Georgia Vrioni

An eternal microbe: Brucella DNA load persists for years after clinical cure.

BACKGROUND Despite the continuing high incidence of brucellosis, vague aspects of pathophysiology, diagnosis, and treatment continue to exist, particularly with regard to the ability of Brucella species to survive inside the host. METHODS A quantitative real-time polymerase chain reaction assay was used for monitoring bacterial DNA load in brucellosis-affected patients throughout different disease stages. Three or more specimens per patient were obtained (1 at diagnosis, 1 at the end of treatment, and at least 1 during the follow-up period) from 39 patients with acute brucellosis. RESULTS The majority of patients (87% at the end of treatment, 77% at 6 months after treatment completion, and 70% at >2 years after treatment) exhibited persistent detectable microbiological load despite being asymptomatic. The 3 patients who experienced relapse did not exhibit any statistically significant difference in their bacterial load at any stage of disease or during follow-up. CONCLUSION Brucella melitensis DNA persists despite appropriate treatment and apparent recovery. This finding offers a new insight into the pathophysiology of the disease: B. melitensis is a noneradicable, persisting pathogen.

Characteristics of Meropenem Heteroresistance in Klebsiella pneumoniae Carbapenemase (KPC)-Producing Clinical Isolates of K. pneumoniae

ABSTRACT Meropenem heteroresistance was investigated in six apparently meropenem-susceptible, Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae (KPC-KP) clinical isolates, compared with that in carbapenemase-negative, meropenem-susceptible controls. In population analyses, the KPC-KP isolates grew at meropenem concentrations of 64 to 256 μg/ml. Heteroresistant colonies had significantly elevated expression of the bla KPC gene compared with the native populations but did not retain heteroresistance when subcultured in drug-free media. Time-kill assays indicated that meropenem alone was not bactericidal against KPC-KP but efficiently killed the control strains.

Heteroresistance to Meropenem in Carbapenem-Susceptible Acinetobacter baumannii

ABSTRACT The characteristics of carbapenem heteroresistance were studied in 14 apparently carbapenem-susceptible Acinetobacter baumannii isolates. The MICs for carbapenems were determined, and the isolates were genotyped by pulsed-field gel electrophoresis (PFGE) and sequence typing (ST). Population analysis, testing of the stability of the heteroresistant subpopulations, and time-killing assays were performed. The agar dilution MICs of both imipenem and meropenem for the native isolates ranged from 0.25 to 4 mg/liter. The isolates belonged to nine PFGE types and exhibited seven ST allelic profiles. Population analysis revealed subpopulations that grew in the presence of imipenem at concentrations of up to 8 mg/liter and meropenem at concentrations of up to 32 mg/liter. The meropenem-heteroresistant subpopulations of 11 isolates exhibited stable resistance with MICs that ranged from 16 to >32 mg/liter; their PFGE profiles were identical to those of the native isolates. Time-kill assays with meropenem revealed less pronounced killing for 10 isolates. These findings indicate that meropenem pressure can produce meropenem-heteroresistant subpopulations that might subsequently select for highly resistant strains.

Usefulness of Herpes Consensus PCR methodology to routine diagnostic testing for herpesviruses infections in clinical specimens.

The purposes of the study were to assess the usefulness of simultaneously amplifying herpes simplex virus 1 and 2, varicella-zoster virus, cytomegalovirus, Epstein-Barr virus and human herpesvirus 6 DNA in various clinical specimens and to analyze clinical events in patients presenting positive results. A total of 763 clinical samples obtained from 758 patients, including 115 cerebrospinal fluids, 102 aqueous fluids, 445 swabs from genital (152), oro-facial (138) and other (155) skin lesions, 96 eye swabs and 5 bronchoalveolar lavages, were tested by using the Consensus polymerase chain reaction methodology. The clinical files of the patients were consulted retrospectively. 171 of the 758 patients (22.5%) were positive for at least one of the six target viruses: herpes simplex virus 1 (n = 95), varicella-zoster virus (n = 40), herpes simplex virus 2 (n = 21), herpes simplex virus 1 plus herpes simplex virus 2 (n = 8), cytomegalovirus (n = 4), Epstein-Barr virus (n = 1), human herpesvirus 6 (n = 1), and herpes simplex virus 1 plus human herpesvirus 6 (n = 1). The Consensus methodology enabled the rapid and accurate detection of herpesviruses in various clinical specimens and provided a reliable tool in the diagnosis of herpetic infections.

Utility of Real-Time PCR in the Diagnosis of Primary Epstein-Barr VirusInfection

Background: Despite the availability of several serological markers, Epstein-Barr virus (EBV) status of some patients is not easily resolved. Objectives: The aim of the present study was to investigate the quantification and the diagnostic utility of EBV DNA detection as an adjunct to serological diagnosis of primary EBV infection. Study Design: Sera from 118 patients referred for suspected primary EBV infection, were tested for heterophile antibodies (HA), IgM antibodies against viral capsid antigen (VCA IgM) and IgG against nuclear antigen (EBNA IgG). A quantitative real time EBV PCR assay (Light Cycler EBV Quant kit) was simultaneously performed in plasma of these patients. Results: EBV DNA was detected in 43 of 46 patients (93.5%) with serologically confirmed primary infection. By performing real time RCR in the remaining 72 samples, 24 additional cases were diagnosed: in 20 of them, VCA IgM was positive but not HA; in 4 cases, HA were positive, but not VCA IgM. EBV DNA load was detectable in all samples drawn until day 12 after onset of symptoms; 20 days after onset all samples were negative. Higher viral load levels were detected in younger patients and in male patients. Conclusions: The use of EBV PCR assay resulted in an increase in definitive diagnosis of primary EBV infection, enhancing overall diagnostic efficacy by 20.3%. Real time PCR is a reliable tool for diagnosis of primary EBV infection early in the course of disease and may especially serve as a useful diagnostic supplement in serologically unclear cases of EBV infection.

First Case of Lung Abscess due to Salmonella enterica Serovar Abony in an Immunocompetent Adult Patient.

In healthy individuals, nontyphoidal Salmonella species predominantly cause a self-limited form of gastroenteritis, while they infrequently invade or cause fatal disease. Extraintestinal manifestations of nontyphoidal Salmonella infections are not common and mainly occur among individuals with specific risk factors; among them, focal lung infection is a rare complication caused by nontyphoidal Salmonella strains typically occurring in immunocompromised patients with prior lung disease. We describe the first case of a localized lung abscess formation in an immunocompetent healthy female adult due to Salmonella enterica serovar Abony. The patient underwent lobectomy and was discharged after full clinical recovery. This case report highlights nontyphoidal Salmonellae infections as a potential causative agent of pleuropulmonary infections even in immunocompetent healthy adults.

A life-threatening case of disseminated nocardiosis due to Nocardia brasiliensis.

Nocardiosis is a rare disease caused by infection with Nocardia species, aerobic actinomycetes with a worldwide distribution. A rare life-threatening disseminated Nocardia brasiliensis infection is described in an elderly, immunocompromised patient. Microorganism was recovered from bronchial secretions and dermal lesions, and was identified using molecular assays. Prompt, timely diagnosis and appropriate treatment ensured a favorable outcome.