Clinical significance of quantitative blood cultures in newborn infants

AIM: To evaluate quantitative blood culture as a secondary test on a positive blood culture for the diagnosis of sepsis in newborn infants. METHOD: A 15-month prospective study of colony forming units (CFU) on positive blood cultures from newborn infants clinically suspected of having bacterial sepsis. Growth of bacteria in peripheral blood cultures was quantified using the isolater 1.5 microbial tube lysis direct plating culture system. Colony forming units were evaluated against a clinical assessment of infection. RESULTS: Of 137 positive blood cultures, 71 (51.8%) were taken from neonates with clinically defined infection and 66 (48.2%) were from non-infected infants. The clinical and biographical data in these two groups were similar. Coagulase negative staphylococci were the most commonly isolated organisms in each group (60.6% vs 93.9%). Eight deaths from sepsis occurred in the clinically infected group. Eighty-five per cent of sepsis was late onset. Although a CFU count > or = 30/mL predicted sepsis (sensitivity 83%, specificity 60%, positive predictive value 69%, negative predictive value 76%), a CFU count < 30/mL did not rule out serious sepsis. The higher the CFU count the greater the likelihood of sepsis. CONCLUSION: Quantitative blood culture was not shown to be a sensitive secondary test on a positive blood culture to distinguish clinical sepsis from culture contamination. Although a positive threshold of > or = 30 CFU/mL proved to be optimal, improvement in test performance would be expected with a lower incidence of culture contamination.     

Panniculitis with pseudomonas septicaemia in AIDS

A 27 year old female with acquired immunodeficiency syndrome (AIDS) developed tender erythematous nodules on her thighs. A skin biopsy of the lesions showed septal panniculitis and venulitis and Pseudomonas species was cultured from both the urine and the skin biopsy tissue. The lesions resolved on antibiotic therapy. Panniculitic nodules may represent an early stage of ecthyma gangrenosum which is a well recognised cutaneous complication of pseudomonas septicaemia.     

Low levels of mannose-binding lectin do not affect occurrence of severe infections or duration of fever in acute myeloid leukaemia during remission induction therapy

PURPOSE: To estimate the clinical significance of low serum concentrations of mannose-binding lectin (MBL) in patients with acute myeloid leukaemia (AML) during initial cancer chemotherapy. PATIENTS AND METHODS: 80 consecutive, newly diagnosed, and unselected AML patients (age 18-77 yr) undergoing remission induction chemotherapy. The patients were examined for 28 d. MAIN FINDINGS: Low levels of serum MBL (<1,000 microg/L) were found in 16/80 patients at diagnosis. This frequency is similar to what is found in the general population. In the remaining 64 patients, MBL concentrations were significantly higher than in controls and showed only a slight rise during the period of antineoplastic chemotherapy with its associated infectious complications. Low levels of MBL did not affect overall survival or morbidity in terms of incidence or duration of fever, or occurrence of septicaemia or pneumonia. Long-term survival was likewise independent of MBL concentration. CONCLUSION: MBL levels have no discernible influence on the occurrence or course of infections in AML patients during the initial hospitalisation. The predominant immunodeficiency during this phase is the profound granulocytopenia, which also compromises important effector functions of MBL. The finding in most AML patients of elevated MBL concentrations on admission is most likely because of the role of MBL as an acute phase reactant.     

The outcome of children admitted to intensive care with meningococcal septicaemia

Objective To review our experience of children with meningococcal septicaemia, and to validate, in our group, severity scores used in different populations to predict outcome.Design Retrospective review of case notes and charts.Patients A total of 35 children were admitted to the paediatric intensive care unit (ICU) in the Royal Children's Hospital (RCH) in the 8 years between January 1985 and December 1992 with proven meningococcal septicaemia.Results Ages ranged from 4 months to 16 years, with a median age of 20 months. The median meningococcal score was 4 and the median PRISM score was 20, with scores above these being significantly associated with death (P<0.0001). Thirty-two children (91%) received infusions of colloid for hypovolaemia and twenty-nine (83%) received one or more inotropic drugs. Twenty-one children (60%) required mechanical ventilation for a median of 16.5 h (range 7–574). Seven children (20%) underwent plasmapheresis. Six children (17%) underwent haemofiltration and two (6%), peritoneal dialysis. One patient received extracorporeal membrane oxygenation (ECMO) because of circulatory failure. Twenty-one children (60%) developed disseminated intravascular coagulation, renal failure and/or skin or limb necrosis. The overall survival was 66%, and all survivors are functionally normal.Conclusion The mortality from the disease remains at 34% despite the technological advances in intensive care. The PRISM and meningococcal scores are useful in predicting outcome. Novel methods of treatment (e.g., plasmapheresis or ECMO) may be valuable.     

Investigation of contaminated parenteral nutrition fluids associated with an outbreak of Serratia odorifera septicaemia

An outbreak of fatal septicaemia caused by Serratia odorifera biotype 1 involved infants at several hospitals; the common vehicle of infection was contaminated parenteral nutrition fluid. The transfusate had been made up in a flexible film isolator system. The implicated organism was recovered from surfaces inside the isolator, despite routine decontamination procedures having been carried out shortly before. Our investigation into the origin of contamination revealed several shortcomings in the infusate compounding process. We noted deficiencies in cleaning and decontamination procedures, and in storage and sterility testing policies, but the origin and mechanism of the contamination were unclear. Withdrawal of parenteral nutrition products and revision of decontamination procedures terminated the outbreak. The efficacy of peracetic acid treatment of flexible film isolators, given the circumstances of this outbreak, may need further investigation. Regular training and assessment of admixture technicians is important.     

Growth inhibition of pathogenic yeasts by Pseudomonas aeruginosa in vitro: clinical implications in blood cultures

The interaction between yeasts and bacteria may have clinical implications in polymicrobial septicaemia. The in vitro effect of Pseudomonas aeruginosa on five pathogenic yeast species, Candida albicans, Candida tropicalis, Candida parapsilosis, Candida glabrata and Cyptococcus neoformans, was investigated. Yeast inhibition assays were performed in an aerobic blood culture medium, inoculated with yeast cells (inoculum 1–10 CFU ml ^?1) and bacterial cells (inoculum 10?10⁷ CFU m1^?1). Interactions between P. aeruginosa and yeasts were determined after incubation by enumeration of pure and mixed cultures. Growth of all isolates tested was completely or partially inhibited by P. aeruginosa in blood culture medium, the phenomenon depending on the yeast genus and bacterial inoculum. Suppression of fungal growth was also observed in bacterial culture filtrate. This in vitro antifungal activity may preclude yeast recovery from blood cultures in mixed infections.     

羊败血性链球菌病的流行及诊治

2005年12月至2006年10月,乌鲁木齐城郊牧场流行一种以患羊唇部、下颌、颈部、胸侧部出现皮下脓肿,食欲下降,体质消瘦,怀孕母羊流产,妊娠后期母羊死亡;剖检以肺脏出现纤维素性肺炎及卡他性化脓肺炎;注射羊链球菌活菌苗后1个月出现羔羊死亡的传染病,经流行病学调查、症状、剖检诊断、细菌培养鉴定和免疫预防,确诊为羊败血性链球菌病。     

Prognostic role of screening tests of haemostasis and underlying diseases in acute disseminated intra-vascular coagulation in adults

Summary. The significance of precipitating causes of acute disseminated intra-vascular coagulation (DIC) and the severity of derangement of haemostasis based on laboratory investigations carried out initially were evaluated in 98 patients and was related to the fatal outcome in them. It was seen that septicaemia was the commonest precipating cause. Survival was better in patients in whom DIC was precipitated by obstetric causes compared with those with septicaemia (P < 0.01). Death was also more frequently associated in patients with higher prothrombin time (PPT) ratio (> 1.5) and/or higher activated partial thromboplastin time (APTT) ratio (> 2.5) as compared to their lower values (P < 0.01 each). Death occurred in all the seventeen patients in whom septicaemia was present along with PPT ratio of > 1.5. It is concluded that deranged haemostasis and presence of septicaemia both independent of each other, contribute to the fatal outcome in acute DIC. Combination of both is associated with poorest prognosis.     

Successful caspofungin treatment of multidrug resistant Candida parapsilosis septicaemia in an extremely low birth weight neonate

Candida septicaemia with multidrug resistance is an uncommon event in preterm neonates. We present an extremely low birth weight infant (gestational age of 27 weeks, birth weight of 980 g) who developed congenital Candida parapsilosis septicaemia. Because the fungus was resistant both to amphotericin B and fluconazole, caspofungin was chosen for therapy. The fungus was successfully eradicated without any clinical or laboratory adverse effects.