[Sporotrichoid nocardiosis by Nocardia brasiliensis]. / Nocardiosis esporotricoide por Nocardia brasiliensis.

Nocardia brasiliensis is a gram-positive, branched, aerobic, acid-resistant, rod-shaped bacillus that inhabits in soil, rotten organic matter and waters. Cutaneous nocardiosis in immunocompetent individuals can manifest in three different forms: actinomycetoma, superficial skin infection or lymphocutaneous infection. A case of an 85-year-old woman with an ulcerated lesion on the back of her left hand with erythematous papules in the lymphatic tract infected by N. brasiliensis is described. The microorganism was presumptively identified by conventional and inexpensive methods for a medium complexity laboratory at the species level. The morphological characteristics of colonies, the mold smell, a positive Kinyoun stain and the presence of aerial mycelium were the key tests to identify the genus. Species level identification was confirmed by mass spectrometry (MALDI-TOF MS). The trimethoprim-sulfamethoxazole treatment was effective as this agent was active in the susceptibility testing.

Identification and molecular epidemiology of methicillin resistant Staphylococcus pseudintermedius strains isolated from canine clinical samples in Argentina.

BACKGROUND: Staphylococcus pseudintermedius is the leading cause of pyoderma in dogs and the frequent use of antimicrobial treatment is associated to the development of resistance to nearly all classes of antibiotics. Despite S. pseudintermedius significance, our understanding of the molecular mechanism of ß-lactam resistance and its genetic diversity remains limited. We aimed to: i) determine the phenotypic resistance profile of methicillin resistant Staphylococcus pseudintermedius (MRSP) isolated from infected dogs in three different veterinary hospitals in Buenos Aires, Argentina; ii) identify the SCCmec elements and resistance genes; and iii) analyze the clonal relationship between isolates and in regard of dominant lineages found in the world. RESULTS: In addition to the differential levels of ß-lactam resistance, MRSP isolates (n = 10) showed resistance to 5-6 families of antibiotics, and were therefore categorized as multidrug-resistant. All the isolates were variant of SCCmec V homologous to S. aureus; additional SCCmecFinder analysis classified five of the genomes as SCCmec type V (5C2&5) with mecA (encodes for PBP2a), mecRI and mecI and all the genes closely related to the reference SCCmec type V S. aureus TSGH17 strain. In the remaining five strains, mecA was present, although other genes associated with SCCmec V including mecR1 and mecI were missing. PBP2a was inducible in low level resistance strains (MRSP 8151), and constitutively expressed in MRSP 8150, suggesting different mecA regulatory mechanisms. MRSP isolates showed significant genetic diversity: eight PFGE clonal types and six multilocus-sequence typing (MLST) sequence types (STs) (339, 649, 919, 920, 921 and 922), including four new STs genetically distinct from STs reported in other geographic areas. Comparative genomics and phylogenetic analyses of the MRSP showed a correlation between the genetic content and the phenotypes, and established the genetic relationship between the isolates. CONCLUSIONS: MRSP could be a threat to animal health due to it concerning level of antimicrobial resistance. Our study highlights genetic and epidemiological aspects of multidrug-resistant MRSP strains from Argentina showing high degree of correlation between the resistance genes and the phenotype of the isolates and, furthermore, they appeared evolutionary closer to major worldwide reported ST68 and ST71.

[KPC-producing Klebsiella pneumoniae colonization at a University Hospital]. / Colonización por Klebsiella pneumoniae productora de carbapenemasa tipo KPC en un Hospital Universitario.

A surveillance study was conducted at a University Hospital in Buenos Aires City aimed to assess the rates of colonization with carbapenemase-producing strains of Klebsiella pneumoniae, which are bacteria of utmost epidemiological importance. To this end, rectal swabs collected from all inpatients were cultured for the presence of these bacteria. Two point prevalence surveys showed high prevalence rates (up to 25%). The following variables were evaluated in all inpatients: place of origin (home or other chronic care center), age, prolonged hospitalization, antibiotics for at least 72 hours prior to swabbing, intensive care unit requirements for at least 24 hours, mechanical ventilation assistance for more than 4 days, hemodialysis requirements, need for surgery, enteral feeding through a nasogastric tube, and functional evaluation according to the Karnofsky performance scale. The variable associated with the highest statistical significance was the use of nasogastric enteral feeding. Also, the length of stay was significantly higher and the functional status was significantly worse in colonized patients. As for the prior use of antibiotics, results were close to statistical significance but without reaching it. Measures were implemented in order to control the spread of the microorganism in the acute setting and beyond. Upon implementation of such measures, a third prevalence survey was performed that showed a decrease in the horizontal transmission of the microorganism.

[Anaerobiospirillum succiniciproducens and Desulfovibrio desulfuricans in 2 cases of insidious bacteremia]. / Anaerobiospirillum succiniciproducens y Desulfovibrio desulfuricans en 2 casos de bacteriemias insidiosas.

Two cases of insidious bacteremia by uncommon curve and spiral-shaped, motile anaerobic gram-negative rods are presented. Both of them were of an unclear origin and occurred in immunosuppressed patients with simultaneous diseases. The key tests for the identification of Anaerobiospirillum were its micromorphology, a strictly anaerobic condition, negative catalase activity, the special-potency disk profile, glucose fermentation, and ß-NAG production. Desulfovibrio species was identified by all the above preliminary tests but with a different disk profile, as well as for being asaccharolytic and desulfoviridin and H2S producer. We here alert about the resistance or intermediate susceptibility of Anaerobiospirillum succiniciproducens against antimicrobial agents, such as metronidazole, one of the first-line drugs used for the treatment of anaerobic gram-negative infections. Aminopenicillins with ß-lactamase-inhibitor combinations and imipenem were active for this agent. Desulfovibrio desulfuricans was ß-lactamase producer and resistant to cephalosporins, while metronidazole, imipenem and levofloxacin were active. A reliable identification of these microorganisms is important for establishing the best therapeutic scheme.

[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.

[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.

[Consenso Argentino Intersociedades de Infección Urinaria 2018-2019 - Parte I]. / Argentine Intersociety Consensus on Urinary Infection 2018-2019 - Part I.

The Argentine Society of Infectious Diseases and other scientific societies have updated these recommendations based on data on urinary tract infections in adults obtained from a prospective multicenter study conducted in Argentina during 2016-2017. Asymptomatic bacteriuria should be treated only in pregnant women, who should also be systematically investigated; the antibiotics of choice are nitrofurantoin, amoxicillin, clavulanic/amoxicillin, cephalexin and trimethoprim-sulfamethoxazole. In procedures involving injury to the urinary tract with bleeding, it is recommended to request urine culture and, in the presence of bacteriuria, antimicrobial treatment according to sensitivity should be prescribed from immediately before up to 24 hours after the intervention. In women, cystitis can be treated with nitrofurantoin, cephalexin or fosfomycin, while trimethoprim-sulfamethoxazole and fluoroquinolones are not recommended; pyelonephritis can be treated with ciprofloxacin, cefixime or cephalexin in ambulatory women or ceftriaxone, cefazolin or amikacin in those who are hospitalized. In men, urinary tract infections are always considered complicated; nitrofurantoin or cephalexin are recommended for 7 days, alternatively fosfomycin should be given in a single dose. In men, ciprofloxacin, ceftriaxone or cefixime are suggested for pyelonephritis on ambulatory treatment whereas ceftriaxone or amikacin are recommended for hospitalized patients. Acute bacterial prostatitis can be treated with ceftriaxone or gentamicin. Fluoroquinolones were the choice treatment for chronic bacterial prostatitis until recently; they are no longer recommended due to the increasing resistance and recent concerns regarding the safety of these drugs; alternative antibiotics such as fosfomycin are to be considered.

La Sociedad Argentina de Infectología y otras sociedades científicas han actualizado estas recomendaciones utilizando, además de información internacional, la de un estudio multicéntrico prospectivo sobre infecciones del tracto urinario del adulto realizado en Argentina durante 2016-2017. La bacteriuria asintomática debe ser tratada solo en embarazadas, a quienes también se las debe investigar sistemáticamente; los antibióticos de elección son nitrofurantoína, amoxicilina, amoxicilina-clavulánico, cefalexina y trimetoprimasulfametoxazol. Ante procedimientos que impliquen lesión con sangrado del tracto urinario se recomienda solicitar urocultivo para pesquisar bacteriuria asintomática, y, si resultara positivo, administrar antimicrobianos según sensibilidad desde inmediatamente antes hasta 24 horas luego de la intervención. En mujeres, la cistitis puede ser tratada con nitrofurantoina, cefalexina, o fosfomicina y no se recomienda usar trimetoprima-sulfametoxazol o fluoroquinolonas; en pielonefritis puede emplearse ciprofloxacina, cefixima o cefalexina si el tratamiento es ambulatorio o ceftriaxona, cefazolina o amikacina si es hospitalario. En los hombres, las infecciones del tracto urinario se consideran siempre complicadas. Se recomienda tratamiento con nitrofurantoina o cefalexina por 7 días, o bien monodosis con fosfomicina. Para la pielonefritis en hombres se sugiere ciprofloxacina, ceftriaxona o cefixima si el tratamiento es ambulatorio y ceftriaxona o amikacina si es hospitalario. Se sugiere tratar las prostatitis bacterianas agudas con ceftriaxona o gentamicina. En cuanto a las prostatitis bacterianas crónicas, si bien su tratamiento de elección hasta hace poco fueron las fluoroquinolonas, la creciente resistencia y ciertas dudas sobre la seguridad de estas drogas obligan a considerar el uso de alternativas como fosfomicina.

Changing epidemiology of KPC-producing Klebsiella pneumoniae in Argentina: Emergence of hypermucoviscous ST25 and high-risk clone ST307.

OBJECTIVES: To assess the epidemiological features of 76 Klebsiella pneumoniae carbapenemase (KPC)-producing Klebsiella pneumoniae (KPC-Kp) isolates recovered from three hospitals in Buenos Aires, Argentina, during 2015-2017. METHODS: Antimicrobial susceptibilities were determined according to CLSI Clinical and Laboratoy Standards guidelines. Molecular typing of KPC-Kp was performed by pulsed-field gel electrophoresis (PFGE)-Xbal and multilocus sequence typing. Plasmid encoded genes involved in carbapenem, fosfomycin and colistin resistance were detected by polymerase chain reaction (PCR) and sequencing. Also, mgrB inactivation was investigated in those colistin-resistant isolates. Genetic platforms involved in horizontal spread of blaKPC were investigated by PCR mapping. RESULTS: Besides ß-lactams, high resistance rates were observed for gentamycin, quinolones and trimethoprim-sulfamethoxazole. KPC-Kp sequence type (ST)258 corresponded to 26% of the isolates, while 42% corresponded to ST25. The other isolates were distributed in a diversity of lineages such as ST11 (10.5%), ST392 (10.5%), ST307, ST13, ST101, ST15 and ST551. blaKPC-2 was detected in 75 of 76 isolates, and one ST307 isolate harboured blaKPC-3. Tn4401 was identified as the genetic platform for blaKPC in epidemic lineages such as ST258 and ST307. However, in ST25 and ST392, which are usually not related to blaKPC, a blaKPC-bearing non-Tn4401 element was identified. Alterations in mgrB were detected in seven of 11 colistin-resistant isolates. CONCLUSIONS: Despite previous reports in Argentina, ST258 is no longer the absolute clone among KPC-Kp isolates. In the present study, dissemination of more virulent lineages such as the hypermucoviscous ST25 was detected. The emergence of the high-risk clone ST307 and occurrence of blaKPC-3 was noticed for the first time in this region.

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.

Consenso Argentino intersociedades de Infección Urinaria 2018-2019 - Parte I / Consenso Argentino Intersociedades de Infección Urinaria 2018-2019 - Parte I

La Sociedad Argentina de Infectología y otras sociedades científicas han actualizado estas recomendaciones utilizando, además de información internacional, la de un estudio multicéntrico prospectivo sobre infecciones del tracto urinario del adulto realizado en Argentina durante 2016-2017. La bacteriuria asintomática debe ser tratada solo en embarazadas, a quienes también se las debe investigar sistemáticamente; los antibióticos de elección son nitrofurantoína, amoxicilina, amoxicilina-clavulánico, cefalexina y trimetoprima-sulfametoxazol. Ante procedimientos que impliquen lesión con sangrado del tracto urinario se recomienda solicitar urocultivo para pesquisar bacteriuria asintomática, y, si resultara positivo, administrar antimicrobianos según sensibilidad desde inmediatamente antes hasta 24 horas luego de la intervención. En mujeres, la cistitis puede ser tratada con nitrofurantoina, cefalexina, o fosfomicina y no se recomienda usar trimetoprima-sulfametoxazol o fluoroquinolonas; en pielonefritis puede emplearse ciprofloxacina, cefixima o cefalexina si el tratamiento es ambulatorio o ceftriaxona, cefazolina o amikacina si es hospitalario. En los hombres, las infecciones del tracto urinario se consideran siempre complicadas. Se recomienda tratamiento con nitrofurantoina o cefalexina por 7 días, o bien monodosis con fosfomicina. Para la pielonefritis en hombres se sugiere ciprofloxacina, ceftriaxona o cefixima si el tratamiento es ambulatorio y ceftriaxona o amikacina si es hospitalario. Se sugiere tratar las prostatitis bacterianas agudas con ceftriaxona o gentamicina. En cuanto a las prostatitis bacterianas crónicas, si bien su tratamiento de elección hasta hace poco fueron las fluoroquinolonas, la creciente resistencia y ciertas dudas sobre la seguridad de estas drogas obligan a considerar el uso de alternativas como fosfomicina.

The Argentine Society of Infectious Diseases and other scientific societies have updated these recommendations based on data on urinary tract infections in adults obtained from a prospective multicenter study conducted in Argentina during 2016-2017. Asymptomatic bacteriuria should be treated only in pregnant women, who should also be systematically investigated; the antibiotics of choice are nitrofurantoin, amoxicillin, clavulanic/amoxicillin, cephalexin and trimethoprim-sulfamethoxazole. In procedures involving injury to the urinary tract with bleeding, it is recommended to request urine culture and, in the presence of bacteriuria, antimicrobial treatment according to sensitivity should be prescribed from immediately before up to 24 hours after the intervention. In women, cystitis can be treated with nitrofurantoin, cephalexin or fosfomycin, while trimethoprim-sulfamethoxazole and fluoroquinolones are not recommended; pyelonephritis can be treated with ciprofloxacin, cefixime or cephalexin in ambulatory women or ceftriaxone, cefazolin or amikacin in those who are hospitalized. In men, urinary tract infections are always considered complicated; nitrofurantoin or cephalexin are recommended for 7 days, alternatively fosfomycin should be given in a single dose. In men, ciprofloxacin, ceftriaxone or cefixime are suggested for pyelonephritis on ambulatory treatment whereas ceftriaxone or amikacin are recommended for hospitalized patients. Acute bacterial prostatitis can be treated with ceftriaxone or gentamicin. Fluoroquinolones were the choice treatment for chronic bacterial prostatitis until recently; they are no longer recommended due to the increasing resistance and recent concerns regarding the safety of these drugs; alternative antibiotics such as fosfomycin are to be considered.

Colonización por Klebsiella pneumoniae productora de carbapenemasa tipo KPC en un hospital universitario / KPC-producing Klebsiella pneumoniae colonization at a University Hospital

Se realizó un estudio de vigilancia en un Hospital Universitario de la Ciudad Autónoma de Buenos Aires con el fin de determinar la prevalencia de colonización por cepas de Klebsiella pneumoniae productora de carbapenemasa, bacterias de gran importancia epidemiológica. A tal fin, se investigó su presencia en cultivos de hisopados rectales de todos los pacientes internados. Se realizaron dos cortes de prevalencia en los cuales se encontraron tasas de hasta 25%. Además, se analizaron las siguientes variables en toda la población estudiada: procedencia (domicilio u otro centro de cuidados crónicos), edad, internación prolongada, uso de antibióticos por al menos 72 horas previas al hisopado, internación en unidad de terapia intensiva, requerimientos de hemodiálisis, necesidad de cirugía, alimentación enteral mediante sonda nasogástrica, asistencia respiratoria mecánica por más de 4 días y evaluación funcional según escala de Karnofsky. La variable asociada a la colonización con mayor significación estadística fue el uso de sonda nasogástrica para alimentación enteral. Además, se observó que el tiempo de internación fue significativamente mayor y la clase funcional fue peor en los pacientes colonizados. En cuanto al uso previo de antibióticos se obtuvieron valores cercanos a la significación estadística, aunque sin alcanzarla. Con base en las variables evaluadas se implementaron medidas de contingencia con el fin de controlar la diseminación del microorganismo. Finalmente, se realizó un tercer corte de prevalencia durante la implementación de dichas medidas, el cual mostró una disminución en la transmisión horizontal del microorganismo.

A surveillance study was conducted at a University Hospital in Buenos Aires City aimed to assess the rates of colonization with carbapenemase-producing strains of Klebsiella pneumoniae, which are bacteria of utmost epidemiological importance. To this end, rectal swabs collected from all inpatients were cultured for the presence of these bacteria. Two point prevalence surveys showed high prevalence rates (up to 25%). The following variables were evaluated in all inpatients: place of origin (home or other chronic care center), age, prolonged hospitalization, antibiotics for at least 72 hours prior to swabbing, intensive care unit requirements for at least 24 hours, mechanical ventilation assistance for more than 4 days, hemodialysis requirements, need for surgery, enteral feeding through a nasogastric tube, and functional evaluation according to the Karnofsky performance scale. The variable associated with the highest statistical significance was the use of nasogastric enteral feeding. Also, the length of stay was significantly higher and the functional status was significantly worse in colonized patients. As for the prior use of antibiotics, results were close to statistical significance but without reaching it. Measures were implemented in order to control the spread of the microorganism in the acute setting and beyond. Upon implementation of such measures, a third prevalence survey was performed that showed a decrease in the horizontal transmission of the microorganism.

Anaerobiospirillum succiniciproducens y Desulfovibrio desulfuricans en 2 casos de bacteriemias insidiosas / Anaerobiospirillum succiniciproducens and Desulfovibrio desulfuricans in 2 cases of insidious bacteremia

Se presentan 2 casos de bacteriemias insidiosas por bacilos gram negativos anaerobios curvos, espiralados, móviles e infrecuentes en pacientes atendidos en un hospital de la ciudad de Buenos Aires. Estas bacteriemias, asociadas al aislamiento de Anaerobiospirillum y Desulfovibrio, fueron de origen poco claro y afectaron a pacientes inmunocomprometidos, con patologías simultáneas. Pruebas claves en la identificación del género Anaerobiospirillum fueron el estudio de la micromorfología, su carácter de anaerobio estricto, el resultado negativo en la prueba de catalasa, el patrón de discos de interés taxonómico, la fermentación de glucosa y la producción de β-N-acetilglucosaminidasa. El género Desulfovibrio se diferenció por el perfil presentado en las pruebas con discos, por ser asacarolítico, sin actividad de enzimas glucosídicas, y por producir desulfoviridina y H2S. Se alerta sobre la resistencia o sensibilidad intermedia de Anaerobiospirillum succiniciproducens (especie a la que correspondió el aislado de Anaerobiospirillum) a algunos de los antimicrobianos de primera línea frente a bacilos gram negativos anaerobios, como el metronidazol; fueron activas las combinaciones de aminopenicilinas con inhibidores de β-lactamasas y el imipenem. Desulfovibrio desulfuricans (especie a la que correspondió el aislado de Desulfovibrio) fue productora de β-lactamasas y resistente a las cefalosporinas; en cambio, fueron activos el metronidazol, el imipenem y la levofloxacina. La identificación confiable de estos microorganismos orienta hacia el mejor esquema terapéutico.

Two cases of insidious bacteremia by uncommon curve and spiral-shaped, motile anaerobic gram-negative rods are presented. Both of them were of an unclear origin and occurred in immunosuppressed patients with simultaneous diseases. The key tests for the identification of Anaerobiospirillum were its micromorphology, a strictly anaerobic condition, negative catalase activity, the special-potency disk profile, glucose fermentation, and β-NAG production. Desulfovibrio species was identified by all the above preliminary tests but with a different disk profile, as well as for being asaccharolytic and desulfoviridin and H2S producer. We here alert about the resistance or intermediate susceptibility of Anaerobiospirillum succiniciproducens against antimicrobial agents, such as metronidazole, one of the first-line drugs used for the treatment of anaerobic gram-negative infections. Aminopenicillins with β-lactamase-inhibitor combinations and imipenem were active for this agent. Desulfovibrio desulfuricans was β-lactamase producer and resistant to cephalosporins, while metronidazole, imipenem and levofloxacin were active. A reliable identification of these microorganisms is important for establishing the best therapeutic scheme.

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.

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.

Five-test simple scheme for species-level identification of clinically significant coagulase-negative staphylococci.

A working scheme developed in our laboratory for identification (by species group and species) of coagulase-negative staphylococci (CNS) was evaluated with 201 consecutive isolates and then validated by using the reference method of Kloos and Schleifer (W. E. Kloos and K. H. Schleifer, J. Clin. Microbiol. 1:82-88, 1975). This five-test simple scheme (referred to here as the simple scheme) combines the novobiocin susceptibility test with tests for urease, pyrrolidonyl arylamidase, ornithine decarboxylase, and aerobic acid from mannose. The addition of one or two tests within a particular species group could then positively identify the isolate. Two commercial systems, Staph-Zym (Rosco) and API-Staph (bioMérieux), along with results obtained by using Rosco diagnostic tablets (nongrowth tests), were also compared with the reference method. One isolate could not be identified even by the reference method. Of the remaining 200 strains, 191 (95.5%) strains were correctly identified with Staph-Zym and 171 strains (85.5%) were correctly identified with API-Staph. The most frequent clinical CNS species isolated were Staphylococcus epidermidis (50.5%), S. haemolyticus (18.5%), S. saprophyticus subsp. saprophyticus (16.0%), S. lugdunensis (6.0%), and S. warneri (2.5%). The simple scheme validated with the reference method has demonstrated an excellent correlation in the identification of the three most frequent species isolated: S. epidermidis, S. haemolyticus, and S. saprophyticus subsp. saprophyticus. With the simple scheme, identification of CNS was possible within 24 h after the enzymatic tests were used, whereas up to 72 h is necessary for the growth tests. This methodology would be very useful in any clinical microbiology laboratory for the presumptive identification of CNS species groups and species.