Descripción de un caso de sepsis abdominal por Desulfovibrio desulfuricans / Description of a case of abdominal sepsis due to Desulfovibrio desulfuricans

Resumen Desulfovibrio spp. son bacterias anaerobias estrictas, ubicuas en la naturaleza, quepueden formar parte del tracto gastrointestinal humano o animal, pero también son bacteriasambientales presentes en el suelo y en el agua. Pueden persistir de manera asintomática enel intestino o comportarse como patógenos oportunistas, asociados con bacteriemia primariae infecciones intraabdominales. El número de infecciones por Desulfovibrio spp. puede estarsubestimado debido a su lenta velocidad de crecimiento y a que muchos laboratorios no realizancultivos en anaerobiosis de manera rutinaria. Pruebas sencillas, como el examen de la movilidaden fresco y de la morfología celular en la coloración de Gram, sumadas a la presencia de SH2en agar SIM y a la observación de una fluorescencia roja a pH alcalino bajo luz UV, seríanindicativas de Desulfovibrio spp. Se describe el caso de una bacteriemia por Desulfovibriodesulfuricans en una mujer con cuadro clínico de sepsis abdominal por apendicitis gangrenosacon fallo multiorgánico.

Abstract Desulfovibrio spp. are strict anaerobes that are ubiquitous in nature. They can reside in the human or animal gastrointestinal tract and, as they are also environmental bacteria, may be present in soil and water. They can persist asymptomatically in the intestine or behave as opportunistic pathogens associated with primary bacteremia and intraabdominal infections. Several Desulfovibrio spp. infections may be underestimated due to their slow growth rate and because many laboratories do not routinely perform anaerobic cultures. Simple tests such as motility detection on a fresh subculture, Gram stain to confirm cell morphology, presence of H2S in SIM agar and production of a red fluorescence in alkaline pH under UV light would be indicative of Desulfovibrio spp.

[Description of a case of abdominal sepsis due to Desulfovibrio desulfuricans]. / Descripción de un caso de sepsis abdominal por Desulfovibrio desulfuricans.

Desulfovibrio spp. are strict anaerobes that are ubiquitous in nature. They can reside in the human or animal gastrointestinal tract and, as they are also environmental bacteria, may be present in soil and water. They can persist asymptomatically in the intestine or behave as opportunistic pathogens associated with primary bacteremia and intraabdominal infections. Several Desulfovibrio spp. infections may be underestimated due to their slow growth rate and because many laboratories do not routinely perform anaerobic cultures. Simple tests such as motility detection on a fresh subculture, Gram stain to confirm cell morphology, presence of H2S in SIM agar and production of a red fluorescence in alkaline pH under UV light would be indicative of Desulfovibrio spp. Here we report the case of Desulfovibrio desulfuricans bacteremia in a woman with clinical picture of abdominal sepsis due to gangrenous appendicitis with multiple organ failure.

Dolosigranulum pigrum en absceso corneal / Dolosigranulum pigrum in corneal abscess

Resumen Dolosigranulum pigrum es un coco gram positivo, anaerobio facultativo, que forma parte de la microbiota oral y del tracto respiratorio superior. Aunque los reportes de infecciones por este microorganismo son escasos, se lo ha asociado a un amplio espectro de enfermedades infecciosas. Se describe el caso de un hombre adulto con un absceso corneal del que se aisló D. pigrum. El microorganismo fue identificado por espectrometría de masas (MALDI-TOF MS) y secuenciación del gen 16S ARNr. A su vez, se logró la identificación presuntiva mediante pruebas fenotípicas claves, como la disposición en racimos en la coloración de Gram, la prueba negativa de la catalasa, la producción de pirrolidonil arilamidasa y leucina aminopeptidasa, el crecimiento en NaCl al 6,5% y la hidrólisis de esculina. Los datos de la literatura y el presente caso respaldan la asociación del microorganismo con infecciones oculares, a menudo de curso destructivo, principalmente en pacientes de edad avanzada.

Abstract Dolosigranulum pigrum is a gram-positive, facultatively anaerobic coccus, which is part of the oral and upper respiratory tract microbiota. Although reports of infections by this microorganism are scarce, it has been associated with a wide spectrum of infectious diseases. The case of an elderly man with a lower corneal abscess, in which Dolosigranulum pigrum was isolated, is described. The microorganism was identified by mass spectrometry (MALDI-TOF MS) and by the sequencingof the 16S rRNAgene. Furthermore, the presumptive identification of the causative agent was achieved by using key phenotypic tests such as the cluster arrangement in Gram stain, the negative catalase test, the production of pyrrolidonyl arylamidase and leucine aminopeptidase activity, the growth in 6.5% NaCl and esculin hydrolysis. The data from the literature (and the present case) support the association of the microorganism with ocular infections, which often take a destructive course, mainly in elderly patients.

Molecular and Phenotypic Characterization of a Multidrug-Resistant Escherichia coli Coproducing OXA-232 and MCR-1.1 in Argentina.

The spread of carbapenem-resistant Enterobacterales has raised concern in clinical settings due to the limited therapeutic options available. OXA-48-like enzymes are still sporadic in South America. The aim of this study was to characterize a multidrug-resistant Escherichia coli isolate from a hospitalized patient in Buenos Aires city. The isolate was characterized phenotypically by determination of its susceptibility pattern, synergistic and colorimetric tests, and molecularly, by PCR, whole genome sequencing, and plasmid analysis. It belonged to ST-744, phylogroup A, and serotype O162/O89: H9. It remained susceptible to ceftazidime, meropenem, aminoglycosides, trimethoprim/sulfamethoxazole, and tigecycline. The presence of blaOXA-232 harbored by a nonconjugative plasmid ColKp3, and blaCTX-M-14, mcr-1.1, and fosL1 in 2 conjugative plasmids, together with their genetic environment, was revealed. To the best of our knowledge, this is the first report of the coproduction of the enzyme OXA-232 and the mcr-1.1 gene in an E. coli clinical isolate in South America in a patient who had not received colistin therapy.

[Dolosigranulum pigrum in corneal abscess]. / Dolosigranulum pigrum en absceso corneal.

Dolosigranulum pigrum is a gram-positive, facultatively anaerobic coccus, which is part of the oral and upper respiratory tract microbiota. Although reports of infections by this microorganism are scarce, it has been associated with a wide spectrum of infectious diseases. The case of an elderly man with a lower corneal abscess, in which Dolosigranulum pigrum was isolated, is described. The microorganism was identified by mass spectrometry (MALDI-TOF MS) and by the sequencing of the 16S rRNA gene. Furthermore, the presumptive identification of the causative agent was achieved by using key phenotypic tests such as the cluster arrangement in Gram stain, the negative catalase test, the production of pyrrolidonyl arylamidase and leucine aminopeptidase activity, the growth in 6.5% NaCl and esculin hydrolysis. The data from the literature (and the present case) support the association of the microorganism with ocular infections, which often take a destructive course, mainly in elderly patients.

Corynebacterium phoceense - a rare Corynebacterium species isolated from a urine sample.

Corynebacterium spp. are Gram-positive rods that are recognized to cause opportunistic diseases under certain predisposing clinical conditions. Some species have been described in urinary tract infections. In this report we document a new episode of urinary tract infection caused by Corynebacterium phoceense and describe the whole-genome sequencing, phenotypic characteristics and mass spectra obtained by matrix-assisted desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Based on genome identification and DNA-to-DNA hybridization, we can assume that our strain is the second isolate of C. phoceense to be described in a urine sample. No other infectious diseases have been reported to be associated with this species.

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.

Análisis microbiológico del tracto genital materno y de la sangre del cordón umbilical en relación con el daño neonatal / Microbiological analysis of the maternal genital tract and umbilical cord blood and its association with neonatal damage

La etiología que conduce al daño neonatal es multifactorial, y los procesos infecciosos pueden estar implicados en él. El objetivo de este estudio fue identificar microorganismos del tracto genital materno asociados con el daño neonatal, a fin de prevenir futuras complicaciones perinatológicas. Se estudiaron 711 embarazadas que concurrieron entre enero de 2010 y julio 2013 al consultorio externo de Obstetricia del Hospital de Clínicas de la UBA para sus controles prenatales, y cuyos partos también tuvieron lugar en dicho nosocomio. En la sangre del cordón umbilical se investigó la presencia de Ureaplasma urealyticum y Mycoplasma hominis mediante el cultivo con sustratos metabólicos (Micofast-Biomerieux), y la de Trichomonas vaginalis por PCR, con primers específicos. El estudio microbiológico del contenido vaginal se efectuó en 288 de las embarazadas en la semana 35 a 37. Se empleó la metodología convencional, a la que se agregó el cultivo en tioglicolato modificado para T. vaginalis. Se investigó la presencia de estreptococos grupo B (EGB) en hisopado anorrectaly de introito vaginal, utilizando enriquecimiento en caldo selectivo y posterior siembra en medio cromogénico. Se utilizaron los test de χ² Yates y de Fisher para muestras independientes, considerándose significativo p < 0,05. La vaginosis bacteriana (VB) se relacionó significativamente con el daño neonatal (p = 0,02), al igual que la presencia de M. hominis (p = 0,03) y de T. vaginalis (p = 0,03) en la sangre del cordón umbilical. Las complicaciones predominantes fueron el parto pretérmino, la rotura prematura de membrana (RPM), el bajo peso y un valor de Apgar <7. No se asoció al daño neonatal la presencia de U. urealyticum (p = 0,35) en el cordón umbilical, ni la de Candidaspp. (p = 0,94) o EGB (p = 0,18) en el tracto genital de las madres. Dado que ciertas alteraciones en la microbiota del tracto genital materno se relacionaron con el dano neonatal, consideramos de fundamental importancia realizar el estudio microbiológico del contenido vaginal durante el embarazo, para prevenir posibles complicaciones maternas y perinatológicas.

The etiology leading to neonatal damage is multifactorial, being genital infections one of the causes. The objective of the study was to identify microorganisms of the maternal genital tract that are associated with neonatal damage, in order to prevent future perinatal complications. Seven hundred and eleven pregnant patients attended their prenatal control during the period January 2010-July 2013. Ureaplasma urealyticum and Mycoplasma hominis presence was investigated in umbilical cord blood by metabolic substrates (Micofast-Biomerieux) and that of T. vaginalis, by PCR using specific primers. The microbiological study of the vaginal contents of 288 pregnant patients at weeks 35 to 37 was performed by conventional methods, adding the modified thioglycolate culture for T. vaginalis. Group B streptococcus (GBS) was investigated in anorectal and vaginal introitus swabs, using selective broth enrichment and subsequent isolation in chromogenic medium. The χ² Yates test and Fisher's test were used for independent samples. A p value <0.05 was considered statistically significant. The pathogens significantly related to neonatal damage were M. hominis (p = 0.03), T. vaginalis (p = 0.03), and BV (p = 0.02). Main complications were preterm birth, premature rupture of membranes (PRM), low weight and Apgar score <7. U. urealyticum (p = 0.35), Candidaspp. (p = 0.94) and GBS (p = 0.18) were not related to neonatal damage. Since different microorganisms of the maternal genital tract were related to neonatal damage, it is very important to perform the microbiological study of vaginal contents during pregnancy to prevent possible maternal and perinatal complications.

[Microbiological analysis of the maternal genital tract and umbilical cord blood and its association with neonatal damage]. / Análisis microbiológico del tracto genital materno y de la sangre del cordón umbilical en relación con el daño neonatal.

The etiology leading to neonatal damage is multifactorial, being genital infections one of the causes. The objective of the study was to identify microorganisms of the maternal genital tract that are associated with neonatal damage, in order to prevent future perinatal complications. Seven hundred and eleven pregnant patients attended their prenatal control during the period January 2010-July 2013. Ureaplasma urealyticum and Mycoplasma hominis presence was investigated in umbilical cord blood by metabolic substrates (Micofast-Biomerieux) and that of T.vaginalis, by PCR using specific primers. The microbiological study of the vaginal contents of 288 pregnant patients at weeks 35 to 37 was performed by conventional methods, adding the modified thioglycolate culture for T.vaginalis. GroupB streptococcus (GBS) was investigated in anorectal and vaginal introitus swabs, using selective broth enrichment and subsequent isolation in chromogenic medium. The χ2 Yates test and Fisher's test were used for independent samples. A p value <0.05 was considered statistically significant. The pathogens significantly related to neonatal damage were M.hominis (p=0.03), T.vaginalis (p=0.03), and BV (p=0.02). Main complications were preterm birth, premature rupture of membranes (PRM), low weight and Apgar score ≤7. U.urealyticum (p=0.35), Candidaspp. (p=0.94) and GBS (p=0.18) were not related to neonatal damage. Since different microorganisms of the maternal genital tract were related to neonatal damage, it is very important to perform the microbiological study of vaginal contents during pregnancy to prevent possible maternal and perinatal complications.

Decreased relative risk of pneumococcal pneumonia during the last decade, a nested case-control study.

BACKGROUND: Streptococcus pneumoniae (SP) is one of the most common pathogens of Community-Acquired Pneumonia (CAP), but recent reports suggest that its incidence may be declining in relation to the use of the conjugate 13-valent pneumococcal vaccine in children. We compared the result of the immunochromatographic SP urinary antigen test (SPUAT) and clinical outcomes in patients with CAP admitted in two periods of time: 2001-2002(CAP1) and 2015-2016(CAP2). METHODS: This was a matched nested case-control study of two prospectively recorded cohorts of patients admitted with CAP, with SPUAT and blood culture performed in all patients. CAP2 cases and CAP1 controls were matched for age ± 4 years, sex, and Pneumonia Severity Index (PSI) score ± 10 points. Odds ratios (OR) for having SPUAT positive was estimated by conditional logistic regression. A multivariate model assessed the contribution of individual variables. RESULTS: Four hundred ninety-eight patients were recruited; 307 during the CAP1 and 191 during the CAP2 periods. Comparing both periods we observed differences, in age, PSI score, and the percentage of smokers, outpatients, previously immunized with pneumococcal vaccine, and positive SPUAT. On the other hand, mortality, admission from nursing homes, pneumococcal bacteremia and hospital admission were not different. After matching, pneumonia due to SP per the SPUAT was observed in 34(23.4%) of CAP1 and in 12(8.3%) of CAP2 patients (p < 0.001), and 6/145 CAP1 vs 33/145 CAP2 patients had received pneumococcal immunization before their admission (p < 0.001). A multivariate analysis confirmed that, independent of falling into PSI class 5, having not received the pneumococcal vaccine and having not survived the episode of pneumonia, there were two factors that increased the probability of having SPUAT positive: developing pneumonia during the CAP1 period (OR = 1.23) and having pneumococcal bacteremia (OR = 2.66). CONCLUSION: We observed a reduction of the role of SP as pathogen, along with an increase in the number of patients who received pneumococcal immunization before admission, in 2015-2016 compared to 2001-2002. In addition, the use of conjugate 13-valent vaccine, starting in 2012 for childhood immunization, could be an additional factor contributing to these changes, as a result of early herd immunity in adults pneumonia.

Characterized non-transient microbiota from stinkbug (Nezara viridula) midgut deactivates soybean chemical defenses.

The Southern green stinkbug (N. viridula) feeds on developing soybean seeds in spite of their strong defenses against herbivory, making this pest one of the most harmful to soybean crops. To test the hypothesis that midgut bacterial community allows stinkbugs to tolerate chemical defenses of soybean developing seeds, we identified and characterized midgut microbiota of stinkbugs collected from soybean crops, different secondary plant hosts or insects at diapause on Eucalyptus trees. Our study demonstrated that while more than 54% of N. viridula adults collected in the field had no detectable bacteria in the V1-V3 midgut ventricles, the guts of the rest of stinkbugs were colonized by non-transient microbiota (NTM) and transient microbiota not present in stinkbugs at diapause. While transient microbiota Bacillus sp., Micrococcus sp., Streptomyces sp., Staphylococcus sp. and others had low abundance, NTM microbiota was represented by Yokenella sp., Pantoea sp. and Enterococcus sp. isolates. We found some isolates that showed in vitro ß-glucosidase and raffinase activities plus the ability to degrade isoflavonoids and deactivate soybean protease inhibitors. Our results suggest that the stinkbugs´ NTM microbiota may impact on nutrition, detoxification and deactivation of chemical defenses, and Enterococcus sp., Yokenella sp. and Pantoea sp. strains might help stinkbugs to feed on soybean developing seeds in spite of its chemical defenses.

Ignavigranum ruoffiae, a rare pathogen that caused a skin abscess.

INTRODUCTION: Ignavigranum ruoffiae is an extremely rare cause of human infections. CASE PRESENTATION: An 83-year-old male with a painless, ten-day-old, erythematous skin abscess on his left flank, which had showed a purulent discharge for 48 h, was admitted to the Emergency service. He was treated with cephalexin, disinfection with Codex water and spray of rifampicin. Five days later, surgical drainage of the abscess was proposed due to the torpid evolution of the patient. Samples were taken for culture, and antibiotic treatment with trimethoprim-sulfamethoxazole was established. The patient returned after 10 days showing healing of the abscess. Microbiological studies showed a few Gram-positive cocci present as single cells and short chains that grew after 72 h of incubation at 35 °C with CO2 on 5 % sheep blood agar. Colonies presented a strong sauerkraut odour. Initial biochemical test results were negative for catalase, aesculin and bile-aesculin, and positive for pyrrolidonyl arylamidase, leucine aminopeptidase and growth in 6.5 % NaCl broth, which prompted the preliminary identification of Facklamia species or I. ruoffiae. The positive result for arginine deamination and negative result for hippurate hydrolysis, failure to produce acid from mannitol, sucrose, sorbitol or trehalose, plus the distinctive sauerkraut odour identified the organism as I. ruoffiae. The phenotypic identification was confirmed by 16S rRNA gene sequence analysis. The strain seemed to be susceptible to the antimicrobials tested but had decreased susceptibility to carbapenems. CONCLUSION: This case provides more insights into the phenotypic characteristics and antimicrobial resistance profile of I. ruoffiae.

Bifidobacterium scardovii aislado de 2 muestras consecutivas de orina / Bifidobacterium scardovii isolated from 2 consecutive urine samples

La especie Bifidobacterium scardovii está constituida por bacilos gram positivos anaerobios facultativos, cuyo desarrollo es estimulado por el CO2 y la anaerobiosis. Excepcionalmente se la ha asociado a infecciones humanas. Se presenta el caso de un paciente anoso con infección urinaria por B. scardovii y Enterococcus faecalis, ambos microorganismos aislados en 2 urocultivos consecutivos. El bacilo no desarrolló en los medios de cultivo habituales, pero sí en agar chocolate en CO2 y en agar Brucella suplementado, incubados durante 72 h a 35°C. La coloración de Gram alertó acerca de su presencia al observarse abundantes bacilos gram positivos irregulares con extremos bifurcados en forma de Y, y escasos cocos gram positivos. Es importante la coloración de Gram en orinas con piuria y la siembra en medios enriquecidos por tiempos prolongados. En este caso, sin el resultado del Gram y con el desarrollo de E. faecalis, no hubiésemos advertido la presencia del agente mayoritario.

Bifidobacterium scardovii species consists of facultative anaerobic gram-positive rods whose growth is stimulated by CO2 and anaerobiosis. Exceptionally it has been associated with infections in humans. An elderly male patient with a urinary tract infection due to B. scardovii and Enterococcus faecalis is presented here; both microorganisms were isolated from two consecutive urine samples. The bacillus did not grow on standard media, but on chocolate agar incubated in CO2 and on supplemented Brucella agar in an anaerobic atmosphere, incubated for 72 h at 35°C. Gram staining with abundant irregular gram-positive rods with Y-shaped ends and some gram-positive cocci alerted to its presence. The importance of the Gram stain test in urine samples with pyuria and the growth on enriched media for long periods is highlighted here. In this case, if we had not had the Gram stain test results, and had considered only the E. faecalis growth, we would have lost the major etiologic agent.

[Bifidobacterium scardovii isolated from 2 consecutive urine samples]. / Bifidobacterium scardovii aislado de 2 muestras consecutivas de orina.

Bifidobacterium scardovii species consists of facultative anaerobic gram-positive rods whose growth is stimulated by CO2 and anaerobiosis. Exceptionally it has been associated with infections in humans. An elderly male patient with a urinary tract infection due to B. scardovii and Enterococcus faecalis is presented here; both microorganisms were isolated from two consecutive urine samples. The bacillus did not grow on standard media, but on chocolate agar incubated in CO2 and on supplemented Brucella agar in an anaerobic atmosphere, incubated for 72h at 35°C. Gram staining with abundant irregular gram-positive rods with Y-shaped ends and some gram-positive cocci alerted to its presence. The importance of the Gram stain test in urine samples with pyuria and the growth on enriched media for long periods is highlighted here. In this case, if we had not had the Gram stain test results, and had considered only the E. faecalis growth, we would have lost the major etiologic agent.

Un caso inusual de quiste sebáceo infectado por Dermabacter hominis / Unusually infected sebaceous cyst by Dermabacter hominis

La especie Dermabacter hominis está constituida por bacilos gram positivos corineformes, anaerobios facultativos, que forman parte de la microbiota residente de la piel. Excepcionalmente se ha asociado a estos microorganismos con infecciones en pacientes inmunocomprometidos o muy debilitados. Se describe el caso de una mujer adulta joven, inmunocompetente, con un quiste sebáceo en el cuello, infectado por D. hominis como único agente etiológico. Se logró la identificación fenotípica del agente causal mediante pruebas simples basadas en el esquema originalmente propuesto por Funke y Bernard, factibles de ser realizadas en un laboratorio hospitalario de microbiología. Características fenotípicas como la morfología cocoide, el olor acre/espermático, la hidrólisis de la esculina, la producción de pirrolidonil arilamidasa y de lisina y ornitina descarboxilasas son pruebas claves en la identificación de D. hominis. La espectrometría de masas (MALDI-TOF MS) confirmó la identificación fenotípica.

Dermabacter hominis species is constituted by Gram positive facultative anaerobic coryneform rods being part of the resident microbiota human skin, and exceptionally associated to infections in immunocompromised or severely debilitated patients. An immunocompetent young adult woman with a neck sebaceous cyst infected by D. hominis as unique etiologic agent is presented. Phenotypic identification of the causative agent was achieved through simple tests, based on the originally scheme proposed by Funke and Bernard, and feasible to be performed in a hospital Microbiology Laboratory. Phenotypic characteristics as coccoid morphology, the acrid/spermatic odor, esculin hydrolysis, the production of pyrrolidonyl-arylamidase, lysine and ornithine decarboxylase, are key tests to identify D. hominis. The matrix-asisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) confirmed the phenotypic identification.

[Unusually infected sebaceous cyst by Dermabacter hominis]. / Un caso inusual de quiste sebáceo infectado por Dermabacter hominis.

Dermabacter hominis species is constituted by Gram positive facultative anaerobic coryneform rods being part of the resident microbiota human skin, and exceptionally associated to infections in immunocompromised or severely debilitated patients. An immunocompetent young adult woman with a neck sebaceous cyst infected by D. hominis as unique etiologic agent is presented. Phenotypic identification of the causative agent was achieved through simple tests, based on the originally scheme proposed by Funke and Bernard, and feasible to be performed in a hospital Microbiology Laboratory. Phenotypic characteristics as coccoid morphology, the acrid/spermatic odor, esculin hydrolysis, the production of pyrrolidonyl-arylamidase, lysine and ornithine decarboxylase, are key tests to identify D. hominis. The matrix-asisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) confirmed the phenotypic identification.

Intra-abdominal infections due to Comamonas kerstersii.

Herein, we report four cases of Comamonas kerstersii intra-abdominal infections representing the first report of human infections caused by this Comamonas species. In addition, our work demonstrates the association of C. kerstersii with peritonitis secondary to appendix rupture.

Is a strategy based on routine endotracheal cultures the best way to prescribe antibiotics in ventilator-associated pneumonia?

OBJECTIVES: The objectives of this study were to evaluate if a strategy based on routine endotracheal aspirate (ETA) cultures is better than using the American Thoracic Society/Infectious Diseases Society of America (ATS/IDSA) guidelines to prescribe antimicrobials in ventilator-associated pneumonia (VAP). METHODS: This was a prospective, observational, cohort study conducted in a 15-bed ICU and comprising 283 patients who were mechanically ventilated for ≥48 h. Interventions included twice-weekly ETA; BAL culture was done if VAP was suspected. BAL (collected at the time of VAP) plus ETA cultures (collected≤7 days before VAP) (n=146 different pairs) were defined. We compared two models of 10 days of empirical antimicrobials (ETA-based vs ATS/IDSA guidelines-based strategies), analyzing their impact on appropriateness of therapy and total antimicrobial-days, using the BAL result as the standard for comparison. RESULTS: Complete ETA and BAL culture concordance (identical pathogens or negative result) occurred in 52 pairs; discordance (false positive or false negative) in 67, and partial concordance in two. ETA predicted the etiology in 62.4% of all pairs, in 74.0% of pairs if ETA was performed≤2 days before BAL, and in 46.2% of pairs if ETA was performed 3 to 7 days before BAL (P=.016). Strategies based on the ATS/IDSA guidelines and on ETA results led to appropriate therapy in 97.9% and 77.4% of pairs, respectively (P<.001). The numbers of antimicrobial-days were 1,942 and 1,557 for therapies based on ATS/IDSA guidelines and ETA results, respectively (P<.001). CONCLUSIONS: The ATS/IDSA guidelines-based approach was more accurate than the ETA-based strategy for prescribing appropriate, initial, empirical antibiotics in VAP, unless a sample was available≤2 days of the onset of VAP. The ETA-based strategy led to fewer days on prescribed antimicrobials.