Clinical index to predict bacteraemia caused by staphylococci

Abstract. Objectives. To define risk factors associated with bacteraemia caused by Staphylococcus aureus or coagulase-negative staphylococci; and to use them to define patients in need of empiric anti-staphylococcal antibiotic treatment. Design, Derivation set: observational, prospective study; validation set: retrospective analysis of a prospectively collected database. Setting. Derivation set: Beilinson Medical Centre, Petah Tiqva, Israel—a 900-bed university hospital. Validation set: St Thomas's Hospital, London, UK—an 800-bed teaching hospital. Subjects. All episodes of bacteraemia detected at Beilinson Medical Centre between March 1988 and September 1990 (derivation set, n = 1410), and at St Thomas's Hospital during 1987–1990 (validation set, n = 1040). Interventions. None. Main outcome measures. Percentage of staphylococcal bacteraemia in groups of patients defined by the models. Results. The following factors were associated with Staphylococcus aureus bacteraemia: focus of infection (whether high or low risk), haemodialysis, intravenous drug abuse and infection acquired in the orthopaedic ward. A logistic model was used to divide the derivation set into three groups with percentages of Staphylococcus aureus bacteraemia of 1.8%, 13.2% and 33.7% (P < 0.0001); and the validation group 2.5%, 18.2% and 53.2% (P < 0.0001). Factors associated with coagulase-negative staphylococcal bacteraemia were: central or peripheral intravenous catheter as the focus of infection, a preterm neonate, the presence of a central intravenous catheter, low temperature, and a low white blood cell count. A second model including those factors was used to divide the derivation set into three groups with percentages of coagulase-negative staphylococcal bacteraemia of 1.9%, 22.8%, and 43% (P < 0.0001). In the validation set, the percentages were 2.9%, 22.4% and 31.0% (P < 0.001). Conclusions. The present study defines groups at high risk for staphylococcal bloodstream infection, in which empiric treatment should include an anti-staphylococcal drug.     

Macrolide–lincosamide–streptogramin B resistance phenotypes and genotypes among Staphylococcus aureus clinical isolates in Japan

In total, 269 methicillin-resistant Staphylococcus aureus (MRSA) and 434 methicillin-susceptible S. aureus (MSSA) isolates were investigated to determine their macrolide-lincosamide-streptogramin B (MLS(B)) resistance phenotypes and genotypes. The constitutive phenotype (61.3% in MRSA, 1.3% in MSSA) and erm(A) gene predominated among the 261 erythromycin-resistant MRSA isolates, while the inducible phenotype (38.7% in MRSA, 94.0% in MSSA) and erm(C) gene were more prevalent among the 150 erythromycin-resistant MSSA isolates. There was a higher incidence of the MLS(B) inducible phenotype compared with other countries, perhaps because MLS(B) antibiotics are not recommended as first-line agents against S. aureus in Japan.     

Thoracotomy in the acute phase of staphylococcal lung disease

Two cases of staphylococcal lung disease in young infants are described. In each instance a life-threatening bronchopleural fistula in the acute phase was successfully managed by thoracotomy and suture repair. Offprint requests to: A. W. Auldist     

Severe acute myocardial infarction during a staphylococcal septicemia with meningoencephalitis

We report the first case of lethal intracranial haemorrhage complicating a treatment by rt-PA in a patient presenting with a simultaneous staphylococcal septicemia with meningoencephalitis and an acute myocardial infarction with cardiogenic shock. The presence of microvascular lesions in the central nervous system seems to be important risk factor for intracranial haemorrhage and we recommend extreme caution in the use of thrombolytic treatment in septicemic patients with acute myocardial infarction, particularly when neurological symptoms are present.     

金黄色葡萄球菌儿童株耐药性分析

目的 了解儿童中金黄色葡萄球菌所致疾病的分布及其对常用抗生素的敏感情况。方法 收集连续12个月的临床致病株，根据菌落形态、革兰染色特点和乳胶凝集实验对金黄色葡萄球菌进行初步筛选，用细菌自动鉴定系统Vitek GPI卡和GPS-101卡进行菌株鉴定和药敏试验。结果 分离到金黄色葡萄球菌145株，其中来自呼吸道感染患儿痰或咽拭子培养109株，占75．17％，来自血培养16株，占11．03％，来自脓液、阴道分泌物培养分别占6．21％和5．51％。药敏试验显示92．4l％的菌株产生β-内酰胺酶，96．55％的菌株对青霉素耐药，但耐苯唑西林的仅占6．21％。99．31％和100％的菌株分别对利福平和万古霉素敏感，对环丙沙星、阿莫西林／棒酸、头孢唑林、复方新诺明、庆大霉素和林可霉素的敏感率分别为95．86％、93．10％、92．41％、86．21％、84．83％和80．69％，37．93％的菌株对红霉素耐药。结论金黄色葡萄球菌常引起儿童呼吸道感染，对苯唑西林的耐药率低．该药仍是治疗小儿会黄色葡萄球菌感染的有效药物。     

In vitro Virulenz wundinfizierender Staphylokokken-Isolate von schwerbrandverletzten Patienten

Zusammenfassung 30Staphylococcus aureus Stämme von drittgradig verbrannten Patienten wurden hinsichtlich ihrer Fähigkeit zur Hämolysingenerierung und ihres Vermögens zur Histaminfreisetzung aus Mastzellen (RPMC) untereinander verglichen. Die bakteriellen Kulturüberstande von 8 Stämmen aus Wundbiopsien zeigten signifikant niedrigere in vitro Aktivitäten als die übrigen Staphylokokken-Kulturüberstände. Bei dem Vergleich der in vitro Aktivitäten der gewaschenen Bakterienzellen ergab sich ein umgekehrtes Verhältnis. Diese Befunde zeigen, daß beiS. aureus Isolaten, welche zum Zeitpunkt einer invasiven Brandwundeninfektion isoliert werden können, die mikrobiellen Pathogenitätsfaktoren an die Bakterienzelle gebunden bleiben.

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In vitro measurement of pathogenicity ofStaphylococcus aureus isolated from heavily burned patients

Summary The hemolysin and histamine releasing activity of 30S. aureus strains isolated from third degree burns of heavily burned patients was detected. The culture supernatants (cs) ofStaphylococcus aureus isolated during episodes of invasive burn wound infection displayed significantly lower amounts of hemolysin and histamine releasing activity as compared to cs of bacteria isolated when no sign of septicemia was present. In contrast, when washed bacterial cells were analysed, a reversed ratio could be observed. These data clearly indicate that in strains isolated during invasive burn wound infection pathogenicity factors remain attached to the bacterial surface of the staphylococci investigated.

Gefördert durch das Bundesamt für Zivilschutz (ZS 8-122-42)     

Characterisation of non-multiresistant methicillin-resistant Staphylococcus aureus (including EMRSA-15) in Kuwait Hospitals

This study characterised non-multiresistant methicillin-resistant Staphylococcus aureus (nmMRSA) isolates from Kuwait hospitals to ascertain whether they were community-acquired MRSA (CA-MRSA). Forty-two nmMRSA isolates obtained between July 2001 and October 2003 were analysed by staphylococcal cassette chromosome mec (SCCmec) typing, bacteriophage typing, production of Panton-Valentine leukocidin (PVL), urease and staphylococcal enterotoxins A, B, C and D, TSST-1, and by pulsed-field gel electrophoresis (PFGE). Forty-one isolates were SCCmec type IV, and one isolate was SCCmec type III. The isolates belonged to six PFGE patterns, with two types, A and D, distributed in six and four hospitals, respectively. Most (n = 26; 61.9%) isolates produced urease. These isolates were mainly from wound and skin infections, showed low-level methicillin resistance (MIC 8-48 mg/L), and nine carried genes for PVL. These characteristics, together with their carriage of the type-IV SCCmec, identified the isolates as CA-MRSA. Ten of the 16 urease-negative isolates produced staphylococal enterotoxin C; 12 reacted weakly with phage 75, and were resistant to clindamycin and/or erythromycin, which are characteristics of EMRSA-15. Thus, this study identified the co-existence of two types of nmMRSA, i.e., CA-MRSA and EMRSA-15, in Kuwait hospitals.     

Antibiotic resistance in Staphylococcus aureus colonising the intestines of Swedish infants

Staphylococcus aureus has become a frequent coloniser of the intestinal tract of infants, but the health effects of such colonisation are not clear. In this study, the antibiotic resistance patterns of 116 S. aureus strains from the commensal intestinal microflora were determined. The strains were obtained from 81 Swedish infants who had been followed with regular stool samples and registration of antibiotic usage during their first year of life. The faecal population levels of the individual strains and the duration of their persistence in the microflora had been determined previously. The prevalence of antibiotic resistance among the 116 strains was modest: methicillin, 0%; penicillin G, 78%; erythromycin A, 3%; tetracycline, 2%; clindamycin, 0.9%; and fusidic acid, 0.9%. Colonisation by antibiotic-resistant strains was unrelated to antibiotic consumption by individual infants. Antibiotic-resistant strains were as capable of persisting in the intestinal microflora and reaching high faecal population levels as fully susceptible strains. No strain lost or acquired resistance during the colonisation period. Thus, antibiotic-resistant strains of S. aureus seem to be as fit for competition in the large bowel microflora as susceptible strains, even in the absence of selective pressure from antibiotics. This may aggravate the ecological consequences of antibiotic resistance development.     

Response of body temperature and serum iron concentration to repeated pyrogen injection in rabbits

We measured body temperature and serum iron concentration after five daily consecutive injections of febrile doses of Salmonella typhosa lipopolysaccharide (0.1 g/kg) and two doses of Staphylococcus aureus cell walls (1×10⁷ and 5×10⁷ cells) in rabbits. Tolerance to endotoxin injection, as manifest by a significant attenuation in the body temperature elevation, developed after the first injection of endotoxin. The endotoxin-induced fall in serum iron concentration was attenuated significantly by the 5th day of endotoxin injection. In contrast, no tolerance developed in either the body temperature or serum iron response following repeated daily injections of S. aureus. Rabbits rendered tolerant to endotoxin showed normal febrile and serum iron responses to subsequent S. aureus injection. Rabbits given serial injections of S. aureus, although not tolerant to S. aureus itself, exhibited attenuated body temperature responses but not serum iron responses to endotoxin injection. We suggest that repeated injection of endotoxin diminishes the ability of endotoxin to stimulate endogenous pyrogen (EP) synthesis and/or release, a property not shared by the gram-positive pyrogen S. aureus. However, repeated injection of S. aureus weakens the central endotoxin-EP pathway.