Fluoroquinolone-resistant Streptococcus agalactiae isolates from Argentina.

Fluoroquinolone resistance is a growing problem that has only recently emerged in S. agalactiae. Between 2005-2007, WHONET--Argentina network evaluated levofloxacin susceptibility in 1128 clinical S. agalactiae isolates, 10 (0.9%) of which proved to be resistant. Nine of them had come from 5 hospitals (in Buenos Aires City and 4 Argentinean provinces) and recovered from urine (n=7) and vaginal screening cultures (n=2). Three strains were also resistant to macrolides, lincosamides and B streptogramins due to the ermA gene. All nine fluoroquinolone-resistant isolates bore the same two mutations, Ser79Phe in ParC and Ser81Leu in GyrA proteins. Genetic relationships were analyzed by Apal-PFGE and two clones were determined, A (n=6) and B (n=3). To our knowledge, these are the first fluoroquinolone-resistant S. agalactiae isolates detected in Latin America.

First report of VanA Enterococcus gallinarum dissemination within an intensive care unit in Argentina.

Enterococcusgallinarum is intrinsically resistant to low levels of vancomycin and has been described as a colonizing microorganism causing bacteraemia and infection among immunosupresed patients. Between August 2000 and February 2001, 15 highly glycopeptide-resistant E. gallinarum isolates, one from blood and the remaining from rectal swabs, were recovered in a general hospital of Buenos Aires Province, Argentina. All isolates were characterized by biochemical assays, and displayed MICs of vancomycin in the range 16-128 mg/l and MICs of teicoplanin in the range 16-32 mg/l. In all cases, PCR analysis yield positive results for both vanC1 and vanA genes. E. gallinarum isolates were classified as two clonal types by SmaI-PFGE: clone A (n = 8) and clone B (n = 7) and both harboured a transferable vanA element.

[Clinical and epidemiologic analysis of intestinal tract colonization with vancomycin-resistant enterococci in an intensive care unit]. / Análisis clínico-epidemiológico de la portación intestinal de enterococos resistentes a vancomicina en una unidad de terapia intensiva.

Intestinal tract colonization with vancomycin resistant enterococci (VRE) was studied during five months and 25 days. Out of 171 patients hospitalized in the intensive care unit, 124 (73%) were included in this study. Thirty five of them (28%) were recognized as colonized with VRE. VRE isolates (n = 35) were identified as Enterococcus faecium (n = 18), Enterococcus gallinarum (n = 16), and Enterococcus raffinosus (n = 1). All of them were resistant to vancomycin (MIC90 = 512 microg/ml) and to teicoplanin (MIC90 = 32 microg/ml), having the vanA gene. By means of molecular methods a high homology was found among E. faecium and E. gallinarum isolates, respectively, suggesting their spread as a kind of outbreak. No significant differences in age or sex were found among colonized and non-colonized patients (p > 0.05). On the other hand, the hospitalization time and the use of broad-spectrum antibiotics were associated with colonization. From this study we highlight the importance of enhancing all measures of control and prevention of hospital infections, carefully analyzing the empiric antimicrobial schemes, trying to reduce the hospital stage, and following the surveillance to evaluate the efficacy of such procedures.

[Bacteremia caused by Enterococcus gallinarum with a high level of glycopeptide resistance: 1st documented cases in Argentina]. / Bacteriemia por Enterococcus gallinarum con alto nivel de resistencia a glicopéptidos: primer caso documentado en Argentina.

A case of bacteremia due to high-level-vancomycin- (MIC = 64 micrograms/ml) and high-level-teicoplanin- (MIC = 32 micrograms/ml) resistant Enterococcus gallinarum is described. Both genes, van C1 and van A, respectively conferring natural low-level resistance and acquired high-level resistance to vancomycin, were found in the enterococcal genoma. The present is the first report of an E. gallinarum isolate showing the van A genotype in Argentina.

[Analysis of the MGTI (Mycobacteria Growth Indicator Tube) system in the primary isolation of mycobacteria]. / Análisis del sistema MGIT (Mycobacteria Growth Indicator Tube) en el aislamiento primario de micobacterias.

The advantages of Mycobacteria Growth Indicator Tube (MGIT) system were analyzed and compared to Löwenstein-Jensen (LJ) and Stonebrink (S) solid media when searching for a fast method to diagnose tuberculosis and mycobacterioses, which should be easy to perform in laboratories and of non-invasive reading. All nonsterile specimens were pretreated with Petroff method. A total of 191 specimens were processed (among which 152 were pulmonary and 39 extrapulmonary). Twenty-nine tested positive by one of the methods employed. The rate of recovery of smear positive specimens (ED+) was of 92% with LJ/S, and 85% with MGIT. The mean time to detect a positive result was 18.7 days with MGIT, and 20.6 days with LJ/S. The rate of recovery of smear negative specimens (ED-) was 88.2% with LJ, 70.6% with S, and 23.5% with MGIT. The mean time to detect a positive result were 38.5; 26.5 and 29 days, respectively. During this experiment, MGIT did not seem to have any advantage over the traditional methods, particularly when working with samples containing a low number of bacilli (p < 0.05). It is obviously necessary to make a comparative study with a large amount of cases which might support this observation and to analyze the influence of the reagents employed in the pre-treatment of the specimens on the MGIT system's efficacy to detect mycobacteria.

[Activity of 14 antimicrobials against Eikenella corrodens]. / Actividad de catorce antimicrobianos sobre Eikenella corrodens.

Eikenella corrodens is a gram-negative bacillus that colonizes as normal flora of the mouth, the upper respiratory tract and the gastrointestinal tract. The aim of this study was to determine the susceptibility patterns against fourteen antibiotics of 25 E. corrodens strains isolated at our hospital. MICs were determined by the agar dilution technique using Müeller-Hinton agar with sheep blood (5% v/v) to penicillin, ampicillin, ampicillin-sulbactam, cephalotin, cefoxitin, ceftiaxone, colistin, gentamicin, amikacin, erythromycin, rifampin, ciprofloxacin and clindamycin. The most active antibiotics were ciprofloxacin and ceftriaxone (MIC90 = 0.008 and 0.125 microgram/ml, respectively), whereas eritromycin, gentamicin and amikacin showed less activity. Only one strain was beta lactamase positive, and it was inhibited by sulbactam. Erithromycin, gentamicin and amikacin had poor activity (MIC90 = 16.8 and 64 micrograms/ml, respectively), whereas all the strains were uniformly resistant to clindamycin (MIC > or = 32 micrograms/ml). We suggest about the need of periodical surveys of E. corrodens susceptibility patterns, since strains have been found with decreased susceptibility against antibiotics which are currently being used for the treatment of infectious diseases.

[False-positive cultures due to cross contamination in tuberculosis laboratories]. / Falsos cultivos positivos por contaminación cruzada en laboratorios de tuberculosis.

Fifteen episodes of Mycobacterium tuberculosis laboratory cross-contamination suspected between 1996 and 2001 at 6 laboratories in Buenos Aires City and suburbs were investigated by IS6110 RFLP. Thirteen episodes were confirmed. Even though BACTEC 460 produced the highest number of confirmed episodes in a single laboratory, the most extended one occurred while employing conventional culture procedures in solid medium. The double repetitive element-polymerase chain reaction (DRE-PCR) was applied to 8 of these episodes and produced concordant results with those of the RFLP. The DRE-PCR appears to be a valuable tool for the prompt identification of false positive cultures. The timely rectification of defects in laboratory protocols can avert false diagnoses of tuberculosis and unnecessary prolonged treatments.

Análisis clínico-epidemiológico de la portación intestinal de enterococos resistentes a vancomicina en una unidad de terapia intensiva / Clinical and epidemiologic analysis of intestinal tract colonization with vancomycin-resistant enterococci in an intensive care unit

En un período de cinco meses y 25 días se investigó la portación intestinal de enterococos resistentes a vancomicina (EVR). Se estudiaron 124 pacientes (73%) de 171 admitidos en la unidad de terapia intensiva (UTI), 35 de los cuales (28%) resultaron ser portadores. Los aislamientos de EVR (n=35) fueron identificados como Enterococcus faecium (n=18), Enterococcus gallinarum (n=16) y Enterococcus raffinosus (n=1). Todos los aislamientos estudiados fueron resistentes a vancomicina (VAN) (CIM90= 512 µg/ml) y teicoplanina (CIM90= 32 µg/ml) y portaban el gen vanA. Los estudios de tipificación molecular mostraron un alto grado de homología entre los aislamientos de E. faecium (un clon dominante) y E. gallinarum (dos tipos clonales), sugiriendo su diseminación a modo de brote. No se encontraron diferencias significativas con la edad y el sexo de los pacientes no portadores (p>0,05), pero si con el tiempo de hospitalización y el uso de esquemas antibióticos de amplio espectro (p<0,05), estando estos dos factores asociados al estado de portación. Se deduce de este estudio, la importancia de maximizar las medidas de prevención y control de las infecciones nosocomiales, analizar los esquemas empíricos empleados, tratar de disminuir el tiempo de hospitalización y continuar con los estudios de vigilancia para evaluar la eficacia de las acciones implementadas.

Intestinal tract colonization with vancomycin resistant enterococci (VRE) was studied during five months and 25 days. Out of 171 patients hospitalized in the intensive care unit, 124 (73%) were included in this study. Thirty five of them (28%) were recognized as colonized with VRE. VRE isolates (n = 35) were identified as Enterococcus faecium (n=18), Enterococcus gallinarum (n=16), and Enterococcus raffinosus (n=1). All of them were resistant to vancomycin (MIC90= 512 µg/ml) and to teicoplanin (MIC90= 32 µg/ml), having the vanA gene. By means of molecular methods a high homology was found among E. faecium and E. gallinarum isolates, respectively, suggesting their spread as a kind of outbreak. No significant differences in age or sex were found among colonized and non-colonized patients (p>0.05). On the other hand, the hospitalization time and the use of broad-spectrum antibiotics were associated with colonization. From this study we highlight the importance of enhancing all measures of control and prevention of hospital infections, carefully analyzing the empiric antimicrobial schemes, trying to reduce the hospital stage, and following the surveillance to evaluate the efficacy of such procedures.

Análisis del sistema MGIT (Mycobacteria Growth Indicator Tube) en el aislamiento primario de micobacterias / Analysis of the MGTI (Mycobacteria Growth Indicator Tube) system in the primary isolation of mycobacteria

The advantages of Mycobacteria Growth Indicator Tube (MGIT) system were analyzed and compared to L÷wenstein-Jensen (LJ) and Stonebrink (S) solid media when searching for a fast method to diagnose tuberculosis and mycobacterioses, which should be easy to perform in laboratories and of non-invasive reading. All nonsterile specimens were pretreated with Petroff method. A total of 191 specimens were processed (among which 152 were pulmonary and 39 extrapulmonary). Twenty-nine tested positive by one of the methods employed. The rate of recovery of smear positive specimens (ED+) was of 92 with LJ/S, and 85 with MGIT. The mean time to detect a positive result was 18.7 days with MGIT, and 20.6 days with LJ/S. The rate of recovery of smear negative specimens (ED-) was 88.2 with LJ, 70.6 with S, and 23.5 with MGIT. The mean time to detect a positive result were 38.5; 26.5 and 29 days, respectively. During this experiment, MGIT did not seem to have any advantage over the traditional methods, particularly when working with samples containing a low number of bacilli (p < 0.05). It is obviously necessary to make a comparative study with a large amount of cases which might support this observation and to analyze the influence of the reagents employed in the pre-treatment of the specimens on the MGIT system's efficacy to detect mycobacteria.

Bacteriemia por Enterococcus gallinarum con alto nivel de resistencia a glicopéptidos: primer caso documentado en Argentina / Bacteremia due to high-level vancomycin resistant Enterococcus gallinarum: first case reported in Argentina

En este trabajo se presenta un caso de bacteriemia por Enterococcus gallinarum con resistencia a altos niveles de vancomicina (CIM=ug/ml) y teicoplanina (CIM=32 ug/ml), coincidentes con el fenotipo Van A. Se comprobó que esta bacteria, además de contener el gen van C1 propio de la especie, que le confiere resistencia natural a bajos niveles de vancomicina, también era portadora del gen van A. Esta es la notificación del primer aislamiento clínico de E.gallinarum portador del genotipo van A en la Argentina.

Actividad de catorce antimicrobianos sobre Eikenella corrodens / [Activity of 14 antimicrobials against Eikenella corrodens]

Eikenella corrodens is a gram-negative bacillus that colonizes as normal flora of the mouth, the upper respiratory tract and the gastrointestinal tract. The aim of this study was to determine the susceptibility patterns against fourteen antibiotics of 25 E. corrodens strains isolated at our hospital. MICs were determined by the agar dilution technique using M³eller-Hinton agar with sheep blood (5

v/v) to penicillin, ampicillin, ampicillin-sulbactam, cephalotin, cefoxitin, ceftiaxone, colistin, gentamicin, amikacin, erythromycin, rifampin, ciprofloxacin and clindamycin. The most active antibiotics were ciprofloxacin and ceftriaxone (MIC90 = 0.008 and 0.125 microgram/ml, respectively), whereas eritromycin, gentamicin and amikacin showed less activity. Only one strain was beta lactamase positive, and it was inhibited by sulbactam. Erithromycin, gentamicin and amikacin had poor activity (MIC90 = 16.8 and 64 micrograms/ml, respectively), whereas all the strains were uniformly resistant to clindamycin (MIC > or = 32 micrograms/ml). We suggest about the need of periodical surveys of E. corrodens susceptibility patterns, since strains have been found with decreased susceptibility against antibiotics which are currently being used for the treatment of infectious diseases.

Falsos cultivos positivos por contaminación cruzada en laboratorios de tuberculosis / False-positive cultures due to cross contamination in tuberculosis laboratories

Fifteen episodes of Mycobacterium tuberculosis laboratory cross-contamination suspected between 1996 and 2001 at 6 laboratories in Buenos Aires City and suburbs were investigated by IS6110 RFLP. Thirteen episodes were confirmed. Even though BACTEC 460 produced the highest number of confirmed episodes in a single laboratory, the most extended one occurred while employing conventional culture procedures in solid medium. The double repetitive element-polymerase chain reaction (DRE-PCR) was applied to 8 of these episodes and produced concordant results with those of the RFLP. The DRE-PCR appears to be a valuable tool for the prompt identification of false positive cultures. The timely rectification of defects in laboratory protocols can avert false diagnoses of tuberculosis and unnecessary prolonged treatments.