Clinical correlates of herpes simplex virus type 1 loads in the lower respiratory tract of critically ill patients.

BACKGROUND: The significance of isolation of herpes simplex virus (HSV) type 1 from the lower respiratory tract in critically ill patients on mechanical ventilation is still unclear. In the current study, we used polymerase chain reaction techniques to quantify HSV-1 to further evaluate its role. OBJECTIVES: The hypothesis was that high loads reflect invasive pulmonary disease related to prolonged mechanical ventilation and increased mortality, as opposed to shedding from the upper respiratory tract, which leads to lower viral loads. STUDY DESIGN: We prospectively studied 77 consecutive patients admitted to the intensive care unit and analyzed 136 tracheal aspirates or bronchoalveolar lavage fluids, taken when clinically indicated in the diagnostic workup of fever, radiologic pulmonary infiltrates, progressive respiratory insufficiency or combinations. Samples were cultured for bacteria and yeasts according to routine microbiological methods and HSV-1 loads were determined by real time quantitative PCR. Viral loads were expressed per number of cells recovered. RESULTS: HSV-1 load was directly related to the simplified acute physiology score II (rs=0.47, P=0.04) when the first specimen taken proved positive for HSV-1. HSV-1 positivity concurred with Candida spp. colonization. Patients with and without a HSV-1 load did not differ with respect to pulmonary and systemic courses and vital outcomes. CONCLUSIONS: The data suggest that HSV-1 in the lower respiratory tract originates from shedding in the upper respiratory tract in about 30% of critically ill patients, following immune suppression and reactivation, without invasively infecting the lung. No attributable mortality was observed.

Evolution and viral characteristics of a long-term circulating resistant HIV-1 strain in a cluster of treatment-naive patients.

BACKGROUND: Transmitted resistant HIV may revert to wild-type in the absence of drug pressure due to reduced replication capacity (RC). We observed eight therapy-naive patients infected with HIV harbouring four mutations at nucleoside reverse transcriptase inhibitor (NRTI) resistance-related positions: M41L, T69S, L210E and T215S. If partial reverted resistance patterns like these are detected at baseline, concerns for more extensive resistance in the quasispecies often directs selection of first-line combination antiretroviral therapy (cART) towards more complex regimens. METHODS: Genotypic resistance testing and phylogenetic analysis was performed using pol sequences of 400 therapy-naive patients and 1322 patients with at least one NRTI-related mutation. Reverse transcriptase (RT) genes were cloned into a reference strain and RC was investigated. RESULTS: Phylogenetic analysis showed that all eight patients are part of a transmission cluster (bootstrap value 92%). The patients resided in three distinct geographical regions and were either homosexually or heterosexually infected. Prior negative serology and analysis of base ambiguity demonstrated circulation for at least 7 years. In vivo evolution showed a mixture with wild-type (T215S/T) in only one untreated patient more than 6 years after diagnosis. The reverted resistance pattern did not confer a substantial reduction in RC compared with wild-type, explaining its persistence in vivo and long-term circulation in the population. Four patients started cART; three of them received quadruple cART. All patients showed good virological and immunological response. CONCLUSIONS: Long-term circulation transcending distinct regions and transmission groups suggests reversion occurred in previous hosts in the transmission chain. Identification of clusters using epidemiological data and active-partner tracing may broaden therapeutic options in cases of transmitted resistance.

Rapid identification of pathogens in blood cultures with a modified fluorescence in situ hybridization assay.

We evaluated a modified fluorescence in situ hybridization (FISH) assay for rapid (<1 h) identification of microorganisms in growth-positive blood cultures. The results were compared to those of the standard FISH technique and conventional culturing. The rapid identification of microorganisms with modified FISH can have important effects on clinical management of patients with bloodstream infections.

Faster identification of pathogens in positive blood cultures by fluorescence in situ hybridization in routine practice.

Rapid identification of microorganisms in blood cultures is required to optimize empirical treatment at an early stage. Fluorescence in situ hybridization (FISH) can reduce the time to identification of microorganisms in growth-positive blood cultures. In this study, we evaluated the performance, time to identification, and potential clinical benefits of FISH compared to those of conventional culture methods in routine practice. After Gram staining, blood culture fluids were simultaneously further identified with FISH and with conventional culture methods. Results and points in time of FISH and culture identification (provisional and final identifications) were collected and compared. For 91% of microorganisms, the genus or family name was identified, and for 79%, the species name could be attributed. The sensitivity and specificity of the individual probes exceeded 95%, except for the Enterobacteriaceae probe (sensitivity, 89%). Cross-hybridization was obtained with the Klebsiella pneumoniae probe for Klebsiella oxytoca. The time gains of FISH and final culture identification were more than 18 h for bacteria and 42 h for yeasts. With FISH, Staphylococcus aureus was differentiated from coagulase-negative staphylococci 1.4 h faster than by provisional identification (P < 0.001). In conclusion, FISH allows rapid and reliable identification of the majority of microorganisms in growth-positive blood cultures. The substantial time gain of identification with FISH may allow same-day adjustment of antimicrobial therapy, and FISH is especially useful if no provisional identification is obtained. With further extension of the number of probes and a reduction in turnaround time, FISH will become a very useful diagnostic tool in the diagnosis of bloodstream infections.

Cefpirome as empirical treatment for febrile neutropenia in patients with hematologic malignancies.

Cefpirome, a fourth generation cephalosporin, was administered during 154 episodes of febrile neutropenia in 106 patients. We assessed the clinical efficacy of cefpirome and its activity against isolated pathogens in neutropenic patients with hematologic malignancies. In addition, the pharmacokinetics and optimal dosing regimen of cefpirome during neutropenia were investigated.

Herpes simplex virus type 1 and normal protein permeability in the lungs of critically ill patients: a case for low pathogenicity?

INTRODUCTION: The pathogenicity of late respiratory infections with herpes simplex virus type 1 (HSV-1) in the critically ill is unclear. METHODS: In four critically ill patients with persistent pulmonary infiltrates of unknown origin and isolation of HSV-1 from tracheal aspirate or bronchoalveolar lavage fluid, at 7 (1-11) days after start of mechanical ventilatory support, a pulmonary leak index (PLI) for 67Gallium (67Ga)-transferrin (upper limit of normal 14.1 x 10(-3)/min) was measured. RESULTS: The PLI ranged between 7.5 and 14.0 x 10(-3)/min in the study patients. Two patients received a course of acyclovir and all survived. CONCLUSIONS: The normal capillary permeability observed in the lungs argues against pathogenicity of HSV-1 in the critically ill, and favors that isolation of the virus reflects reactivation in the course of serious illness and immunodepresssion, rather than primary or superimposed infection in the lungs.

Respiratory herpes simplex virus type 1 infection/colonisation in the critically ill: marker or mediator?

BACKGROUND: The clinical significance and pulmonary pathogenicity of herpes simplex virus type 1 (HSV-1) in mechanically ventilated, critically ill patients are unclear. OBJECTIVE: To determine the clinical features and course of respiratory HSV-1 infections/colonisations in the critically ill, in order to evaluate the contribution to outcome. DESIGN: A retrospective cohort study in the intensive care unit of an university hospital, involving 22 patients with a HSV-1 isolated from bronchoalveolar lavage (BAL) fluid, divided into survivors (n = 13) and non-survivors (n = 9). All patients except for one survivor had been intubated and were mechanically ventilated. RESULTS: Non-survivors had acquired HSV-1 sooner on mechanical ventilation than survivors. Prior chronic heart disease was more prevalent in non-survivors than in survivors and, at the time of HSV-1 isolation, the mean creatinine level was higher (P < 0.05) in the former. Survivors had a somewhat greater fall in body temperature after a 10-day course of antiviral therapy than non-survivors, but the lung radiographic abnormalities prior to and after the course did not differ. There were no major differences in cardiorespiratory variables between outcome groups and causes of death and were judged not to relate, in general, to HSV-1. CONCLUSIONS: Critically ill patients in whom HSV-1 from BAL is isolated, have about 40% chance of dying, mainly because of severe underlying disease and comorbidity, which may predispose to endogenous reactivation of the virus. There is no clinical evidence for direct cardiorespiratory pathogenicity and beneficial effects of antiviral therapy. HSV-1 isolated from lung secretions may thus be a marker rather than a mediator of severe illness.