Implementing the number needed to harm in clinical practice: risk of myocardial infarction in HIV-1-infected patients treated with abacavir.

OBJECTIVES: The D:A:D study group reported a 1.9-fold increased relative risk (RR) of myocardial infarction (MI) associated with current or recent use of abacavir. The number needed to harm (NNH) incorporates information about the underlying risk of MI and the increased RR of MI in patients taking abacavir. METHODS: NNH was calculated as the reciprocal of the difference between the underlying risks of MI with and without abacavir use. A parametric statistical model was used to calculate the underlying risk of MI over 5 years. RESULTS: The relationship between NNH and underlying risk of MI is reciprocal, resulting in wide variation in the NNH with small changes in underlying risk of MI. The smallest changes in NNH are in the medium- and high-risk groups of MI. The NNH changes as risk components are modified; for example, for a patient who smokes and has a systolic blood pressure (sBP) of 160 mmHg and a 5-year risk of MI of 1.3% the NNH is 85, but the NNH increases to 277 if the patient is a nonsmoker and to 370 if sBP is within the normal range (120 mmHg). CONCLUSIONS: We have illustrated that the impact of abacavir use on risk of MI varies according to the underlying risk and it may be possible to increase considerably the NNH by decreasing the underlying risk of MI using standard of care interventions, such as smoking cessation or control of hypertension.

Isolation of lytic bacteriophage against Vibrio harveyi.

AIMS: The isolation of lytic bacteriophage of Vibrio harveyi with potential for phage therapy of bacterial pathogens of phyllosoma larvae from the tropical rock lobster Panulirus ornatus. METHODS AND RESULTS: Water samples from discharge channels and grow-out ponds of a prawn farm in northeastern Australia were enriched for 24 h in a broth containing four V. harveyi strains. The bacteriophage-enriched filtrates were spotted onto bacterial lawns demonstrating that the bacteriophage host range for the samples included strains of V. harveyi, Vibrio campbellii, Vibrio rotiferianus, Vibrio parahaemolyticus and Vibrio proteolyticus. Bacteriophage were isolated from eight enriched samples through triple plaque purification. The host range of purified phage included V. harveyi, V. campbellii, V. rotiferianus and V. parahaemolyticus. Transmission electron microscope examination revealed that six purified phage belonged to the family Siphoviridae, whilst two belonged to the family Myoviridae. The Myoviridae appeared to induce bacteriocin production in a limited number of host bacterial strains, suggesting that they were lysogenic rather than lytic. A purified Siphoviridae phage could delay the entry of a broth culture of V. harveyi strain 12 into exponential growth, but could not prevent the overall growth of the bacterial strain. CONCLUSIONS: Bacteriophage with lytic activity against V. harveyi were isolated from prawn farm samples. Purified phage of the family Siphoviridae had a clear lytic ability and no apparent transducing properties, indicating they are appropriate for phage therapy. Phage resistance is potentially a major constraint to the use of phage therapy in aquaculture as bacteria are not completely eliminated. SIGNIFICANCE AND IMPACT OF THE STUDY: Phage therapy is emerging as a potential antibacterial agent that can be used to control pathogenic bacteria in aquaculture systems. The development of phage therapy for aquaculture requires initial isolation and determination of the bacteriophage host range, with subsequent creation of suitable phage cocktails.

Prediction of phenotypic susceptibility to antiretroviral drugs using physiochemical properties of the primary enzymatic structure combined with artificial neural networks.

OBJECTIVES: Genotypic interpretation systems extrapolate observed associations in datasets to predict viral susceptibility to antiretroviral drugs (ARVs) for given isolates. We aimed to develop and validate an approach using artificial neural networks (ANNs) that employ descriptors of physiochemical properties for mutations in HIV-1 protease (PR) and reverse transcriptase (RT) to predict phenotypic susceptibility to all currently approved ARVs. METHOD: We extracted pairs of PR and RT gene sequences (n=1507; 98.5% sub-type B) and their corresponding exact phenotype values (PhenoSense only, n=10 132) from the Stanford HIV database. All amino acid positions and mixture codes were accounted for. For each ARV, an ANN was trained with 10-fold internal cross-validation. The predictive abilities of these trained ANNs were validated on separate datasets. RESULTS: Correlation coefficients between observed and predicted phenotype values in the 10-fold cross-validation ranged from: 0.75 (tenofovir) to 0.94 [lamivudine (3TC)] for nucleoside RT inhibitors (NRTIs); 0.82 [efavirenz (EFV)] to 0.83 [nevirapine (NVP)] for non-nucleoside RT inhibitors (NNRTIs); and 0.83 (atazanavir) to 0.92 (ritonavir) for PR inhibitors (PIs). For the validation set the correlation coefficients ranged from 0.76 (didanosine) to 0.96 (3TC) for NRTIs; 0.68 (EFV) to 0.81 (NVP) for NNRTIs; and 0.88 (amprenavir) to 0.95 (saquinavir) for PIs. For C sub-type predictions, with ANNs trained on sub-type B data, the correlation coefficient was 0.89. CONCLUSIONS: ANNs, based on the physiochemical properties of the PR and RT amino-acid sequences, predict phenotypic susceptibility to ARVs inhibiting these enzymes to an extent that is comparable to routine phenotypic susceptibility testing. These ANNs can also be used to predict resistance to C sub-types.

Microbial diversity of mid-stage Palinurid phyllosoma from Great Barrier Reef waters.

AIMS: This study aimed to determine the bacterial community associated with wild-caught, mid-stage larvae of spiny lobsters (Palinuridae) in their native oligotrophic marine environment, and to compare their diversity and composition with communities associated with aquaculture-reared larvae of the tropical rock lobster Panulirus ornatus. METHODS AND RESULTS: Bacterial clone libraries constructed from wild P. ornatus (two libraries) and Panulirus penicillatus (one library) larvae (phyllosoma) revealed a dominance of alpha-proteobacterial sequences, with Sulfitobacter spp.-affiliated sequences dominating both P. ornatus libraries and constituting a major portion of the P. penicillatus library. Vibrio-related sequences were rarely detected from wild phyllosoma clone libraries in contrast to similar studies of aquaculture-reared animals. Scanning electron microscopy analysis revealed low levels of bacterial colonization on the external carapace of wild phyllosoma, again in contrast to aquaculture-reared animals, which are often colonized with filamentous bacteria (mainly Thiothrix sp.) that compromise their health. Fluorescence in situ hybridization of sectioned wild phyllosoma tissue displayed low overall abundance of bacteria within the tissue and on external surfaces, with alpha-, beta-, and gamma-Proteobacteria being confirmed as members of this bacterial community. CONCLUSIONS: The consistency in predominant clone sequences retrieved from the three libraries indicated a conserved microbiota associated with wild phyllosoma. In addition, the observed differences in the microbial composition and load of reared and wild phyllosoma are indicative of the different environments in which the animals live. SIGNIFICANCE AND IMPACT OF THE STUDY: Bacterial disease during early larval stages is a major constraint currently hindering the development of an aquaculture industry for the ornate rock lobster P. ornatus. Knowledge of the microbial community associated with wild animals will be advantageous for the identification of bacteria that may promote animal health.

Maternal mortality in Guinea-Bissau: the use of verbal autopsy in a multi-ethnic population.

BACKGROUND: In developing countries with scanty resources it is very important to have reliable data to establish priorities for the health sector; e.g. to reduce maternal mortality it is necessary to determine the most important causes. The majority of deaths, however, occur without previous contact with the health system and consequently conventional analyses of death certificates are not feasible. Instead, studies have been carried out in some developing countries with various forms of post-mortem interviews, the so-called verbal autopsies (VA). METHODS: We developed a structured interview with filter questions, which was applied to all deaths of women of fertile age in a cohort of 10,000 women living in 100 clusters in Guinea-Bissau and followed over a period of 6 years. The cause of death was ascertained by means of a series of diagnostic algorithms for the most common causes of maternal mortality, including postpartum haemorrhage, antepartum haemorrhage, puerperal infection, obstructed labour, eclampsia, abortion, and ectopic pregnancy. RESULTS: Of the 350 deaths of women of fertile age, 32% were maternal and it seems unlikely that a significant proportion of maternal deaths have not been classified correctly. Using the diagnostic algorithm 70% could be given a specific diagnosis, the most important causes being postpartum haemorrhage (42% [29/69]), obstructed labour (19% [13/69]), and puerperal infection (16% [11/69]). We attempted to identify the factors that are critical for obtaining sufficient information to reach a diagnosis. In the univariate analyses, it was important whether the respondent had been present during the last illness (P = 0.04) and whether the death occurred more than one week after delivery (P = 0.04). The husband was a better respondent than a co-wife (P = 0.08), and men in general provided more specific information than women (P = 0.08). Furthermore, information appeared to be better if the woman had died in the rainy season (P = 0.08). The length of the recall period, parity, age of woman, place of death, rural/urban residence, and ethnic group were not decisive. In the multivariate analysis sex and presence of respondent and time after delivery were significantly associated with the risk of not reaching a specific diagnosis. Women are less likely to provide adequate information for a diagnosis than men (odds ratio [OR] 3.1; 95% confidence interval [CI]: 1.2-8.1). Respondents that did not reside in the village during the departed woman's illness/delivery carried equal risk of not reaching a conclusion (OR 3.1; CI: 1.1-9.1). Deaths occurring more than one week after delivery were also less likely to be classified (OR 6.1; CI: 1.7-22.0). CONCLUSION: The VA described in the present paper left 30% of the maternal deaths unclassified without a specific diagnosis. Had all interviews been with husbands, only 14% would have remained unclassified. If we had only asked people who were present during the terminal phase of the victim's illness the proportion of classified deaths would have risen from 70% to 75%. It is likely that delayed maternal deaths have not been adequately covered by the present algorithms, but they may also simply be more difficult to describe due to the duration of the disease episode. In contrast to methods by which cause of death is established by a panel of medical experts, the present VA should be economically and technically viable in areas where health workers have only minimal training.

Secretion rate of intestinal immunoglobulins, complement factor C3, "acute phase" reactants, and albumin in the perfused ileum and jejunum of normal man.

A new method for assessment of the intestinal secretion rate of immunoglobulins and other proteins is evaluated. The procedure involves a combination of luminal perfusion of a defined intestinal segment and analysis of the aspirated perfusates by rocket immunoelectrophoresis. The technique is sensitive and reliable. A material from the normal human jejunum and ileum is presented. The method is proposed as an investigative tool for characterization of the local immunological system of the small intestine.