Anesthesia-associated carbon monoxide exposures among surgical patients.

OBJECTIVE: To estimate the extent of, and evaluate risk factors for, elevated carboxyhemoglobin levels among patients undergoing general anesthesia and to identify the source of carbon monoxide. DESIGN: Matched case-control study to measure carboxyhemoglobin levels. SETTING: Large academic medical center. PARTICIPANTS: 45 surgical patients who underwent general anesthesia RESULTS: Case-patients were more likely than controls to undergo surgery on Monday or Tuesday (10/15 vs 7/30; matched odds ratio [mOR], 7.7; 95% confidence interval [CI95], 1.8-34; P=.01), in one particular room (7/15 vs 4/30; mOR, 8.5; CI95, 1.5-48; P=.03) or in a room that was idle for > or =24 hours (11/15 vs 1/30; mOR, 95.5; CI95, 8.0-1,138; P< or =.001). In a multivariate model, only rooms, and hence the anesthesia equipment, that were idle for > or =24 hours were independently associated with elevated intraoperative carboxyhemoglobin levels (OR, 22.4; CI95, 1.5-338; P=.025). Moreover, peak carboxyhemoglobin levels were correlated with the length of time that the room was idle (r=0.7; CI95, 0.3-0.9). Carbon monoxide was detected in the anesthesia machine outflow during one case-procedure. No contamination of anesthesia gas supplies or CO2 absorbents was found. CONCLUSIONS: Carbon monoxide may accumulate in anesthesia circuits left idle for > or =24 hours as a result of a chemical interaction between CO2-absorbent granules and anesthetic gases. Patients administered anesthesia through such circuits may be at increased risk for elevated carboxyhemoglobin levels during surgery or the early postoperative period.

Giardia lamblia and Cryptosporidium infections in child day-care centers in Fulton County, Georgia.

Risk factors for the introduction, spread and persistence of Cryptosporidium and Giardia lamblia infections in child day-care centers are not well understood. In 1989 and 1990 stool specimens were obtained from 292 diapered children attending 17 randomly selected day-care centers in Fulton County, GA; 8 (2.7%) children in 2 centers were infected with Cryptosporidium and 21 (7.2%) children in 7 centers were infected with Giardia. In 1986 the prevalence of Cryptosporidium and Giardia in these same centers had been 0.4 and 11.0%, respectively; the prevalence of Cryptosporidium, but not Giardia, increased significantly (P = 0.04) between 1986 and 1989 to 1990. Risk factors for Giardia infection included day-care attendance for greater than 3 months, the presence of toddlers in the classroom and the presence of other children in the household. Day-care centers with a Giardia-positive child in 1986 were not more likely to have an infected child in 1989 to 1990. Cryptosporidium, like Giardia, may be endemic in day-care centers in Fulton County.

Use of pooled formalin-preserved fecal specimens to detect Giardia lamblia.

Three formalin-preserved fecal specimens from the same child attending a child-care center were pooled and compared with the three separate individual specimens by a single microscopic examination of concentration sediment for Giardia lamblia. The sensitivity of the pooled system was 100% when two or more individual specimens were positive and 88% when only one individual specimen was positive. The organism density in a single specimen was not a factor of whether the pool of specimens was positive or negative. Nearly half of the pools that contained positive specimens had only one of three specimens with positive results, reinforcing the need for multiple stool examinations when diagnosing G. lamblia infections.

Evaluation of a commercially available enzyme-linked immunosorbent assay for Giardia lamblia antigen in stool.

The lack of a quick, simple, and inexpensive diagnostic test has limited the ability of public health officials to rapidly assess and control outbreaks of Giardia lamblia in child day-care centers. We evaluated the performance of a commercially available enzyme-linked immunosorbent assay (ELISA) for the detection of a G. lamblia-associated antigen in stool. Stool specimens were collected from the diapers of 426 children attending 20 day-care centers, fixed in 10% Formalin and polyvinyl alcohol, and examined by microscopy by Formalin concentration and trichrome staining techniques. Specimens were also tested visually and spectrophotometrically by ELISA. Of 99 tests positive by microscopy, 93 were visually positive by ELISA (sensitivity, 93.9%). Of 534 tests negative for G. lamblia by microscopy, 32 (6.0%) were ELISA positive. However, on the basis of examination of multiple specimens from the same child, none of these could be considered false-positive ELISAs; the specificity of the ELISA was therefore 100%. The sensitivity of both microscopy and ELISA improved as the number of specimens per child increased. An optical density value of greater than 0.040 was 98.0% sensitive and 100% specific for G. lamblia. This ELISA, which appeared to be more sensitive for G. lamblia than did microscopic examination of stool, should be useful as an epidemiologic tool, particularly in day-care settings, and may also have a role in confirming clinical diagnoses of giardiasis.

An evaluation of the use of medical examiner data for epidemiologic surveillance.

To assess the value of medical examiner (ME) data bases for use in epidemiologic surveillance, we compared data from non-injury deaths that became ME cases to all non-injury deaths occurring in 1984 among Fulton County, Georgia residents. The decedents in the ME series were younger and included a large proportion of Black males. Although not representative of all deaths in a community, ME data bases include demographic and medical information that is often difficult to collect in community studies and in other surveillance systems.

Epidemic keratoconjunctivitis: report of an outbreak in an ophthalmology practice and recommendations for prevention.

In Fall 1981, an outbreak of acute infectious conjunctivitis with keratitis (EKC) occurred in patients who had visited a private ophthalmology clinic just prior to onset of illness. Among an estimated 2,200 patient visits to the office from August 10 to October 15, 1981 for problems unrelated to infectious conjunctivitis, 39 (1.8%) persons subsequently developed EKC. The median incubation period was 6.5 days (range, 1 to 14 days). A case-control study was done to identify risk factors associated with contracting EKC; patients with EKC were more likely than control patients to have been examined by one or the other of two of the four ophthalmologists at the clinic and to have undergone procedures such as tonometry or foreign body removal. Adenovirus was isolated from conjunctival swabs from four of five persons with conjunctivitis; three were type 8 and one was type 7. Recognition of the problem and improved handwashing practices were associated with terminating the outbreak. This outbreak illustrates the potential for transmission of adenovirus infection during the provision of eye care. Infection control practitioners should be familiar with measures for the prevention of such infections among ophthalmology patients.

Epidemiologic analysis of a cluster of homicides of children in Atlanta.

Between July 1, 1979, and March 15, 1981, there were 22 unsolved homicides and two unsolved disappearances of Atlanta children. Using epidemiologic methods, we attempted to identify factors that had put children at an increased risk of homicide. That all victims in this cluster were black, killed away from home, and that asphyxiation was overrepresented suggests that the cluster was discrete. The cluster was not homogeneous in relation to location of the victim's area of residence or location of the body; however, the median distance of 9.3 miles from home to body suggests that in some cases a motor vehicle was involved. A neighborhood-based study of the male victims and age- and sex-matched controls showed that victims more often ran errands for money (relative risk, 7.9) and were more often alone on the streets or in shopping centers; therefore, they may have been more approachable than other children in the neighborhood.

A cluster of cases of Mycobacterium chelonei keratitis associated with outpatient office procedures.

We studied three cases of keratitis caused by Mycobacterium chelonei, a nontuberculous mycobacterial species. The cases occurred in two women, 76 and 80 years old, and one man, 67 years old, treated as outpatients in the same office. One case followed suture removal and the other two occurred after posterior capsulotomy. Corneal lesions appeared within two to three weeks of trauma and were white, round infiltrates with indistinct margins and radiating projections. The lesions were found at all levels of the stroma and were associated with an epithelial defect. Anterior chamber reaction varied from a minimal response to a hypopyon. One patient responded to topical therapy with amikacin and erythromycin, but the other two patients required penetrating keratoplasties because of deep abscesses, which progressed toward the sclera despite therapy. These cases emphasized the possibility of rapidly growing nontuberculous mycobacteria producing serious ocular infections.

Nosocomial hepatitis A transmission by an adult patient with diarrhea.

Hepatitis A occurred in five registered nurses, a licensed practical nurse, and a recently discharged patient at a community hospital; one of these seven was asymptomatic. All had been exposed to a woman with confirmed hepatitis A who had undergone elective cholecystectomy and who had had vomiting, diarrhea, and fecal incontinence during the eight days before onset of jaundice. Of the 107 hospital workers identified as having at least some exposure to the source patient, 58 (54.2 percent) had no pre-existing antibody to hepatitis A virus (anti-HAV) and were considered susceptible. Six persons, including the five clinically ill registered nurses, had IgM-specific anti-HAV. The infection attack rate was 5.6 percent for all exposed hospital workers but 10.3 percent for the 58 who were serosusceptible. Risk of infection was highest for persons with documented or probable contact with the source patient and for registered nurses. Among hospital personnel, the prevalence of anti-HAV increased with age but varied inversely with socioeconomic status. Hospital personnel and patients may be at risk for hepatitis A infection when exposed to patients who are in the prodromal stage of hepatitis A. Vomiting, diarrhea, and fecal incontinence may increase the risk of transmission.