Aggregatibacter actinomycetemcomitans infection in children: two case reports and a review of the literature.

Aggregatibacter actinomycetemcomitans (Aa), a Gram-negative coccobacillus commonly associated with endocarditis, poses a rare diagnostic challenge in pediatric cases. The presentation of two pediatric cases-myositis and chest mass-highlights novel aspects, including unusual symptom presentations in children which can be mistaken for malignancy. The limited sensitivity of standard blood tests complicates diagnosis, leading to delayed diagnosis and treatment. Representative samples must be taken, especially if blood cultures are negative. Despite advances in detection methods, diagnosing Aa infection remains difficult due to its rarity in children and variable clinical presentation. In conclusion, a comprehensive understanding of Aa infection in children is essential for early and effective diagnostic and therapeutic management.

ß LACTA test performance for detection of extended-spectrum ß-lactamase-producing Gram-negative bacilli directly on bronchial aspirates samples: a validation study.

OBJECTIVES: Incidence of extended-spectrum ß-lactamase-producing Gram-negative bacilli (ESBL-PE-GNB)-related infections is worryingly increasing worldwide. ESBL-PE-GNB detection directly on bronchial aspirate samples (BAS) performed for suspected pneumonia may help save empirical carbapenems. Our objectives were to optimize ß-LACTA™ test (BLT) realization and evaluate BLT performance for ESBL-PE-GNB detection directly on BAS. METHODS: We studied BLT technical optimization using BAS of different matrix types spiked with increasing concentrations of CTX-M-15-producing Klebsiella pneumoniae; in vitro validation of BLT diagnostic performance on 17 ESBL enzymes, belonging to CTX-M, SHV, TEM, OXA, GES, VEB and PER groups; and clinical validation of BLT performance on 126 BAS prospectively collected from seven intensive care units. RESULTS: After optimization, BLT detected with 100% sensitivity the presence of CTX-M-15-producing K. pneumoniae spiked in sterile BAS for inoculums upon two or more GNB per field upon microscopic Gram staining examination (MGSE). The BLT accurately detected the 17 ESBLs tested at 106 CFU/mL and all ESBLs except Pseudomonas aeruginosa-related OXA-14 at 104 CFU/mL. Among the 126 BAS of the validation cohort, 21 (17%) gave positive BLT (ten in BAS positive and 11 in BAS negative on MGSE). All BLT-positive BAS grew with ESBL-PE-GNB, including five hyper-L2-producing Stenotrophomonas maltophilia strains. BLT detected ESBL-PE-GNB directly on clinical BAS positive for GNB on MGSE and/or growing with ≥104 CFU/mL with 100% sensitivity, specificity, and positive and negative predictive values. CONCLUSIONS: BLT is an accurate tool for ESBL-PE-GNB detection directly on BAS. Further studies are needed to evaluate the impact of BLT-guided early antimicrobial de-escalation strategies.

Evaluation of the Andromas matrix-assisted laser desorption ionization-time of flight mass spectrometry system for identification of aerobically growing Gram-positive bacilli.

Matrix-associated laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) is a rapid and simple microbial identification method. Previous reports using the Biotyper system suggested that this technique requires a preliminary extraction step to identify Gram-positive rods (GPRs), a technical issue that may limit the routine use of this technique to identify pathogenic GPRs in the clinical setting. We tested the accuracy of the MALDI-TOF MS Andromas strategy to identify a set of 659 GPR isolates representing 16 bacterial genera and 72 species by the direct colony method. This bacterial collection included 40 C. diphtheriae, 13 C. pseudotuberculosis, 19 C. ulcerans, and 270 other Corynebacterium isolates, 32 L. monocytogenes and 24 other Listeria isolates, 46 Nocardia, 75 Actinomyces, 18 Actinobaculum, 11 Propionibacterium acnes, 18 Propionibacterium avidum, 30 Lactobacillus, 21 Bacillus, 2 Rhodococcus equi, 2 Erysipelothrix rhusiopathiae, and 38 other GPR isolates, all identified by reference techniques. Totals of 98.5% and 1.2% of non-Listeria GPR isolates were identified to the species or genus level, respectively. Except for L. grayi isolates that were identified to the species level, all other Listeria isolates were identified to the genus level because of highly similar spectra. These data demonstrate that rapid identification of pathogenic GPRs can be obtained without an extraction step by MALDI-TOF mass spectrometry.

Ofloxacin: new applications for the prevention of urinary tract infections in renal graft recipients.

BACKGROUND: Urinary tract infections (UTIs), the most common form of bacterial infection in kidney transplant recipients, recently have been demonstrated to be detrimental for long-term graft outcome. Therefore, reinforcing antibiotic prophylaxis might be vital, in addition to basic hygiene recommendations, surgical care, and prophylaxis by trimethoprim-sulfamethoxazole. METHODS: In 2006, a Legionella pneumophila contamination of our department's water pipes meant that all the patients undergoing renal transplantation underwent a 1-month regimen of ofloxacin (OFLO) (200 mg every other day). We took this opportunity to measure the incidence of UTI, including acute pyelonephritis (APN), in 100 consecutive patients transplanted before (n = 50) and after (n = 50) this treatment decision was reached. We also studied the antimicrobial resistance profiles in our department and in the rest of the hospital. RESULTS: No patient developed Legionnaire's disease. A dramatic decrease in the incidence of UTI (-63%) was also seen in patients undergoing OFLO treatment. Logistic regression analysis demonstrated that the use of OFLO was independently associated with a reduction in UTI (odd ratio [OR] = 0.31%, 95% confidence interval [CI] 0.11-0.84, P = 0.02) and APN (OR = 0.21%, 95% CI 0.07-0.98, P = 0.045). This protection was sustained during the whole first year post transplantation. As for resistance rates, we observed a decrease in the susceptibility of Pseudomonas aeruginosa to ciprofloxacin in our nephrology department, compared with that observed in the rest of the hospital. The incidence of multi-resistant bacteria was stable. DISCUSSION: Our unintentional extension of prophylactic antibiotherapy with OFLO gave rise to a dramatic decrease in the 1-year incidence of UTI and APN in kidney recipients. Emergence of resistant strains is, however, a major concern.

Acute pyelonephritis represents a risk factor impairing long-term kidney graft function.

Urinary tract infections (UTIs) and acute pyelonephritis (APN) often occur after renal transplantation, but their impact on graft outcome is unclear. One hundred and seventy-seven consecutive renal transplantations were investigated to evaluate the impact of UTIs and APN on graft function. The cumulative incidence of UTIs was 75.1% and that of APN was 18.7%. UTIs occurred mainly during the first year after transplantation and Escherichia coli, Pseudomonas aeruginosa and Enteroccocus sp. were the most frequent pathogens identified. The risk of developing APN was higher in female (64%) than in male recipients, and was correlated with the frequency of recurrent UTIs (p < 0.0001) and rejection episodes (p = 0.0003). APN did not alter graft or recipient survival, however, compared to patients with uncomplicated UTIs, patients with APN exhibited both a significant increase in serum creatinine and a decrease in creatinine clearance, already detected after 1 year (aMDRD-GFR: APN: 39.5 +/- 12.5; uncomplicated UTI: 54.6 +/- 21.7 mL/min/1.73 m(2), p < 0.01) and still persistent ( approximately - 50%) 4 years after transplantation. Multivariate analysis revealed that APN represents an independent risk factor associated with the decline of renal function (p = 0.034). Therefore, APN may be associated with an enduring decrease in renal graft function.

NhaA, an Na(+)/H(+) antiporter involved in environmental survival of Vibrio cholerae.

Vibrio cholerae, the agent of cholera, is a normal inhabitant of aquatic environments, in which it survives under a wide range of conditions of pH and salinity. In this work, we identified the nhaA gene in a wild-type epidemic strain of V. cholerae O1. nhaA encodes a protein of 382 amino acids that is very similar to the proteins NhaA of Vibrio parahaemolyticus, Vibrio alginolyticus ( approximately 87% identity), and Escherichia coli (56% identity). V. cholerae NhaA complements an E. coli nhaA mutant, enabling it to grow in 700 mM NaCl, pH 7.5, indicating functional homology to E. coli NhaA. However, unlike E. coli, the growth of a nhaA-inactivated mutant of V. cholerae was not restricted at various pH and NaCl concentrations, although it was inhibited in the presence of 120 mM LiCl at pH 8.5. Nevertheless, using a nhaA'-lacZ transcriptional fusion, we observed induction of nhaA transcription by Na(+), Li(+), and K(+). These results strongly suggest that NhaA is an Na(+)/H(+) antiporter contributing to the Na(+)/H(+) homeostasis of V. cholerae. nhaA-related sequences were detected in all strains of V. cholerae from the various serogroups. This gene is presumably involved in the survival and persistence of free-living bacteria in their natural habitat.

[Molecular epidemiology of strains of Staphylococcus aureus resistant to methicillin, sensitive to aminoglycosides]. / Epidémiologie moléculaire de souches de staphylocoque doré résistantes à la méticilline, sensibles aux aminosides.

Twenty methicillin-resistant Staphylococcus aureus (MRSA) isolates surprisingly susceptible to all aminoglycosides, macrolides, sulfonamides and tetracycline were recovered from 20 elderly patients (mean age, 77) hospitalized in 4 neighbouring facilities between 1996 and 1998. Molecular typing of the isolates performed by restriction fragment length polymorphism of the coagulase gene (PCR-RFLP) and pulsed-field gel electrophoresis (PFGE) of Sma I macrorestriction fragments of total DNA, demonstrated the existence of distinct bacterial clones. Epidemic spreading was demonstrated for at least 2 clones, while others were responsible for sporadic cases. Most of the isolates of this study appeared to be genetically related to strains of MRSA resistant to aminoglycosides and macrolides included as controls, suggesting that multiresistant MRSA may have evolved recently in a manner that resulted in greater susceptibility to certain antibiotics.

The rfaD locus: a region of rearrangement in Vibrio cholerae O139.

We analyzed the rfaD locus of the novel epidemic Vibrio cholerae strain O139, a putative region of rearrangement. This region includes 4 orfs in the same orientation. Two orfs, rfaD(O139) and orf2(O139) were almost identical to those described in V. cholerae O1. In contrast, the two other orfs upstream from rfaD(O139), designated orfA(O139) and orfB(O139), were absent from V. cholerae O1, but present in environmental strains of V. cholerae O22, O141 and O155. These results suggest that a chromosomal rearrangement might have occurred in the vicinity of rfaD in V. cholerae O1, resulting in the emergence of V. cholerae O139. The putative source of exogenous DNA might have been V. cholerae O22, O141 and O155.