- Volume 69, Issue 7, 2020

Introduction. Diarrhoeagenic Escherichia coli (DEC) are difficult to distinguish from non-pathogenic commensal E. coli using traditional culture methods. The implementation of PCR targeting specific virulence genes characteristic of the five DEC pathotypes, has improved the detection of DEC in faecal specimens from patients with symptoms of gastrointestinal disease.

Aim. Antimicrobial resistance (AMR) profiles of 660 strains of DEC isolated between 2015 and 2017 from UK travellers reporting symptoms of gastrointestinal disease were reviewed to look for evidence of emerging AMR associated with travellers’ diarrhoea.

Methodology. All isolates of DEC were sequenced, and sequence type, serotype, pathotype markers and AMR profiles were derived from the genome data.

Results. A travel history was provided for 54.1 % (357/660) of cases, of which 77.0 % (275/357) reported travel outside the UK within 7 days of onset of symptoms, and 23.0 % (82/357) reported no travel in that time frame. Of the 660 strains of DEC in this study, 265 (40.2 %) samples were identified as EAEC, 48 (7.3 %) as EIEC, 61 (9.2 %) were ETEC and 286 (43.3 %) were EPEC. EPEC caused the highest percentage of infections in children (40.6 %) whilst the highest proportion of cases reporting recent travel were infected with ETEC (86.1 %). There were 390/660 (59.0 %) isolates resistant to at least one antimicrobial on the panel tested (EIEC, 81.3 %; ETEC, n=65.6 %; EAEC, n=73.2 %; EPEC, 40.9 %) and 265/660 (40.2 %) were multidrug-resistant (EIEC, 33.3 %; ETEC, 32.8 %; EAEC, 56.2 %; EPEC, 28.0 %). Genes conferring resistance to the beta-lactams and fluroquinolones were highest in the EAEC pathotype, 56.6 and 60.7%, respectively.

Conclusions. Increasing MDR, along with resistance to the fluroquinolones and the third-generation cephalosporins, in DEC causing travellers’ diarrhoea provides further evidence for the need to restrict the use of antimicrobial agents and continuous monitoring.

Introduction. Increasing evidence demonstrates unfavourable outcomes in bloodstream infections (BSI) due to the carbapenem-resistant Acinetobacter baumannii complex (CRAB).

Aim. To investigate the differences in risk factors, clinical characteristics and outcomes in patients with A. baumannii complex BSI stratified by carbapenem resistance, a prospective multi-center study was conducted.

Methodology. Information was collected in a predefined form. A total of 317 cases was included for comparison between CRAB BSI vs. carbapenem-susceptible A. baumannii complex (CSAB) BSI. Among these cases, 229 cases were defined as CRAB BSI and 88 cases as CSAB BSI.

Results. Univariable analysis showed that male gender, underlying neurologic disease, prior carbapenems exposure, intensive care unit (ICU) stay, presence of central venous catheter, endotracheal intubation, tracheotomy, Foley catheter, nasogastric intubation, lower respiratory tract infections and catheter-related infections were more prevalent in CRAB BSI. Only male gender, prior carbapenems exposure and presence of endotracheal intubation persisted as independent risk factors for acquiring CRAB BSI. Patients with CRAB BSI displayed unfavourable outcomes characterized by failure of pathogen clearance, continuous fever, disease aggravation and higher incidence of 30-day all-cause mortality. Multivariate analysis demonstrated carbapenem resistance as an independent risk factor for 30-day all-cause mortality.

Conclusion. Our findings reveal the epidemiological differences between CRAB BSI and CSAB BSI in a Chinese cohort. Our data suggest that carbapenem resistance has a significant impact on mortality for patients with A. baumannii complex BSI, further strengthening the importance of active prevention and control strategies for the spread of CRAB in Chinese hospitals.

Introduction. Pneumonia is highly prevalent in intensive care units (ICUs), with high associated mortality. Empirical treatment prioritizes breadth of coverage while awaiting laboratory diagnosis, often at the expense of antimicrobial stewardship. Microarrays use multiple parallel polymerase chain reactions to enable a rapid syndromic approach to laboratory diagnosis.

Aim. To evaluate the clinical and laboratory implications of introducing a bespoke 22-pathogen TaqMan Array Card (TAC) for rapid pathogen detection in deep respiratory samples from adult ICUs.

Methodology. TAC results from all ICU patients prospectively tested over a 9-month period at Cambridge’s Clinical Microbiology and Public Health Laboratory were compared to those of corresponding conventional microbiological assays (culture-, PCR- or serology-based) in terms of result agreement and time-to-result availability. Clinical impact was assessed by retrospective review of medical records.

Results. Seventy-one patients were included [45 (63 %) male, median age 59). Overall result agreement was 94 %, with TAC detecting more pathogens than conventional methods. TAC detected Streptococcus pneumoniae more readily than culture (7 vs 0 cases; P=0.02). TAC did not detect Aspergillus spp. in eight culture- or galactomannan-positive cases. The median turnaround time (1 day) was significantly shorter than that of bacterial/fungal culture, Pneumocystis jirovecii PCR and galactomannan testing (each 3 days; P<0.001), atypical bacteria serology (13 days; P<0.001) and Mycobacterium tuberculosis culture (46 days; P<0.001). Earlier result availability prompted discontinuation of unnecessary antimicrobials in 15/71 (21 %) cases, but had no bearing on patient isolation/deisolation.

Conclusion. TAC provided greater overall yield of pathogen detection and faster turnaround times, permitting earlier discontinuation of unnecessary antimicrobials.

Introduction. Childhood tuberculosis meningitis is a severe form of tuberculosis with high morbidity and mortality. The diagnosis is frequently missed and delayed due to lack of sensitive tests like acid-fast bacilli (AFB) smear and delayed results by culture.

Aims. To compare the role of IS6110 and protein antigen b PCR in cerebrospinal fluid (CSF) for rapid diagnosis of tuberculous meningitis (TBM) in children.

Methodology. Forty-five cases of TBM and 20 controls were enrolled in this prospective study.

Results. The mean ages of cases and controls were 4.2±0.5 years and 4.5±0.7 years, respectively. In the TBM group, two-thirds of the children were <4 years of age, and 62 % were males. Sensitivities of AFB smear examination, Löwenstein–Jensen (LJ) medium and bactenecin (BACTEC) culture in cases were 4.4, 0 and 2.2%, respectively. The protein antigen b PCR was most sensitive as it was positive in 35 (77.8 %) of TBM patients; IS6110 PCR was positive in 27 (60 %) patients. Both PCR-based tests had higher positivity than conventional tests and BACTEC culture. No significant difference was seen between the PCR tests. Excellent agreement was observed between both PCR-based tests as they were concordant for 26 positive samples and 35 negative samples.

Conclusion. Protein b PCR is a sensitive and rapid method for the diagnosis of TBM (sensitivity 77.8 %). Both PCRs were more sensitive than smear, LJ and BACTEC. The specificity of both PCR was 100 %.

Introduction. Bacillus cereus harbouring Ba813, a specific chromosomal marker of Bacillus anthtacis, is found in patients with severe manifestations and causes nosocomial outbreaks.

Aim. We assessed the genetic characteristics and virulence of Ba813(+) B. cereus in a hospital setting.

Methodology. Three neutropenic patients with haematological malignancy developed B. cereus bacteraemia within a short period. Fifteen B. cereus were isolated from different sites in a haematology ward. A total of 18 isolates were evaluated for Ba813- and B. anthracis -related virulence, food poisoning-related virulence, genetic diversity, bacteria motility and biofilm formation.

Results. Ba813(+) B. cereus was detected in 33 % (1/3) of patients and 66 % (9/15) of the hospital environment. The 18 strains were divided into 2 major clusters (clade 1 and clade 2), and 14 strains were classified into clade 1. All Ba813(+) strains, including four sequence types, were classified into clade 1/the cereus III lineage, which is most closely related to the anthracis lineage. Two strains belonging to clade 1/non-cereus III carried the B. anthracis -associated cap gene, but not Ba813. B. cereus, including Ba813(+) strains, had significantly lower prevalence of enterotoxin genes than clade 2 strains. In clade 1, B. cereus , Ba813(+) strains showed significantly higher swimming motility and biofilm formation ability than Ba813(−) strains.

Conclusion. Ba813(+) B. cereus , which are genetically closely related to B. anthracis , were abundant in a haematological ward. Ba813(+) B. cereus with high motility and biofilm formation abilities may spread easily in hospital environments, and could become a hospital-acquired infection.

Introduction. Globally, human bocavirus (HBoV) has been detected in respiratory samples from patients suffering from upper and lower respiratory diseases. In Kuwait, little is known about the epidemiological and clinical characterization of the virus and genetic characterization of the virus as a respiratory pathogen is unknown.

Aim. This study aims to explore the molecular epidemiology and clinical features of HBoV isolates in patients with respiratory diseases.

Methodology. Retrospectively, between 2018 and 2020, 5941 respiratory samples from patients with respiratory diseases were screened for respiratory viruses using multiplex real-time PCR. Samples that were positive for HBoV were then subjected to NP1 and VP1/PV2 phylogenetic analysis.

Results. HBoV was detected in 1.9 % of the patients, with a peak incidence of infection among children <1 year old. Co-infection with other respiratory viruses was observed in 56.8 % of HBoV-positive patients. Fever, cough and respiratory distress were the most common clinical features of HBoV infection. Phylogenetic analysis of the Kuwaiti HBoV isolates revealed that all the isolates were of the HBoV-1 genotype, with slight sequence variations among the isolates.

Conclusion. This study illustrated the predominance of the HBoV-1 genotype in patients with respiratory diseases in Kuwait with minimal genetic variability. It also highlighted the clinical features of HBoV-1 infection, verifying its role in respiratory diseases.

Introduction. Multidrug-resistant tuberculosis (MDR-TB) is a major public health problem globally, including in Indonesia. Whole-genome sequencing (WGS) analysis has rarely been used for the study of TB and MDR-TB in Indonesia.

Aim. We evaluated the use of WGS for drug-susceptibility testing (DST) and to investigate the population structure of drug-resistant Mycobacterium tuberculosis in Java, Indonesia.

Methodology. Thirty suspected MDR-TB isolates were subjected to MGIT 960 system (MGIT)-based DST and to WGS. Phylogenetic analysis was done using the WGS data. Results obtained using MGIT-based DST and WGS-based DST were compared.

Results. Agreement between WGS and MGIT was 93.33 % for rifampicin, 83.33 % for isoniazid and 76.67 % for streptomycin but only 63.33 % for ethambutol. Moderate WGS–MGIT agreement was found for second-line drugs including amikacin, kanamycin and fluoroquinolone (73.33–76.67 %). MDR-TB was more common in isolates of the East Asian Lineage (63.3%). No evidence of clonal transmission of DR-TB was found among members of the tested population.

Conclusion. Our study demonstrated the applicability of WGS for DST and molecular epidemiology of DR-TB in Java, Indonesia. We found no transmission of DR-TB in Indonesia.