Peritonitis primaria por neumococo en un hospital pediátrico de Argentina / Primary pneumococcal peritonitis in a pediatric hospital from Argentina

Resumen La peritonitis por neumococo comprende un pequeno subconjunto de pacientes con enfermedad invasiva (ENI). Durante 15 años (2005-2020) de vigilancia de ENI en un hospital de pediatría, se detectaron 5 casos de peritonitis primaria. Los pacientes, 3 ninas y 2ninos con una media de edad de 5 anos, experimentaron signos y síntomas peritoneales; 3 de ellos presentaban síndrome nefrótico. En coincidencia con los perfiles locales, todos los aislamientos fueron sensibles a betalactámicos, una cepa expresó resistencia a tetraciclina y cotrimoxazol y otra solo a cotrimoxazol. Los serotipos encontrados en 4/5 cepas (una resultó no viable) fueron 1, 19F, 15C y 23A. Los ninos fueron tratados con cefalosporinas de tercera generación o con ampicilina, gentamicina y metronidazol; todos evolucionaron favorablemente. Se destaca la importancia del hallazgo de Streptococcus pneumoniae en peritonitis primarias en niños. Este trabajo contribuye al conocimiento de esta enfermedad en particular y al de la epidemiología local de la ENI.

Abstract Pneumococcal peritonitis represents a small subset of patients suffering from inva-sive pneumococcal disease (IPD). We describe 5 cases of primary peritonitis documented in the pediatric hospital over 15 years (2005-2020) of IPD surveillance. The patients, 3girls and 2boys with a mean age of 5 years, experienced peritoneal signs and symptoms; 3of them suffered from nephrotic syndrome. Based on the local resistance profiles, all isolates were sensitive to beta-lactams, one strain showed resistance to cotrimoxazole and tetracycline while another strain, to cotrimoxazole only. Serotypes found in 4/5 strains (one was non-viable) were: 1, 19F, 15C and 23A. Children were treated with third-generation cephalosporins or ampicillin, gentamicin and metronidazole and all of them evolved favorably. Pneumococcal etiology should be included in the differential diagnosis of acute abdominal pain in children. Our study aims to contribute to the knowledge of this condition and to the local epidemiology of IPD.

[Primary pneumococcal peritonitis in a pediatric hospital from Argentina]. / Peritonitis primaria por neumococo en un hospital pediátrico de Argentina.

Pneumococcal peritonitis represents a small subset of patients suffering from invasive pneumococcal disease (IPD). We describe 5 cases of primary peritonitis documented in the pediatric hospital over 15 years (2005-2020) of IPD surveillance. The patients, 3girls and 2boys with a mean age of 5 years, experienced peritoneal signs and symptoms; 3of them suffered from nephrotic syndrome. Based on the local resistance profiles, all isolates were sensitive to beta-lactams, one strain showed resistance to cotrimoxazole and tetracycline while another strain, to cotrimoxazole only. Serotypes found in 4/5 strains (one was non-viable) were: 1, 19F, 15C and 23A. Children were treated with third-generation cephalosporins or ampicillin, gentamicin and metronidazole and all of them evolved favorably. Pneumococcal etiology should be included in the differential diagnosis of acute abdominal pain in children. Our study aims to contribute to the knowledge of this condition and to the local epidemiology of IPD.

[Pneumococcal osteoarticular infections in children admitted to a Pediatric Reference Hospital from Misiones, Argentina. Thirteen years of surveillance]. / Infección neumocócica osteoarticular en niños atendidos en un hospital pediátrico de referencia de Misiones, Argentina. Trece años de vigilancia.

Streptococcus pneumoniae is a rare cause of osteoarticular infections. We describe 5documented cases that occurred in 2005, 2009, 2011, 2015 and 2017 in patients admitted to the Pediatric Provincial Reference Hospital of Misiones. These cases corresponded to a 4-year-old boy and 4 girls aged 11, 10, 6 years and 4 months with a diagnosis of osteomyelitis of the scapula and humerus, arthritis of the hip, ankle and osteomyelitis of the distal fibula. All of them were in good general condition on admission and one of them was seropositive for human immunodeficiency virus. All the recovered isolates were susceptible to ß-lactams and only one isolate showed joint resistance to macrolides and tetracycline. Three isolates were serotyped, 2of which carried vaccine serotypes (19F and 7F). Despite its low frequency, the etiology of S.pneumoniae should be considered among the osteoarticular infections. Our findings enhance the role of the Bacteriology laboratory in the diagnosis by microbiological culture and contribute to documenting the epidemiological behavior of this pathogen.

Neisseria meningitidis aislada de muestras de hombres que tienen sexo con hombres / Neisseria meningitidis isolated from patients in men who have sex with men

Resumen En los períodos 2000-2004 y 2014-2015 se investigó la presencia de Neisseria meningitidis en 1.143 y 544 hombres que tienen sexo con hombres respectivamente, atendidos en el marco de un programa de enfermedades de transmisión sexual. Se determinó la prevalencia de este agente, su distribución en serogrupos y su sensibilidad a los antimicrobianos. Se obtuvieron hisopados faríngeos, rectales y uretrales, que se sembraron en medio selectivo Thayer Martin modificado. La identificación se realizó mediante pruebas bioquímicas convencionales y por espectrometría de masas (MALDI-TOF). En el segundo período estudiado, sobre 85 aislamientos procedentes de faringes se investigaron los serogrupos B, C, W e Y mediante PCR. Se determinó la CIM de penicilina, ceftriaxona, rifampicina, azitromicina y ciprofloxacina en 66 aislamientos obtenidos en el primer período y en 102 logrados en el segundo. La prevalencia de N. meningitidis fue del 17,8% en el primer período y del 28,1% en el segundo; este microorganismo se aisló más frecuentemente de fauces. Los serogrupos hallados fueron B (31,5%), Y (7,6%) y W (3,3%), con un 9,8% de aislamientos no capsulados; los restantes corresponderían a otros serogrupos. El 34,8% y el 63,7% de los aislados estudiados correspondientes al primer y segundo período, respectivamente, tuvieron sensibilidad intermedia a la penicilina, y un 11,8% de los evaluados en el segundo período fueron resistentes a dicho antibiótico. Todos los aislados estudiados fueron sensibles a ceftriaxona y a ciprofloxacina (excepto 3, con CIM entre 0,25 y 0,5(g/ml), el 3% fueron resistentes a rifampicina y el 2% fueron no sensibles a azitromicina. La portación de N. meningitidis en hombres que tienen sexo con hombres fue elevada y hubo un alto porcentaje de cepas no sensibles a penicilina. El serogrupo B fue prevalente.

Abstract During the periods 2000-2004 and 2014-2015, Neisseria meningitidis was investigated in men who have sex with men, 1143 and 544 respectively, who consulted in the sexually-transmitted disease program. Prevalence, serogroup distribution and susceptibility to antibiotics were determined. Pharyngeal, rectal and urethral swabs were cultivated on selective Thayer-Martin modified medium. The identification was performed by biochemical tests and mass spectrometry by MALDI-TOF. Serogroups B, C, W and Y were investigated by PCR in 85 isolates recovered from the pharynx belonging to the second period. MICs of penicillin, ceftriaxone, rifampicin, azithromycin and ciprofloxacin were determined for 66 and 102 isolates from periods 1 and 2 respectively, according to CLSI. The prevalence of N. meningitidis was 17.8% and 28.1%, in periods 1 and 2 respectively; the isolates were mainly recovered from the pharynx. The distribution of serogroups was B 31.5%; Y 7.6%; W 3.3% and 9.8% non-capsulated and the rest would belong to other serogroups. Isolates classified as intermediate to penicillin were 34.8% and 63.7% (first and second periods, respectively); moreover, 11.8% of the isolates from the second period were resistant. All isolates were susceptible to ceftriaxone, to ciprofloxacin (except 3 isolates with MIC values between 0.25 and 0.5(g/ml), 3% were resistant to rifampicin and 2% were not susceptible to azithromicin. The prevalence of N. meningitidis carriage in men who have sex with men was high with a high rate of penicillin non-susceptible isolates. B was the prevalent serogroup.

[Neisseria meningitidis isolated from patients in men who have sex with men]. / Neisseria meningitidis aislada de muestras de hombres que tienen sexo con hombres.

During the periods 2000-2004 and 2014-2015, Neisseria meningitidis was investigated in men who have sex with men, 1143 and 544 respectively, who consulted in the sexually-transmitted disease program. Prevalence, serogroup distribution and susceptibility to antibiotics were determined. Pharyngeal, rectal and urethral swabs were cultivated on selective Thayer-Martin modified medium. The identification was performed by biochemical tests and mass spectrometry by MALDI-TOF. Serogroups B, C, W and Y were investigated by PCR in 85 isolates recovered from the pharynx belonging to the second period. MICs of penicillin, ceftriaxone, rifampicin, azithromycin and ciprofloxacin were determined for 66 and 102 isolates from periods 1 and 2 respectively, according to CLSI. The prevalence of N. meningitidis was 17.8% and 28.1%, in periods 1 and 2 respectively; the isolates were mainly recovered from the pharynx. The distribution of serogroups was B 31.5%; Y 7.6%; W 3.3% and 9.8% non-capsulated and the rest would belong to other serogroups. Isolates classified as intermediate to penicillin were 34.8% and 63.7% (first and second periods, respectively); moreover, 11.8% of the isolates from the second period were resistant. All isolates were susceptible to ceftriaxone, to ciprofloxacin (except 3 isolates with MIC values between 0.25 and 0.5µg/ml), 3% were resistant to rifampicin and 2% were not susceptible to azithromicin. The prevalence of N. meningitidis carriage in men who have sex with men was high with a high rate of penicillin non-susceptible isolates. B was the prevalent serogroup.

Identificación y sensibilidad a los antimicrobianos de aislados de estreptococos del grupo viridans provenientes de pacientes internados en un hospital universitario de la ciudad de Buenos Aires / Identification and antibiotic susceptibility of viridans group streptococci isolates recovered from patients hospitalized at a teaching hospital in Buenos Aires City

Los estreptococos del grupo viridans (EGV) son agentes causales de infecciones localizadas e invasivas. Dada la gravedad de las infecciones producidas por EGV sumada a las escasas comunicaciones actuales en nuestro país, los objetivos de este trabajo fueron la identificación y el estudio de la sensibilidad a los antibióticos de aislados caracterizados como EGV, recuperados de pacientes internados, para actualizar el conocimiento sobre el perfil de resistencia y la epidemiología de las infecciones ocasionadas por EGV. Se recuperaron 132 aislados de EGV en el Hospital de Clínicas «José de San Martín¼ en el período 2011-2015. La identificación se realizó mediante pruebas convencionales y espectrometría de masas (Matrix Assisted Laser Desorption Ionization - Time of Flight Mass Spectrometry). El grupo Streptococcus anginosus fue el más frecuente (42%) seguido por el grupo Streptococcus mitis (33%). Dentro del grupo S. mitis se excluyó a Streptococcus pneumoniae. El 100% de los aislados fue sensible a ertapenem, linezolid y vancomicina; el 96,9% a cef-triaxona y cefepima. Se encontró un 25,8% de resistencia a penicilina (I+R) fundamentalmente en aislados de grupo S. mitis. La resistencia a tetraciclina fue del 27,2% y solo 2/132 aislados fueron resistentes a levofloxacina. Los valores de CIM de gentamicina oscilaron entre 0,5 y 32 -og/ml. El 17,4% de los aislados presentó resistencia a eritromicina sin diferencia significativa en la distribución de fenotipos M y MLS. Los resultados muestran la importancia de la vigilancia continua de las infecciones producidas por estos microorganismos con el fin de generar aportes para la elección de la terapia antibiótica adecuada.

Members of the viridans group streptococci (VGS) are the cause of local and invasive infections. Due to the severity of these infections and taking into account that reports regarding epidemiological aspects are scarce, the aims of this work were the identification and the study of the antibiotic susceptibility profiles of the isolates recovered from patients that were hospitalized in order to find out about the resistance level and the epidemiology of infections in which VGS are involved. A hundred and thirty two isolates identified as VGS were isolated at Hospital de Clínicas «José de San Martín¼ during the period 2011-2015. The identification was performed by biochemical test and mass spectrometry by Matrix Assisted Laser Desorption Ionization -Time of Flight Mass Spectrometry. Streptococcus anginosus group was prevalent (42%) followed by Streptococcus mitis group (33%). In the latter, isolates of Streptococcus pneumoniae were excluded. All the VGS isolates were susceptible to ertapenem, meropenem, linezolid and vancomycin; 25.8% were resistant (I+R) to penicillin, being prevalent in the S. mitis group. Regarding ceftriaxone and cefepime 96.9% of the isolates were susceptible. Only two isolates were resistant to levofloxacin, 27.2% to tetracycline and it was not found high level resistance to gentamycin (MIC range 0.5-32 µg/ml). Resistance to erythromycin was 17.4% with no significant difference between M and MLS phenotypes. The most active antibiotics were in addition to ceftriaxone and cefepime, vancomycin, ertapenem, meropenem and linezolid. These results highlight the importance of the continuous surveillance of the infections caused by VGS in order to predict a correct antibiotic therapy.

High virulence of methicillin resistant Staphylococcus aureus ST30-SCCmecIVc-spat019, the dominant community-associated clone in Argentina.

Community-acquired methicillin resistant Staphylococcus aureus emerged as a worldwide health problem in the last few years. In Argentina, it is found in 70% of skin and skin structure infections in previously healthy adult patients and causes severe invasive diseases. The ST30-SCCmecIVc-spat019 clone is predominant in adult infections and has displaced the previously prevalent ST5-SCCmecIVa-spat311 clone in community settings. In the present work we compared the virulence of both clones in order to explain the displacement, and found that ST30-IVc is associated with invasive infections in adult patients from Argentina and possesses a different virulence-associated genes profile compared to ST5-IVa. A representative strain of ST30 lineage has a more aggressive behavior in animal models of infection and expresses higher level of Fibronectin binding protein A coding gene, which could enhance the bacterial invasion capacity.

[Two multidrug-resistant Salmonella infantis isolates behave like hypo-invasive strains but have high intracellular proliferation]. / Dos aislamientos de Salmonella infantis multirresistentes se comportan como hipoinvasivos pero con elevada proliferación intracelular.

In this work, plasmid-encoded virulence factors in two Salmonella Infantis isolates carrying multiresistance plasmids were investigated. In addition, their invasion and proliferative ability in non-phagocytic cells was studied. None of them showed the typical determinants of virulence plasmids (spy operon). The invasion assays of S. Infantis isolates on eukaryotic cells showed a decreased ability to invade but they remained and proliferated in the cytoplasm regardless of having used a permissive (HeLa) or non-permissive (NRK) cell line. Finally, there was no microscopic evidence suggesting a bactericidal effect of these eukaryotic cell lines on the isolates tested.

Dos aislamientos de Salmonella Infantis multirresistentes se comportan como hipoinvasivos pero con elevada proliferación intracelular

En este trabajo se investigó la presencia de determinantes característicos de plásmidos de virulencia en dos aislamientos clínicos de Salmonella Infantis portadores de plásmidos de multirresistencia. Además, se estudió la capacidad de invasión y proliferación en células eucariotas no fagocíticas. Ninguno de los aislamientos de S. Infantis mostró los determinantes genéticos que caracterizan a los plásmidos de virulencia para este género (operón spv). Los ensayos de invasión sobre líneas celulares eucariotas mostraron que los aislamientos de S. Infantis presentan una capacidad de invasión disminuida pero persisten y proliferan en el citoplasma, independientemente de utilizar una línea celular permisiva (HeLa) o no permisiva (NRK) para tal fin. Finalmente, no se observaron indicios microscópicos que podrían hacer sospechar un efecto bactericida de estas líneas celulares sobre los aislamientos estudiados.(AU)

Two multidrug-resistant Salmonella Infantis isolates behave like hypo-invasive strains but have high intracellular proliferation. In this work, plasmid-encoded virulence factors in two Salmonella Infantis isolates carrying multiresistance plasmids were investigated. In addition, their invasion and proliferative ability in non-phagocytic cells was studied. None of them showed the typical determinants of virulence plasmids (spv operon). The invasion assays of S. Infantis isolates on eukaryotic cells showed a decreased ability to Invade but they remained and proliferated In the cytoplasm regardless of having used a permissive (HeLa) or non-permissive (NRK) cell line. Finally, there was no microscopic evidence suggesting a bactericidal effect of these eukaryotic cell lines on the Isolates tested.(AU)

Dos aislamientos de Salmonella Infantis multirresistentes se comportan como hipoinvasivos pero con elevada proliferación intracelular

En este trabajo se investigó la presencia de determinantes característicos de plásmidos de virulencia en dos aislamientos clínicos de Salmonella Infantis portadores de plásmidos de multirresistencia. Además, se estudió la capacidad de invasión y proliferación en células eucariotas no fagocíticas. Ninguno de los aislamientos de S. Infantis mostró los determinantes genéticos que caracterizan a los plásmidos de virulencia para este género (operón spv). Los ensayos de invasión sobre líneas celulares eucariotas mostraron que los aislamientos de S. Infantis presentan una capacidad de invasión disminuida pero persisten y proliferan en el citoplasma, independientemente de utilizar una línea celular permisiva (HeLa) o no permisiva (NRK) para tal fin. Finalmente, no se observaron indicios microscópicos que podrían hacer sospechar un efecto bactericida de estas líneas celulares sobre los aislamientos estudiados.

Two multidrug-resistant Salmonella Infantis isolates behave like hypo-invasive strains but have high intracellular proliferation. In this work, plasmid-encoded virulence factors in two Salmonella Infantis isolates carrying multiresistance plasmids were investigated. In addition, their invasion and proliferative ability in non-phagocytic cells was studied. None of them showed the typical determinants of virulence plasmids (spv operon). The invasion assays of S. Infantis isolates on eukaryotic cells showed a decreased ability to Invade but they remained and proliferated In the cytoplasm regardless of having used a permissive (HeLa) or non-permissive (NRK) cell line. Finally, there was no microscopic evidence suggesting a bactericidal effect of these eukaryotic cell lines on the Isolates tested.

Transcriptional analysis of the bla(CTX-M-2) gene in Salmonella enterica serovar Infantis.

Transcriptional organization of bla(CTX-M-2) present in a multiresistance plasmid of Salmonella enterica serovar Infantis suggests the presence of more than one promoter involved in the expression of the beta-lactamase gene. At least two bla(CTX-M-2)-specific mRNAs (near to 1 kb and 5 kb) were evidenced. Two +1 signals were detected at -22 bp and -59 bp of bla(CTX-M-2) defining two putative promoters.

Obtención de mutantes dicloxacilina resistentes en Listeria monocytogenes / Isolation of dicloxacillin resistant mutants from Listeria monocytogenes

A partir de la cepa sensible de Listeria monocytogenes ATCC: 15313 se obtuvieron 10 mutantes espontáneas Dicloxacilina resistentes, indiferenciables de la cepa parenteral mediante pruebas bioquímicas convencionales y análisis electroforético de sus perfiles proteicos en presencia de detergentes. La disminución en la susceptibilidad frente a Dicloxacilina no fue en todas las cepas acompañada por una disminución paralela en la susceptibilidad frente a Penicilina G. Estudios morfológicos demostraron que algunas de las mutantes, creciendo a dosis subinhibitorias de Dicloxacilina, presentan profundas alteraciones en su morfología, entre la que se cuenta la formación de estructuras helicoidales (AU)

Obtención de mutantes dicloxacilina resistentes en Listeria monocytogenes / Isolation of dicloxacillin resistant mutants from Listeria monocytogenes

A partir de la cepa sensible de Listeria monocytogenes ATCC: 15313 se obtuvieron 10 mutantes espontáneas Dicloxacilina resistentes, indiferenciables de la cepa parenteral mediante pruebas bioquímicas convencionales y análisis electroforético de sus perfiles proteicos en presencia de detergentes. La disminución en la susceptibilidad frente a Dicloxacilina no fue en todas las cepas acompañada por una disminución paralela en la susceptibilidad frente a Penicilina G. Estudios morfológicos demostraron que algunas de las mutantes, creciendo a dosis subinhibitorias de Dicloxacilina, presentan profundas alteraciones en su morfología, entre la que se cuenta la formación de estructuras helicoidales