Epidemiology and emm types among group A streptococcal pharyngitis in Finland: a prospective laboratory-based study.

PURPOSE: Streptococcus pyogenes (mostly termed group A Streptococcus - GAS) is the most important bacterial causative of pharyngitis. However, epidemiology of GAS pharyngitis is not widely established. This study describes GAS pharyngitis cases and emm-type distribution in a prospective study covering over 2 years in two Hospital Districts in Finland. METHODS: A prospective, systematic collection of GAS pharyngitis isolates was conducted between March 2018 and December 2020 in two large Hospital Districts in Finland. Patient characteristics (age, gender) were included if available. All GAS isolates collected were emm typed. RESULTS: Altogether 1320 GAS pharyngitis strains were collected, 904 in the Hospital District 1 (HD1) and 416 in Hospital District 2 (HD2). In HD1, age and gender data were available. Females were overrepresented (58% of all cases). In addition, the age and gender distributions were noted to be significantly different (p < 0.0001) with females having a more uniform distribution until age of 40. emm28 was common among the age group of 20-29-year-olds and emm89 in children under 10 years of age, respectively. In HD1, most of the isolates were collected during winter and autumn months. Significant differences by season in the frequency of emm12, emm89, emm75 and group of "others" were observed. CONCLUSION: Age distribution among GAS pharyngitis cases was significantly different between genders (p < 0.0001). In addition, age group specific and seasonal variations in emm GAS types causing the disease were observed. These findings warrant further investigation, especially for understanding population-based spread of GAS even in more detail.

Presence of Streptococcus pyogenes in the throat in invasive Group A Streptococcal disease: a prospective two-year study in two health districts, Finland.

PURPOSE: Streptococcus pyogenes (Group A Streptococcus, GAS) is an important human pathogen that can cause severe invasive (iGAS) infections. Throat carriage has been assumed to possibly lead to hematogenous seeding. Retrospective studies may estimate the incidence of throat carriage in iGAS patients inaccurately. In this study we aimed to gather data on the presence of GAS in the throat among iGAS patients in a prospective setting. METHODS: We conducted a prospective clinical study covering iGAS infections in adult patients in two university hospitals in Finland from June 2018 to July 2020. Recruited patients' throats were swabbed for culture and isothermal amplification tests (IAT) to search for GAS. The study was registered at ClinicalTrials.gov as ID NCT03507101. RESULTS: We enrolled 45 patients. Throat swabs were obtained from 39/45 (87%) patients. Ten patients (22%) had a positive IAT for GAS. They were statistically significantly more likely to be male (9/10 [90%] vs 13/29 [45%], p = .024). Several different emm types caused the iGAS infections. CONCLUSIONS: GAS was frequently observed in throat swabs of patients with iGAS infection. This may suggest that hematogenous seeding from the nasopharynx is a possible portal of entry.

Low rate of asymptomatic carriage and salivary immunoglobulin A response to Group A Streptococci in the healthy adult population in Finland.

Streptococcus pyogenes, also called group A streptococcus (GAS), is a human pathogen causing a wide range of infections ranging from mild tonsillitis to severe, life threatening conditions such as bacteraemia, necrotizing fasciitis, and streptococcal toxic shock syndrome. GAS may also colonise the oropharynx without causing any signs of disease which is known as asymptomatic carriage. This study aims to investigate IgA responses against GAS and oral streptococci from saliva samples collected from healthy Finnish adults. In addition, asymptomatic throat GAS carriage was studied. The study participants consisted of healthy adult volunteers who provided one saliva sample, a throat swab, and a background questionnaire. Total salivary IgA, and GAS specific IgA were analysed from the saliva samples using enzyme-linked immunosorbent assays (ELISA) and the results were compared to oral streptococci specific IgA levels. Asymptomatic GAS throat carriers were identified by bacterial culture, and the isolates were emm typed. Samples from a total of 182 individuals were analysed. The median salivary IgA concentration was 62.9 µg/ml (range 17.3-649.9 µg/ml), and median GAS and oral streptococcal specific IgA concentrations 2.7 and 3.3 arbitrary units (AU, range 1.4-7.4 AU and 1.6-12.0 AU), respectively. Three individuals with asymptomatic GAS throat carriage were identified.

Performance of the Check-Direct ESBL Screen for BD MAXTM for detection of asymptomatic faecal carriage of extended-spectrum ß-lactamase (ESBL)-producing Escherichia coli and Klebsiella pneumoniae.

OBJECTIVES: Accurte diagnostic methods are crucial for the detection of extended-spectrum ß-lactamase-producing Enterobacterales (ESBL-E). Besides culture-based gold-standard methods, new molecular gene detection tests are reaching the market. The aim of this study was to investigate the performance of the direct quantitative PCR (qPCR)-based methods Check-Direct ESBL and CPE Screen for BD MAXTM in relation to traditional culture-based methods for detection of ESBL-E faecal carriage. METHODS: Faecal samples were collected from healthy adult volunteers. Samples were cultured on chromogenic ESBL agar plates and were screened for ESBL-producing Escherichia coli and Klebsiella pneumoniae. Confirmed ESBL- and AmpC-producing isolates were further analysed using whole-genome sequencing. In addition, faecal samples were analysed using Check-Direct ESBL and CPE Screen for BD MAXTM and the results were compared with the gold-standard culture-based method. RESULTS: Of 176 faecal samples examined, 11 (6.3%) grew ESBL-producing E. coli or K. pneumoniae isolates. Among 173 analysed samples, Check-Direct ESBL Screen for BD MAXTM detected 22 (12.7%) ESBL-positive samples. No carbapenemase-producing isolates were detected. Two culture-positive samples remained negative with Check-Direct ESBL Screen for BD MAXTM. Culture-negative but qPCR-positive discrepancy was observed in 12 samples (6.9%). Altogether, concordant results were obtained for 158 samples (91.3%; 9 positive and 149 negative). CONCLUSION: Check-Direct ESBL Screen for BD MAXTM is a fast screening method for ESBL carriage. However, several discrepant results were observed, which hinders interpretation. More clinical samples should be tested in combination with culture to evaluate the true benefits of this method.

The first human report of mobile colistin resistance gene, mcr-1, in Finland.

Colistin resistance mediated by mobile mcr-1 gene has raised concern during the last years. After steep increase in mcr-1 reports, other mcr-gene variants (mcr-2 to mcr-5) have been revealed as well. In 2016, a clinical study was conducted on asymptomatic stool carriage of extended spectrum beta-lactamase (ESBL) producing Escherichia coli and Klebsiella pneumoniae among Finnish adults. All suspected ESBL producing bacterial isolates were first tested by phenotypic ESBL-confirmation methods, and then further analyzed with whole genome sequencing to identify the resistance genes. We found one study subject carrying a colistin resistant E. coli with a transferrable mcr-1 gene. This multi-drug resistant isolate, although initially suspected to be an ESBL producer, did not carry any ESBL genes, but was proven to carry several other resistance genes by using whole genome sequencing. Sequence type was ST93. The mcr-1 gene was connected to IncX4 plasmid which suggests that the colistin resistance gene locates in the respective plasmid. Here, we report the finding of a mcr-1 harboring human E. coli isolate from Finland. Clinical antimicrobial resistance (AMR) rates are low in Finland, and mobile colistin resistance has not been reported previously. This highlights the importance of AMR surveillance also in populations with low levels of resistance.

Antimicrobial susceptibility testing of Finnish Bordetella pertussis isolates collected during 2006-2017.

OBJECTIVES: Macrolides, such as azithromycin and erythromycin, are first-line drugs for the (prophylactic) treatment of pertussis. This study aimed to screen for macrolide-, quinolone- or trimethoprim/sulfamethoxazole (SXT)-resistant strains among Finnish Bordetella pertussis isolates. METHODS: Antimicrobial susceptibility testing was performed on 148 B. pertussis strains isolated during 2006-2017. Isolates were analysed by allele-specific PCR for detection of the macrolide resistance-associated mutation A2047G in the 23S rRNA gene. The gyrA gene was sequenced for detection of the A260G mutation associated with quinolone resistance. For phenotyping, a random selection was made by selecting every third isolate (n=50) to determine the minimum inhibitory concentrations (MICs) for erythromycin and azithromycin by Etest and the inhibition zone size for nalidixic acid (NAL) and SXT by single disk diffusion assay. RESULTS: Neither the macrolide resistance-associated mutation A2047G nor the quinolone resistance-associated mutation A260G was detected in any of the B. pertussis isolates. MICs of azithromycin and erythromycin ranged between 0.016-0.19µg/mL and 0.016-0.25µg/mL, respectively. The size of the inhibition zone surrounding the NAL disk ranged between 22-27mm in diameter. The inhibition zone surrounding the SXT disk ranged between 24-37mm in diameter. No isolates resistant to any of the tested antimicrobials were identified. CONCLUSIONS: The allele-specific PCR is a simple and useful tool for screening B. pertussis resistance to macrolides. All Finnish isolates tested were susceptible to macrolides, quinolones and SXT.