-fed dairy farms.

Aim. We undertook a New Zealand wide cross-sectional study to determine the prevalence of AmpC-producing E. coli carried by dairy cattle.

Methodology. Paddock faeces were sampled from twenty-six dairy farms and were processed for the selective growth of both extended-spectrum beta-lactamase (ESBL)- and AmpC-producing E. coli . Whole genome sequence analysis was carried out on 35 AmpC-producing E. coli .

Results. No ESBL- or plasmid mediated AmpC-producing E. coli were detected, but seven farms were positive for chromosomal mediated AmpC-hyperproducing E. coli . These seven farms were associated with a higher usage of injectable amoxicillin antibiotics. Whole genome sequence analysis of the AmpC-producing E. coli demonstrated that the same strain (<3 SNPs difference) of E. coli ST5729 was shared between cows on a single farm. Similarly, the same strain (≤15 SNPs difference) of E. coli ST8977 was shared across two farms (separated by approximately 425 km).

Conclusion. These results infer that both cow-to-cow and farm-to-farm transmission of AmpC-producing E. coli has occurred.

Introduction . Capnocytophaga species are common inhabitants of the oral cavity and can be responsible for systemic diseases in immunocompromised patients with granulocytopenia. Furthermore, it has been reported that some clinical isolates of Capnocytophaga species produce extended-spectrum β-lactamases (ESBLs).

Gap statement. Information is lacking about the types of β-lactamase genes possessed by Capnocytophaga spp. and the antimicrobial susceptibility of Capnocytophaga spp. possessing each β-lactamase gene.

Aim. The aim of this study was to investigate the presence of β-lactamase genes in clinical strains of β-lactamase-producing Capnocytophaga species isolated from clinical samples acquired at Shinshu University Hospital and examine the antimicrobial susceptibility of those strains.

Methodology. The β-lactamase-producing Capnocytophaga species (n=49) were obtained from clinical specimens. PCR assays were used to detect bla CfxA, bla CSP, bla TEM, bla CepA/CblA and transposon Tn4555 genes. Southern hybridization assays were used to detect bla CfxA and bla CSP. The minimum inhibitory concentration of some β-lactams was determined using the E-test method.

Results. PCR analysis indicated that the bla CfxA gene was present in 15 (30.6 %) and the bla CSP gene in 35 (69.3 %) of the 49 Capnocytophaga strains investigated, . Both bla CfxA and bla CSP genes were detected in a Capnocytophaga gingivalis strain. The PCR results were confirmed by Southern hybridization assays. Transposon Tn4555 was only detected in Capnocytophaga spp. harbouring the bla CfxA gene. All the β-lactamase-producing Capnocytophaga isolates were susceptible to ceftazidime–clavulanic acid, cefoxitin and imipenem. In contrast, most of the isolates were resistant to amoxicillin.

Conclusions. The clinical isolates of Capnocytophaga spp. showed a high prevalence of the bla CSP gene in Japan. The presence of the bla CSP gene was distributed in Capnocytophaga sputigena as well as other Capnocytophaga spp. These results seem to suggest the dissemination of bla CfxA and bla CSP β-lactamase genes among Capnocytophaga species.

Introduction. Global poliovirus eradication is a public health emergency of international concern. The acute flaccid paralysis (AFP) surveillance programme in South Africa has been instrumental in eliminating polioviruses and keeping the country poliovirus free.

Gap statement. The sensitivity of surveillance for polioviruses by every African country is of global interest in the effort to ensure global health security from poliovirus re-emergence.

Aim. To describe the epidemiology of polioviruses from AFP cases and environmental samples in South Africa and to report the performance of the AFP surveillance system for the years 2016–2019 against targets established by the World Health Organization (WHO).

Methods. Stool specimens from AFP or suspected AFP cases were received and tested as per WHO guidelines. Environmental samples were gathered from sites across the Gauteng province using the grab collection method. Concentration was effected by the two-phase polyethylene glycol method approved by the WHO. Suspected polioviruses were isolated in RD and/or L20B cell cultures through identification of typical cytopathic effects. The presence of polioviruses was confirmed by intratypic differentiation PCR. All polioviruses were sequenced using the Sanger method, and their VP1 gene analysed for mutations.

Results. Data from 4597 samples (2385 cases) were analysed from the years 2016–2019. Two cases of immunodeficiency-associated vaccine-derived poliovirus (iVDPV) type 3 were detected in 2017 and 2018. A further 24 Sabin type 1 or type 3 polioviruses were detected for the 4 years. The national surveillance programme detected an average of 3.1 cases of AFP/100 000 individuals under 15 years old (2.8/100 000–3.5/100 000). The stool adequacy of the samples received was 53.0 % (47.0–55.0%), well below the WHO target of 80 % adequacy. More than 90 % of results were released from the laboratory within the turnaround time (96.6 %) and non-polio enteroviruses were detected in 11.6 % of all samples. Environmental surveillance detected non-polio enterovirus in 87.5 % of sewage samples and Sabin polioviruses in 12.5 % of samples.

Conclusion. The AFP surveillance programme in South Africa is sensitive to detect polioviruses in South Africa and provided no evidence of wild poliovirus or VDPV circulation in the country.

Introduction

Pigeon droppings are among the major environmental sources of Cryptococcus neoformans AFLP1/VNI, from where the organism infects susceptible humans and animals resulting in cryptococcosis. Until now, C. neoformans AFLP1B/VNII was the only molecular type reported in Nigeria. Effective clinical treatment of this infection has occasionally been stymied by the emergence of antifungal non-susceptible, and resistant strains of C. neoformans AFLP1/VNI.

Hypothesis/Gap Statement

Pigeon droppings harbour C. neoformans and HIV/AIDS patients are among the susceptible population to develop cryptococcal infection. Epidemiological data on cryptococcal prevalence is limited in Nigeria.

Aim

To investigate the environmental prevalence of C. neoformans in South-eastern Nigeria and compare the isolates with other lineages by using molecular and microbiological tools.

Methodology

A total of 500 pigeon droppings and 300 blood samples of HIV/AIDS patients were collected, respectively, from five market squares and three tertiary healthcare centres within the Nsukka area of South-eastern Nigeria. The antifungal susceptibility of the C. neoformans isolates to amphotericin B, fluconazole, 5-fluorocytosine, itraconazole, voriconazole, posaconazole, and isavuconazole was investigated based on the CLSI M27-A3 protocol. Yeasts were identified by MALDI-TOF MS, thereafter Cryptococcus MLST was performed according to the International Society for Human and Animal Mycology (ISHAM) consensus scheme.

Results

C. neoformans was recovered from 6 (1.2 %) pigeon droppings and 6 (2 %) blood cultures of HIV/AIDS patients. Molecular analyses indicated that all cryptococcal isolates belong to serotype A and the AFLP1/VNI molecular type with sequence type (ST)32. Infection with C. neoformans was independent of sex and age of the patients investigated. All C. neoformans isolates were susceptible to the seven antifungal agents.

Conclusion

This is the first report on the prevalence of C. neoformans AFLP1/VNI (ST32) in environmental and clinical samples from Nigeria. The antifungal susceptibility indicates that antifungal resistance by C. neoformans is yet a rare occurrence in Nigeria.

Alteration in the composition of the gut microbiota can lead to a number of chronic clinical diseases. Akkermansia muciniphila is an anaerobic bacteria constituting 3–5% of the gut microbial community in healthy adults. This bacterium is responsible for degenerating mucin in the gut; its scarcity leads to diverse clinical disorders. In this review, we focus on the role of A. muciniphila in diabetes, obesity and atherosclerosis, as well as the use of this bacterium as a next-generation probiotic. In regard to obesity and diabetes, human and animal trials have shown that A. muciniphila controls the essential regulatory system of glucose and energy metabolism. However, the underlying mechanisms by which A. muciniphila alleviates the complications of obesity, diabetes and atherosclerosis are unclear. At the same time, its abundance suggests improved metabolic disorders, such as metabolic endotoxemia, adiposity insulin resistance and glucose tolerance. The role of A. muciniphila is implicated in declining aortic lesions and atherosclerosis. Well-characterized virulence factors, antigens and cell wall extracts of A. muciniphila may act as effector molecules in these diseases. These molecules may provide novel mechanisms and strategies by which this bacterium could be used as a probiotic for the treatment of obesity, diabetes and atherosclerosis.

National surveillance of shigellosis in England revealed an increase in sexually transmitted Shigella flexneri in adult males in 2019 that persisted throughout 2020. We observed a resurgence of azithromycin-resistant S. flexneri serotype 3a, and the emergence of two novel multidrug-resistant clades of S. flexneri 2a and S. flexneri 1b.

Dengue is endemic in Brazil, and several Brazilian cities are affected by frequent seasonal outbreaks of the disease. During the outbreaks the possibility of transfusion-transmitted dengue (TTD) is increased, mainly by the presence of asymptomatic or oligosymptomatic infections in eligible blood donors. The retrospective assessment of anti-DENV IgM and NS1 seroprevalence during a given time interval may indicate the need for measures for the previous screening of DENV infection in blood donors. In this context, we performed retrospective screening for anti-DENV IgM and NS1 in blood donors from the Federal District of Brazil during the early outbreak that occurred in 2019, the largest outbreak in recent years. In total, 450 blood donations were screened for anti-DENV IgM and DENV NS1 using commercial enzyme-linked immunosorbent assay kits (Panbio Dengue IgM Capture ELISA and Platelia Dengue NS1 Ag, respectively). Among the tested plasma samples, 16 % (72/450) presented anti-DENV IgM; no samples presented DENV NS1. Despite the apparent absence of antigenaemia in tested blood donations, the high prevalence of anti-DENV IgM highlights the importance of DENV screening in blood donors, principally during outbreak periods.