Nasal staphylococci and sepsis in hospital patients

Microbial contamination of topical medicaments used in the treatment and prevention of pressure sores

Topical medicaments used in the treatment and prevention of pressure sores in patients in three hospitals were examined for Pseudomonas aeruginosa and Staphylococcus aureus contamination. Contamination rates were found to vary between hospitals and were affected by differences in the packaging of the product and in the method of application used by the nursing staff.

Primary postoperative wound infection due to Staphylococcus pyogenes

Using S. pyogenes as a tracer organism, an examination of the importance of air-borne infection of clean wounds in the modern, plenum-ventilated operating room has been made. It appears that, for most surgical procedures, additional ultra-clean air installations are not necessary. It has been shown that even if the air is sterile, the skin remains a possible source of infection. This is especially so as far as the patient's skin is concerned. It will remain so, since the skin cannot be sterilized. Indeed, until the ecology of the skin is better understood, rigorous efforts directed toward its disinfection may compromise its inherent defense mechanisms and its protective bacterial flora. It will be argued by some that operating rooms with ultraclean air should be afforded for certain specialized procedures in sugery; for example, those in which prosthetic materials are being implanted or in which the patient's immune mechanisms are depressed. Although not disagreeing with this, I wish to note that the only controlled trial on this aspect of surgery that exists to date shows no advantage for patients randomly apportioned to have hip arthroplasty, either in an isolator or in the same modern operating room but without the isolator. From this experience, I believe that any further trial of this nature, if it is to be controlled to a similar high level, will require very large numbers of patients to show even a marginal advantage for ultraclean air or isolator installations over the modern, plenum-ventilated and meticulously managed operating suite. The verdict on the need to install ultraclean air plant for operating rooms must, therefore, be couched in the third alternative that exists under Scots Law-- "not proved." I suggest the money could be better spent on devising methods to keep skin pathogens out of surgical wounds. Perhaps more urgently, there is a need to discover how to increase the defense mechanisms of the wound milieu to implanted harmful bacteria. There is also a pressing need to improve the ward environment with the aim of diminishing secondary infections of surgical wounds.

Isolation care of infection-prone burn patients

An experimental and clinical study of spread of colonisation between burn patients, and their susceptibility to infection, was performed. Burn patients' polymorphonuclear neutrophil granulocytes (PMN) functioned poorly, particularly during the second week after injury which coincided with maximum growth of bacteria in the burn wound. Patients with large burns often dispersed S. aureus and Ps. aeruginosa but also beta-hemolytic Streptococcus to the air of their rooms. Airborne transfer of these bacteria was practically eliminated by nursing in single isolation rooms with plenum ventilation. In such rooms, cross-contamination was carried mainly via clothes. Patients with small burns sometimes were important sources of such contamination although they dispersed little bacteria to the air. A thorough change of barrier dress after close contact nursing delayed the first exogenous S. aureus colonisation until after the time of greatest impairment in PMN functions. A further reduction in cross-contamination would be possible with barrier garments impermeable to fluids and bacteria on points of contact, as shown in experiments with plastic apron as protective dress. Measurements of penetration through fabrics of particles suspended in air, commercially used, did not correlate to the performance of garments made from the fabrics in experimental nursing and clinical use. Bacteria were shown to penetrate fabrics through rubbing, particularly when wet where the microcolonies present on the cloth were separated into smaller units. An instrument was designed which measured such penetration, and was used to select fabrics for barrier garments. Tightly fitting barrier garments increased the disperal of bacteria from clothes worn underneath them. The wearing of barrier garments should therefore be restricted to close contact nursing. An open-roofed plastic patient isolator was designed and built. It did not appreciably reduce cross-contamination and gave psychological and practical problems. It seemed not to be a realistic alternative to better protective garments in isolation rooms.

Airborne infection in a fully air-conditioned hospital. IV. Airborne dispersal of Staphylococcus aureus and its nasal acquisition by patients

Studies in a newly built hospital furnished with complete air conditioning where most of the patients are nursed in 6-bed rooms showed that the transfer of air from one patient room to another was very small, especially when there was substantial flow of air in a consistent direction between the patient rooms and the corridor, and that the direct transfer of airborne particles was even less. There was, however, no evidence of any reduction in the rates of nasal acquisition of Staphylococcus aureus compared with those to be found in naturally ventilated hospitals. The numbers of Staph. aureus found in the air of a given room that appeared to have originated from patient carriers in other rooms were many times greater than could be accounted for by direct airborne transfer. Although there was evidence that many carriers were not detected, detailed study showed that this excess transfer to the air of other rooms was genuine. It seems probable on the basis of investigations in this hospital and elsewhere that this excess transfer occurs indirectly, through dispersal from the clothing of the nursing and medical staff into the air of another room of strains with which their outer clothes have become contaminated while dealing with patients. Reduction in direct airborne transfer of micro-organisms from one room to another, whether by ventilation or other means, can only be of clinical advantage if transfer by other routes is, or can be made, less than that by the direct airborne route.

Factors that influence surgical wound infections. Role of prophylactic antibiotic therapy

A comprehensive review of the factors responsible for postoperative wound sepsis is discussed, along with the experimental basis for the use of prophylatic antibiotics and a review of the results of the use of systemic and topical antibiotics on the incidence of surgical wound infections. Based on the data presented, suggestions are made which should minimize the development of postoperative wound infections.

Nasal carriage of Staphylococcus aureus in a general surgical unit

Nasal carriage of staphylococci was found in 50 per cent of in-patients in a general surgical unit and in 26 per cent of out-patients. While 32 per cent of in-patients carried resistant organisms in their noses a high percentage of out-patients (17 per cent) also were carriers of resistant organisms. Eighty per cent of staff carried staphylococci in their noses, 67 per cent being resistant organisms. Although the ‘hospital staphvlococcus’ was found in 5 per cent of patients and 15 per cent of attending staff, only 1 per cent of in-patients and none of the out-patients or staff carried multiple-resistant organisms. Age does appear to have some bearing on the carriage of bacteria in the anterior nares.

In contrast to other studies, this work failed to reveal any relationship between wound infection and nasal carriage of staphylococci. These findings suggess that general dissemination of bacteria in the hospital environment may be of greater importance than autoinfection as a cause of wound sepsis.

Staphylococcal infection in subdivided general surgical wards

The spread of Staphylococcus aureus was studied in three general surgical wards of identical design which consisted of a number of separate rooms, and the results were compared with those in the same unit previously studied, in subdivided wards elsewhere and in large open wards.The nasal carrier rate of Staph. aureus by patients rose during their stay in the ward, but its peak rate was comparable with minimum rates reported in other subdivided wards and was lower than in open wards.Staphylococcal sepsis rates were lower than in most open wards and were also much lower than those found previously in the same unit when overcrowding was common and each sex had its own ward.

Surgical wound sepsis

With the help of a surgical nurse and using data-processing techniques, a prospective clinical study was conducted to determine the wound infection rate in two hospitals in Calgary. The overall sepsis rate was 5.2% and the clean wound rate 3.5%. The latter is the more meaningful figure as it allows for comparison between hospitals, specialties and individuals and is a good guide for hospital morbidity reviews. The groundwork for succeeding wound infection is laid in the operating theatre, and it is believed that wound infection would be reduced more by attention to Halsted's principles than by more rigid aseptic techniques. It is estimated that wound sepsis costs the Province of Alberta 1.5 million dollars per year for hospitalization alone. This amounts to roughly $1 per person per year. The annual cost of a prospective study such as the present one is approximately $7000. This is equivalent to the cost of hospitalizing 24 patients with infected wounds for one week (at $300 per week). One dividend of a prospective study is an associated reduction in infection rate. This reduction more than pays for the cost of the program.

Studies of the effectiveness of an isolation ward

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Importance of the carrier state as a source of Staphylococcus aureus in wound sepsis

The relationship of pre-operative nasal and skin carriage of Staphylococcus aureus to wound colonization and sepsis was studied in 269 patients. Thirty-seven per cent of 96 carriers developed wound colonization as compared to 16 % among non-carriers (a statistically significant difference). The wound sepsis rates were 17 % and 9 % respectively. The combination of nasal and skin carriage was an important factor, since the sepsis rate among skin carriers (most of whom were nasal carriers as well) was 22%. Among carriers, the homologous strain was recovered from the majority of wound colonizations and from all instances of wound sepsis. A carrier strain also was recovered from 52% of the wounds colonized and from 50% of septic wounds in the entire study group. Profuse nasal carriage resulted in a significantly greater number of septic wounds (31%) than sparse carriage (9%). Wound cultures before closure, and skin from the initial incision site only once yielded a patient's carrier strain or a strain of Staph. aureus that was later recovered from the wound. The results indicate that measures designed to control the carrier state or to isolate the wound from the external environment should reduce wound sepsis by approximately one half.

Excellent technical aid was furnished by Eleanor Ford, R. N., Edith E. Silverman, Adrienne Marus, M. S., and Patricia Welch.

Acquisition of Staphylococcus aureus by patients undergoing cytotoxic therapy in an ultra-clean isolation unit

The twenty-four young women and one man treated in an ultra-clean isolation ward should have had a low incidence of staphylococcal infection on grounds of age, sex and clean environment alone. However, they apparently acquired new strains of Staph. aureus at the rate of 4·7/100 patient weeks (3·9 multiple resistant strains/100 patient weeks) from the sixth week after admission onwards.

Environmental factors contributing to infection included introduction of resistant strains by the patients on admission, contact between patients in the unit, and failure to eliminate nasal carriage in staff and patients.

Host susceptibility was increased by malignancy, and by antibiotic and cytotoxic therapy. The nasal carriage rate of Staph. aureus was significantly greater for patients with repeated episodes of leucopenia induced by cytotoxic drugs.

A survey of staphylococcal infections in group 9 hospitals

This is a three-year survey of staphylococcal infection in the Watford group of hospitals. The organisms are divided into groups according to their pattern of sensitivity to antibiotics. The spread of Staphylococcus pyogenes in a maternity hospital and the measures taken to eradicate it are described.

Yearly incidence of penicillin-resistant staphylococci in man since 1942

For this study of the year-by-year change in the incidence of carriage of or infection by penicillin-resistant, coagulase-positive or haemolytic staphylococci in man, 248 contributions to the medical literature have been analysed and grouped under three main headings: people in hospitals, people with clinical signs attending out-patients' wards or doctors' surgeries, and people not currently receiving medical care.This analysis shows that there has been a steady increase in resistant strains among persons of the first group from 1942 to 1955, followed by a slight decrease to 1959, possibly owing to more discriminating use of penicillin. A steady increase was found in the other two groups from 1942 to 1959, the rate of increase being more pronounced among the group with clinical signs.The authors draw attention to the possible influence of the ingestion of penicillin with food on the incidence of resistant strains; the occurrence of such strains in certain foods; and the need for standardized techniques for sampling, for testing for staphylococci and for determining resistance.