A. Mosca

High Dose, Extended-Interval Colistin Administration in Critically Ill Patients: Is this the Right Dosing Strategy? A Preliminary Study

In critically ill patients with otherwise untreatable nosocomial infection due to gram-negative bacteria susceptible only to colistin, a high-dose, extended-interval colistin dosing regimen is, according to the pharmacokinetic/pharmacodynamic behavior of the drug, associated with low renal toxicity and high efficacy.

Colistin-associated Acute Kidney Injury in Severely Ill Patients: A Step Toward a Better Renal Care? A Prospective Cohort Study

BACKGROUND Critically ill patients with severe sepsis or septic shock may need relatively high colistin daily doses for efficacy against multidrug-resistant and extensively drug-resistant gram-negative rods. However, acute kidney injury (AKI) may represent a major dose-limiting adverse effect of colistin. We sought to determine AKI occurrence and to identify factors influencing AKI risk in severely ill patients receiving colistin according to a recently proposed dosing strategy. METHODS A prospective, observational, cohort study involving patients with severe sepsis or septic shock who received colistin was performed. AKI was defined according to Acute Kidney Injury Network criteria. Colistin administration was driven by a modified pharmacokinetics-pharmacodynamics (PK/PD)-based dosing approach. RESULTS Of 70 patients who received colistin at a median daily dose of 9 million IU (MIU; interquartile range, 5.87-11.1 MIU), 31 (44%) developed AKI. In univariate analysis, age, Acute Physiology and Chronic Health Evaluation (APACHE) II score, Sequential Organ Failure Assessment (SOFA), score and baseline renal impairment were significantly associated with AKI. Moreover, patients with AKI were less frequently treated with adjuvant ascorbic acid (P = .003). In multivariate analysis, independent predictors of AKI were baseline renal impairment (adjusted hazard ratio, 4.15; 95% confidence interval, 1.9-9.2; P < .001) and age (1.03; 1.0-1.05; P = .028), whereas a strong independent renal-protective role emerged for ascorbic acid (0.27; .12-.57; P < .001). CONCLUSIONS In severely ill patients receiving colistin according to a PK/PD-driven dosing approach, baseline renal impairment and older age strongly predict AKI occurrence, but concomitant administration of ascorbic acid markedly reduces AKI risk, allowing safer use of colistin.

Detection of Mycobacterium tuberculosis DNA in blood of patients with acute pulmonary tuberculosis by polymerase chain reaction and non-isotopic hybridisation assay

The detection of Mycobacterium tuberculosis DNA in peripheral blood mononuclear cells (PBMC) by PCR and non-isotopic hybridisation assay was evaluated for the laboratory diagnosis of pulmonary M. tuberculosis infection. The PCR technique was based on the presence of IS6110, a DNA sequence specific for M. tuberculosis, and performed on PBMC from 30 patients belonging to the fifth group of the American Thoracic Society (ATS) classification of tuberculosis. The identification of amplification products was confirmed after electrophoresis by hybridisation with a non-isotopic probe in a DNA enzyme immunoassay (DEIA). Of the 30 blood samples studied by the PCR-DEIA technique, 26 gave positive results and four gave negative results. Blood samples from 30 subjects in a control group were negative by this technique. The data suggest that PCR-DEIA of blood may provide a sensitive, specific and useful means of diagnosing mycobacterial infection.

Prevalence of antibodies to Bartonella henselae in patients with suspected cat scratch disease (CSD) in Italy

Cat scratch disease (CSD) is a relatively new diagnosed illness with clinical signs of self-limiting regional lymphadenopathy accompanied by symptoms of fever and malaise, to encephalopathy and neuropathy, occurring after a cat scratch or flea bite. Bartonella henselae is now accepted as the etiologic agent of CSD. From January 1994 to September 1998, 412 patients were evaluated for suspect CSD in Italy. Sera were tested for antibodies to B. henselae by a commercially available indirect immunofluorescent assay (IFA), based on B. henselae-infected Vero-cells as the antigen substrate. Of the 412 patients, 26 (6.3%) were considered positive having titers of immunoglobulin G (IgG) to B. henselae of 64 or higher. In these patients CSD was indeed confirmed by either histopathologic examination of lymph nodes biopsy or fourfold raise in antibody titers. Nevertheless, sera were tested by IFA for Afipia felis and one showed a double reactivity to B. henselae and A. felis. Finally, three sera, negative to B. henselae serology, were positive to A. felis. Three hundred and eighty-six patients received alternative diagnoses. One hundred and twenty-five serum samples from control subjects were negative by IFA for either B. henselae or A. felis. Moreover, a cross-reactivity with sera from patients affected by other diseases was not observed. Our study shows that the ascertained cases of CSD are etiologically determined by B. henselae, IFA assay is confirmed as a useful tool in the laboratory diagnosis and, over a 5 years period of study, the incidence of CSD in Italy has been low.

Preliminary evidence of endotoxic activity of Bilophila wadsworthia

In this study we describe two properties of the Gram-negative bacterium Bilophila wadsworthia, namely the ability to clot Limulus lysate and the capacity to induce the production of tissue factor-like procoagulant activity by human mononuclear cells in vitro. Although exhibited at a lower degree when compared with those of typical Gram-negative bacteria or Gram-negative endotoxin those activities may account in part for Bilophilas pathogenicity. The capacity indeed to induce fibrin formation through the interaction with mononuclear cells suggests one mechanism by which the microorganism might cause abscess formation in the host. Moreover, since this activity is dependent on the number of Bilophila interacting with mononuclear cells, we hypothesize that this biological activity is closely influenced by growth environment.

Rapid and sensitive detection of blaKPC gene in clinical isolates of Klebsiella pneumoniae by a molecular real-time assay

BackgroundThe aim of this study was the rapid identification of blaKPC gene in 38 Klebsiella pneumoniae clinical isolates with reduced susceptibility to carbapenems. The modified Hodge Test (MHT) was carried out to phenotypically determine whether resistance to carbapenems was mediated by a carbapenemase. The detection of the blaKPC gene was performed by real-time acid nucleic sequence-based amplification (NASBA™™), specifically designed for the detection of KPC RNA target.ResultsThirty-two/38 isolates evaluated by MHT showed the production of carbapenemases, while all the strains exhibited the production of KPC by inhibition test with phenylboronic acid (the combined disk test with IPM/IPM plus phenylboronic acid). The detection of blaKPC gene by Nuclisens EasyQ KPC yielded positive results in 38/38 (100%) strains. The presence of blaKPC gene was confirmed in all K. pneumoniae isolates when tested by the gold standard PCR assay.ConclusionsIn consideration of the serious challenge represented by infections due to K. pneumoniae it appears necessary the rapid identification of carbapenemases in clinical settings as it is made possible by the use of NASBA™ assay.

Species Distribution and In Vitro Azole Susceptibility of Aspergillus Section Nigri Isolates from Clinical and Environmental Settings

ABSTRACT Aspergillus section Nigri includes species of interest for animal and human health, although studies on species distribution are limited to human cases. Data on the antifungal susceptibilities and the molecular mechanism of triazole resistance in strains belonging to this section are scant. Forty-two black Aspergillus strains from human patients (16 isolates), animals (14 isolates), and the environment (12 isolates) were molecularly characterized and their in vitro triazole susceptibilities investigated. Aspergillus tubingensis was isolated from humans, animals, and environmental settings, whereas Aspergillus awamori and Aspergillus niger were isolated exclusively from humans. Phylogenetic analyses of β-tubulin and calmodulin gene sequences were concordant in differentiating A. tubingensis from A. awamori and A. niger. Voriconazole and posaconazole (PSZ) were the most active triazoles. One A. tubingensis strain was resistant to itraconazole and PSZ and one A. niger strain to PSZ. Sequence analysis of the cyp51A gene revealed different sequence types within a species, and A. tubingensis strains were also phylogenetically distinct from A. awamori/A. niger strains according to the strain origin and susceptibility profile. Genetic analysis of the cyp51A sequences suggests that two nonsynonymous mutations resulting in amino acid substitutions in the CYP51A protein (changes of L to R at position 21 [L21R] and of Q to R at position 228 [Q228R]) might be involved in azole resistance. Though azole resistance in black Aspergillus isolates from animals and rural environments does not represent a threat to public health in Southern Italy, the use of triazoles in the clinical setting needs to better monitored. The cyp51A sequence is useful for the molecular identification of black Aspergillus, and point mutations in protein sequences could be responsible for azole resistance phenomena.

Imipenem-Resistant Campylobacter fetus Bloodstream Infection

Campylobacter fetus (C. fetus) is a fastidious, curved, Gram-negative bacillus that has been increasingly associated with human disease. Although Campylobacter bacteremia is uncommon, the number of cases is increasing in elderly or immunocompromised patients, especially those with underlying conditions such as liver disease or cancer 1,2. We present a case of bacteremia due to C. fetus subsp. fetus in a liver-recipient patient. A 47-year-old patient with transplanted liver with underlying cardiovascular disease and receiving immunosuppressive therapy with cyclosporin was admitted to the hospital because of fever and pain in both legs. Laboratory findings were: hemoglobin 11.2 g/dL; white blood cells 5x100/mm3 with 87.6% neutrophils; C-protein 41 mg/dL; erythrocyte sedimentation rate 33 mm/h; HCV positivity. Lower extremity arterial doppler revealed the presence of atheromasic plaque in the left femoral artery without stenosis. samples were taken for blood cultures and antibiotic treatment was started with 500 mg/daily levofloxacin. The patient’s temperature dropped to 37°C and after 5 days he was discharged from hospital. However, his blood culture became positive after a week and Gram stain showed spiral-shaped Gram-negative rods. The strain was subcultured on Blaser Wang agar at 42°C in a 5% CO2 atmosphere (candle jar), and was identified by conventional biochemical tests such as C. fetus ssp coli. The strain was definitively identified as C. fetus spp fetus by 16s ribosomal RnA gene sequencing (Big Dye Terminator Cycle sequencing v.3.1 Ready Reaction Kit, Allied Biosystems). sensitivity testing was performed by agar diffusion technique on Mueller Hinton agar supplemented with 5% sheep blood. The zone diameters measured around each disk were interpreted according to recommendations for Campylobacter of the Antibiogram Committee of the French society for Microbiology 3. The strain was susceptible to erythromycin, clindamycin, ciprofloxacin, cloramphenicol and resistant to ceftriaxone, ceftazidime and imipenem. in particular, C. fetus was not inhibited by imipenem, as it had a zone diameter of 6 mm. Our case further supports the concept that C. fetus bacteremia should be suspected in patients with fever, immunodeficiency and cardiovascular damage. The cardiovascular localization might be related to the vascular tropism of C. fetus due to either the presence on its surface of a receptor with high affinity for the endothelium or the local production of procoagulant activity leading to fibrin formation. severe septicemia was probably prevented in our patient by the early treatment with levofloxacin. Pacanowski et al. reported that 15% of patients with Campylobacter bacteremia died within 30 days either in the absence of therapy with appropriate antibiotics or when third generation cephalosporins are prescribed 2. in this regard Gazaigne et al. suggested imipenem as the most active drug 4. in this regard it is noteworthy that our strain was in vitro resistant to imipenem, which is indicated as initial therapy for severe infections 4. This possibility should be kept in mind since a correct early antimicrobial approach strongly conditions a favorable outcome in the patient.

Tuberculous Otitis Media with Facial Paralysis: A Clinical and Microbiological Diagnosis—A Case Report

The tuberculosis of the ear is rare, and in most cases the clinical picture resembles that of a chronic otitis media. The diagnosis is often delayed, and this can lead to irreversible complications such as hearing loss and/or facial paralysis. In view of its rare occurrence, we report a case of primary tuberculous otitis media in a 87-year-old female patient. The diagnosis was made on the basis of both histological and microbiological findings. In particular, gene amplification techniques such as real-time polymerase chain reaction are useful method for rapid diagnosis and detecting tuberculous bacilli usually present at very low number. Early diagnosis is essential for the prompt institution of antituberculous therapy.

The production of short-chain fatty acids by periodontopathic bacteria contributes to the impairment of local host defence

Abstract It is here hypothesized that the production of short-chain fatty acids by periodontopathic bacteria represents an important moment in the progression of the periodontitis lesion through the inhibition of mononuclear cell-mediated formation of fibrin.