Changes in incidence and aetiology of bacteraemia arising in hospital practice

Bacteraemia in man and animals: an overview

Bacteraemia signifies invasion of the bloodstream by bacteria. In most systemic infections in man and animals, bacteria enter the blood at some stage during the infection and are rapidly distributed throughout the body. A wide variety of organisms have been associated with bacteraemia. Prompt detection of the aetiological agents of bacteraemia is of prime importance in clinical microbiology. There are no defined recommendations for blood cultures in animals but both conventional and improved methods are available for detection of bacteraemia in man. The consequences of bacteraemia are as diverse as the potential aetiological agents. Monoclonal antibodies to the core glycolipid (lipid A) seems very promising for the treatment of bacteraemia and septic shock caused by Gram-negative bacteria in man and animals.

Septicaemia in a teaching hospital in Kuwait--I: Incidence and aetiology

During a period of 18 months of study, blood cultures were performed on 3845 patients in hospital with clinical signs of infection. Among these, 214 (5.6%) episodes of septicaemia were diagnosed which correspond to 10.9/1000 hospital admissions. About 80% of the episodes were due to Gram-negative organisms, most common of which were Escherichia coli (19.6%), Salmonella spp (16.5%) and Klebsiella spp (15.1%). Gram-positive organisms implicated in 20% of episodes were mainly Staphylococcus aureus (9.3%) and enterococci (4.9%). Of all the septicaemias 62.0% were community-acquired with Salmonella spp. being the organism most commonly implicated. Hospital-acquired infections were mainly due to Serratia spp, Pseudomonas spp and Flavobacterium spp. The antibiotic resistance pattern of the organisms showed that hospital-acquired organisms had relatively high resistance to most antibiotics as compared with community-acquired organisms.

Systemic treatment of septicaemia caused by P. aeruginosa with special reference to azlocillin

Of the pathogens causing septicaemia due to Gram-negative bacteria at Zentrum der Inneren Medizin, Frankfurt, over a 7-year period (1974-80), 16.8 per cent were due to P. aeruginosa. Analysis of all septicaemias over this period, however, shows a decrease from 13 per cent in the 3-year period 1974-76 to 8 per cent in 1977-79 and 5 per cent P. aeruginosa septicaemia in 1980. The overall mortality rate was 66 per cent, most of the patients dying within 24 hours. Azlocillin and Piperacillin are at present the drugs of choice for systemic therapy of pseudomonas infections, preferably in combination with an aminoglycoside.

Staphylococcus aureus bacteraemia: 400 episodes in St Thomas's Hospital

Four hundred episodes of Staphylococcus aureus bacteraemia occurred in St Thomas's Hospital from 1969 to 1983, accounting for 17.5% of all episodes of bacteraemia. The mortality was 24%, half attributable to underlying disease, and was highest in patients over 50. Almost 60% of the bacteraemias were acquired in hospital, and the source of the organism was generally obvious, with vascular access sites the most common (37%). Bone and joint infections accounted for 11.5% of episodes and endocarditis for 7%. Most staphylococci were resistant to penicillin only; three isolates were resistant to methicillin and five to fusidic acid. Microbiologists seldom influenced directly the choice of initial antibiotic treatment (though this usually conformed to the hospital's antibiotic prescribing policy) but had considerable influence over definitive treatment, usually cloxacillin or flucloxacillin alone or in combination with fusidic acid. S aureus bacteraemia is easy to identify and treat, though underlying disease may influence the outcome. Efforts should be made to prevent the largely iatrogenic disease.

Septicaemia in a medical intensive care unit. Clinical, biochemical and microbiological data of 109 cases

Blood cultures were obtained from 39% of all 574 admissions to our Medical Intensive Care Unit. (ICU); in 109 (19%) a pathogenic organism was demonstrated. 45% of the septicaemias were detected within the first 48 h of ICU stay have been considered as "non ICU-acquired". Septicaemic patients were significantly older, had longer ICU stays and a higher mortality rate (62%) than non septicaemic patients (28%) (p less than 0.05). Gram negative organisms (69%) predominated over gram positive (29%) and Serratia marcescens and coagulase positive Staphylococcus were the most frequently isolated. Shock appeared in 32% and had an extremely high mortality (91%) and was associated with the presence of "multiple species septicaemia". Prior to the septicaemia the survivors differed from the fatalities only in the level of serum albumin; this was significantly lower in patients with gram negative in comparison with gram positive septicaemias and in patients who developed shock. Arterial, pulmonary artery and urinary catheters, and endotracheal devices were used frequently in these patients and were statistically associated with the presence of septicaemia. The airway was the most frequent possible source for the septicaemia.

Septicemia I. A prospective study on etiology, underlying factors and sources of infection

In a prospective study, 110 cases of proved and 41 of probable septicemia were analysed. Underlying diseases or factors were common, also in young patients, often narcotic drug or alcohol abusers. In one third, septicemia was probably hospital-acquired. Streptococci, staphylococci and gram-negative enteric rods were most common, followed by pneumococci and haemophilus species. Staphylococci and gram-negative enteric rods dominated in patients hospitalized at or before the onset of disease, and staphylococci in patients with vascular foreign bodies and in drug addicts. Enteric rods were common in elderly patients with urogenital disease, especially after instrumentation. Among streptococci, alpha-streptococci dominated; they did not emanate as often from dental foci as expected. In 2 of 3 asplenic patients with extensive hemorrhages pneumococci were found. Bacteria of low virulence and fungi occurring as opportunists were rare. Mixed infections, present in 4 cases, were severe. Portals of entry could often be proved or assumed. In half of all patients, the same organism was isolated from a primary focus as from blood. The importance of underlying illnesses and factors and of invasive procedures was evident. A tentative etiological diagnosis could often be made, based on case history, underlying factors and the probable portal of entry.

Effect of cyclophosphamide on the immune response to Pseudomonas aeruginosa in mice

Natural resistance in mice to Pseudomonas aeruginosa was decreased 10-fold with a single dose of 300 mg of cyclophosphamide (CY) per kg intraperitoneally. Mice were resistant to infection when immunized actively with Pseudomonas vaccine or passively with Pseudomonas immune serum before receiving CY. Syngeneic spleen, thymus and/or bone marrow cells were transfused into CY-treated recipient mice. Protective anti-Pseudomonas antibody was elicited in the recipient mice when they were vaccinated 1 day after receiving normal spleen cells and challenged 8 days after vaccination. When 1.6 X 10(7) normal thymus and bone marrow cells were infused before vaccination, 69% of the recipients of both cell preparations responded serologically compared with 15 and 27% of those receiving either thymus or bone marrow cells, respectively. CY-treated thymus or bone marrow cell recipients were resistant to Pseudomonas infection when 6 X 10(7) of either cell population was transfused.

Bacteremia in a general hospital. A prospective study of 102 consecutive cases

A prospective clinical-bacteriological study of 102 consecutive cases of confirmed bacteremia at a Copenhagen City general hospital was carried out during 5 months of 1973 with special concern given to focus of infection and acquisition of microorganisms. Valid positive cultures were obtained from 7.2 patients per 1000 admissions. 50 of the 102 bacteremias were by all probability acquired in the hospital, mainly due to transurethral manipulations or intravenous lines. Pneumonia and hepatobiliary infections accounted for most of the non-hospital acquired bacteremias. 26/102 patients died in relation to the bacteremia. Escherichia coli and Staphylococcus aureus caused more than half of the infections. Bacteremia caused by proteus, klebsiella, enterobacter species of staphylococci was in most cases nosocomial and carried the highest mortality, i.e. 40%, verus 15% when other organisms were responsible. It is concluded that nosocomial bacteremia is a frequent and life-endangering complication which is often preceded by certain diagnostic or therapeutic procedures, not invariably linked to severe underlying diseases. Consequently, attempts to reduce bacteremic episodes should include surveillance of ecological factors and certain hospital procedures.

Bacteremia: the significance of outside versus inside hospital origin

168 patients with bacteremia seen in 1965-1969 were studied with regard to mortality rate, age and sex distribution, sources of infection, predisposing factors and infecting organisms. Special attention was drawn to outside hospital originating bacteremia vis-a-vis hospital-acquired bacteremia. In general, the results obtained were essentially in agreement with earlier experiences elsewhere. The most striking observations were, firstly, the grave prognosis associated with hospital-acquired bacteremia and, secondly, the dominant role played by gram-negative bacilli.

Genetic basis, epidemiology, and future significance of antibiotic resistance in Staphylococcus aureus: a review

Images

Bacteriocine typing of Klebsiella spp

One hundred and six strains of Klebsiella spp were examined for their ability to produce bacteriocine. Nine of these, together with one strain from the National Collection of Type Cultures, were selected and used to type Klebsiella strains from various sources. Strains were typed by testing their sensitivity to bacteriocines produced by the standard set of 10 strains. Eight hundred strains were tested and 77% of these were typable and could be divided into a relatively large number of groups, some of which occurred consistently more frequently than others.This simple method has been shown to have some value in epidemiological investigations.

Bacteraemia in patients receiving human cadaveric renal transplants

During a two-year period (1966 to 1968) 70 patients were admitted to the Renal Transplantation Unit at St Mary's Hospital and 22 (31%) developed bacteraemia. Eighteen of the 25 episodes of bacteraemia occurred after transplantation and seven before. The typical clinical syndrome was uncommon and was only seen in 32% of cases. The presence of shock was not recognizable in the majority of patients probably because they were already receiving steroid therapy. The commonest infecting organism was Ps. aeruginosa (nine cases) and Gram-negative bacilli accounted for 72% of the bacteraemias. Staph. aureus was isolated in five patients.A likely source of the infecting organism was found in 80% of cases and the commonest source was the urinary tract. Serious complications were present in 13 episodes of bacteraemia, and these were peritonitis before transplantation, necrosis of the donor ureter, and severe rejection or polar infarction in the donor kidney after transplantation. Bacteraemia due to Gram-negative bacilli was associated with complications in 61% of cases. Ps. aeruginosa was almost invariably isolated from complicated cases though Esch. coli was only seen in simple cases. Antibiotic treatment was successful in 64% of cases but the cure rate was higher (86%) before transplantation than after transplantation (55%). Although the presence of complications did not affect the cure rate in Gram-positive bacteraemia, the cure rate in complicated Gram-negative bacteraemias was poor and associated with a mortality of over 70%. Patients receiving human cadaveric renal transplants are susceptible to all kinds of bacterial infection including bacteraemia, and the results of antibiotic treatment are dependent on both the nature of the infecting organism and the presence of serious underlying complications.

Generalized infection of gnotobiotic piglets with E. coli of feline origin

Images

Polyserositis Induced by Escherichia coli in Gnotobiotic Swine

The oral administration of an 18-hr broth culture of Escherichia coli 06: isolated from a cat to 3-day-old gnotobiotic (germ-free) piglets resulted in bacteremia and polyserositis. Sixteen pigs, selected from four litters, were used in the study. E. coli of the same serotype employed was the only bacterial agent demonstrable and recovered from moribund and dead piglets. Attempts to recover virus or PPLO (mycoplasma) from these animals were unsuccessful. A polyserositis syndrome was not encountered among neonatal pigs in experiments with 14 other serotypes of E. coli ; hence it was considered to be a syndrome closely associated with the infection caused by this particular strain of E. coli.

Some bacteraemias encountered in hospital practice

This is a retrospective study of the results of 4,642 blood cultures taken from 2,190 patients from 1960 to 1967 in one London hospital. The results suggested that an increased incidence of bacteraemias at this particular hospital was mainly due to the increase in the number of patients having blood cultures. Some of the bacteraemias were terminal or transient and probably of doubtful clinical significance.

Single-blind comparative trial of trimethoprim-sulphamethoxazole and ampicillin in the treatment of exacerbations of chronic bronchitis

Fifty patients with exacerbations of chronic bronchitis were treated with either a combination of trimethoprim 320 mg. and sulphamethoxazole 1,600 mg. a day or ampicillin 2 g. a day. The trial, carried out as a single-blind procedure, showed that the combination was more effective as judged by clinical response and reduction in sputum volume and purulence, with eradication of pathogenic organisms. No appreciable side-effects were encountered with either treatment, and it is suggested that the trimethoprim-sulphamethoxazole combination may be a safe and useful drug in the treatment of chronic bronchitis.

Gram-negative bacilli in burns

In a period of two years, 865 strains of Gram-negative bacilli other than Pseudomonas aeruginosa isolated from burns were identified by a range of tests. The commonest species were Proteus mirabilis, Escherichia coli, and Enterobacter cloacae. Many strains of Klebsiella aerogenes, Enterobacter aerogenes, and Bacterium anitratum were also found.A large proportion of the strains were tested for sensitivity to nalidixic acid, ampicillin, kanamycin, chloramphenicol, tetracycline, and carbenicillin, and smaller numbers of strains were tested for sensitivity to cephaloridine, polymyxin, streptomycin, sulphadiazine, sulfamylon, and trimethoprim. The proportion of strains sensitive and resistant to different antibacterial agents varied widely with species of bacteria. A large proportion of the strains of E. coli and P. mirabilis were resistant to ampicillin, which was much used in treatment; resistance appeared least often towards nalidixic acid, kanamycin, trimethoprim, and gentamicin. Multiple resistance occurred less often among strains of E. coli than among Klebsiella spp, Enterobacter spp, and P. mirabilis. Phage and serological typing of Ps. aeruginosa showed that most infections of burns with this organism were due to strains previously found in other patients in the same ward. Taken with other evidence, this supported the view that most infections with Ps. aeruginosa were not acquired from the patient's own flora but from sources in the hospital environment.

Sensitivity of Gram-negative bacilli to ampicillin after six years' clinical use

A total of 1,102 clinical isolates of Gram-negative bacilli was obtained from four hospitals during 1967 and these cultures were tested for sensitivity to ampicillin. Approximately 80% of the strains of Escherichia coli and 90% of the strains of Proteus mirabilis, the two organisms most frequently isolated, were sensitive to ampicillin. Klebsiella-Enterobacter species and Pseudomonas aeruginosa were generally insensitive. Comparison of these results with data obtained in an earlier study with Gram-negative organisms isolated in 1961 showed that there had been no significant increase in the incidence of resistance of Gram-negative bacilli to ampicillin during the period 1961-67. The majority of ampicillin-resistant strains of E. coli isolated in 1967 transferred ampicillin resistance to a sensitive strain of E. coli K12. Only four ampicillin-resistant strains of E. coli isolated in 1961 were available for transferable resistance tests but all four strains transferred ampicillin resistance. Infective or transferable resistance was therefore a feature of ampicillin resistance of certain Gram-negative bacteria before ampicillin became generally available for clinical use.

Coliform bacteraemia in infants

The incidence of patients with positive blood cultures from which a single species of coliform bacillus was isolated is given for the years 1962 to 67. There has been an increase during these years particularly in neonatal infants: 91 cases were recorded in babies under 6 months of age, and the bacteriological and clinical findings have been related in 85. Children born either prematurely or as a multiple birth and those with congenital malformations showed a predisposition to this form of infection. Many of the remaining cases had an associated localised infection.

Some aspects of the cause of the increase in coliform bacteraemia in babies are discussed and the severity and possible implications of the infection are emphasised.