Studiesof a patient isolator unit and prophylactic antibiotics in cancer chemotherapy. General techniques and preliminary results

Epidemiology and source of infection in cancer patients with febrile neutropenia: an experience from a developing country

BACKGROUND

Febrile neutropenia (FN) is a life-threatening complication that predisposes cancer patients to serious infections. This study aims to describe the epidemiology and source of infection in cancer patients with FN in a tertiary care hospital.

METHODS

A hospital-based retrospective study was conducted in a large tertiary care hospital from January 2020 to December 2021. Data on cancer patients with FN were collected from the hospital information system.

RESULTS

150 cancer patients with FN were identified during the study period. Most patients were males (98; 65.3%), and the mean age of participants was 42.2 ± 16.0 years. Most patients (127; 84.7%) had hematologic malignancies, and acute myeloid leukemia was the most common diagnosis (42; 28%), followed by acute lymphocytic leukemia (28; 18.7%) and Hodgkin's lymphoma (20; 13.3%). Fifty-four (36%) patients had a median Multinational Association for Supportive Care in Cancer (MASCC) scores greater than 21. Regarding the outcome, nine (6%) died, and 141(94%) were discharged. The focus of fever was unknown in most patients (108; 72%). Among the known origins of fever were colitis (12; 8%), pneumonia (8; 5.3%), cellulitis (6; 4%), bloodstream infections (7; 4.6%), perianal abscess (2; 1.3%) and others. The median duration of fever was two days, and the median duration of neutropenia was seven days. Sixty-three (42%) patients had infections: 56 (73.3%) were bacterial, four (2.6%) were viral, two (1%) were fungal and 1 (0.7%) was parasitic. Among the bacterial causes, 50 cases (89.2%) were culture-positive. Among the culture-positive cases, 34 (68%) were gram-positive and 22 (44%) were gram-negative. The most frequent gram-positive bacteria were E. faecalis (9; 18% of culture-positive cases), and the most frequent gram-negative organisms were Klebsiella pneumoniae (5; 10%). Levofloxacin was the most commonly used prophylactic antibiotic (23; 15.33%), followed by acyclovir (1610.7%) and fluconazole in 15 patients (10%). Amikacin was the most popular empiric therapy, followed by piperacillin/tazobactam (74; 49.3%), ceftazidime (70; 46.7%), and vancomycin (63; 42%). One-third of E. faecalis isolates were resistant to ampicillin. Approximately two-thirds of Klebsiella pneumoniae isolates were resistant to piperacillin/tazobactam and ceftazidime. Amikacin resistance was proven in 20% of isolates.

CONCLUSIONS

The majority of patients suffered from hematologic malignancies. Less than half of the patients had infections, and the majority were bacterial. Gram-positive bacteria comprised two-thirds of cases. Therefore, empiric therapy was appropriate and in accordance with the antibiogram of the isolated bacteria.

Emerging trends in aggregation induced emissive luminogens as bacterial theranostics

The emergence and spread of pathogenic bacteria, particularly antibiotic-resistant strains pose grave global concerns worldwide, which demand for the rapid development of highly selective and sensitive strategies for specific bacterial detection, identification, imaging and therapy. The fascinating feature of aggregation-induced emissive molecules (AIEgens) to display fluorescence in aggregate form can be suitably coupled with nanotechnology for developing theranostic AIE dots that can offer convenient and customised functions such as sensing, imaging, detection, discrimination and cell kill of different bacterial types. The initial section of the article reveals the necessity for incorporating diagnostic imaging with antibacterial therapy, while the latter part delivers mechanistic insights on the benefits of AIE fluorophores in theranostic applications. Further, the review illustrates the recent advancements of AIEgens as theranostic nanolights in bacterial detection, identification and eradication. The review is organised according to the different classes of AIE-active bacterial theranostics such as carrier-free nanoprodrugs, nanomachines for synergistic imaging-guided cancer treatment and bacterial kill, AIE polymers, bioconjugates and nanoparticle carriers. By elucidating their design principles and applications, as well as highlighting the recent trends and perspectives that can be further explored, we hope to instill more research interest in AIE bacterial theranostics for future translational research.HighlightsCombination of aggregation induced emissive fluorophores and nanotechnology for developing bacterial theranostics.AIE theranostics with customised functions for bacterial imaging, detection, discrimination and cell kill.

Efficacy of selective digestive decontamination in patients with multiple myeloma undergoing high-dose chemotherapy and autologous stem cell transplantation

Selective digestive decontamination (SDD) with the oral, non-absorbable antimicrobial substances gentamicin, vancomycin and amphotericin B was optionally used at our institution to reduce the risk of gastrointestinal tract derived infections in multiple myeloma (MM) patients undergoing high-dose chemotherapy with subsequent autologous stem cell transplantation (HDCT/ASCT). The majority of patients received sulfamethoxazole-trimethoprim as pneumocystis pneumonia prophylaxis. From 203 patients receiving their first HDCT/ASCT between 2009 and 2015, we compared retrospectively 90 patients receiving SDD to 113 patients not receiving SDD. The administration of SDD was associated with a reduction of bacterial infections after HDCT/ASCT (overall: 8% versus 24%, p = .002; gram-negative pathogens: 1% versus 11%, p = .006) and less use of systemic antibiotics (62% versus 77%, p = .022). Omission of SDD was an independent risk factor for developing neutropenic fever and bloodstream infections. SDD could be an option to reduce bacterial infections in patients undergoing HDCT/ASCT that needs to be tested in prospective trials.

Autologous Stem Cell Transplantation in Patients With Multiple Myeloma: An Activity-based Costing Analysis, Comparing a Total Inpatient Model Versus an Early Discharge Model

BACKGROUND

Activity-based costing (ABC) was developed and advocated as a means of overcoming the systematic distortions of traditional cost accounting.

MATERIALS AND METHODS

We calculated the cost of high-dose chemotherapy and autologous stem cell transplantation (ASCT) in patients with multiple myeloma using the ABC method, through 2 different care models: the total inpatient model (TIM) and the early-discharge outpatient model (EDOM) and compared this with the approved diagnosis related-groups (DRG) Italian tariffs.

RESULTS

The TIM and EDOM models involved a total cost of €28,615.15 and €16,499.43, respectively. In the TIM model, the phase with the greatest economic impact was the posttransplant (recovery and hematologic engraftment) with 36.4% of the total cost, whereas in the EDOM model, the phase with the greatest economic impact was the pretransplant (chemo-mobilization, apheresis procedure, cryopreservation, and storage) phase, with 60.4% of total expenses. In an analysis of each episode, the TIM model comprised a higher absorption than the EDOM. In particular, the posttransplant represented 36.4% of the total costs in the TIM and 17.7% in EDOM model, respectively. The estimated reduction in cost per patient using an EDOM model was over €12,115.72. The repayment of the DRG in Calabrian Region for the ASCT procedure is €59,806. Given the real cost of the transplant, the estimated cost saving per patient is €31,190.85 in the TIM model and €43,306.57 in the EDOM model.

CONCLUSION

In conclusion, the actual repayment of the DRG does not correspond to the real cost of the ASCT procedure in Italy. Moreover, using the EDOM, the cost of ASCT is approximately the half of the TIM model.

Inching toward cure of acute myeloid leukemia: a summary of the progress made in the last 50 years

Despite some claims to the contrary, I believe substantial progress has been made in the last half century toward cure of acute myeloid leukemia in children and adults. The tried and true mechanism for this progress has been clinical trial and error. This method has been supplemented with an ever-increasing amount of work at the clinical laboratory interface that is beginning to allow us to develop specific therapy for afflicted individuals. This review details where we stand today and how we got here.

Infections in Patients with Cancer: Overview

Patients with neoplastic disease are often highly susceptible to severe infections. The following factors influence the types, severity, and response to therapy of these infections: (1) Changing epidemiology of infections; (2) cancer- and/or treatment-associated neutropenia; (3) acquired immune deficiency states such as cellular immune defect; (4) recent development of new-generation diagnostic tools including widely available DNA amplification tests; (5) effective intervention for infection prevention; (6) empiric or presumptive therapy during high-risk periods; (7) availability of new classes of highly active antimicrobial drugs; (8) strategies to promote hosts’ immune response; and (9) future measures. This introductory chapter intended for the reader to become familiar with the important historical milestones in the understanding and development in the field of infectious diseases in immunosuppressed patients with an underlying neoplasms and patients undergoing hematopoietic stem cell trans­plantation.

Normal hospital and low-bacterial diet in patients with cytopenia after intensive chemotherapy for hematological malignancy: a study of safety

BACKGROUND

The purpose of this randomized, controlled pilot study is to address the question whether normal hospital diet (NHD) is safe when compared with low-bacterial diet (LBD) given to prevent infections in cytopenic patients who receive antimicrobial prophylaxis (AP).

PATIENTS AND METHODS

The patients were randomized into two groups: one group to receive AP and LBD, the other to receive the same AP and NHD. The primary outcome parameter is colonization of the digestive tract with aerobic gram-negative bacilli and yeasts. Secondary outcome parameters were infections and total societal costs.

RESULTS

No statistically significant differences between treatment groups were observed regarding the primary outcome parameter, gut colonization by yeasts or gram-negative bacilli, or infections, use of antimicrobials, days with fever and total societal costs.

CONCLUSION

On the basis of the results of this pilot study, NHD appears to be as safe as LBD in patients with chemotherapy-induced cytopenia. Furthermore, the results indicate that LBD may offer no additional benefit as an infection preventive measure to the measures already implemented, such as AP. Thus, a larger randomized study, powered adequately to determine noninferiority of NHD to LBD is warranted and safe to be carried out.

The Effect of the Neutropenic Diet in the Outpatient Setting: A Pilot Study

PURPOSE/OBJECTIVES

To determine whether use of the neutropenic diet in the outpatient setting decreases the number of febrile admissions and positive blood cultures associated with chemotherapy-induced neutropenia.

DESIGN

Descriptive pilot study.

SETTING

Outpatient chemotherapy unit of a medical center in a major metropolitan area.

SAMPLE

Convenience sample of 28 patients aged 33-67 years beginning treatment with 1 of 13 chemotherapy regimens.

METHODS

Twelve-week prospective study beginning on day 1 of chemotherapy cycle 1. Patients received instructions regarding the neutropenic diet before starting chemotherapy. Adherence assessment telephone calls were made at weeks 6 and 12. Hospital admission charts were reviewed at study completion.

MAIN RESEARCH VARIABLES

Adherence with neutropenic diet, number of febrile admissions, and number of positive blood cultures.

FINDINGS

Sixteen patients were compliant with the neutropenic diet, four of which were admitted for neutropenia with gram-negative rods. No significant differences were found in the rates of febrile admissions or positive blood cultures between compliant and noncompliant patients.

CONCLUSIONS

Clinical significance in this pilot study is related to the time required for diet education, content of diet education regarding food restrictions, and difficulty adhering to diet requirements given the multitude of side effects (e.g., nausea, vomiting, mouth sores, diarrhea) of chemotherapy.

IMPLICATIONS FOR NURSING

No clear evidence exists that the neutropenic diet makes a difference in overall rates of infection. Nursing research to compare the neutropenic diet with a less restrictive food safety education-focused diet is needed to guide clinical practice.

Home care versus hospital care of patients with hematological malignancies and chemotherapy-induced cytopenia

BACKGROUND

The purpose of this review study is to examine the accumulating evidence of safety of home care, with regard to infection-related morbidity and mortality, for patients with chemotherapy-induced cytopenia, in light of previous studies on the necessity of protective isolation (PI).

PATIENTS AND METHODS

The existing literature on PI, and home care of cytopenic patients after chemotherapy, published in the English language, based on a Medline search, is reviewed.

RESULTS

The studies published so far on home care versus hospital care are all non-randomized studies and confirm that home care of cytopenic patients is safe, in terms of morbidity and mortality due to infections. On the other hand, the majority of studies on the comparison of PI with standard hospital care conclude that an infection-preventive effect of PI exists. The pooled statistics performed confirmed that such an effect of PI exists regarding the occurrence of severe infections, although no benefit to mortality has been shown.

CONCLUSIONS

Regarding home care, only the results of a prospective, randomized study of sufficient power will enable definitive conclusions to be drawn as to whether home care is equally safe as hospital-based care with PI.

The neutropenic diet: what's the evidence?

Despite improved survival of children with cancer, opportunistic infections remain a significant cause of morbidity and mortality in this population. Several interventions have been tried to decrease the incidence of infection by reducing patients' exposure to bacteria during neutropenia. The neutropenic diet is one such intervention that was intended to limit the introduction of bacteria into the host's gastrointestinal tract. The only studies evaluating this diet have used this strategy in combination with multiple other interventions, and the independent effect of this diet remains unknown. More research about the neutropenic diet is needed to establish its effectiveness in clinical practice.

Prospective randomized trial of antibiotic prophylaxis in acute leukemia

Patients undergoing initial remission induction chemotherapy for acute leukemia in a protected environment unit were randomly assigned to parenteral antibiotic prophylaxis or oral and parenteral antibiotic prophylaxis. Complete remissions were obtained in 82 percent of the 45 patients receiving oral and parenteral antibiotic prophylaxis and 76 percent of the 41 patients receiving parenteral antibiotic prophylaxis. Approximately 20 percent of the patients in both groups have had a continuous complete remission for more than five years. The episodes of fever of unknown origin and major infection were significantly more common in patients receiving parenteral antibiotic prophylaxis, although the episodes of local infection were similar in both groups. The duration of remission and survival was similar in both groups. Hence, the oral and parenteral antibiotic regimen was more effective for infection prophylaxis, but had no effect on response to antileukemic chemotherapy.

The use of sterile and low microbial diets in ultraisolation environments

The evidence for the use of sterile and low microbial diets in ultraisolation environments is reviewed. Studies have suggested that sterile food is not required for gut sterilization when oral nonabsorbable antibiotics are used, but if a low microbial food contains an antibiotic-resistant organism, colonization can occur. There may be a beneficial effect on the incidence of infection by serving pathogen-free foods, either sterile or low microbial, to the immunosuppressed patient regardless of type of environment, yet the comparative effectiveness of sterile and low microbial diets in preventing introduction of new pathogens accessing the host via the mouth, oropharynx, and esophagus has not been systematically evaluated.

Evaluation of a protective environment in the management of granulocytopenic patients: a comparative study

Fever, clinical infection, bacteriologically documented infection, and death from infection were evaluated in 95 consecutive uninfected patients with severe granulocytopenia (less than 0.5 x 10(6)/liter). Patients were randomly allocated to reverse isolation and prophylactic oral nonabsorbable antibiotics or to open ward care. The microbiologic surveillance of air samples and stool cultures showed reduction of pathogenic organisms in patients treated in protective environment units. There was a statistically significant reduction in the incidence of fever (80% vs. 39.6%; P less than 0.001), clinical infections (55.3% vs. 25%; P less than 0.01), bacteriologically documented infections (53.2% vs. 20.8%; P less than 0.01), and deaths from infections (25.5% vs. 8.3%; P = 0.02) in patients treated in a protective environment as compared with patients treated on the open ward.

Protected environment - prophylactic antibiotic program for malignant sarcomas: randomized trial during remission induction chemotherapy

Fifty-one valuable patients with malignant sarcomas were randomly allocated to receive three courses of remission induction chemotherapy with cyclophosphamide, vincristine, Adriamycin, and dimethyl triazeno imidazole carboxamide (CYVADIC) on the protected environment-prophylactic antibiotic for the control group (P = 0.22). The response rates (complete plus partial) were 71% and 67%, respectively. The durations of response were similar for both groups of patients, but the PEPA patients survived substantially longer (median, 84 weeks vs. 58 weeks). The frequency of infection was significantly lower among the PEPA patients, and the doses of CYVADIC could be escalated more often among these patients. Dosage escalation was associated with a higher complete remission rate and lower fatality rate.

Protected environments in cancer chemotherapy: design and function of a large unit

The construction of a new hospital building permitted the design of a new protected environment unit. The design and operating procedures of this unit are described. Microbiological monitoring has been conducted using air sampling, floor sampling, and settling plates. Microbial contamination is substantially lower in the protected environment unit than in comparable locations elsewhere in the hospital.

Treatment of acute leukemia in protected environment units

Thirty evaluable patients with acute leukemia (AL), aged 14 to 48-year-old received remission induction chemotherapy on a protected environment-prophylactic antibiotic program. Twenty-seven (90%) of these patients achieved complete remission and 17 remained in complete remission for 1 to 22 months. Although these patients spent 36% of their time with neutrophil counts less than 100/mm3, they spent only 20% of their time with fever. Major infection was present during only 7% of the days when neutrophil count was less than 100/mm3. No patient died of an infectious complication during remission induction therapy.

Protected environment-prophylactic antibiotic program for malignant lymphoma. Randomized trial during chemotherapy to induce remission

Fifty-eight patients with malignant lymphoma were randomly allocated to receive three courses of chemotherapy to induce remission with CHOP-Bleo on the protected environment-prophylactic antibiotic (PEPA) program (30 patients) or as controls (28 patients). The complete remission rate for all patients was 74 per cent, for patients with diffuse histiocytic lymphoma 78 per cent and for patients with nodular poorly differentiated lymphocytic lymphoma 65 per cent. There were no significant differences in response rates and duration of responses between those on the PEPA program and control patients. The frequency of infection was significantly lower among the patients on the PEPA program, and dosage escalation of the chemotherapeutic agents was accomplished more often among these patients. Dosage escalation did not increase the complete remission rate, but it did reduce the relapse rate and signficantly reduced the fatality rate. The duration of remission and survival was significantly longer for those patients who received dosage escalation.

A controlled study of the efficacy of granulocyte transfusions in patients with neutropenia

A randomized clinical trial to determine the efficacy of granulocyte transfusions in neutropenic patients with infection was conducted. Criteria for patient selection included a proved infection, a granulocyte count of less than 300/mm3, availability of a suitable donor and failure to respond to at least 72 horus of appropriate antibiotic therapy. Thirty patients were assigned at random to receive either granulocyte transfusions or to serve as a control group. Antibiotic therapy was continued in both groups. Responses were judged by the degree of diminution of infectious episodes and survival. The results showed that 11 of 13 control patients failed to respond during the period of observation, whereas 10 of 17 patients given transfusions responded. The results were statistically significantly different (p less than 0.05). The median survival was 22.5 days in the group given transfusions (group 2) and 7.7 in the control group (group 1) (p less than 0.01). The granulocyte transfusions were most effective in patients with hypocellular marrows who failed to recover during the period of observation. These results indicate that granulocyte transfusions are effective in the short-term control of infections in neutropenic patients.

Successful retransplantation of bone marrow following failure of initial engraftment in a patient with aplastic anemia

Histobompatible sibling bone marrow was transplanted to a patient withsevere aplastic anemia. The first transplant failed, but a second transplantfrom the same donor was successfully performed with a new and more potentimmunosuppressive regimen. Successful retransplantation after marrow graftrejection is now possible.

The use of plastic isolators to prevent infection in neutropenic patients

Over the last 5 years plastic isolators have been used for the prevention of infection in patients with severe neutropenia. Fifteen patients in differing stages of acute myeloid and chronic granulocytic leukaemia were managed in isolators for a total of 110 patient-weeks. The mean duration of isolation for each patient was 7·4 weeks with a range of 2-14 weeks. There was no evidence that any of the isolated patients acquired infection with any exogenous micro-organism. The psychological problems of isolation proved less onerous for the patients than had been anticipated by the medical and nursing staff and no patient had to be removed from isolation for psychiatric reasons. Unfortunately the reduced incidence of clinical infection in the isolated patients was not obviously associated with an increase in effectiveness of their anti-leukaemic treatment.

Early consolidation chemotherapy for adults with acute leukemia in remission

Three courses of intensive consolidation therapy were administered to 13 patients with acute leukemia after they achieved complete remission. The patients were randomly allocated to receive their therapy in or out of a protected environment unit and with or without antibiotic prophylaxis. The results suggest that the protected-environment-prophylactic-antibiotic program may have protected the patients from infection, although the numbers in each group are too small for meaningful comparison. However, early consolidation therapy was not beneficial, since the duration of remission and survival of these patients was less than that of a group of comparable patients who received only conventional maintenance therapy.

Plastic isolators for treatment of acute leukaemia patients under "germ-free" conditions

A gnotobiotic isolation system based on those developed in veterinary research has been constructed for hospital use. Fifteen patients with leukaemia and neutropenia spent a total of 110 weeks in plastic isolators, and none acquired any infection. Endogenous flora was effectively suppressed by topical antiseptics and gastrointestinal decontamination effected with nonabsorbable antibiotics. The isolator system was acceptable to patients and staff and much cheaper than the use of sterile rooms. Other advantages of the system are portability, easy storage, and use on ordinary open wards without prejudice to the microbiological protection afforded. It is as yet uncertain whether protective environments of this type will substantially improve the outcome of treatment for the acute leukaemias.

Infections in cancer patients on a protected environment-prophylactic antibiotic program

A total of 102 studies were conducted on 89 patients receiving cancer chemotherapy while on a protected environment-prophylactic antibiotic program. Major infections occurred during 22 studies. The majority of both minor and major infections originated during the first five weeks after the patients entered the protected environment units. The frequency of infectious complications was inversely related to the circulating neutrophil count. The majority of infections were cases of cellulitis, pharyngitis, pneumonia and septicemia. Most of the infections were caused by gram-negative bacilli. The majority of organisms causing infection had persisted in the patients after their entry into the protected environment units despite the use of prophylactic antibiotics.

Treatment of acute leukemia in adults

Improvement in the management of acute leukemia in adults has not progressed nearly so rapidly as has the treatment of childhood leukemia. One important difference is that most adults have myeloblastic or related forms of the disease (AML), whereas the majority of children have lymphoblastic leukemia (ALL). However, even adults with ALL fail to respond as well to a similar regimen as do children with the same type of leukemia. In a recent series of patients with ALL who were treated with the complex multiple drug "L-2" protocol, the incidence of complete remission in adults was 78% vs. 99% in children, and the median duration of remission was only 24 months in the adults, whereas it has not yet been reached in the children and is projected to be over 4 years. In AML and the related nonlymphoblastic forms of acute leukemia, therapy is still unsatisfactory in both adults and children. With the best current drug treatment schedules, the incidence of complete remission is now better than 50%, but it is often difficult to compare the exact remission rates in different series because of differences in reporting results. In adults treated with the multiple drug "L-6" protocol, the incidence of remission in previously untreated patients was 56% and the median duration of remission was 10 months. The median survival of all patients (responders and non-responders) was 1 year whereas that of responders only was 2 years. It is encouraging that a significant proportion of those patients with AML who have complete remissions now remain in remission for extended periods; about 45% of patients responding to the "L-6" protocol remained in remission over 1 year, and 18% have been in continuous remission for 2 to over 4 years. Even after discontinuing treatment, some patients with AML stay in remission for long periods, and it is possible that some of them may have been cured. If this proves to be true, it becomes of great importance to determine what is different about the patients who do exceptionally well as compared to the majority who continue to die within a year. However, no consistent nor distinctive favorable prognostic features have yet been identified.

Oropharyngeal cultures of patients in protected environment units: evaluation of semiquantitative technique during antibiotic prophylaxis

A semiquantitative culture technique was used to monitor the microbial flora of the oropharynx of 30 patients receiving antibiotic prophylaxis in protected environment units. After institution of antibiotic prophylaxis, the median concentration of organisms in the oropharynx fell by 2 logs but gradually increased by 1 log and then remained stable. Neisseria spp., Micrococcus sp., and Streptococci were generally eradicated by the antibiotics but were replaced by Lactobacilli and yeast. Four of nine enteric organisms persisted despite in vitro sensitivity to the antibiotic regimens. Yeast were cultured from the initial specimens of only 17% of the 30 patients, but they were cultured subsequently from specimens of 80% of the 20 patients who remained in protected environment units for at least 8 weeks.

Oral antibiotic prophylaxis in protected environment units: effect of nonabsorbable and absorbable antibiotics on the fecal flora

Eight patients in protected environment units received by the oral route a solution of gentamicin and vancomycin which completely suppressed all 78 strains of bacteria originally present in their stools. However, when the solution was discontinued bacteria were cultured again from the stools of every patient. Twenty-nine of the 42 strains cultured at this time were also cultured from pretreatment specimens. Oral absorbable antibiotics were given to six of these patients, but they eliminated only 10 of the 32 strains cultured from their stools. Seven of the 16 strains which persisted became resistant to the oral absorbable antibiotic. To achieve maximum effect, oral nonabsorbable antibiotic regimens must be continued as long as the patient remains in a protected environment unit.

Microbiological evaluation of protected environments during patient occupancy

Microbiological monitoring has been conducted in two life island (LI) units and two laminar airflow (LAF) rooms while they were occupied by patients undergoing cancer chemotherapy. There were only 5 organisms per 1,000 ft(3) of air sampled in LAF rooms, 31 organisms in LI units, and over 3,000 organisms in regular hospital rooms. None of the floor samples obtained from hospital rooms was sterile, compared to over 70% in LAF rooms. The rate of deposition of organisms onto settling plates was one organism per 4.5 hr in LAF rooms compared to one organism per 0.08 hr in hospital rooms. Potential pathogens were isolated much more frequently from environmental samples obtained from hospital rooms than from LI units or LAF rooms. Two sites of persistent contamination arose in the LAF rooms: the vinyl tile flooring and the water supply system. Over half of the potential pathogens cultured from the protected environment units were cultured initially from the patients who occupied the units.

Semiquantitative oropharyngeal culture technique

A semiquantitative method for determining the concentration of organisms constituting the normal oropharyngeal flora has been developed. Eleven species of organisms were isolated from the 18 subjects studied. The concentration of organisms in multiple samples, taken at 5-min intervals, was quite similar. The concentration of organisms increased slightly at the end of the day. Obtaining specimens on different days of the week did not appreciably affect the concentration or kinds of organisms. Eating had only a minimal effect on the oropharyngeal flora, but brushing teeth reduced the concentration of organisms substantially. When specimens were obtained 6 months after the initial specimens, the concentration of organisms remained the same but the species of organisms isolated varied considerably. The gargle method was compared to a swab method and proved to be superior. This method of obtaining oropharyngeal culture specimens is reliable and useful as a means of monitoring the normal oropharyngeal flora.