Alain Gervaix

Bio: Alain Gervaix is an academic researcher from Geneva College. The author has contributed to research in topics: Procalcitonin & Population. The author has an hindex of 39, co-authored 179 publications receiving 4974 citations. Previous affiliations of Alain Gervaix include University of California, San Diego & University of California, Los Angeles.

A new reporter cell line to monitor HIV infection and drug susceptibility in vitro

Abstract: Determination of HIV infectivity in vitro and its inhibition by antiretroviral drugs by monitoring reduction of production of p24 antigen is expensive and time consuming. Such assays also do not allow accurate quantitation of the number of infected cells over time. To develop a simple, rapid, and direct method for monitoring HIV infection, we generated a stable T-cell line (CEM) containing a plasmid encoding the green fluorescent protein (humanized S65T GFP) driven by the HIV-1 long terminal repeat. Clones were selected that displayed low constitutive background fluorescence, but a high level of GFP expression upon infection with HIV. HIV-1 infection induced a 100- to 1,000-fold increase in relative fluorescence of cells over 2 to 4 days as monitored by fluorescence microscopy, cytofluorimetry, and flow cytometry. Addition of inhibitors of reverse transcriptase, protease, and other targets at different multiplicities of infection permitted the accurate determination of drug susceptibility. This technique also permitted quantitation of infectivity of viral preparations by assessment of number of cells infected in the first round of infection. In conclusion, the CEM-GFP reporter cell line provides a simple, rapid, and direct method for monitoring HIV infectivity titers and antiretroviral drug susceptibility of syncytium-inducing strains.

The role of penicillin in benign skin rashes in childhood: a prospective study based on drug rechallenge.

Abstract: Background Delayed-onset urticarial or maculopapular rashes are frequently observed in children treated with β-lactams. Many are labeled "allergic" without reliable testing. Objective Determine the etiology of these rashes by exploring both infectious and allergic causes. Methods Children presenting to the emergency department with delayed-onset urticarial or maculopapular rashes were enrolled. Acute and convalescent sera were obtained for viral screening along with a throat swab. Subjects underwent intradermal and patch skin testing for β-lactams 2 months after presentation. Anti–β-lactam blood allergy tests were also obtained. All subjects underwent an oral challenge test (OCT) with the culprit antibiotic. Results Eighty-eight children were enrolled between 2006 and 2008. There were 11 (12.5%) positive intradermal and no positive patch tests. There were 2 (2.3%) positive blood allergy tests. There were 6 (6.8%) subjects with a positive OCT, 2 were intradermal-negative, and 4 were intradermal-positive. No OCT reactions were more severe than the index event. Most subjects had at least 1 positive viral study, 54 (65.9%) in the OCT negative group. Conclusion In this situation, β-lactam allergy is clearly overdiagnosed because the skin rash is only rarely reproducible (6.8%) by a subsequent challenge. Viral infections may be an important factor in many of these rashes. OCTs were positive in a minority of intradermal skin test–positive subjects. Patch testing and blood allergy testing provided no useful information. OCTs should be considered in all children who develop a delayed-onset urticarial or maculopapular rash during treatment with a β-lactam.

Bedside procalcitonin and C-reactive protein tests in children with fever without localizing signs of infection seen in a referral center

Abstract: Objective. To assess the value of bedside tests for predicting the occurrence of severe bacterial infections (SBIs) in children with fever without source. Methods. We conducted a prospective study of 99 children, aged 7 days to 36 months, who were seen for fever >38°C and no localizing sign of infection at the emergency department of the University Children’s Hospital of Geneva. Blood procalcitonin (PCT), C-reactive protein (CRP), and interleukin-6 (IL-6) values were determined using rapid tests and were compared with the total white blood cell (WBC) count with differential and clinical score. Specificity, sensitivity, predictive values, and multilevel likelihood ratios (LRs) with posttest probabilities of disease were calculated. Results. Twenty-nine (29%) children received a diagnosis of having an SBI. PCT had the best sensitivity (93%) and negative predictive value (96%). Band count had the best specificity (93%), but its positive predictive value was only 38%. Multilevel LRs revealed that a PCT concentration 2 ng/mL (LR: 5.2) increased the probability of SBI to 68% in 19 (19%) children. For CRP, values 100 mg/L (LR: 14.483) generated posttest probabilities for SBI of 9.7% (61 subjects) and 86.5% (14 subjects), respectively. For WBC count, the posttest probabilities of SBI were modestly changed from the pretest prevalence. Conclusions. PCT and CRP performed better than IL-6, WBC, and/or band count in predicting the occurrence of SBI. PCT and CRP bedside tests may be useful tools for emergency and private practice doctors and should be considered in the initial work-up of children with fever without source.

Validation of the "Step-by-Step" Approach in the Management of Young Febrile Infants

Abstract: BACKGROUND: A sequential approach to young febrile infants on the basis of clinical and laboratory parameters, including procalcitonin, was recently described as an accurate tool in identifying patients at risk for invasive bacterial infection (IBI). Our aim was to prospectively validate the Step-by-Step approach and compare it with the Rochester criteria and the Lab-score. METHODS: Prospective study including infants ≤90 days with fever without source presenting in 11 European pediatric emergency departments between September 2012 and August 2014. The accuracy of the Step-by-Step approach, the Rochester criteria, and the Lab-score in identifying patients at low risk of IBI (isolation of a bacterial pathogen in a blood or cerebrospinal fluid culture) was compared. RESULTS: Eighty-seven of 2185 infants (4.0%) were diagnosed with an IBI. The prevalence of IBI was significantly higher in infants classified as high risk or intermediate risk according to the Step by Step than in low risk patients. Sensitivity and negative predictive value for ruling out an IBI were 92.0% and 99.3% for the Step by Step, 81.6% and 98.3% for the Rochester criteria, and 59.8% and 98.1% for the Lab-score. Seven infants with an IBI were misclassified by the Step by Step, 16 by Rochester criteria, and 35 by the Lab-score. CONCLUSIONS: We validated the Step by Step as a valuable tool for the management of infants with fever without source in the emergency department and confirmed its superior accuracy in identifying patients at low risk of IBI, compared with the Rochester criteria and the Lab-score.

Iconography : The role of penicillin in benign skin rashes in childhood: A prospective study based on drug rechallenge

Abstract: Background Delayed-onset urticarial or maculopapular rashes are frequently observed in children treated with β-lactams. Many are labeled “allergic” without reliable testing. Objective Determine the etiology of these rashes by exploring both infectious and allergic causes. Methods Children presenting to the emergency department with delayed-onset urticarial or maculopapular rashes were enrolled. Acute and convalescent sera were obtained for viral screening along with a throat swab. Subjects underwent intradermal and patch skin testing for β-lactams 2 months after presentation. Anti–β-lactam blood allergy tests were also obtained. All subjects underwent an oral challenge test (OCT) with the culprit antibiotic. Results Eighty-eight children were enrolled between 2006 and 2008. There were 11 (12.5%) positive intradermal and no positive patch tests. There were 2 (2.3%) positive blood allergy tests. There were 6 (6.8%) subjects with a positive OCT, 2 were intradermal-negative, and 4 were intradermal-positive. No OCT reactions were more severe than the index event. Most subjects had at least 1 positive viral study, 54 (65.9%) in the OCT negative group. Conclusion In this situation, β-lactam allergy is clearly overdiagnosed because the skin rash is only rarely reproducible (6.8%) by a subsequent challenge. Viral infections may be an important factor in many of these rashes. OCTs were positive in a minority of intradermal skin test–positive subjects. Patch testing and blood allergy testing provided no useful information. OCTs should be considered in all children who develop a delayed-onset urticarial or maculopapular rash during treatment with a β-lactam.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

The outcome of childhood Haemophilus influenzae meningitis. A population based study.

Abstract: OBJECTIVE To determine the morbidity and mortality from childhood Haemophilus influenzae type b (Hib) meningitis in a well defined population. DESIGN Retrospective survey 1985-1987 and prospective surveillance of hospital laboratories 1989-1990. Information on outcome of meningitis was obtained from hospital records and attending physicians and, in 1989-1990, from a survey of the children's parents. SETTING Sydney Statistical Division, which had a population of children aged 0-4 years of 229,165 in 1986 and 263,758 in 1990. PATIENTS Eligible children were aged from one month to four years and had clinical and microbiological evidence of Hib meningitis on standard criteria. RESULTS There were 229 eligible children. Twelve were excluded (seven died and five had pre-existing neurological deficits). A neurological deficit was detected at the time of hospital discharge in 45 patients (21%) and persisted for 12 months or longer in 29 patients (13%). Follow-up information was available for 165 (96%) children who were normal at the time of hospital discharge and persistent deficits were recorded in 12 (7%) of these children. Forty-one children (19%) had readily recognisable neurological or hearing problems: nine (4%) had persistent severe neurological deficits and seven (3%) had severe hearing loss requiring hearing aids or a cochlear implant. Age had a significant influence on outcome. The youngest children were significantly more likely to be admitted to intensive care. Severe neurological deficits showed a significant negative trend with increasing age (P = 0.03). Severe unilateral or bilateral sensorineural loss (odds ratio [OR] 8.0, 95% confidence interval [CI] 1.5-81) and ataxia at discharge (OR 13.3, 95% CI 2.8-128) were noticeably more common in children over two years of age, with a significant positive trend (P < or = 0.001) with increasing age. Patients requiring intensive care were much more likely to have an adverse outcome, particularly if positive pressure ventilation was needed. CONCLUSIONS These data provide population-based estimates of the minimum incidence of adverse outcomes from Hib meningitis in an urban community with good access to medical services. This is important in assessing the impact of Hib vaccination, as meningitis is responsible for most of the long-term morbidity from childhood invasive Hib disease. Determination of the relationship between morbidity and age is important for assessing alternative vaccine strategies.

The green fluorescent protein

Abstract: In just three years, the green fluorescent protein (GFP) from the jellyfish Aequorea victoria has vaulted from obscurity to become one of the most widely studied and exploited proteins in biochemistry and cell biology. Its amazing ability to generate a highly visible, efficiently emitting internal fluorophore is both intrinsically fascinating and tremendously valuable. High-resolution crystal structures of GFP offer unprecedented opportunities to understand and manipulate the relation between protein structure and spectroscopic function. GFP has become well established as a marker of gene expression and protein targeting in intact cells and organisms. Mutagenesis and engineering of GFP into chimeric proteins are opening new vistas in physiological indicators, biosensors, and photochemical memories.

Waves of resistance: Staphylococcus aureus in the antibiotic era

Abstract: Staphylococcus aureus is notorious for its ability to become resistant to antibiotics. Infections that are caused by antibiotic-resistant strains often occur in epidemic waves that are initiated by one or a few successful clones. Methicillin-resistant S. aureus (MRSA) features prominently in these epidemics. Historically associated with hospitals and other health care settings, MRSA has now emerged as a widespread cause of community infections. Community or community-associated MRSA (CA-MRSA) can spread rapidly among healthy individuals. Outbreaks of CA-MRSA infections have been reported worldwide, and CA-MRSA strains are now epidemic in the United States. Here, we review the molecular epidemiology of the epidemic waves of penicillin- and methicillin-resistant strains of S. aureus that have occurred since 1940, with a focus on the clinical and molecular epidemiology of CA-MRSA.