Some bacteraemias encountered in hospital practice

Septicaemia in the elderly

A retrospective study was made of 44 elderly patients with bacteraemia treated in the period 1974-1980. Positive blood cultures in 5 cases were considered clinically insignificant. Twenty-six of the remaining 39 patients were found to have a Gram-negative bacteraemia, mainly associated with urinary tract infection. Abnormalities of liver function were common but 5 jaundiced patients with Gram-negative infection were shown to have stones in the common bile duct. The value of blood cultures as a diagnostic aid in the non-specifically ill elderly patient is emphasized.

Clinical significance of enterococci in blood cultures from adult patients

The significance of enterococci in the blood cultures of 79 adult patients encountered in a 21-month period was reviewed by means of clinical data. One blood culture consisted of an aerobic and an anaerobic bottle. Patients were divided according to the clinical picture into those with "likely", "possible", and "dubious" septicemia. Those with "likely" septicemia showed significantly more positive sets and more often two positive bottles in a single set taken on the same day than patients in the other categories. They also grew cultures with shorter detection times, with 90% of all cultures eventually yielding enterococci within three days after collection. Finally, probability figures relating positivity in one or two bottles to detection time and category of significance are presented. They may be used prospectively to assess the chances of a blood cultures reflecting any of the three above categories.

Severe clinical conditions associated with Bacillus cereus and the apparent involvement of exotoxins

Twenty-one cases of infection with Bacillus cereus are summarised. The histories supplied showed that at least 15 of these were associated with severe or potentially severe symptoms including two deaths. Analysis of the production of exotoxins, including haemolysin and phospholipase, by these strains is given, and the relevance of these metabolites to the severity of the condition is discussed. Three incidents of bovine mastitis resulting from B. cereus and involving three deaths are also included. The observations presented here together with those of previous reports which are reviewed indicate that B. cereus may be of clinical importance, not just an opportunist but also as an agent of potentially severe infections in its own right.

Neonatal meningitis due to Enterobacter cloacae

Enterobacter species, in recent years, have been divided into E aerogenes, E hafniae, E liquefaciens, and E cloacae. Early reviews of neonatal meningitis include some cases due to Klebsiella-Aerobacter,(1) and recent reviews(2,3) include Enterobacter which did not divide them into species of Enterobacter. Reported here is a case of neonatal meningitis due to a gram-negative organism, Enterobacter cloacae.

[Microbiological diagnosis of septicemia]

To detect microorganisms in the blood it is necessary not only that the microbiologist uses reliable methods, but also that the clinician takes a sufficient number of blood samples at the right point in time using a correct method for drawing the blood. The best results are obtained if the blood sample is transferred to the culture media at the bedside. The media should contain anticoagulants, osmosis stabilizers and preparations to neutralize the microbial action of the blood (caused by intrinsic and extrinsic factors). Up until now sodium polyanetholsulfonate ("Liquoid") has proved to be the most suitable additive. The procedure used for blood culturing must enable growth of aerobes, anaerobes and microbes with cell-wall damage. Today, modern methods such as radiometry, impedance measurement and microcalorimetry are used or are in the process of being developed which facilitate screening for positive cultures. Antigens, cell-wall constituents and metabolites of bacteria and fungi present in the blood stream can be detected by means of counter-immunoelectrophoresis, the Limulus test and gas chromatography, without culturing being necessary. Concentration techniques such as filtration and centrifugation are also being refined to enable a more reliable and earlier detection of septicemia.

Nationwide epidemic of septicemia caused by contaminated intravenous products. I. Epidemiologic and clinical features

Between mid-1970 and April 1, 1971, Enterobacter cloacae or E. agglomerans septicemia developed in 378 patients in 25 American hospitals while they were receiving intravenous products manufactured by one company. Each of the hospitals noted a marked increase in the incidence of such septicemia during this period. Enterobacter agglomerans (formerly designated Erwinia, herbicola-lathyri group) was better known as a plant pathogen and had been a human blood pathogen only rarely in the past. Septicemia caused by E. cloacae had also been uncommon.

Bacteraemia after open-heart surgery

We have analysed the bacteraemias occurring before discharge from hospital in patients subjected to open-heart surgery. The overall incidence was 2·7%. The predominant organisms at first were staphylococci and streptococci, but in the later years of the study almost all positive blood cultures were due to Gram-negative bacilli. Short-term prophylactic antibiotics were used throughout. Eleven of the 12 Gram-positive bacteraemias occurred after the period of antibiotic prophylaxis; eight of the patients had endocarditis and a further three had serious wound infections. Most of the 32 Gram-negative bacillaemias occurred while antibiotics were being given. Some were transient phenomena in well patients; others were associated with terminal states. Infection was a major cause of death in four patients, however, and two patients had endocarditis. Serratia, providence, hafnia, and citrobacter were all identified as well as the more usual escherichia, klebsiella, and pseudomonas. We discuss the possible origins and management of these bacteraemias.