Browsing by Subject "Antibiotic resistance"

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  • Möller, Vidar; Östholm-Balkhed, Åse; Berild, Dag; Fredriksson, Mats; Gottfredsson, Magnus; Holmbom, Martin; Järvinen, Asko; Kristjansson, Mar; Rydell, Ulf; Sonksen, Ute Wolff; Kolmos, Hans Joern; Hanberger, Håkan (2021)
    Background The Nordic countries have comparable nationwide antibiotic resistance surveillance systems and individual antibiotic stewardship programmes. The aim of this study was to assess antibiotic resistance among major pathogens in relation to practice guidelines for hospital antibiotic treatment and antibiotic use in Nordic countries 2010-2018. Methods Antibiotic resistance among invasive isolates from 2010-2018 and aggregated antibiotic use were obtained from the European Centre for Disease Prevention and Control. Hospital practice guidelines were obtained from national or regional guidelines. Results Antibiotic resistance levels among Escherichia coli and Klebsiella pneumoniae were similar in all Nordic countries in 2018 and low compared to the European mean. Guidelines for acute pyelonephritis varied; 2nd generation cephalosporin (Finland), 3rd generation cephalosporins (Sweden, Norway), ampicillin with an aminoglycoside or aminoglycoside monotherapy (Denmark, Iceland and Norway). Corresponding guidelines for sepsis of unknown origin were 2nd (Finland) or 3rd (Sweden, Norway, Iceland) generation cephalosporins, carbapenems, (Sweden) combinations of penicillin with an aminoglycoside (Norway, Denmark), or piperacillin-tazobactam (all Nordic countries). Methicillin-resistant Staphylococcus aureus rates were 0-2% and empirical treatment with anti-MRSA antibiotics was not recommended in any country. Rates of penicillin non-susceptibility among Streptococcus pneumoniae were low (
  • Rebelo, Andreia; Duarte, Barbara; Ferreira, Carolina; Moura, Joana; Ribeiro, Sofia; Freitas, Ana R.; Coque, Teresa M.; Willems, Rob; Corander, Jukka; Peixe, Luisa; Antunes, Patricia; Novais, Carla (2023)
    Poultry meat has been a vehicle of antibiotic resistant bacteria and genes. Yet, the diversity of selective pressures associated with their maintenance in the poultry-production chain remains poorly explored. We evaluated the susceptibility of Enterococcus spp. from chicken meat collected 20 years apart to antibiotics, metals, acidic pH and peracetic acid-PAA. Contemporary chicken-meat samples (n = 53 batches, each including a pool of neck skin from 10 single carcasses) were collected in a slaughterhouse facility using PAA as disinfectant (March-August 2018, North of Portugal). Broilers were raised in intensive farms (n = 29) using CuSO4 and organic acids as feed additives. Data were compared with that of 67 samples recovered in the same region during 1999-2001. All 2018 samples had multidrug resistant-MDR isolates, with >45 % carrying Enterococcus faecalis, Enterococcus faecium or Enterococcus gallinarum resistant to tetracycline, erythromycin, ampicillin, quinupristin-dalfopristin, ciprofloxa-cin, chloramphenicol or aminoglycosides. Resistance rates were similar (P > 0.05) to those of 1999-2001 samples for all but five antibiotics. The decrease of samples carrying vancomycin-resistant isolates from 46 % to % between 1999-2001 and 2018 was the most striking difference. Isolates from both periods were similarly susceptible to acid pH [minimum-growth pH (4.5-5.0), minimum-survival pH (3.0-4.0)] and to PAA (MIC90 = 100-120 mg/L/MBC90 = 140-160 mg/L; below concentrations used in slaughterhouse). Copper tolerance genes (tcrB and/or cueO) were respectively detected in 21 % and 4 % of 2018 and 1999-2001 samples. The tcrB gene was only detected in E. faecalis (MICCuSO4 > 12 mM), and their genomes were compared with other international ones of chicken origin (PATRIC database), revealing a polyclonal population and a plasmid or chromosomal location for tcrB. The tcrB plasmids shared diverse genetic modules, including multiple antimicrobial resistance genes (e.g. to tetracyclines, chloramphenicol, macrolide-lincosamide-streptogramin B-MLSB, aminoglycosides, bacitracin, coccidiostats). When in chromosome, the tcrB gene was co-located closely to merA (mercury) genes. Chicken meat remains an important vehicle of MDR Enterococcus spp. able to survive under diverse stresses (e.g. copper, acid) potentially contributing to these bacteria maintenance and flux among animal-environment -humans.
  • Lyhs, Ulrike; Ikonen, Ilona; Pohjanvirta, Tarja; Raninen, Kaisa; Perko-Mäkelä, Päivikki; Pelkonen, Sinikka (2012)
    Background: Extraintestinal pathogenic Escherichia coli bacteria (ExPEC) exist as commensals in the human intestines and can infect extraintestinal sites and cause septicemia. The transfer of ExPEC from poultry to humans and the role of poultry meat as a source of ExPEC in human disease have been discussed previously. The aim of the present study was to provide insight into the properties of ExPEC in poultry meat products on the Finnish retail market with special attention to their prevalence, virulence and phylogenetic profiles. Furthermore, the isolates were screened for possible ESBL producers and their resistance to nalidixic acid and ciprofloxacin was tested. Methods: The presence of ExPEC in 219 marinated and non-marinated raw poultry meat products from retail shops has been analyzed. One E. coli strain per product was analyzed further for phylogenetic groups and possession of ten virulence genes associated with ExPEC bacteria (kpsMT K1, ibeA, astA, iss, irp2, papC, iucD, tsh, vat and cva/cv) using PCR methods. The E. coli strains were also screened phenotypically for the production of extended-spectrum β-lactamase (ESBL) and the susceptibility of 48 potential ExPEC isolates for nalidixic acid and ciprofloxacin was tested. Results: E. coli was isolated from 207 (94.5%) of 219 poultry meat products. The most common phylogenetic groups were D (50.7%), A (37.7%), and B2 (7.7%). Based on virulence factor gene PCR, 23.2% of the strains were classified as ExPEC. Two ExPEC strains (1%) belonged to [O1] B2 svg+ (specific for virulent subgroup) group, which has been implicated in multiple forms of ExPEC disease. None of the ExPEC strains was resistant to ciprofloxacin or cephalosporins. One isolate (2.1%) showed resistance to nalidixic acid. Conclusions: Potential ExPEC bacteria were found in 22% of marinated and non-marinated poultry meat products on the Finnish retail market and 0.9% were contaminated with E. coli [O1] B2 svg+ group. Marinades did not have an effect on the survival of ExPEC as strains from marinated and non-marinated meat products were equally often classified as ExPEC. Poultry meat products on the Finnish retail market may have zoonotic potential.
  • Lahtinen, Perttu; Mattila, Eero; Anttila, Veli-Jukka; Tillonen, Jyrki; Teittinen, Matti; Nevalainen, Pasi; Salminen, Seppo; Satokari, Reetta; Arkkila, Perttu (2017)
    Fecal microbiota transplantation (FMT) is effective in recurrent Clostridium difficile infection (rCDI). Knowledge of the safety and efficacy of FMT treatment in immune deficient patients is scarce. FMT has been suggested as a potential method for an increasing number of new indications besides rCDI. Among our FMT-treated rCDI patients, we reviewed those with major comorbidities: two human immunodeficiency virus patients, six haemodialysis patients, two kidney transplant patients, two liver transplant patients and a patient with chronic lymphatic leukaemia. We also reviewed those treated with FMT for indications other than rCDI: Salmonella carriage (two patients), trimethylaminuria (two patients), small intestinal bacterial overgrowth (SIBO; one patient), and lymphocytic colitis (one patient), as well as a common variable immunodeficiency patient with chronic norovirus infection and ESBL-producing Escherichia coli (E. coli) carriage. Of the thirteen rCDI patients treated with FMT, eleven cleared the CDI. The observed adverse events were not directly attributable to FMT. Concerning the special indications, both Salmonellas and ESBL-producing E. coli were eradicated. One trimethylaminuria patient and one SIBO-patient reported a reduction of symptoms. Three patients did not experience a benefit from FMT: chronic norovirus, lymphocytic colitis and the other fish malodour syndrome. There were no reported side effects in this group. FMT appeared to be safe and effective for immunocompromised patients with rCDI. FMT showed promise for the eradication of antibiotic-resistant bacteria, but further research is warranted.
  • Saarinen, Petri (Helsingfors universitet, 2014)
    Enterococci is a group of gram positive bacteria part of human intestinal flora. While generally harmless, several species of the group are known to cause severe infections in humans, including bloodstream infections leading to sepsis. Since Enterococci are naturally resistant to many antibiotics, the use of glycopeptides, considered a”last resort” drugs, is common in treatment of enterococcal infections. In recent years, however, the emergence of glycopeptide resistant Enterococci (GRE) has been an increasing concern for clinics and microbiology laboratories around the world, creating a need for fast and accurate screening tests differentiating the glycopeptide resistant Enterococcus strains from the non-resistant ones. In this study, a combined PCR and microarray hybridization based method for identification of the clinically most prevalent GRE was established as a part of commercial sepsis diagnostic test called Prove-it™ Sepsis. Already identifying the most common Enterococcus species (E.faecium and E.faecalis), the detection of glycopeptide resistance causing ligase genes vanA and vanB and species level identification of intrinsically glycopeptide resistant E.gallinarum and E.casseliflavus were added as part of the the test. Primers were designed for sequencing vanA and vanB genes and multiple strains, provided by a Finnish clinical laboratory Huslab, were sequenced. Sequence regions unique to these genes were identified according to sequence alignment data containing the sequenced gene regions and other relevant sequences found in public sequence databases. Based on these data, primers were designed for the amplification of the selected gene regions. For identification of the amplified gene regions, a set of hybridization probes were designed and printed on microarray. In addition, probes for identifying E.casseliflavus and E.gallinarum were designed based on sequence aligment data gathered from Mobidiag Ltd. private biobank. The identification of these species was based on topoisomerase encoding gyrB gene amplified by the Prove-it™ Sepsis broad range PCR. Several primers for the amplification of vanA and vanB genes were designed and one primer pair for each was selected to be integrated to the Prove-it™ Sepsis multiplex-PCR. Similarily, multiple hybridization probes were designed for detecting vanA, vanB, E.casseliflavus and E. gallinarum. Four probes for each target gene region were selected to be integrated to the commercial test. With this modified test, 12 pure culture samples of clinical origin were tested and the results were compared to the ones provided by the laboratory of clinical microbiology of Hôspital de bicêtre (Paris, France). Results provided by the modified PCR and microarray test were identical to the reference results in 11 out of 12 cases.
  • Koivuniemi, Artturi; Fallarero, Adyary; Bunker, Alex (2019)
    The development of antimicrobial agents that target and selectively disrupt biofilms is a pressing issue since, so far, no antibiotics have been developed that achieve this effectively. Previous experimental work has found a promising set of antibacterial peptides: β2,2-amino acid derivatives, relatively small molecules with common structural elements composed of a polar head group and two non-polar hydrocarbon arms. In order to develop insight into possible mechanisms of action of these novel antibacterial agents, we have performed an in silico investigation of four leading β2,2-amino acid derivatives, interacting with models of both bacterial (target) and eukaryotic (host) membranes, using molecular dynamics simulation with a model with all-atom resolution. We found an unexpected result that could shed light on the mechanism of action of these antimicrobial agents: the molecules assume a conformation where one of the hydrophobic arms is directed downward into the membrane core while the other is directed upwards, out of the membrane and exposed above the position of the membrane headgroups; we dubbed this conformation the “can-can pose”. Intriguingly, the can-can pose was most closely linked to the choice of headgroup. Also, the compound previously found to be most effective against biofilms displayed the strongest extent of this behavior and, additionally, this behavior was more pronounced for this compound in the bacterial than in the eukaryotic membrane. We hypothesize that adopting the can-can pose could possibly disrupt the protective peptidoglycan macronet found on the exterior of the bacterial membrane.
  • Sartelli, Massimo; Labricciosa, Francesco M.; Coccolini, Federico; Coimbra, Raul; Abu-Zidan, Fikri M.; Ansaloni, Luca; Al-Hasan, Majdi N.; Ansari, Shamshul; Barie, Philip S.; Angel Cainzos, Miguel; Ceresoli, Marco; Chiarugi, Massimo; Claridge, Jeffrey A.; Cicuttin, Enrico; Dellinger, Evan Patchen; Fry, Donald E.; Guirao, Xavier; Hardcastle, Timothy Craig; Hecker, Andreas; Leppäniemi, Ari K.; Litvin, Andrey; Marwah, Sanjay; Maseda, Emilio; Mazuski, John E.; Memish, Ziad Ahmed; Kirkpatrick, Andrew W.; Pagani, Leonardo; Podda, Mauro; Rasa, Huseyin Kemal; Sakakushev, Boris E.; Sawyer, Robert G.; Tumietto, Fabio; Xiao, Yonghong; Aboubreeg, Wedad Faraj; Adamou, Harissou; Akhmeteli, Lali; Akin, Emrah; Alberio, Maria Grazia; Alconchel, Felipe; Magagi, Ibrahim Amadou; Arauz, Ana Belen; Argenio, Giulio; Atanasov, Boyko C.; Atici, Semra Demirli; Awad, Selmy Sabry; Baili, Efstratia; Bains, Lovenish; Bala, Miklosh; Baraket, Oussama; Baral, Suman; Belskii, Vladislav A.; Benboubker, Moussa; Ben-Ishay, Offir; Bordoni, Pierpaolo; Boumediene, Abdalia; Brisinda, Giuseppe; Cavazzuti, Laura; Chandy, Sujith J.; Chiarello, Maria Michela; Cillara, Nicola; Clarizia, Guglielmo; Cocuz, Maria-Elena; Cocuz, Iuliu Gabriel; Conti, Luigi; Coppola, Raffaella; Cui, Yunfeng; Czepiel, Jacek; D'Acapito, Fabrizio; Damaskos, Dimitrios; Das, Koray; De Simone, Belinda; Delibegovic, Samir; Demetrashvili, Zaza; Detanac, Dzemail S.; Dhingra, Sameer; Di Bella, Stefano; Dimitrov, Evgeni N.; Dogjani, Agron; D'Oria, Mario; Dumitru, Irina Magdalena; Elmangory, Mutasim M.; Enciu, Octavian; Fantoni, Massimo; Filipescu, Daniela; Fleres, Francesco; Foghetti, Domitilla; Fransvea, Pietro; Gachabayov, Mahir; Galeiras, Rita; Gattuso, Gianni; Ghannam, Wagih M.; Ghisetti, Valeria; Giraudo, Giorgio; Gonfa, Kebebe Bekele; Gonullu, Emre; Hamad, Yousif Tag Elsir Y.; Hecker, Matthias; Isik, Arda; Ismail, Nizar; Ismail, Azzain; Jain, Sumita Agarwal; Kanj, Souha S.; Kapoor, Garima; Karaiskos, Ilias; Kavalakat, Alfie J.; Kenig, Jakub; Khamis, Faryal; Khokha, Vladimir; Kiguba, Ronald; Kim, Jae Il; Kobe, Yoshiro; Kok, Kenneth Yuh Yen; Kovacevic, Bojan M.; Kryvoruchko, Igor Andreevich; Kuriyama, Akira; Landaluce-Olavarria, Aitor; Lasithiotakis, Konstantinos; Lohsiriwat, Varut; Lostoridis, Eftychios; Luppi, Davide; Vega, Gustavo Miguel Machain; Maegele, Marc; Marinis, Athanasios; Martines, Gennaro; Martinez-Perez, Aleix; Massalou, Damien; Mesina, Cristian; Metan, Gokhan; Guadalupe Miranda-Novales, Maria; Mishra, Shyam Kumar; Mohamed, Mohaned Ibrahim Hussein; Mohamedahmed, Ali Yasen Y.; Mora-Guzman, Ismael; Mulita, Francesk; Musina, Ana-Maria; Navsaria, Pradeep H.; Negoi, Ionut; Nita, Gabriela Elisa; O'Connor, Donal B.; Alberto Ordonez, Carlos; Pantalone, Desire; Panyko, Arpad; Papadopoulos, Aristeidis; Pararas, Nikolaos; Pata, Francesco; Patel, Tapan; Pellino, Gianluca; Perra, Teresa; Perrone, Gennaro; Pesce, Antonio; Pintar, Tadeja; Popivanov, Georgi Ivanov; Porcu, Alberto; Quiodettis, Martha Alexa; Rahim, Razrim; Mitul, Ashrarur Rahman; Reichert, Martin; Rems, Miran; Reynolds Campbell, Glendee Yolande; Rocha-Pereira, Nuno; Rodrigues, Gabriel; Roncancio Villamil, Gustavo Eduardo; Rossi, Stefano; Sall, Ibrahima; Kafil, Hossein Samadi; Sasia, Diego; Seni, Jeremiah; Seretis, Charalampos; Serradilla-Martin, Mario; Shelat, Vishal G.; Siribumrungwong, Boonying; Slavchev, Mihail; Solaini, Leonardo; Tan, Boun Kim; Tarasconi, Antonio; Tartaglia, Dario; Toma, Elena Adelina; Tomadze, Gia; Toro, Adriana; Tovani-Palone, Marcos Roberto; van Goor, Harry; Vasilescu, Alin; Vereczkei, Andras; Veroux, Massimiliano; Alberto Weckmann, Sergio; Widmer, Lukas Werner; Yahya, AliIbrahim; Zachariah, Sanoop K.; Zakaria, Andee Dzulkarnaen; Zubareva, Nadezhda; Zuidema, Wietse P.; Di Carlo, Isidoro; Cortese, Francesco; Baiocchi, Gian Luca; Maier, Ronald; Catena, Fausto (2022)
    Background The objectives of the study were to investigate the organizational characteristics of acute care facilities worldwide in preventing and managing infections in surgery; assess participants' perception regarding infection prevention and control (IPC) measures, antibiotic prescribing practices, and source control; describe awareness about the global burden of antimicrobial resistance (AMR) and IPC measures; and determine the role of the Coronavirus Disease 2019 pandemic on said awareness. Methods A cross-sectional web-based survey was conducted contacting 1432 health care workers (HCWs) belonging to a mailing list provided by the Global Alliance for Infections in Surgery. The self-administered questionnaire was developed by a multidisciplinary team. The survey was open from May 22, 2021, and June 22, 2021. Three reminders were sent, after 7, 14, and 21 days. Results Three hundred four respondents from 72 countries returned a questionnaire, with an overall response rate of 21.2%. Respectively, 90.4% and 68.8% of participants stated their hospital had a multidisciplinary IPC team or a multidisciplinary antimicrobial stewardship team. Local protocols for antimicrobial therapy of surgical infections and protocols for surgical antibiotic prophylaxis were present in 76.6% and 90.8% of hospitals, respectively. In 23.4% and 24.0% of hospitals no surveillance systems for surgical site infections and no monitoring systems of used antimicrobials were implemented. Patient and family involvement in IPC management was considered to be slightly or not important in their hospital by the majority of respondents (65.1%). Awareness of the global burden of AMR among HCWs was considered very important or important by 54.6% of participants. The COVID-19 pandemic was considered by 80.3% of respondents as a very important or important factor in raising HCWs awareness of the IPC programs in their hospital. Based on the survey results, the authors developed 15 statements for several questions regarding the prevention and management of infections in surgery. The statements may be the starting point for designing future evidence-based recommendations. Conclusion Adequacy of prevention and management of infections in acute care facilities depends on HCWs behaviours and on the organizational characteristics of acute health care facilities to support best practices and promote behavioural change. Patient involvement in the implementation of IPC is still little considered. A debate on how operationalising a fundamental change to IPC, from being solely the HCWs responsibility to one that involves a collaborative relationship between HCWs and patients, should be opened.
  • Rutgersson, Carolin; Ebmeyer, Stefan; Lassen, Simon Bo; Karkman, Antti; Fick, Jerker; Kristiansson, Erik; Brandt, Kristian K.; Flach, Carl-Fredrik; Larsson, D.G. Joakim (2020)
    The widespread practice of applying sewage sludge to arable land makes use of nutrients indispensable for crops and reduces the need for inorganic fertilizer, however this application also provides a potential route for human exposure to chemical contaminants and microbial pathogens in the sludge. A recent concern is that such practice could promote environmental selection and dissemination of antibiotic resistant bacteria or resistance genes. Understanding the risks of sludge amendment in relation to antibiotic resistance development is important for sustainable agriculture, waste treatment and infectious disease management. To assess such risks, we took advantage of an agricultural field trial in southern Sweden, where land used for growing different crops has been amended with sludge every four years since 1981. We sampled raw, semi-digested and digested and stored sludge together with soils from the experimental plots before and two weeks after the most recent amendment in 2017. Levels of selected antimicrobials and bioavailable metals were determined and microbial effects were evaluated using both culture-independent metagenome sequencing and conventional culturing. Antimicrobials or bioavailable metals (Cu and Zn) did not accumulate to levels of concern for environmental selection of antibiotic resistance, and no coherent signs, neither on short or long time scales, of enrichment of antibiotic-resistant bacteria or resistance genes were found in soils amended with digested and stored sewage sludge in doses up to 12 metric tons per hectare. Likewise, only very few and slight differences in microbial community composition were observed after sludge amendment. Taken together, the current study does not indicate risks of sludge amendment related to antibiotic resistance development under the given conditions. Extrapolations should however be done with care as sludge quality and application practices vary between regions. Hence, the antibiotic concentrations and resistance load of the sludge are likely to be higher in regions with larger antibiotic consumption and resistance burden than Sweden.
  • Cairns, Johannes; Borse, Florian; Mononen, Tommi; Hiltunen, Teppo; Mustonen, Ville (2022)
    The impact of fitness landscape features on evolutionary outcomes has attracted considerable interest in recent decades. However, evolution often occurs under time-dependent selection in so-called fitness seascapes where the landscape is under flux. Fitness seascapes are an inherent feature of natural environments, where the landscape changes owing both to the intrinsic fitness consequences of previous adaptations and extrinsic changes in selected traits caused by new environments. The complexity of such seascapes may curb the predictability of evolution. However, empirical efforts to test this question using a comprehensive set of regimes are lacking. Here, we employed an in vitro microbial model system to investigate differences in evolutionary outcomes between time-invariant and time-dependent environments, including all possible temporal permutations, with three subinhibitory antimicrobials and a viral parasite (phage) as selective agents. Expectedly, time-invariant environments caused stronger directional selection for resistances compared to time-dependent environments. Intriguingly, however, multidrug resistance outcomes in both cases were largely driven by two strong selective agents (rifampicin and phage) out of four agents in total. These agents either caused cross-resistance or obscured the phenotypic effect of other resistance mutations, modulating the evolutionary outcome overall in time-invariant environments and as a function of exposure epoch in time-dependent environments. This suggests that identifying strong selective agents and their pleiotropic effects is critical for predicting evolution in fitness seascapes, with ramifications for evolutionarily informed strategies to mitigate drug resistance evolution.
  • Laaveri, Tinja; Sterne, Jesper; Rombo, Lars; Kantele, Anu (2016)
    Looking at the worldwide emergency of antimicrobial resistance, international travellers appear to have a central role in spreading the bacteria across the globe. Travellers' diarrhoea (TD) is the most common disease encountered by visitors to the (sub) tropics. Both TD and its treatment with antibiotics have proved significant independent risk factors of colonization by resistant intestinal bacteria while travelling. Travellers should therefore be given preventive advice regarding TD and cautioned about taking antibiotics: mild or moderate TD does not require antibiotics. Logical alternatives are medications with effects on gastrointestinal function, such as loperamide. The present review explores literature on loperamide in treating TD. Adhering to manufacturer's dosage recommendations, loperamide offers a safe and effective alternative for relieving mild and moderate symptoms. Moreover, loperamide taken singly does no predispose to contracting MDR bacteria. Most importantly, we found no proof that would show antibiotics to be significantly more effective than loperamide in treating mild/moderate TD. (C) 2016 The Authors. Published by Elsevier Ltd.
  • Chaguza, Chrispin; Cornick, Jennifer E.; Harris, Simon R.; Andam, Cheryl P.; Bricio-Moreno, Laura; Yang, Marie; Yalcin, Feyruz; Ousmane, Sani; Govindpersad, Shanil; Senghore, Madikay; Ebruke, Chinelo; Du Plessis, Mignon; Kiran, Anmol M.; Pluschke, Gerd; Sigauque, Betuel; McGee, Lesley; Klugman, Keith P.; Turner, Paul; Corander, Jukka; Parkhill, Julian; Collard, Jean-Marc; Antonio, Martin; von Gottberg, Anne; Heyderman, Robert S.; French, Neil; Kadioglu, Aras; Hanage, William P.; Everett, Dean B.; Bentley, Stephen D.; PAGe Consortium (2016)
    Background: Pneumococcus kills over one million children annually and over 90 % of these deaths occur in low-income countries especially in Sub-Saharan Africa (SSA) where HIV exacerbates the disease burden. In SSA, serotype 1 pneumococci particularly the endemic ST217 clone, causes majority of the pneumococcal disease burden. To understand the evolution of the virulent ST217 clone, we analysed ST217 whole genomes from isolates sampled from African and Asian countries. Methods: We analysed 226 whole genome sequences from the ST217 lineage sampled from 9 African and 4 Asian countries. We constructed a whole genome alignment and used it for phylogenetic and coalescent analyses. We also screened the genomes to determine presence of antibiotic resistance conferring genes. Results: Population structure analysis grouped the ST217 isolates into five sequence clusters (SCs), which were highly associated with different geographical regions and showed limited intracontinental and intercontinental spread. The SCs showed lower than expected genomic sequence, which suggested strong purifying selection and small population sizes caused by bottlenecks. Recombination rates varied between the SCs but were lower than in other successful clones such as PMEN1. African isolates showed higher prevalence of antibiotic resistance genes than Asian isolates. Interestingly, certain West African isolates harbored a defective chloramphenicol and tetracycline resistance-conferring element (Tn5253) with a deletion in the loci encoding the chloramphenicol resistance gene (cat(pC194)), which caused lower chloramphenicol than tetracycline resistance. Furthermore, certain genes that promote colonisation were absent in the isolates, which may contribute to serotype 1's rarity in carriage and consequently its lower recombination rates. Conclusions: The high phylogeographic diversity of the ST217 clone shows that this clone has been in circulation globally for a long time, which allowed its diversification and adaptation in different geographical regions. Such geographic adaptation reflects local variations in selection pressures in different locales. Further studies will be required to fully understand the biological mechanisms which makes the ST217 clone highly invasive but unable to successfully colonise the human nasopharynx for long durations which results in lower recombination rates.
  • Chaguza, Chrispin; Cornick, Jennifer E; Harris, Simon R; Andam, Cheryl P; Bricio-Moreno, Laura; Yang, Marie; Yalcin, Feyruz; Ousmane, Sani; Govindpersad, Shanil; Senghore, Madikay; Ebruke, Chinelo; Du Plessis, Mignon; Kiran, Anmol M; Pluschke, Gerd; Sigauque, Betuel; McGee, Lesley; Klugman, Keith P; Turner, Paul; Corander, Jukka; Parkhill, Julian; Collard, Jean-Marc; Antonio, Martin; von Gottberg, Anne; Heyderman, Robert S; French, Neil; Kadioglu, Aras; Hanage, William P; Everett, Dean B; Bentley, Stephen D (BioMed Central, 2016)
    Abstract Background Pneumococcus kills over one million children annually and over 90 % of these deaths occur in low-income countries especially in Sub-Saharan Africa (SSA) where HIV exacerbates the disease burden. In SSA, serotype 1 pneumococci particularly the endemic ST217 clone, causes majority of the pneumococcal disease burden. To understand the evolution of the virulent ST217 clone, we analysed ST217 whole genomes from isolates sampled from African and Asian countries. Methods We analysed 226 whole genome sequences from the ST217 lineage sampled from 9 African and 4 Asian countries. We constructed a whole genome alignment and used it for phylogenetic and coalescent analyses. We also screened the genomes to determine presence of antibiotic resistance conferring genes. Results Population structure analysis grouped the ST217 isolates into five sequence clusters (SCs), which were highly associated with different geographical regions and showed limited intracontinental and intercontinental spread. The SCs showed lower than expected genomic sequence, which suggested strong purifying selection and small population sizes caused by bottlenecks. Recombination rates varied between the SCs but were lower than in other successful clones such as PMEN1. African isolates showed higher prevalence of antibiotic resistance genes than Asian isolates. Interestingly, certain West African isolates harbored a defective chloramphenicol and tetracycline resistance-conferring element (Tn5253) with a deletion in the loci encoding the chloramphenicol resistance gene (cat pC194), which caused lower chloramphenicol than tetracycline resistance. Furthermore, certain genes that promote colonisation were absent in the isolates, which may contribute to serotype 1’s rarity in carriage and consequently its lower recombination rates. Conclusions The high phylogeographic diversity of the ST217 clone shows that this clone has been in circulation globally for a long time, which allowed its diversification and adaptation in different geographical regions. Such geographic adaptation reflects local variations in selection pressures in different locales. Further studies will be required to fully understand the biological mechanisms which makes the ST217 clone highly invasive but unable to successfully colonise the human nasopharynx for long durations which results in lower recombination rates.