Genomic epidemiology of Staphylococcus aureus isolated from bloodstream infections in South America during 2019 supports regional surveillance.

Staphylococcus aureus remains one of the leading causes of infections worldwide and a common cause of bacteraemia. However, studies documenting the epidemiology of S. aureus in South America using genomics are scarce. We hereby report on the largest genomic epidemiology study to date of both methicillin-resistant S. aureus (MRSA) and methicillin-susceptible S. aureus (MSSA) in South America, conducted by the StaphNET-SA network. We characterised 404 genomes recovered from a prospective observational study of S. aureus bacteraemia in 58 hospitals from Argentina, Bolivia, Brazil, Paraguay and Uruguay between April and October 2019. We show that a minority of S. aureus isolates are phenotypically multi-drug resistant (5.2%), but more than a quarter are resistant to macrolide-lincosamide-streptogramin B (MLSb). MSSA were more genetically diverse than MRSA. Lower rates of associated antimicrobial resistance in community-associated(CA)-MRSA versus hospital-associated (HA)-MRSA were found in association with three S. aureus genotypes dominating the MRSA population: CC30-MRSA-IVc-t019-lukS/F-PV+, CC5-MRSA-IV-t002-lukS/F-PV- and CC8-MRSA-IVc-t008-lukS/F-PV+-COMER+. These are historically from a CA origin, carry on average fewer antimicrobial resistance determinants, and often lack key virulence genes. Surprisingly, CC398-MSSA-t1451-lukS/F-PV- related to the CC398 human-associated lineage is widely disseminated throughout the region, and is described here for the first time as the most prevalent MSSA lineage in South America. Moreover, CC398 strains carrying ermT (largely responsible for the MLSb resistance rates of MSSA strains: inducible iMLSb phenotype) and sh_fabI (related to triclosan resistance) were recovered from both CA and HA origin. The frequency of MRSA and MSSA lineages differed between countries but the most prevalent S. aureus genotypes are high-risk clones widely distributed in the South American region without a clear country-specific phylogeographical structure. Therefore, our findings underline the need for continuous genomic surveillance by regional networks such as StaphNET-SA. This article contains data hosted by Microreact.

Characterization of Streptococcus equi subsp. zooepidemicus isolates containing lnuB gene responsible for the L phenotype.

Within the framework of the ß-hemolytic streptococci surveillance carried out by the National Reference Laboratory from Uruguay, three putative Streptococcus equi subsp. zooepidemicus (SEZ) were received from different health centers. Being these the first reports associated with human infections in Uruguay, the objective of this work was to confirm their identification, to determine their genetic relationship and to study their antibiotic susceptibility. Using four different methods, they were identified as SEZ, a subspecies which has been described as the etiologic agent of rare and severe zoonosis in a few cases in other countries. The three isolates presented different pulsotypes by PFGE; however, two of them appeared to be related and were confirmed as ST431 by MLST, while the remaining isolate displayed ST72. Their resistance profile exhibited an unexpected feature: despite all of them were susceptible to macrolides, they showed different levels of resistance to clindamycin, i.e. they had the so-called "L phenotype". This rare trait is known to be due to a nucleotidyl-transferase, encoded by genes of the lnu family. Although this phenotype was previously described in a few SEZ isolates, its genetic basis has not been studied yet. This was now analyzed by PCR in the three isolates and they were found to contain a lnuB gene. The lnuB sequence was identical among the three isolates and with many lnuB sequences deposited in data banks. In conclusion, for the first time in Uruguay, three SEZ isolates recovered from non-epidemiologically related cases of human invasive infection were identified. Moreover, this is the first report about the presence of a lnu gene in the S. equi species, revealing the active lateral spread of the lnuB in a new streptococcal host.

The direct effect of pneumococcal conjugate vaccines on invasive pneumococcal disease in children in the Latin American and Caribbean region (SIREVA 2006-17): a multicentre, retrospective observational study.

BACKGROUND: Streptococcus pneumoniae isolated from patients with invasive pneumococcal disease has been subjected to laboratory-based surveillance in Latin American and Caribbean countries since 1993. Invasive pneumococcal diseases remain a major cause of death and disability worldwide, particularly in children. We therefore aimed to assess the direct effect of pneumococcal conjugate vaccines (PCVs) on the distribution of pneumococcal serotypes causing invasive pneumococcal disease in children younger than 5 years before and after PCV introduction. METHODS: We did a multicentre, retrospective observational study in eight countries that had introduced PCV (ie, PCV countries) in the Latin American and Caribbean region: Argentina, Brazil, Chile, Colombia, Dominican Republic, Mexico, Paraguay, and Uruguay. Cuba and Venezuela were also included as non-PCV countries. Isolate data for Streptococcus pneumoniae were obtained between 2006 and 2017 from children younger than 5 years with an invasive pneumococcal disease from local laboratories or hospitals. Species' confirmation and capsular serotyping were done by the respective national reference laboratories. Databases from the Sistema Regional de Vacunas (SIREVA) participating countries were managed and cleaned in a unified database using Microsoft Excel 2016 and the program R (version 3.6.1). Analysis involved percentage change in vaccine serotypes between pre-PCV and post-PCV periods and the annual reporting rate of invasive pneumococcal diseases per 100 000 children younger than 5 years, which was used as a population reference to calculate percentage vaccine type reduction. FINDINGS: Between 2006 and 2017, 12 269 isolates of invasive pneumococcal disease were collected from children younger than 5 years in the ten Latin American and Caribbean countries. The ten serotypes included in ten-valent pneumococcal conjugate vaccine (PCV10) decreased significantly (p<0·0001) after any PCV introduction, except for the Dominican Republic. The percentage change for the ten vaccine serotypes in PCV10 countries was -91·6% in Brazil (530 [72·9%] of 727 before, 27 [6·1%] of 441 after); -85·0% in Chile (613 [72·6%] of 844 before, 44 [10·9%] of 404] after); -84·7% in Colombia (231 [63·1%] of 366 before, 34 [9·7%] of 352 after); and -73·8% in Paraguay (127 [77·0%] of 165 before, 22 [20·2%] of 109 after). In the 13-valent pneumococcal conjugate vaccine (PCV13) countries, the percentage change for the 13 vaccine serotypes was -59·6% in Argentina (853 [85·0%] of 1003 before, 149 [34·3%] of 434 after); -16·5% in the Dominican Republic (95 [80·5%] of 118 before, 39 [67·2%] of 58 after); -43·7% in Mexico (202 [73·2%] of 276 before, 63 [41·2%] of 153 after); and -45·9% in Uruguay (138 [80·7%] of 171 before, 38 [43·7%] of 87 after). Annual reporting rates showed a reduction from -82·5% (6·21 before vs 1·09 after per 100 000, 95% CI -61·6 to -92·0) to -94·7% (1·15 vs 0·06 per 100 000, -89·7 to -97·3) for PCV10 countries, and -58·8% (2·98 vs 1·23 per 100 000, -21·4 to -78·4) to -82·9% (7·80 vs 1·33 per 100 000, -76·9 to -87·4) for PCV13 countries. An increase in the amount of non-vaccine types was observed in the eight countries after PCV introduction together with an increase in their percentage in relation to total invasive strains in the post-PCV period. INTERPRETATION: SIREVA laboratory surveillance was able to confirm the effect of PCV vaccine on serotypes causing invasive pneumococcal disease in the eight PCV countries. Improved monitoring of the effect and trends in vaccine type as well as in non-vaccine type isolates is needed, as this information will be relevant for future decisions associated with new PCVs. FUNDING: None. TRANSLATIONS: For the Portuguese and Spanish translations of the abstract see Supplementary Materials section.

Tracing Back the Evolutionary Route of Enteroinvasive Escherichia coli (EIEC) and Shigella Through the Example of the Highly Pathogenic O96:H19 EIEC Clone.

Enteroinvasive Escherichia coli (EIEC) cause intestinal illness through the same pathogenic mechanism used by Shigella spp. The latter species can be typed through genomic and phenotypic methods used for E. coli and have been proposed for reclassification within E. coli species. Recently the first appearance of a highly pathogenic EIEC O96:H19 was described in Europe as the causative agent of two large outbreaks that occurred in Italy and in the United Kingdom. In contrast to Shigella spp and to the majority of EIEC strains, EIEC O96:H19 fermented lactose, lacked pathoadaptive mutations, and showed good fitness in extracellular environment, similarly to non-pathogenic E. coli, suggesting they have emerged following acquisition of the invasion plasmid by a non-pathogenic E. coli. Here we describe the whole genome comparison of two EIEC O96:H19 strains isolated from severe cases of diarrhea in Uruguay in 2014 with the sequences of EIEC O96:H19 available in the public domain. The phylogenetic comparison grouped all the O96:H19 strains in a single cluster, while reference EIEC strains branched into different clades with Shigella strains occupying apical positions. The comparison of the virulence plasmids showed the presence of a complete conjugation region in at least one O96:H19 EIEC. Reverse Transcriptase Real Time PCR experiments confirmed in this strain the expression of the pilin-encoding gene and conjugation experiments suggested its ability to mobilize an accessory plasmid in a recipient strain. Noteworthy, the tra region was comprised between two reversely oriented IS600 elements, which were also found as remnants in another EIEC O96:H19 plasmid lacking the tra locus. We hypothesize that an IS-mediated recombination mechanism may have caused the loss of the conjugation region commonly observed in EIEC and Shigella virulence plasmids. The results of this study support the hypothesis of EIEC originating from non-pathogenic E. coli through the acquisition of the virulence plasmid via conjugation. Remarkably, this study showed the ability of a circulating EIEC strain to mobilize plasmids through conjugation, suggesting a mechanism for the emergence of novel EIEC clones.

Presence of genes encoding enterotoxins in Staphylococcus aureus isolates recovered from food, food establishment surfaces and cases of foodborne diseases.

The aim of this study was to describe the microbiological characteristics and profile of genes encoding enterotoxins in 95 Staphylococcus aureus isolates obtained between April 2011 and December 2014 from foodstuffs, persons and surfaces of retail food stores. After microbiological identification and antimicrobial susceptibility testing, polymerase chain reactions (PCR) were performed, targeting sea, seb, sec, sed and see genes that code for classical enterotoxins (ET) A-E, and three additional genes: seg , seh and sei , coding for so-called "new enterotoxins" G, H and I. The isolates were characterized by Pulsed Field Gel Electrophoresis (PFGE), and five selected isolates were further analyzed through Multi Locus Sequence Typing (MLST). It is noteworthy that 54.7% of the examined isolates harbored one or more of the investigated ET gene types. Most positive isolates carried more than one ET gene up to five types; seg was the most frequent ET gene, followed by sei. Five enterotoxin-coding isolates also coded for some antimicrobial resistance genes. Two of them, and four additional non-enterotoxic isolates carried erm genes expressing inducible clindamycin resistance. PFGE-types were numerous and diverse, even among enterotoxin-coding strains, because most isolates did not belong to known foodborne outbreaks and the sampling period was long. MLST profiles were also varied, and a new ST 3840 was described within this species. ST 88 and ST 72 enterotoxin-coding isolates have been identified in other regions in association with foodborne outbreaks. This manuscript reports the first systematic investigation of enterotoxin genes in S. aureus isolates obtained from foodstuffs and infected people in Uruguay.

Colonización nasofaríngea por serotipos de Streptococcus pneumoniae en niños uruguayos antes y después de la introducción de las vacunas antineumocóccicas conjugadas / Nasopharyngeal colonization from Streptococcus pneumoniae serotypes in Uruguayan children before and after pneumococcal conjugate vaccines / Colonização nasofaríngea por sorotipos de Streptococcus pneumoniae em crianças uruguaias antes e após da introdução de vacinas pneumocócicas conjugadas

Resumen: Las vacunas conjugadas neumocóccicas (VCN) son efectivas para el control de las infecciones severas en niños y también limitan la colonización nasofaríngea por los serotipos que integran sus fórmulas. En Uruguay, no se dispone de publicaciones recientes sobre los serotipos albergados en el reservorio nasofaríngeo de los niños, ni antes ni luego de la introducción de las VCN. Con el objetivo de caracterizar la colonización nasofaríngea de niños menores de 2 años y describir los serotipos de S. pneumoniae identificados antes y después de la introducción de las vacunas conjugadas antineumocóccicas en el certificado esquema de vacunación (CEV) de Uruguay, se llevó a cabo un estudio descriptivo, retrospectivo, incluyendo tres períodos de tiempo: años 2002- 2003 y 2014-2015 en Paysandú, y 2012-2013 en Montevideo. Los aislamientos de S. pneumoniae se realizaron en laboratorios locales y la serotipificación por "quellung" se efectuó en el Departamento de Laboratorios de Salud Pública. Se procesaron 831 muestras, con 54,8% de recuperación de neumococos (n=456), de los cuales 223 fueron tipificados. El estudio previo a la vacunación mostró portación de serotipos invasores, con predominio de los serotipos 6A, 6B, 14 y 19F, todos incluidos en la vacuna 13-valente. En los niños de la policlínica de HIV, la colonización por neumococos invasores fue mucho menor, y el otro estudio, también posvacunación, evidenció la casi desaparición de cepas invasoras (6/93), con predominio de serotipos poco habituales, lo que constituyó un llamado de atención para instrumentar una vigilancia que monitorice la dinámica de la colonización infantil.

Summary: Pneumococcal conjugate vaccines (PCV) are effective against children's severe infections and they also constrain nasopharyngeal colonization due to the serotypes in their formulas. There are no recent publications in Uruguay regarding serotypes hosted in the children's nasopharyngeal reservoir, either from before or after the introduction of the PCV. With the purpose of characterizing nasopharyngeal colonization of children under 2 years of age and describing the S. pneumoniae serotypes before and after the pneumococcal conjugate vaccines in the Uruguayan National Vaccination Report, we carried out a descriptive retrospective study including three periods: 2002- 2003 and 2014-2015 in Paysandú, and 2012-2013 in Montevideo. S. pneumoniae was isolated in local laboratories and the "quellung" serotypification was carried out in the Laboratories of the Public Health Department. We processed 831 samples and recovered 54.8% pneumococci (n=456), of which 223 were typified. Prior to the vaccination, the study showed invasive serotype carriage, mainly of the 6A, 6B, 14 and 19F serotypes, all included in the 13-valent vaccine. At the HIV clinic, colonization from invasive pneumococci was much lower and the post vaccination study showed the almost complete disappearance of the invasive strains (6/93), mainly of the less common serotypes, which called the attention towards the increase of vigilance towards the monitoring of children colonization dynamics.

Resumo: As Vacinas Pneumocócicas Conjugadas (VPC) são eficazes contra infecções graves em crianças e também restringem a colonização nasofaríngea, devido aos sorotipos utilizados em suas fórmulas. Não há publicações recentes no Uruguai relativas aos sorotipos que incluem reservatório nasofaringeos nas crianças, nem de antes ou depois das vacinas VPN. Com o objetivo de caracterizar a colonização nasofaríngea de crianças menores de 2 anos de idade e descrevendo os sorotipos S. pneumoniae antes e depois das vacinas antipneumocócicas conjugadas no Relatório Nacional de Vacinação do Uruguai, realizou-se um estudo retrospectivo descritivo, incluindo três períodos: 2002- 2003 e 2014-2015 em Paysandú e 2012-2013 em Montevideo. S. pneumoniae foi isolada em laboratórios locais e a soro tipificação "quellung" foi realizada nos Laboratórios do Departamento de Saúde Pública. Foram processadas 831 amostras e recuperado 54,8% de pneumococo (n = 456), dos quais 223 foram tipificados. Antes da vacinação, o estudo mostrou transporte de sorotipos invasores, principalmente dos sorotipos 6A, 6B, 14, 19F, todos incluídos na vacina 13-valente. Na clínica de HIV, a colonização invasiva de pneumococos foi muito menor, e o estudo pós-vacinação mostrou o desaparecimento quase total das cepas invasivas (6/93), principalmente dos sorotipos menos comuns, o que sugere a necessidade de aumentar a vigilância no monitoramento da dinâmica de colonização de crianças.

Alarma por la resistencia a antimicrobianos: situación actual y desafíos / Antimicrobial resistance alarm: current situation and challenges

La creciente resistencia a los antimicrobianos (RAM) es un problema apremiante que de no combatirse a tiempo puede comprometer la salud de las generaciones futuras, con un retorno a la era preantibiótica. Frente a esa amenaza, los organismos sanitarios internacionales convocaron a todos los países para coordinar renovadas estrategias de lucha contra la RAM, promoviendo el enfoque de "una salud" con la participación de diferentes actores e instituciones. Este manuscrito proporciona información actualizada, explicando que la RAM no es más un dilema médico sino un fenómeno complejo que además afecta la producción agroveterinaria, el desarrollo y la economía de los países. La exposición a antibióticos contribuye a la selección de mutantes resistentes y favorece la transferencia horizontal de elementos genéticos móviles como plásmidos, integrones y tranposones que portan varios genes de resistencia contra distintas familias de antibióticos. Las antibioticoterapias, aún en situaciones justificadas, ejercen presiones selectivas que favorecen el predominio de mutantes bacterianas resistentes, por lo que es preciso evitar las infecciones, optimizando la higiene y el empleo de vacunas. También se ensayan terapias alternativas, por ejemplo basadas en bacteriófagos o probióticos. El Plan de Acción Mundial para controlar la RAM propuesto por la Organización Mundial de la Salud, la Organización Mundial de Salud Animal y la Organización de las Naciones Unidas para la Alimentación y el Desarrollo comprende cinco objetivos: mejorar la conciencia y el conocimiento sobre la resistencia antimicrobiana; reforzar la vigilancia y la investigación; reducir la incidencia de la infección; optimizar el uso de antimicrobianos, y asegurar una financiación duradera que asegure la persistencia de las acciones de control.

The recent increase of antimicrobial resistance is a compelling problem that may compromise the health of future generations and result in us going back to the pre-antibiotic era, unless it is battled on time. In order to face this threat, global health organizations called countries to articulate new strategies to fight against antimicrobial resistance, by encouraging them to adopt a health centered approach that involves different actors and institutions. This report provides updated information, explaining the reasons why antimicrobial resistance is no longer a medical dilemma but rather a complex phenomenon that also affects agricultural and livestock production and the development and economy of countries. Antibiotic exposure contributes to the selection of resistant mutants and favors the horizontal transference of mobile genetic elements (MGE) such as plasmids, integrons and transposons, which carry several resistance genes against antibiotic families. Antibiotic therapy, still in justified situations, exerts selective pressure that favors the predominance of resistant bacteria mutants, and thus infections need to be avoided by optimizing hygiene conditions and relying on immunization. Also, alternative therapies are tried, as those based on bacteriophagists or probiotics. The Global Action Plan proposed by theWHO, theWorld Organization for Animal Health and the FAO to control antimicrobial resistance comprises five goals: to improve awareness and knowledge on antimicrobial resistance; to strengthen surveillance and research; to reduce the incidence of infection; to optimize the use of antimicrobial agents and to ensure a lasting funding that guarantees the continuation of control actions.

A crescente resistência aos antimicrobianos (RAM) é um problema grave que, se não for combatido rapidamente, pode comprometer a saúde das próximas gerações, com um retorno à era pré-antibiótica. Considerando esta ameaça, os organismos sanitários internacionais convocaram todos os países para coordenar novas estratégias de luta contra a RAM, promovendo um enfoque de saúde, com a participação de diferentes atores e instituições. Este manuscrito proporciona informação atualizada, explicando que a RAM não é mais um dilema médico, mas um fenómeno complexo que afeta também a produção agro veterinária, o desenvolvimento e a economia dos países. A exposição a antibióticos contribui para a seleção demutantes resistentes e favorece a transferência horizontal de elementos genéticos móviles como plasmídeos, integrons e tranposons que portam vários genes de resistência contra distintas famílias de antibióticos. As antibioticoterapias, mesmo emsituações justificadas, exercem pressões seletivas que favorecem o predomínio de mutantes bacterianos resistentes, e, portanto é preciso evitar as infeções, otimizando a higiene e o uso de vacinas. Também foram feitos ensaios com terapias alternativas, por exemplo, baseadas em bacteriófagos ou probióticos. O Plano de Ação Mundial para controlar a RAM, proposto pela OMS, OIE e FAO compreende cinco objetivos:melhorar a consciência e o conhecimento sobre resistência antimicrobiana; reforçar a vigilância e a pesquisa; reduzir a incidência das infecções; otimizar o uso de antimicrobianos, e garantir um financiamento duradouro que assegure a persistência das ações de controle.

Analysis of plasmid-mediated quinolone and oxyimino-cephalosporin resistance mechanisms in Uruguayan Salmonella enterica isolates from 2011-2013.

This study characterised the mechanisms of fluoroquinolone and oxyimino-cephalosporin resistance in human Salmonella enterica isolates in Uruguay. Salmonella enterica isolates were collected from 2011-2013 and were selected based on non-susceptibility to ciprofloxacin and/or oxyimino-cephalosporins. The disk diffusion assay was performed for various antibiotics, and the ciprofloxacin minimum inhibitory concentration (MIC) was determined following CLSI guidelines. Genetic relatedness was determined following PulseNet protocols. Extended-spectrum ß-lactamases, ampC alleles and plasmid-mediated quinolone resistance were characterised by PCR and sequencing. Plasmid analyses were carried out by conjugation or transformation assays, and plasmid-encoded genes were identified by PCR. Mutations in the quinolone resistance-determining region of gyrases were sought by PCR and sequencing. Among 579 isolates, 105 (18.4%) ciprofloxacin-non-susceptible (CIP-NS) isolates, 9 (1.6%) oxyimino-cephalosporin-resistant isolates and 2 (0.3%) isolates resistant to both antibiotic families were detected. Thirteen isolates carried qnrB alleles (twelve qnrB19 and one qnrB2), four carried blaCTX-M-8, two blaCTX-M-14, two blaSHV-2 and three blaCMY-2-like genes. No correlation was found between mutations in gyrases and ciprofloxacin MICs. Several co-circulating clones of S. enterica ssp. enterica serovar Typhimurium were detected; conversely, S. enterica ssp. enterica serovar Enteritidis corresponded mainly to a single circulating clone. Nine (75%) of twelve of CIP-NS extraintestinal isolates shared the same pulsotype with intestinal isolates. During the study period, the frequency of CIP-NS isolates increased, albeit with ciprofloxacin MICs of 0.125-0.5mg/L. Detection of the same quinolone-resistant clones recovered both from intestinal and extraintestinal samples highlights the significance of epidemiological surveillance of antibiotic susceptibility for every human Salmonella isolate.

Effect of pneumococcal conjugate vaccination in Uruguay, a middle-income country.

BACKGROUND: In 2008, a 7-valent pneumococcal conjugate vaccine (PCV7) was introduced into the routine childhood immunization program in Uruguay, with a 2+1 schedule. In 2010, PCV13 replaced PCV7, and the same 2+1 schedule was used. The effect of these pneumococcal vaccines on the incidence of invasive pneumococcal infections (IPD) and on serotype distribution was analyzed retrospectively, based on passive national laboratory surveillance. METHODS: Data from 1,887 IPD isolates from 5 years before and 5 years after PCV7 introduction (7 before and 3 after PCV13 introduction) was examined to assess the incidence rate per 100,000 age-specific population of all IPD, PCV7-serotypes, and PCV13-serotypes associated IPD among children < 2 years and 2 to 4 years old, and patients ≥ 5 years old. Trends of frequency for each serotype were also analyzed. RESULTS: Comparison of pre-vaccination (2003-2007) and post-vaccination (2008-2012) periods showed a significant decrease in IPD incidence among children < 2 years old (IR 68.7 to IR 29.6, p<0.001) and children 2 to 4 years (p < 0.04). IPD caused by serotypes in PCV7 was reduced by 95.6% and IPD caused by 6 serotypes added in PCV13 was reduced by 83.9% in children <5 years old. Indirect effects of both conjugate vaccines were observed among patients ≥ 5 years old one year after the introduction of each vaccine, in 2010 for PCV7 and in 2012 for PCV13. Nevertheless, for reasons that still need to be explained, perhaps due to ascertainment bias, total IPD in this group increased after 2007. In 2012, the relative frequency of vaccine serotypes among vaccinated and unvaccinated population declined, except for serotype 3. Non vaccine serotypes with increasing frequency were identified, in rank order: 12F, 8, 24F, 22F, 24A, 15C, 9N, 10A and 33. CONCLUSION: Consecutive immunization with PCV7 and PCV13 has significantly reduced IPD in children < 5 years of age in Uruguay.

Effectiveness of the 7-valent pneumococcal conjugate vaccine against vaccine-type invasive disease among children in Uruguay: an evaluation using existing data.

The 7-valent pneumococcal conjugate vaccine (PCV7) was introduced into the routine immunization program in Uruguay in March 2008 with a 2-dose primary series (given at 2 and 4 months) plus a booster (at 12 months) and a catch-up campaign (two doses given at 15 and 17 months). We used a case-control methodology and existing laboratory surveillance and immunization registry data from Uruguay to evaluate PCV7 effectiveness against vaccine-type invasive pneumococcal disease (VT-IPD). Cases of VT-IPD (with pneumococcus obtained from a normally sterile site) were identified through the National Reference Laboratory. Age- and neighborhood-matched controls were obtained through a national immunization registry in which all children are enrolled at birth regardless of vaccine receipt; all eligible controls were included. Immunization status of cases and controls was assessed through the immunization registry, and conditional logistic regression was used to calculate PCV7 effectiveness. Between April 2008 and February 2010, 44 cases of VT-IPD among children<5 years were identified; 43 (98%) of those children were located in the registry. Among located case patients, 7 (16.3%) were age-eligible to have received at least one dose of PCV7. A total of 637 matched controls were included. Vaccine effectiveness was 91.3% (95% CI: 46.4, 98.6) for ≥ 1 PCV7 doses and 94.8% (95% CI: 43.1, 99.5) for ≥ 2 PCV7 doses. Using existing data we demonstrated high effectiveness of PCV7 against VT-IPD in Uruguay-a middle-income country using a 2-dose primary series plus a booster dose and a limited catch-up campaign. These data also highlight the utility of surveillance and high-quality immunization registries for evaluating the effectiveness of vaccines.

Protection against Streptococcus pneumoniae serotype 1 acute infection shows a signature of Th17- and IFN-γ-mediated immunity.

Acute pneumonia caused by Streptococcus pneumoniae is a major cause of child mortality. Antibodies are considered the main effectors of protection in this clinical presentation of pneumococcal invasive disease. To get new insights into the mechanisms involved in the protective immunity, we established a murine experimental model of protection against acute pneumococcal pneumonia and then evaluated the transcriptional, humoral and cellular responses in protected and non-protected animals. We found that intranasal inoculation of a sublethal dose of S. pneumoniae serotype 1 conferred complete protection against a subsequent challenge with a lethal dose of the same strain. Sublethal infection elicited a strong IgM and IgG antibody response against the capsular polysaccharide, as assessed one week later, and an exacerbated influx of neutrophils into the lungs immediately after the lethal challenge. Genome-wide microarray-based transcriptional analysis of whole lungs showed 149 differentially expressed genes among which we found upregulation of Il17a, Ifng and several IL-17A- and IFN-γ-related genes in protected versus non-protected mice. Kinetics analysis showed higher expression levels of Il17a in protected animals at all time points whereas Ifng was upregulated early in the protected mice and later in the non-protected animals. Intracelluar cytokine staining demonstrated that CD4(+) T cells account for a great proportion of the IL-17A produced in the lungs of protected animals. Overall, these results showed that an upregulation of IL-17A- and a timely regulation of IFN-γ-related gene expression, together with development of a Th17 response, are relevant characteristics of the protective immunity against S. pneumoniae acute pneumonia.

[Detection of rifampicin-resistant strains of Neisseria meningitidis in Uruguay]. / Detección de cepas de Neisseria meningitidis resistentes a rifampicina en el Uruguay.

The objective of this study was to characterize the phenotype and genotype of two isolates of rifampicin-resistant Neisseria meningitidis associated with two independent events involving transmission of severe meningococcal meningitis that occurred in September and October 2010 in Montevideo, Uruguay. The most recent 10 years of data from the national antimicrobial resistance surveillance system were reviewed to estimate the frequency of the particular meningococcal features that were characterized. Rifampicin resistance was studied using the epsilometer test. The serotype and serosubtype of the isolates were determined by ELISA, and the genotype was characterized using DNA digestion with Nhel and pulse field gel electrophoresis. The two isolates were identical: B:2a:P1.5. In the collection of 408 strains of N. meningitidis isolated in Uruguay in the past 10 years, the phenotype only appeared in two isolates, which were sensitive to rifampicin. The two isolates studied also shared a single pulse type, which was different from that of two other rifampicin-resistant isolates obtained in 2003 and 2007. Consequently, it was concluded that both cases of transmission were caused by a single rifampicin-resistant strain, which could have been an import from another country or else the result of a drift from serogroup C to B due to selective pressure exerted by vaccines administered to the population. It is essential to maintain and maximize surveillance. However, since this type of finding has been sporadic so far, unless a secondary case is identified, there is no justification for changing the antimicrobial drug currently being administered to contacts as prophylaxis.

Laboratory-based surveillance of Streptococcus pneumoniae invasive disease in children in 10 Latin American countries: a SIREVA II project, 2000-2005.

BACKGROUND: For the last 14 years the Pan American Health Organization has been promoting surveillance of invasive pneumococcal disease in Latin American children for better understanding of the disease tendencies regarding capsular types circulation in each country and susceptibility to antimicrobials. METHODS: Laboratory-based surveillance data from 10 Latin American countries collected from 2000 to 2005 were analyzed, including serotype distribution and susceptibility to beta-lactam antibiotics. RESULTS: Although 61 different capsular types were identified during the 6-year surveillance, 13 serotypes accounted for 86% of all isolates. These were consistently the most prevalent throughout the study period with serotype 14 predominating. Diminished susceptibility to penicillin was detected in 38% of all Streptococcus pneumoniae isolates, with the highest prevalence in Dominican Republic and Mexico. Decreased susceptibility to penicillin increased in Brazil and Colombia whereas decreased high resistance rates was recorded in Chile. CONCLUSIONS: These data indicate that 10 countries of the Region continue to have high quality laboratory-based surveillance for pneumococcal disease thus generating valuable information so that healthcare decision makers may prioritize interventions. The heptavalent vaccine will potentially cover from 52.4% to 76.5% of strains causing invasive pneumococcal disease and the 13 valent from 76.7% to 88.3%.

[Resistance to non-beta-lactam antibiotics in the clinical isolates of Streptococcus pneumoniae of children in Latin America. SIREVA II, 2000-2005]. / Resistencia a antibióticos no betalactámicos de aislamientos invasores de Streptococcus pneumoniae en niños latinoamericanos. SIREVA II, 2000-2005.

OBJECTIVE: To examine the development of resistance to erythromycin, chloramphenicol, trimethoprim-sulfamethoxazole (TMP-SMZ), and vancomycin of the invasive isolates of Streptococcus pneumoniae obtained from children in 10 Latin American/Caribbean countries during six years of surveillance. METHODS: Analysis of 8 993 isolates of S. pneumoniae recovered in 2000-2005 from children with invasive infections, who were less than 6 years of age, and from Argentina, Brazil, Chile, Colombia, Cuba, Dominican Republic, Mexico, Paraguay, Uruguay, or Venezuela. Antibiotic susceptibility was determined through the methods established and standardized by the SIREVA project. Multidrug resistance was defined as: resistance to three or more antibiotics of the same class; to the non-beta-lactams analyzed by this study; or, to the beta-lactams evaluated by a previous study, in which 37.8% of these isolates showed decreased susceptibility to penicillin. RESULTS: Some degree of resistance was found to TMP-SMZ and erythromycin (56.4% and 15.4% of the isolates studied, respectively), with 4.6% highly resistant to chloramphenicol. All isolates were susceptible to vancomycin. The highest prevalence of TMP-SMZ resistance was observed in the pneumonia isolates; and that of erythromycin, in cases of sepsis (61.6% and 25.5%, respectively; P < 0.01). The highest prevalence of TMP-SMZ resistance was found in Brazil (71.9%), and that of erythromycin, in Mexico (38.2%) and Venezuela (32.9%). The 14, 6B, 19F, and 23F serotypes were most often associated with resistance to the antibiotics in the study. CONCLUSIONS: High and increasing rates of isolates resistant to TMP-SMZ and erythromycin were observed, as well as a decreasing percentage of isolates resistant to chloramphenicol. These trends highlight differences among the countries studied.

Pneumococcal pneumonia in hospitalized Uruguayan children and potential prevention with different vaccine formulations.

OBJECTIVES: To provide information on pneumococcal pneumonias, on their associated serotypes, and to estimate the coverage potentially afforded by antipneumococcal vaccines. STUDY DESIGN: A retrospective study (2000 to 2004) was performed of patients with pneumococcal pneumonia aged 0 to 14 years admitted to the National Reference Children's Hospital in Uruguay. Selected clinical data, radiographic interpretation, and microbiologic reports were obtained for analysis. RESULTS: Of 410 enrolled patients, 384 had consolidated pneumonia/pleural effusion and 26 had infiltrates without consolidation: Pneumococcus was identified in blood or in pleural fluid of 387 patients; 21 serotypes were identified. The most frequent serotypes in decreasing order were serotypes 14, 1, 5, 3, 9V, 6B, and 7F. Forty-eight percent of invasive Streptococcus pneumoniae isolates were obtained from children younger than 24 months. For this group, the 7-valent vaccine would cover 60%, but a 10-valent vaccine would cover 83.8%. CONCLUSIONS: This study provides information on pneumonia of proven S. pneumoniae causes and their associated serotypes, enabling estimation of potential effect of pneumococcal conjugate vaccines.