细菌与病毒感染的鉴别

急性感染早期准确鉴别细菌和病毒感染一直是临床面临的挑战,随着临床各种检验、检测技术的快速发展、长足进步,越来越多的病原学、人体基因学、分子生物学指标用于鉴别细菌与病毒感染。未来将有更多的检测指标采用床旁即时检测方式便于临床应用;将有更精准、丰富的生物医学信息平台和更高效的医院信息系统,进行多指标综合分析,提供更精准的病原诊断,有助于最佳临床实践的实施。     

Comparison of procalcitonin with C-reactive protein, interleukin 6 and interferon-alpha for differentiation of bacterial vs. viral infections.

BACKGROUND: Procalcitonin (PCT) concentration increases in bacterial infections but remains low in viral infections and inflammatory diseases. The change is rapid and the molecule is stable, making it a potentially useful marker for distinguishing between bacterial and viral infections. METHODS: PCT concentration was determined with an immunoluminometric assay on plasma collected at admission in 360 infants and children hospitalized for bacterial or viral infection. It was compared with C-reactive protein (CRP), interleukin 6 and interferon-alpha measured on the same sample. RESULTS: The mean PCT concentration was 46 microg/l (median, 17.8) in 46 children with septicemia or bacterial meningitis. PCT concentration was > 1 microg/l in 44 of 46 in this group and in 59 of 78 children with a localized bacterial infection who had a negative blood culture (sensitivity, 83%). PCT concentration was > 1 microg/l in 16 of 236 children with a viral infection (specificity, 93%). PCT concentration was low in 9 of 10 patients with inflammatory disease and fever. A CRP value > or =20 mg/l was observed in 61 of 236 patients (26%) with viral infection and in 105 of 124 patients (86%) with bacterial infection. IL-6 was > 100 pg/ml in 14% of patients infected with virus and in 53% with bacteria. A secretion of interferon-alpha was found in serum in 77% of viral infected patients and in 8.6% of bacterial infected patients. CONCLUSIONS: In this study a PCT value of 1 microg/l or greater had better specificity, sensitivity and predictive value than CRP, interleukin 6 and interferon-alpha in children for distinguishing between viral and bacterial infections. PCT values are higher in invasive bacterial infections, but the cutoff value of 1 microg/l indicates the severity of the disease in localized bacterial infection and helps to decide antibiotic treatment in emergency room. PCT may be useful in an emergency room for differentiation of bacterial vs. viral infections in children and for making decisions about antibiotic treatments.     

Mixed bacterial and viral infections are common in children

Acute phase and convalescent sera from 51 pediatric patients who had a documented viral infection and no obvious culture-confirmed bacterial infection such as meningitis, otitis media or urinary tract infection were tested by enzyme immunoassay for antibodies to Haemophilus influenzae and Branhamella catarrhalis and by the latex agglutination test for pneumococcal antigens to evaluate the frequency of mixed bacterial and viral infections. A mixed bacterial and viral infection was documented in 19 patients (37%). Seven patients (14%) showed a diagnostic rise in antibodies to H. influenzae and 8 patients (16%) showed an antibody elevation to B. catarrhalis in their paired sera; pneumococcal antigen was detected in acute phase serum from 4 patients (8%). The rate of mixed infections in patients having respiratory symptoms was 52%. High serum C-reactive protein values and white blood cell counts were found significantly more often in those with mixed infections than in those who had viral infections. The results indicate that mixed bacterial and viral infections occur more frequently in children than one could anticipate on the basis of the earlier reports. Mixed bacterial and viral etiology is highly probable in a child who has a defined viral infection with high C-reactive protein and white blood cell count values, especially in the presence of respiratory symptoms.     

Antipyretic efficacy of ibuprofen vs acetaminophen.

OBJECTIVE--To compare the antipyretic efficacy of ibuprofen, placebo, and acetaminophen. DESIGN--Double-dummy, double-blind, randomized, placebo-controlled trial. SETTING--Emergency department and inpatient units of a large, metropolitan, university-based, children's hospital in Michigan. PARTICIPANTS--37 otherwise healthy children aged 2 to 12 years with acute, intercurrent, febrile illness. INTERVENTIONS--Each child was randomly assigned to receive a single dose of acetaminophen (10 mg/kg), ibuprofen (7.5 or 10 mg/kg), or placebo. MEASUREMENTS/MAIN RESULTS--Oral temperature was measured before dosing, 30 minutes after dosing, and hourly thereafter for 8 hours after the dose. Patients were monitored for adverse effects during the study and 24 hours after administration of the assigned drug. All three active treatments produced significant antipyresis compared with placebo. Ibuprofen provided greater temperature decrement and longer duration of antipyresis than acetaminophen when the two drugs were administered in approximately equal doses. No adverse effects were observed in any treatment group. CONCLUSION--Ibuprofen is a potent antipyretic agent and is a safe alternative for the selected febrile child who may benefit from antipyretic medication but who either cannot take or does not achieve satisfactory antipyresis with acetaminophen.     

Viral vs. bacterial pulmonary infections in children (Is roentgenographic differentiation possible?)

This study was conducted to determine whether one could identify viral and bacterial pulmonary infections with confidence. It has been our impression for some time that one could differentiate viral from bacterial pulmonary infections on the basis of roentgenographic findings alone and to test this hypothesis, we conducted this study where the roentgenographic findings first were categorized as being due to viral or bacterial infection and then compared with clinical results. The overall accuracy was just over 90% and our method of analysis is presented.     

Perinatal viral infections.

Among the TORCH agents, the occurrence of rubella and human T-lymphotropic virus type 1 (HTLV-1) in Japan were studied. Rubella epidemics occurred throughout Japan from 1964 to 1969 and from 1975 to 1979. Low prevalences of CRS were observed in northeastern Japan, and high prevalences in southwestern Japan, with the highest in Okinawa. These conditions could be explained by the lower rate of rubella H1 antibody in the female population of southwestern Japan. Time of maternal rubella was in the gestational age interval from 26 to 57 days for cataract, from 25 to 62 days for heart disease and from 16 to 131 days for deafness. HTLV-1 is the causative agent of adult T-cell leukemia. Main route of transmission of this virus is mother-to-child transmission, through breast milk. Among the 311 mother-child pairs in Okinawa, 65 mothers (20.9%) and 10 children (3.2%) were seropositive for HTLV-1. Ten (15.4%) of the 65 seropositive mothers had seropositive children. These children had acquired their HTLV-1 antibodies by the age of 3 years. A significant difference existed between the prevalence rate of HTLV-1 antibodies in mothers and children.     

Fever in young lambs: carotid denervation alters the febrile response to a small dose of bacterial pyrogen.

Experiments were done on 13 young lambs to determine if carotid denervation influences the cardiovascular and metabolic responses to i.v. administration of bacterial pyrogen [Salmonella abortus equi (SAE) 0.3 micrograms]. Each lamb was anesthetized with halothane and prepared for measurements of cardiac output, arterial and mixed venous oxygen saturations, and body core temperature. No sooner than 3 d after surgery, measurements were made during a control period and at 10-min intervals for 120 min after i.v. administration of SAE in seven carotid-intact lambs and six carotid-denervated lambs. Administration of SAE produced a short-lived fever of about 1 degrees C in the carotid-intact lambs, whereas no change in body core temperature was observed in the carotid-denervated lambs. In carotid-intact lambs, the rise in body core temperature began approximately 40 min after administration of SAE and continued for approximately 50 min. This rise in body core temperature was preceded by the onset of shivering and an increase in total body oxygen consumption. Carotid denervation produced changes in some of the cardiovascular variables during the control period (i.e. arterial oxygen content, cardiac index, heart rate, and pulmonary blood pressure); however, there were no additional significant changes in any of the metabolic or cardiovascular variables after administration of SAE. The mechanism of these unexpected findings remains to be determined.     

Fever in respiratory virus infections

The case records of 258 children with adenovirus; influenza A or B virus; parainfluenza 1, 2, or 3 virus; or respiratory syncytial virus infections were studied retrospectively with special attention to the degree and duration of fever. A temperature of 39.0 degrees C or higher was most frequently recorded in adenovirus, influenza A, and influenza B virus infections (in 68%, 84%, and 65%, respectively). The mean highest degree of fever in respiratory virus infections (39.2 degrees C +/- 0.6 degrees C) during hospitalization did not differ from that in defined serious bacterial infections, ie, meningitis, epiglottitis, sepsis, and urinary tract infections (39.3 degrees C +/- 0.7 degrees C). The mean duration of fever varied from 2.5 days (parainfluenza 2) to 5.2 days (influenza B). Of all children with respiratory virus infections, 37% had fever lasting five days or longer. The data show that high and prolonged fever is frequently associated with respiratory virus infections in hospitalized children and that it does not differ significantly from fever in severe bacterial infections.     

Vaccinations against bacterial infections.

1. As with any therapeutic measure, prophylactic vaccination is to be jugded by the correlation between benefit and harm or expenditure. By benefit is meant a not to short-lived substantial decrease in the morbidity and/or mortality. Harm refers to the number and severity of side effects in the individual child vaccinated and expenditure means the economic burden placed upon society. 2. The evaluation of many vaccinations at present varies between two extremes: On the one hand vaccination procedures are considered to provide an opportunity to eradicate most of the infectious diseases, on the other hand there is a tendency to assess side effects more drastically the more likely the danger of the particular disease seems eliminated once and for all. 3. An attempt is made to discuss the achieved or achievable standard of vaccination measures against bacterial infections in the light of 3 classes of vaccines. The first class involves well established and commonly used vaccines such as BCG and DPT vaccines although differences in opinion exist on their future employment. 4. The second class involves newer vaccines or vaccines that are under development as for instance vaccines against meningococci, pneumococci, H. influenzae and enteropathogenic E. coli. 5. The third class includes vaccines whose realisation at present appears to be yet difficult or hardly feasible, for instance vaccines against enterotoxins of enteropathogenic organisms, against lues, gonorrhea or for example against organisms of the infectious hospitalism.     

Transient and chronic neutropenias detected in children with different viral and bacterial infections

Aim: The aim of the study was to identify the relationship of acquired neutropenias with infections in childhood and to assess their course, complications, short and long-term outcome. Method: During a two-year period, all children admitted to the pediatric ward with neutropenia were investigated for underlying infections with indices of infection, cultures of body fluids and serological tests. Results: Sixty-seven previously healthy children, aged (median, 25-75%) 0.7 years (0.2-1.5), were identified with neutropenia (frequency: 2.0%). An infectious agent was identified in 34/67 cases (50.7%) (viral infection: n=24, bacterial: n=10). In 50/67 (74.6%) children, neutropenia recovered within 2 months (transient neutropenia, TN), while in 17/67 (25.4%) of them it persisted for more than two months. Two years after diagnosis 50/67 children (74.6%) accepted to be reassessed. Of these children, 8/50 (16%) remained neutropenic (neutropenic children, NC), while 42/50 had recovered completely. Conclusion: Neutropenia during childhood is usually transient, often following viral and common bacterial infections, does not present serious complications and in the majority, it resolves spontaneously. However, in a significant percentage of patients, neutropenia is discovered during the course of an infection, on a ground of a preceding chronic neutropenic status.     

Leukocyte adhesiveness/aggregation test (LAAT) to discriminate between viral and bacterial infections in children

Objectives: We previously noted that white blood cells (WBC) have increased adhesive properties during bacterial infections. Here, we aim to explore the possibility of using the different adhesive properties of WBC as a means of differentiating between viral and bacterial infections, a common problem in paediatrics. Methods: The adhesive properties of WBC in the peripheral blood of 25 children with documented bacterial infections, 15 with documented viral infections and 36 with probable viral infections, were studied by means of a leukocyte adhesiveness/aggregation slide test (LAAT). The results of the LAAT were compared with those of the other acute phase reactants, namely WBC, differential count and erythrocyte sedimentation rate (ESR), which were taken in the same blood sample in each patient. Results: The sensitivity, specificity and positive predictive value were 92%, 96%, and 92%, respectively for the LAAT; 83%, 87% and 80% for the ESR; 56%, 78% and 56% for the white blood cell count; and 54%, 74% and 50% for the differential count. Conclusions: The presence of bacterial infections in children can be tested using a simple slide test to reveal the increased state of leukocyte adhesiveness/aggregation in the peripheral blood. The LAAT is a reliable, rapid and inexpensive test, and it can be a useful laboratory tool for the paediatrician treating a child with acute febrile illness.     

Evaluation of aztreonam and ampicillin vs. amikacin and ampicillin for treatment of neonatal bacterial infections

In a prospective randomized, open study we evaluated aztreonam (AZ) for treatment of neonatal bacterial infections. There were 147 patients enrolled in the study; 75 received AZ and ampicillin (AMP) and 72 amikacin (AM) and AMP (conventional therapy). Twenty-eight AZ/AMP-treated patients and 32 conventionally treated patients had bacteriologically documented infections caused by gram-negative enteric bacilli or Pseudomonas species. Treatment groups were comparable in age, clinical status, and type and severity of underlying disease at the time of enrollment. Bronchopneumonia and infections caused by Pseudomonas species occurred significantly more often in AM/AMP-treated patients compared with patients given AZ/AMP. Sepsis was documented in 83% of patients in each treatment group and Gram-negative enteric bacilli and Pseudomonas species were the principal pathogens. Median peak serum bactericidal titers against the etiologic agent were 1:64 for the AZ/AMP and 1:16 for AM/AMP-treated patients. Case fatality rates resulting from the primary infection were 7 and 22% (P = 0.011), superinfection occurred in 39% and 34% and treatment failure occurred in 7 and 28% (P = 0.036) of the AZ/AMP and AM/AMP-treated patients, respectively. No clinical adverse reactions were observed in either group. Based on these results aztreonam appears to be at least as effective as and possibly more effective than amikacin when used initially with ampicillin for empiric treatment of neonatal bacterial infections.     

The role of viral and bacterial infections in the development of chronic autoimmune thyroiditis

To specify the role of viral and bacterial infections in the onset of chronic autoimmune thyroiditis, analysis was made of the premorbid state of 118 children aged 4 to 14 years. In 81% of the patients, a number of unfavourable factors were identified: hereditary aggravation as regards thyroid pathology, complicated antenatal period in the presence of chronic viral and bacterial infections in the mother, contact with the sick relatives taking care of the child, frequently occurring viral and bacterial infections in children, resulting in the formation of the polyimmunopathological process. This supports the multifactorial nature of the disease and dictates the necessity of early diagnosis and treatment of acute and chronic infectious diseases not only in the child but also in the relatives.