Biomedical subjects
Publications and source records attributed to F S Rhame.
Peripheral blood mononuclear cells from 142 consecutive patients with antibodies to human immunodeficiency virus type 1 (HIV-1) were cultured for HIV-1. All 72 patients with symptoms of HIV-1 infection were culture positive, as were 69 of 70 asymptomatic patients. Of the 142 patients, 132 (93%) were culture positive within 10 days after initiation of the culture.
The correlation of fecal gram-negative bacilli (GNB), neutropenia, and bacteremia was studied in 45 bone marrow transplant recipients. Weekly stool cultures were prospectively monitored for GNB resistant to routine prophylactic and empiric antimicrobial agents. Seven cases of GNB bacteremia occurred in 45 patients described as follows. Twenty-three patients had no fecal or blood GNB. Fifteen patients had fecal GNB and no blood GNB; three of these latter patients had less than or equal to 50/mm3 circulating white blood cells (WBC) at the time of isolation of fecal GNB but two of the three were concurrently receiving appropriate empiric antibiotics. Two patients had blood GNB but no fecal GNB: one patient had a trimethoprim/sulfamethoxazole (TMP-SMZ)-sensitive isolate that would not be detectable in the feces by our methodology and one patient had feces analyzed only after the bacteremic event. Five patients had fecal GNB and blood GNB: one of these patients did not have a fecal sample analyzed prior to bacteremia but the remaining four patients had the same species/antibiogram of GNB isolated from the feces two to three days prior to the detection of bacteremia. Thus, the fecal GNB could have been used to predict the antibiogram of the subsequent blood GNB. In addition, all four of these latter bacteremic patients had less than or equal to 50/mm3 circulating WBC at the time of documented fecal GNB. Thus, bone marrow transplant recipients with fecal GNB coupled with severe neutropenia (less than or equal to 50/mm3 circulating WBC) were more likely to develop bacteremia (P less than 0.02) than were those with fecal GNB and greater than 50/mm3 circulating WBC.
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Between 16 July and 1 October 1984, prospectively monitored corridor air samples from a bone marrow transplant station revealed a marked increase in airborne thermotolerant Penicillium spores. Simultaneous cultures of outside air showed lower spore counts, which were unchanged before, during, and after the corridor outburst, establishing that the source was within the hospital. Although the corridor was equipped with recirculating high-efficiency particulate air filtration units which provided 16 air changes per h, the mean corridor air count rose to 64.4 thermotolerant Penicillium CFU/m3 during the outburst period. The in-hospital source was ultimately traced to rotting cabinet wood enclosing a sink with leaking pipes in the medication room. It produced approximately 5.5 X 10(5) thermotolerant Penicillium CFU/h. In a patient room supplied by corridor air, an in-room recirculating high-efficiency particulate air filter reduced the mean thermotolerant Penicillium count to 2.2 CFU/m3. No patient illness or colonization occurred as a result of this event, although the cabinet wood, after sterilization, was shown to sustain abundant growth of Aspergillus fumigatus and Aspergillus flavus. Wet organic substrates should be avoided in hospital areas with immunosuppressed patients.
It is widely held that bubbling humidifiers do not produce microaerosols, although prior studies have resulted in conflicting evidence. We have studied this phenomenon in a clean room using an airborne particle counter and samplers for airborne bacteria. At gas flow rates between 10 and 80 L/min, a Cascade 1 humidifier produced between 460 and 999 water droplets/L humidified gas. Total water volume aerosolized was approximately 10(-8) ml/L humidified gas. Seventy-three percent of the particles had diameters between 1 and 5 microns. With the reservoir containing 6.4 X 10(6) P. aeruginosa/ml, it produced between 2 and 9 P. aeruginosa/L humidified gas. Most of the bacteria were in particles of a size likely to be deposited in the lung. This bacterial carry-over was between 20 and 150 times the amount predicted by multiplication of the water volume aerosolized times the concentration of bacteria in the humidifier reservoir. An Air Life humidifier produced fewer particles which were also of a size likely to be deposited in the lung and, when the reservoir contained P. aeruginosa, it aerosolized bacteria. Wick-type humidifiers did not produce detectable aerosol or bacterial carry-over. Although the clinical significance of these findings has not been established, they provide a rationale for the CDC recommendations for procedures designed to keep bubbling humidifier reservoir water uncontaminated.
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The authors describe a rare complication of whiplash injury. Diffuse mediastinitis resulted from extension of a whiplash-induced retropharyngeal abscess into the thorax. Early diagnosis of the cervical infection was masked by the simultaneous presence of infectious mononucleosis. Aggressive surgical management including bilateral thoracotomy was required to resolve the septic course. A review of the literature discusses the pathogenesis of this complication including the route of extension into the mediastinum and supports the use of aggressive surgical therapy to reduce the associated mortality.
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Most nosocomial pathogens cause pneumonia through the following sequence: transit to the patient on the hands of medical personnel or perhaps in food, proliferation in the nasopharynx, and subsequent pulmonary aspiration. There are three exceptional pathogens, each of particular concern as a cause of pneumonia in the immunocompromised patient, which follow atypical routes. Important recent advances in understanding these routes permit more rational preventive measures. This report examines the evidentiary basis for the following pathophysiolgic propositions about these three pathogens: Aspergillus, Pneumocystis carinii, and Legionella. Aspergillus spores are almost ubiquitous. Spore generation, except in very unusual circumstances, takes place outside the hospital. Most spores enter the hospital borne in air by infiltration or because of incomplete filtration. Air filtration systems of moderate efficiency remove Aspergillus spores. Nosocomial pulmonary and disseminated aspergillosis arises from inhalation of airborne spores. A nasopharygeal colonization intermediate step before pulmonary disease has not yet been solidly established. It is now firmly established that airborne Pneumocystic carinii transmission occurs between animals. Airborne acquisition probably occurs early in human life. However, in-hospital, person-to-person transmission has yet to be convincingly demonstrated. Most or all cases of pneumocystosis in adults are due to reactivation of endogenous pulmonary organisms. Intensive diagnostic efforts reveal that Legionella is a common cause of community-acquired and nosocomial pneumonia in hospitals where it had not previously been recognized. However, there are at least a few hospitals where it is an uncommon source of pneumonia. Several hospitals have demonstrated a temporal association between the presence of Legionella in hot water systems and nosocomial cases of Legionella pneumonia. The mechanism or mechanisms of transmission to the patient remain to be delineated. It is also not determined if all hospital hot water systems should be maintained Legionella free.
There have been no documented cases of acquired immunodeficiency syndrome (AIDS) in personnel after a prospectively recognized in-hospital blood exposure. To assess the frequency of such exposure the membership of the Association for Practitioners in Infection Control was surveyed in early June 1983. Thirty-three percent of the membership responded, accounting for 42% of U.S. hospitals with more than 250 beds. Respondents reported needlestick or other significant blood exposures to blood from patients with AIDS occurring in 157 instances and to blood from patients with lymphadenopathy syndrome in 43 instances. Nineteen and twenty of the exposures, respectively, occurred before July 1982. There are two bases for believing that AIDS will not pose a substantial risk to hospital workers: the lack of demonstrated in-hospital AIDS transmission to date and the recognition that other viruses besides the hepatitis B virus--viruses that seem to have less potential for in-hospital transmission--are equally plausible models of AIDS transmission.
Of 114 recipients of pancreatic, renal, and bone marrow transplants who were given trimethoprim-sulfamethoxazole (TMP-SMZ) for antimicrobial prophylaxis, 44 (39%) had a total of 52 fecal isolates of TMP-SMZ-resistant gram-negative bacilli. In most of these 44 patients, the resistant isolate was found at a concentration of greater than or equal to 10(6) organisms/ml of feces. Escherichia coli was the most frequent of the isolates, and Citrobacter freundii was the next most frequent. Eight of the 114 transplant recipients had gram-negative bacteremia; in six of these eight patients, a TMP-SMZ-resistant gram-negative bacillus was the etiologic agent of bacteremia. Four of the latter six patients had stool cultures analyzed prior to the detection of bacteremia; all four had high concentrations (greater than or equal to 10(8)/ml) of fecal TMP-SMZ-resistant E. coli one to 20 days before they were found to have E. coli bacteremia. In each of these instances, the E. coli isolates from the stool and the blood had similar antibiograms. These findings indicated that resistance to TMP-SMZ is becoming more prevalent and that the screening of patients for the presence of fecal TMP-SMZ-resistant Enterobacteriaceae prior to initiation of long-term therapy with this antimicrobial agent may be worthwhile.
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During a community epidemic of influenza B, surveillance throat cultures for influenza were collected from febrile adult patients and hospital employees on three medical wards to determine the frequency and source of influenza among hospitalized patients. Twenty-five cases of influenza B (18.5% of febrile patients) were identified; no clusters of influenza-like illness occurred. The attack rate on two wards was 4.6%. Peak hospital influenza incidence followed that in the community by 1-2 weeks. Twelve of the cases were community-acquired and 13 were nosocomial. 75% of community-acquired cases had three or more common influenza B symptoms, compared with only 39% of nosocomial cases. A viral etiology of fever was suspected clinically in one-half of the cases, but influenza was specifically suspected in only one case. Two ill culture-positive nurses were identified on the job but no asymptomatic carriers were found among ward personnel. We conclude that influenza B cases were present among hospitalized patients in the absence of recognizable clusters of disease and that patients with community-acquired illness as well as nursing personnel may have introduced influenza into the hospital. Influenza B may be difficult to diagnose clinically in hospitalized patients, but viral throat cultures performed in all suspected cases should identify many infected patients.
On 13 September 1981, a 51-year-old seven-story building within our hospital complex was demolished by explosives. The concern that this event might release large numbers of thermotolerant fungi (TF), potentially hazardous to immunosuppressed patients, led us to seal hospital windows and doors. The air-handling systems were also manipulated. Concentrations of airborne TF, especially Aspergillus fumigatus, were determined before and after demolition, using Andersen and Cassella air samplers with inhibitory mold agar plates. Two outdoor and two hospital ward locations were sampled. The plates were incubated at 37 degrees C; the CFU per cubic meter were counted at 72 h. The outdoor concentration of TF increased at one site by an average of 1.8 log10 (10(2) to 10(5] over the predemolition level. A. fumigatus increased 3.3 log10 (10(0) to 10(4] at the other outdoor site. The indoor TF concentrations increased about 1 log10 (10(1) to 10(2] after demolition. Counts on the hospital wards were not remarkable when compared with previous surveillance air sampling. Protective measures apparently minimized the infiltration of TF during explosive demolition.
Four cases of Aspergillus osteomyelitis are presented and the world literature is reviewed, for a total of 19 cases. Aspergillus osteomyelitis is largely a disease of immunosuppressed hosts, although wound and other infections in "normal" hosts are seen. In children, contiguous spread from an adjacent pulmonary infection is most common, whereas in adults hematogenous spread is the rule. The survival rate in immunocompromised patients is poor, whereas the cure rate is uniform in "normal" hosts. A combined medical-surgical therapeutic approach has been used most often and seems appropriate.
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