Reduced vancomycin susceptibility and increased macrophage survival in Staphylococcus aureus strains sequentially isolated from a bacteraemic patient during a short course of antibiotic therapy.

PURPOSE: The purpose of the present study was to determine the relatedness of Staphylococcus aureus strains successively isolated over a 7-day period from a single bacteraemic patient undergoing antibiotic treatment with vancomycin. METHODS: The S. aureus strains had been isolated and sequenced previously. Antibiotic susceptibility testing, population analysis profiling, and lysostaphin sensitivity and phagocytic killing assays were used to characterize these clonal isolates. RESULTS: The seven isolates (MEH1-MEH7) were determined to belong to a common multilocus sequence type (MLST) and spa type. Within the third and fifth day of vancomycin treatment, mutations were observed in the vraS and rpsU genes, respectively. Population analysis profiles revealed that the initial isolate (MEH1) was vancomycin-susceptible S. aureus (VSSA), while those isolated on day 7 were mostly heteroresistant vancomycin-intermediate S. aureus (hVISA). Supporting these findings, MEH7 was also observed to be slower in growth, to have an increase in cell wall width and to have reduced sensitivity to lysostaphin, all characteristics of VISA and hVISA strains. In addition, MEH7, although phagocytosed at numbers comparable to the initial isolate, MEH1, survived in higher numbers in RAW 264.7 macrophages. Macrophages infected with MEH7 also released more TNF-α and IFN-1ß. CONCLUSION: We report an increasing resistance to vancomycin coupled with daptomycin that occurred within approximately 3 days of receiving vancomycin and steadily increased until the infection was cleared with an alternative antibiotic therapy. This study reiterates the need for rapid, efficient and accurate detection of hVISA and VISA infections, especially in high-bacterial load, metastatic infections like bacteraemia.

[Mensurement of airflow resistance in neonatal prongs of nasal CPAP] / Medida da resistência ao fluxo aéreo em peças nasais de CPAP.

OBJECTIVE: To measure airflow resistance in prongs of nasal CPAP, making use of different gas admission flow (GAF) in the ventilation circuit, in different internal diameters of the nasal prongs, besides verifying whether a GAF responding only to the demand of three times the minute-volume(MV) is enough to the circuit not to be cause of CO(2) retention. METHODOLOGY: Nasal prongs, assembled in the original circuits, were used, having their prongs kept open to the atmosphere. Pressure was read at a pressure monitor, in water centimeters, connected to the appropriate entrance of the circuit. A flowmeter balanced to the pressure was used, gauged at 50 psi, installed to the oxygen net of the Hospital, connected to the assessing set of the CPAP circuit. Initially, making use of the 8 l/min flow and keeping the exhaling set of the circuit closed, it was possible to eliminate the nasal prongs larger than two once the measured resistance was equal to zero. Having nasal parts number zero, 1 and 2 selected for this study, the system was then assembled as for the neonate: the inhaling set to the gas source and the exhaling set sunk into different depths in the water seal (2, 4, 6 and 8 centimeters). At the level of patient analysis, in order to assess the CO(2) retention, a mechanical pulmonary ventilation device was used as gas source and a nasal CPAP circuit was assembled to the device in adequate places. GAF values and FiO(2) were determined in the commands of the mechanical ventilation device. The assessment of gas concentration in the ventilation circuit was made while assisting two newborns. Gas samples were obtained within the ventilation circuit in the system assessing set (samples A), and right after the distal prong to the gas entrance (samples B). To determine MV the Tidal Volume (considered 10ml/kg) was multiplied by the respiratory frequency of the patient; GAF was three times MV. RESULTS: To a maximum GAF of 8 litres/min, only prongs sized zero, 1 and 2 showed resistance to the flow, measurable by the method used. There was an increase in resistance in proportion to the raise of GAF and proportionally opposite to the internal diameter of some prongs. Maximum difference in CO(2) partial pressure obtained from the gas given to the ventilation circuit and the one obtained from the nasal prongs was, in average, 0.43mmHg (p <0.5). CONCLUSIONS: Taking into account that during ventilation assistance through nasal CPAP there is the possibility of GAF incurring in the increase in resistance, what would involve a greater effort from the newborn to overcome such resistance during exhaling into the system (generating possibly an unexpected CPAP), and minimum GAF determined is that sufficient to meet no more than three times the MV, the conclusion is that prongs with the largest internal diameter possible and GAF only the necessary to meet, at least, the needs of the demand three times the MV should be used during this therapeutic procedure.

Esquema reduzido de vacinacao anti-rabica humana pre-exposicao e avaliacao de doses anuais de reforco. / Reduced schedule of human pre-exposure antirabies vaccination and evaluation of annual booster doses

Sao apresentados os resultados do emprego de esquema de vacinacao anti-rabica humana pre-exposicao, constituido de 3 doses de vacina tipo Fuenzalida-Palacios administradas a 165 pacientes em dias alternados, mais uma dose de reforco no 30o dia apos a dose inicial. Os titulos de anticorpos foram determinados por prova de soroneutralizacao em amostras de sangue colhidas antes, 30 e 40 dias apos administracao da primeira dose. Verificou-se que no 30o dia, 74,6% dos pacientes apresentaram anticorpos neutralizantes no soro,valor que se elevou a 98,1% no quadragesimo dia, o que mostra a eficacia do esquema em relacao a resposta imunitaria em tempo relativamente curto e a importancia da dose de reforco como estimulo a producao de anticorpos.Nos pacientes submetidos as doses anuais de reforco num periodo de 10 anos, verificou-se aumento gradual da presenca de anticorpos antes da administracao da dose de reforco subsequente, ate atingir valores de 100%. Face aos resultados obtidos foi sugerido que as doses de reforco sejam administradas a intervalos de tempo maiores e precedidas da titulagem de anticorpos a fim de se avaliar da necessidade ou nao de sua administracao