Recurrent Staphylococcus aureus bacteremia.

Sequential blood isolates from eight patients with 10 episodes of recurrent Staphylococcus aureus bacteremia were typed by restriction endonuclease analysis of plasmid DNA (REAP DNA fingerprinting) and immunoblotting. There were six early recurrences (within 2 months of stopping antimicrobial therapy) and four late recurrences. All early recurrences isolates were identical to initial isolates. These recurrences were defined as possible relapses. Three of four late recurrence isolates were different from the preceding isolates recovered from four patients. This was considered indicative of new infections. There was complete concordance between REAP DNA fingerprinting and immunoblot typing results. However, four isolates lacked plasmid DNA and could be typed only by immunoblotting. All initial isolates from different patients were different types by immunoblotting and by REAP DNA fingerprinting (except for those lacking plasmid DNA). The bacterial traits detected by these methods appear to be stable in vivo for up to 3 months. Relapsing infections were associated with the presence of intravascular foreign bodies and vancomycin therapy of the preceding episodes.     

Enteroinvasive Escherichia coli: a cause of bacteremia in patients with AIDS.

A strain of enteroinvasive Escherichia coli was isolated from the blood of a patient with advanced human immunodeficiency virus disease on repeated occasions, associated with severe diarrheal illness. The isolate was killed in vitro by control sera but not by sera collected from the patient before or after his bacterial illnesses.     

Recurrent Microvirgula aerodenitrificans bacteremia

Microvirgula aerodenitrificans is a denitrifying Gram-negative organism first described by Patureau et al. in 1998 (D. Patureau et al., Int. J. Syst. Bacteriol. 48:775-782, 1998). The organism has been isolated globally but has never been described as causative of clinical infection. We describe the first human case of bacteremia attributed to M. aerodenitrificans in an infant with Pompe's disease.     

Immunochemical properties of anti-DNA antibodies in the sera of patients with Escherichia coli bacteremia.

To assess the role of infection in anti-DNA antibody production, the DNA-binding activity of sera from patients with Escherichia coli bacteremia was analyzed. Among 8 patients with bacteremia documented by blood culture, 5 demonstrated increased levels of antibodies to single-stranded DNA from E. coli as measured by enzyme-linked immunosorbent assay. Sera from these patients also reacted with single-stranded DNA from other bacterial and mammalian species as well as certain synthetic polynucleotides including poly-dT and poly-dC. The isotype distribution of these antibodies and their avidity as assessed by competition enzyme-linked immunosorbent assay resembled, moreover, responses of patients with systemic lupus erythematosus. These results suggest that, during the course of infection with E. coli, some patients may produce antibodies with immunochemical properties similar to those arising in systemic lupus erythematosus.     

Association of hydroxamate siderophore (aerobactin) with Escherichia coli isolated from patients with bacteremia.

Clinical isolates of Escherichia coli were examined for the presence of hydroxamate siderophore (aerobactin). The incidence of aerobactin-positive strains of E. coli from the blood was greater than the incidence of these strains isolated from other sites. The presence of aerobactin and the virulence of strains of E. coli in urinary tract infection were also examined in mice. The presence of aerobactin in the strains of E. coli correlated with virulence as measured by proportion of deaths but not with renal infection. These results suggest that the presence of aerobactin may be a significant factor in the invasion of the blood stream.     

Pathogenesis of neonatal Escherichia coli meningitis: induction of bacteremia and meningitis in infant rats fed E. coli K1.

Escherichia coli K1 strains, isolated from human newborns with meningitis, were fed to pathogen-free Sprague-Dawley infant rats by an oral gastric tube. Feeding of 10(3) to 10(11) organisms colonized the intestine of approximately 70% of the animals. At 5 days postfeeding of 3- to 5-day-old rats, bacteremia was detected in 60%, and meningitis occurred in 15% of bacteremic animals. Colonization and bacteremia were age-related. Rats 15 days old had only 19 colonization and 10% bacteremia, and those 30 days old were almost completely resistant to colonization and bacteremia. The intranasal route was less effective in inducing colonization and bacteremia. Intralitter transmission from E. coli K1-fed rats occurred, with 52% of water-fed controls becoming colonized and 15% become bacteremic. Colonization of mothers from their fed infants occurred, but none of five tested developed bacteremia. Other E. coli capsular polysaccharide types were studied. A K92 strain isolated from a newborn with meningitis induced a 77% colonization rate, and 8% of these developed bacteremia without detectable meningitis. An E. coli K100 strain showed a 32% colonization rate, and 2% developed bacteremia. The age relation, relatively high virulence of K1 compared with other capsular types, spontaneous appearance of colonization, bacteremia, and meningitis, and intralitter transmission of colonization and disease in newborn rats closely parellel E. coli epidemiology in human neonates.     

Leukemia and risk of recurrent Escherichia coli bacteremia: genotyping implicates E. coli translocation from the colon to the bloodstream

In patients with leukemia, the portal(s) and reasons for the persistence of an Escherichia coli recurrent bacteremia remain unclear. Adult Hematology Clinic (AHC) databases at the State Clinical Hospital in Gdańsk were reviewed to evaluate the frequency of E. coli bacteremia between 2002 and 2005. Blood and bowel E. coli strains were obtained and the genetic relatedness of the strains was analyzed. The rate of E. coli bacteremia per 1,000 admissions at the AHC was higher (85.0) than in the other clinics of the hospital (2.9), p?<?0.001. A higher mortality was observed in patients with a history of E. coli versus non-E. coli bacteremia [30/95 (31 %) vs. 53/430 (12 %), p?<?0.001]; 72.8 % of patients with leukemia had an unknown source of bacteremia. In 2005, 6 out of 25 (24 %) patients with leukemia had ≥2 episodes of E. coli-positive blood cultures. These gastrointestinal E. coli isolates were replaced within 3–8 weeks with a new E. coli H genotype. A recurrent episode of bacteremia was usually caused by an infection with a transient E. coli H genotype identical to that found in the subject’s bowel. Consistent with the definition of bowel/blood translocation, the bowel appeared to be a portal for E. coli in these subjects and, hence, a clear source for their recurring bacteremia.     

A case of diarrhea, bacteremia, and fever caused by a novel strain of Escherichia coli.

A nonenteropathogenic strain of Escherichia coli from a patient with diarrhea and bacteremia possessed the attaching-effacing eae gene, was invasive in the gentamicin invasion assay, and expressed two types of pili and K1 antigen. This unique combination places the strain in a new category of attaching-effacing E. coli.     

Indwelling device-related bacteremia caused by serum-susceptible Campylobacter coli.

Two isolates of serum-susceptible Campylobacter coli were recovered in a 7-day interval from blood from a patient with hepatocellular carcinoma and liver cirrhosis whose peritoneal-caval (Denver's) shunt malfunctioned. Identical random amplified polymorphic DNA fingerprints, cellular fatty acid chromatograms, and antibiograms of the two isolates indicate that C. coli has the ability to cause catheter-related bacteremia following its colonization of the catheter.     

Recurrent CDC group IVc-2 bacteremia in a human with AIDS.

A 30-year-old man with AIDS developed separate episodes of bacteremia with multiple organisms including CDC group IVc-2, related to an indwelling central venous catheter. Recovery at each interval followed antibiotic therapy and replacement of the central venous access. This is the first reported case of infection with this organism in a patient with AIDS. A review of the biochemical features of this bacterium as well as pertinent literature is presented.     

Recurrent bacteremia due toBrevibacterium casei in an immunocompromised patient

A case of an immunocompromised patient who experienced two episodes of septicemia caused by a coryneform bacterium is reported. Biochemical characteristics and analysis of cellular fatty acids and of cell wall components showed two identical strains ofBrevibacterium casei to be responsible for these infections. The lack of easy-to-perform methods for identification may have led, in the past, to an underestimation of the role of this bacterium, especially in immunocompromised patients.     

Biotyping of Escherichia coli.

We examined the results of tests with 22 substrates for their ability to discriminate a series of 917 strains of Escherichia coli collected from different sources. The tests with three of the substrates were discarded because of difficulties in performance or interpretation, and another nine substrates because they provided little discrimination. The tests used to obtain biotype profiles for strains were those for the fermentation of dulcitol, D-raffinose or sucrose or both, L-rhamnose and L-sorbose, the decarboxylation of L-lysine and L-ornithine, the hydrolysis of aesculin, motility, and prototrophy. Observations on several series of cultures from different sources showed that biotype characters were stable in vivo and after storage on non-selective medium. The biotype profiles obtained were as reliable as partial O serotyping for the routine subtyping of strains of E. coli isolated from the urine of patients with long-term urinary-tract infections and those from other sources in different patients. Biotyping and O serotyping used in conjuction offered a very fine degree of strain discrimination.     

First case of febrile bacteremia due to a wild type and small-colony variant of Escherichia coli

Reported here is a case of a febrile illness caused by a wild type and small-colony variant of Escherichia coli in an anorectic patient. A review of the literature revealed that the formation of small-colony variants in E. coli has been recognized since 1931. In recent years, an association has been established between those variants and chronic recurrent infections. This report describes for the first time the isolation of an E. coli small-colony variant from a blood culture of a patient who had suffered from chronic urinary tract infections in the past.     

Prevalence of virulence genes and clonality in Escherichia coli strains that cause bacteremia in cancer patients

Phenotypic analysis of Escherichia coli strains causing bacteremia in cancer patients suggests that they possess specific virulence properties. To investigate this hypothesis, we compared the frequency of the virulence-related genes cnf1, cnf2, papC, hlyC, and iut in 155 E. coli strains isolated from hospitalized cancer patients with epidemiologically unrelated cases of bacteremia to their frequency in 70 E. coli strains isolated from the feces of healthy unrelated volunteers. Of the blood isolates, 24, 37, and 26% were positive for cnf1, papC, and hlyC, respectively, versus only 6, 17, and 6% of the fecal isolates (P < 0.05 in all instances). By contrast, 47% of both isolates carried the iut gene. The patients' clinical characteristics did not significantly influence these frequencies. The presence on various pathogenicity islands (PAIs) of a combination of the cnf1, papC, and hlyC genes on the chromosome was strongly suggested by Southern blotting of pulsed-field gel electrophoresis (PFGE) patterns with specific DNA probes. The phylogenetic relatedness among 60 strains carrying three, two, one, or no virulence genes and 6 ECOR strains included as references was determined by neighbor joining, the unweighted pair-group method with arithmetic mean, and Wagner analysis of the randomly amplified polymorphic DNA (RAPD) patterns generated by 11 primers. Identification of a major cluster including 96.4% of the strains carrying the cnf1, papC, and hlyC genes and ECOR subgroup B2 strains suggested that the virulent E. coli strains causing bacteremia in cancer patients are closely related to ECOR B2 strains. The presence in the E. coli population surveyed of a strong linkage disequilibrium, and especially of a highly significant correlation between PFGE and RAPD genetic distances, confirms that clonal propagation has a major impact on the E. coli population structure. Nevertheless, low bootstrap values in the phylogenetic tree suggested that frequent genetic exchange inhibits the individualization of discrete genetic lineages, which are stable on an evolutionary scale.     

Therapeutic effectiveness of bacteriophages in the rescue of mice with extended spectrum beta-lactamase-producing Escherichia coli bacteremia

The emergence of multidrug-resistant bacteria has become a global crisis. Accumulating evidence shows that bacteriophages (phages) can rescue animals from a variety of lethal infections and be effective in treating drug-resistant infections in humans. Enterobacteriaceae, producing extended spectrum beta-lactamase enzymes (ESBLs), are resistant to a broad range of beta-lactamase antibiotics. One of the most common ESBL-producing gram-negative bacilli in Enterobacteriaceae is Escherichia coli. Since ESBL-producing E. coli poses a formidable challenge in the management of critically ill patients with bacterial infections, we undertook this study to explore the possible therapeutic utility of phages to control ESBL-producing E. coli infections. The phage ?9882 used in this study was isolated from our hospital sewage and has lytic activity against a broad range of clinical isolates of ESBL-producing E. coli. ESBL-producing E. coli strains (n=30) were isolated in the clinic, and one of them was used to induce bacteremia in a murine model. Bacteremia was established by intraperitoneal (i.p.) injection of 3 x 10(7) CFU/ml, the minimum lethal dose (MLD) of bacterium in this animal model. Mice infected with the MLD of this strain alone died within 14 h, whereas a single i.p. inoculation of ?9882 (MOI > or =10(-4)) given 40 min after the bacterial challenge led to 100% survival at 24-168 h, compared to 0% survival of saline-treated controls. Protection was obtained even when administration of the phage was delayed up to 60 min after the bacterial infection and the survival rate of infected animals was 60% at 168 h. Furthermore, it was shown that the therapeutic efficacy of ?9882 in lethal systemic infection in our model is due to the functional capability of the phage and not the nonspecific immune effects. Our data both in vitro and in vivo revealed that: i) the protection of mice from death occurred only in animals infected with selected bacterial strains and the virulent phage specific to them; ii) when the phages were heat-inactivated, survival of the infected mice was strikingly decreased to 0; and iii) the level of antibody against the phage was not substantially elevated when the bacteremic animals were protected by the phage. The present findings indicate that phages can effectively rescue our mouse model from bacteremia and death, and thus provide the rationale and framework to evaluate the therapeutical efficacy of lytic phages against fatal ESBL-producing E. coli infections in humans.     

The emergence and dissemination of CTX-M-producing Escherichia coli sequence type 131 causing community-onset bacteremia in Israel

Community-onset bloodstream infections caused by extended-spectrum β-lactamase-producing Escherichia coli (ESBL-EC-COBSIs) were investigated over a 7-year-period (2003–2009) in our institution. ESBL-EC-COBSI inclusion criteria were cefotaxime/ceftazidime non-susceptible blood isolates recovered during 48 h upon hospital admission. Forty-one isolates were molecularly characterized. Susceptibilities were determined (Vitek-2) and genotyping was performed [multilocus sequence typing (MLST)]. CTX-M genes were determined [polymerase chain reaction (PCR) and sequencing] and bla _CTX-M-encoding plasmids (n?=?10) were analyzed and compared. Phylogrouping and virulence genes were identified (PCR). The incidence rate of ESBL-EC-COBSIs has increased from 2.94 to 7.87 cases/10,000 admissions. All isolates were multidrug-resistant (MDR), displaying co-resistance to ciprofloxacin (93 %), trimethoprim–sulfamethoxazole (85 %), and gentamicin (51 %). MLST identified ten sequence types (STs), of which five were novel. ST131 accounted for 66 % of the cases (27/41), and dominated over the years (prevalence of 25 % in 2003 and 85 % in 2009). All isolates carried CTX-M genes with the following prevalence: bla _CTX-M-2 (6/8; 75 %) in 2003; bla _CTX-M-15 (9/13, 69 % in 2007); and bla _CTX-M-15 (11/20, 55 %) and bla _CTX-M-14 (7/20, 35 %) in 2009. bla _CTX-M-15- and bla _CTX-M-14-encoding plasmids harbored by ST131 differed. Of all isolates, 98 % belonged to virulent phylogroups B2 (28/41, 68 %) and D (12/41, 29 %), though ST131 isolates carried a higher number of virulence genes compared to other lineages (p?<?0.05). The incidence of ESBL-EC-COBSIs increased 2.7-fold during the period 2003–2009. This increase appears to be related to the emergence and clonal expansion of bla _CTX-M-15- or bla _CTX-M-14-carrying ST131. The superiority of this virulent lineage should be further explored.