M. de Cueto

In vitro activity of fosfomycin against extended-spectrum-beta-lactamase-producing Escherichia coli and Klebsiella pneumoniae: comparison of susceptibility testing procedures

ABSTRACT The agar dilution, broth microdilution, and disk diffusion methods were compared to determine the in vitro susceptibility of 428 extended-spectrum-β-lactamase (ESBL)-producing Escherichia coli and Klebsiella pneumoniae to fosfomycin. Fosfomycin showed very high activity against all ESBL-producing strains. Excellent agreement between the three susceptibility methods was found for E. coli, whereas marked discrepancies were observed for K. pneumoniae.

Fatal levofloxacin failure in treatment of a bacteremic patient infected with Streptococcus pneumoniae with a preexisting parC mutation

ABSTRACT The fatal outcome of levofloxacin treatment in a patient with bacteremic pneumonia caused by Streptococcus pneumoniae with a preexisting parC mutation is reported. Failure was due to the emergence of a gyrA mutation after 4 days of therapy. Problems encountered in detecting first-step mutation isolates are discussed.

Is reduced vancomycin susceptibility a factor associated with poor prognosis in MSSA bacteraemia

OBJECTIVES The known data about the influence of vancomycin MIC on Staphylococcus aureus bacteraemia are contradictory. Our objective was to study the possible impact of vancomycin MIC ≥1.5 mg/L on short- and medium-term mortality. METHODS A prospective cohort study was carried out from March 2008 to January 2011 on adult patients with MSSA bacteraemia admitted to a tertiary hospital located in Seville (Spain). We studied the relationship between vancomycin MIC, accessory gene regulator (agr) type and absence of δ-haemolysin and poor prognosis. All isolates were genotyped by PFGE. Multivariate analysis, including a propensity score for having a vancomycin MIC of ≥1.5 mg/L, was performed by Cox regression. RESULTS One hundred and thirty-five episodes of bacteraemia due to MSSA were included in the analysis. Twenty-nine (21.5%) isolates had a vancomycin MIC of ≥1.5 mg/L by Etest. There were no differences in agr distribution or absence of δ-haemolysin between isolates with reduced vancomycin susceptibility (RVS) and those without. RVS was not more frequent in specific clones; RVS was not associated with higher 14 or 30 day crude mortality (relative risk = 0.44, 95% CI = 0.14-1.35; and relative risk = 1.01, 95% CI = 0.52-1.96) rates, and it did not show higher rates of complicated bacteraemia (14.2% versus 13.8%, P = 0.61). Cox regression analysis did not significantly modify the results for 14 day mortality (HR = 0.39, 95% CI = 0.11-1.34) or 30 day mortality (HR = 0.89, 95% CI = 0.39-2.04). CONCLUSIONS Contrary to previously published data, we did not find a relationship between RVS and higher mortality in patients with MSSA bacteraemia and we did not find a link with higher complicated bacteraemia rates.

Risk factors for severe sepsis in community-onset bacteraemic urinary tract infection: Impact of antimicrobial resistance in a large hospitalised cohort

OBJECTIVE To determine risks factors associated with severe sepsis or septic shock (SS) at admission in patients with community-onset bacteraemic urinary tract infection (CO-BUTI) including the impact of multidrug-resistant (MDR) bacteria. METHODS We analysed a prospective cohort of all consecutive episodes of CO-BUTI requiring hospitalisation in 8 tertiary hospitals of Spain between October 2010 and June 2011. RESULTS Of an overall of 525 CO-BUTI episodes, 175 (33%) presented with SS at admission. MDR bacteria were isolated in 29% (51/175) of episodes with SS and in 33% (117/350) of those without SS (p = 0.32). The main MDR microorganism was Escherichia coli in both groups (25% and 28% respectively). Independent risk factors associated with SS at admission were: having fatal underlying conditions, McCabe score II/III (OR 1.90; 95%CI 1.23-2.92; p = 0.004), presence of an indwelling urethral catheter (OR 3.01; 95%CI 1.50-6.03; p = 0.002) and a history of urinary tract obstruction (OR 1.56; 95%CI 1.03-2.34; p = 0.03). After considering interactions, indwelling urethral catheters were a risk factor only for patients without fatal underlying conditions. CONCLUSIONS SS at hospital admission occurred in a third of CO-BUTI. Mainly host factors, and not the causative microorganisms or antimicrobial resistance patterns had an impact on the presence of SS.

Bacteremia caused by nonhemolytic group B streptococci

Case Report A 75-yr-old woman with a history of type 2 noninsulin-dependent diabetes and hepatic cirrhosis with previous acute episodes of encephalopathy was admitted to the hospital because of abdominal swelling, tenderness of several day’s duration, and nausea On physical examination, the patient was afebrile and had tender hepatomegaly, ascites, and jaundice with normal central nervous system findings. The white blood cell count was 8,100/mm3 (85% neutrophils, 12% lymphocytes, and 3% monocytes). Prythrocyte sedimentation rate was 102 mm at the first hour. Other hematologic studies, metabolic profile, and liver function tests showed increased serum amylase (2,832 U/L), hyperglycemia, and hyperbilirubinemia An ultrasonogmphic study was done and a clinical diagnosis of acute pancreatitis was confiied. Medical therapy was begun, and the disease was self-limited within 3 d after treatment was instituted On the fifth day after admission, the patient underwent gynecological exploration because of vaginal discomfort, and a sample of the purulent vaginal discharge was sent to microbiology laboratory for culture. On the sixth day, she suddenly developed fever (39”C), and three sets of blood cultures were obtained. Empiric treatment with cefotaxime (2 g tid i.v.) was begun, yet the patient remained febrile. The vaginal sample grew a pure culture of a gram-positive, nonhemolytic coccus subsequently identified as Sneptoc0ccus agalactiue (3). The same microorganism also grew in all three blood culture sets after overnight incubation (BacTAlert system, Organon Teknika). A Gram stain of the blood culture showed gram-positive cocci resembling streptococci. The organism grew on sheep blood agar at 37°C with 5% COZ as small, white, slightly convex, nonhemolytic colonies, and hemolysis was not detectable on lifting a colony from the agar. The isolate was catalase-negative, PYRand bile esculin-negative, bacitracin-resistant, and did not grow in the presence of 6.5% sodium chloride. In addition, positive reactions for voges-Proskauer and hippurate hydrolysis tests were obtained. Group B streptococcal antigen was demonstrated with the PhadeBact test system (Karo Bio Diagnostics, Sweden), and a biochemical profile consistent with group B streptococci was obtained with the API 20 Strep test (bioM&ieux, France). Serotyping of the isolate by agglutination with antisera to GBS serotypes I through V (Dako A/S, Denmark) produced agglutination with the type II antisera. Repeated subcultures of the isolate onto blood agar under aerobic and anaerobic conditions failed to produce beta hemolysis. No pigment production was seen when the isolate was cultured in Granada medium, a selective and differential pigmentenhancing culture medium (4).