A 10-year study of bacteremia

Sensitivity of 523 Blood Culture Isolates to 33 Antibiotics

523 blood culture isolates collected during 18 months (July 1980-December 1981) were analysed by the agar dilution method for sensitivity to 33 antibiotics. Breakpoints corresponding to the SIR system were used but for N-formimidoyl-thienamycin (N-f-thienamycin), azthreonam and fosfomycin serial dilutions were made. Aminoglycosides (netilmicin, gentamicin, amikacin and tobramycin) inhibited from 90 to 86% of the strains. This was comparable to the percentage inhibited by some cephalosporins (cefotaxime, cefoperazone, ceftazidime, ceftriaxone, cefuroxime, cephamandole and moxalactam) ranging from 95 to 89%. A very high number of strains (99%) were inhibited by N-f-thienamycin. By combination of certain antibiotics more than 99% of the strains could be inhibited.

Pneumococcal bacteraemia during a recent decade

We retrospectively reviewed 159 episodes of bacteraemic pneumococcal infection in 157 adult patients at the Helsinki University Central Hospital during two periods between 1976 and 1979 and 1986 and 1989. We looked especially at changes in underlying diseases and prognostic factors. The overall case fatality rate was 21% and there was a small diminishing trend in that rate from 28% (16/58) in the late 1970s to 17% (17/101) in the late 1980s. The patients who died in the late 1980s were younger than those who died in the earlier period. The most common underlying factors were alcohol abuse, cardiovascular diseases and chronic obstructive pulmonary diseases. Old age was neither a predisposing factor nor did it predict the outcome. No significant changes in underlying diseases or prognostic factors were noted during the two periods studied except a small decrease in connective tissue diseases as underlying conditions. The factors related to increased fatality included hepatic cirrhosis, a combination of pneumonia and meningitis, complications such as shock, respiratory insufficiency, central nervous system disorders and circulatory acidosis, and laboratory findings such as thrombocytopenia, absence of leucocytosis and increased amounts of serum creatinine, aspartate aminotransferase and alanine aminotransferase on admission to the hospital. Previous splenectomy and malignant diseases were not associated with higher mortality. The thrombocytopenia at the time of positive blood culture and the circulatory acidosis as a complication seemed to be independently the most useful predictive factors for a fatal outcome using multivariate logistical regression analysis after adjustment to classic risk factors.

Septicemia and endocarditis, 1965-1980, in a Swedish university hospital for infectious diseases

A 16-year (1965-1980) retrospective clinical study of septicemia and endocarditis was performed at a hospital for infectious diseases. 634 patients (74.5%) had septicemia, 138 (16.2%) endocarditis and 79 (9.3%) suspected endocarditis. The mean age was 55 years, 472 were males and 379 females. Predisposing underlying conditions were recognized in 89.2%. Gram-positive cocci (62.3%) dominated over gram-negative rods (29.5%). The most common causative organisms of septicemia were Staphylococcus aureus (22.4%) and Escherichia coli (20.2%), and of endocarditis, S. aureus (47.1%) and alpha haemolytic streptococci (21.0%). The overall fatality rate was 17.7% and was highest in infections caused by gram-negative rods and S. aureus. In septicemia the rate was 15.3% and in endocarditis 37.0%. Unfavourable prognostic factors were high age, endocarditis and underlying conditions such as haematological diseases and various other factors.

Bacteraemia among children in hospital--a four year prospective study

The incidence of bacteraemia in children (excluding newborn babies) admitted to a general hospital during the period 1978 to 1981 was 3.2 patients per 1000 admissions. Of the total, nosocomial bacteraemia comprised 0.7 patients per 1000 admissions. Analysis of some probable risk factors showed that the chance of acquiring bacteraemia in the first year of life was 6.8 times that for older children, the difference being statistically significant (P less than 0.001). The male to female ratio was 1.7: but this difference was not statistically significant. Overall the case mortality rate was 4.5%. For nosocomial bacteraemia the rate was much higher (14.3%) than that of community acquired bacteraemia (1.9%) with a risk of dying 7.5 times greater (P less than 0.01). Of the pathogens isolated 71.2 per cent were Gram-negative, Escherichia coli being the most common followed by Salmonella typhi. Among the Gram-positive organisms isolated, as well as overall, the pneumococcus was the most common pathogen. Pneumonia and gastroenteritis were the underlying conditions most often found. Since the pneumococcus was the most common pathogen, and in all of our patients originated in the community, physicians who treat in out-patient clinics as well as emergency rooms should be aware of this and look especially for the early symptoms and signs of disease likely to be caused by this organism.

A study of bacteremias in Denmark from 1977-1978

The results of blood cultures from a large number of Danish hospitals examined at Statens Seruminstitut in 1977 and 1978 have been analysed. Out of a total of 17, 518 cultures in 1977 and 17,820 in 1978, 1,626 from 830 patients and 1,544 from 832 patients yielded growth of pathogenic microorganisms. Cases of bacteremia with Enterobacteriaceae constituted approximately 50% of cases both in 1977 and 1978. Polymicrobial bacteremia occurred in 8.1% of bacteremic cases in 1977 and 7.5% of those in 1978. The microorganisms isolated and their frequencies were surprisingly similar to those found in 1965 and 1971 in an earlier investigation from this department. No change in antibiotic susceptibility was observed between 1977 and 1978. Retesting of 50 E. coli strains from 1965, 1971 and 1978 for susceptibility towards ampicillin, cephalotin, streptomycin and tetracycline indicated that no significant changes had occurred, contrary to the results of the earlier investigation. This fact stresses the importance of exploring the possibility of unnoticed methodological changes having occurred in the sensitivity testing systems before any conclusions can be drawn concerning apparent differences in antibiotic susceptibilities.

Pneumococcal infections and the possible need for a vaccine

Antibiotics and chemotherapeutics have been available for about 40 years, but still bacterial infections constitute some of the greatest problems in medicine. Pneumococci causing pneumonia, bacteremia, meningitis and otitis are a leading cause of illness and death. The exact incidence and lethality of pneumococcal infections is not known, however, since they are not reportable diseases in most countries and since microbiological diagnosis is difficult. In the latest years some significant progresses have been made for the diagnosis of infections caused by pneumococci, especially pneumonia. This is for example the counterimmunoelectrophoresis (CIE) for antigen determination, the transtracheal aspiration (TTA) for direct bacterial cultivation from trachea, and serological assays like radioimmunoassay (RIA) and enzyme-linked immunosorbent assay (ELISA) for pneumococcal capsular antibody determination. These techniques have further emphasized the significance of pneumococcal infections. The recent finding of pneumococci resistant to penicillin and some other antibiotics also emphasizes the need for immunological prophylaxis. In recent years a vaccine consisting of the purified, most common pneumococcal polysaccharides has been introduced. It has been shown to protect against pneumonia, pneumococcal infections in splenectomized individuals and people with spherocytosis and probably partly against otitis media. Indications for the vaccine are suggested.

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.

Bacteremia and fungemia complicating neoplastic disease. A study of 364 cases

During a 14 month period there were 364 episodes of bacteremia and fungemia at Memorial Sloan-Kettering Cancer Center. The first nine months of the study were retrospective, and the next five prospective. In patients with leukemia or lymphoma (group 1), Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae and Staphylococcus aureus were the most frequently isolated organisms. The mortality in this group was 40.5 per cent. In the patients with solid tumor (group 2), Esch. coli, Staph. aureus, Bacteroides sp. and Candida sp. were most frequent. Mortality was 27.8 per cent. The source of infection in both groups was often indeterminate. High mortality was associated with pulmonary and intraabdominal infection and with Ps. aeruginosa, K. pneumoniae or polymicrobic sepsis. Factors of prognostic significance were the causative microorganism, source of infection and shock. Although mortality was higher in patients with leukopenia than in those with normal leukocyte counts, the differences were not significant. The mortality in this series was low considering the severity of the underlying diseases and the immunosuppressed state of many of the patients. In a prospective, randomly controlled study, mortality was further diminished by infectious disease consultation at the time the positive blood culture was reported. Severe fungal superinfection, predominantly aspergillosis and candidiasis, was found in 52 per cent of the autopsy patients with leukemia or lymphoma (group 1), but in only 8 per cent of those with solid tumors (group 2).

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.