Roger L. Anderson

Toxic-shock syndrome in menstruating women. Association with tampon use and Staphylococcus aureus and clinical features in 52 cases.

To determine the risk factors associated with toxic-shock syndrome (TSS) in menstruating women, we conducted a retrospective telephone study of 52 cases and 52 age-matched and sex-matched controls. Fifty-two cases and 44 controls used tampons (P < 0.02). Moreover, in case-control pairs in which both women used tampons, cases were more likely than controls to use tampons throughout menstruation (42 of 44 vs. 34 of 44, respectively; P < 0.05). There were no significant differences in brand of tampon used, degree of absorbency specified on label, frequency of tampon change, type of contraceptive used, frequency of sexual intercourse, or sexual intercourse during menstruation. Fourteen of 44 cases had one or more definite or probable recurrences during a subsequent menstrual period. In a separate study, Staphylococcus aureus was isolated from 62 of 64 women with TSS and from seven of 71 vaginal cultures obtained from healthy controls (P < 0.001).

Nosocomial respiratory tract infection and colonization with Acinetobacter calcoaceticus. Epidemiologic characteristics.

Nosocomial respiratory tract infection with Acinetobacter calcoaceticus occurs frequently in many hospitals. An outbreak of respiratory tract infections in an intensive care unit provided an opportunity to study clinical and epidemiologic characteristics of such infections. Retrospective studies demonstrated that A. calcoaceticus in sputum was significantly associated with endotracheal intubation (p = 0.03) and continuous positive pressure ventilation (p less than 0.02). After control measures had interrupted the outbreak, a prospective microbiologic investigation demonstrated that one third of the hospital personnel had transient hand colonization with multiple strains of A. calcoaceticus. Pharyngeal, vaginal and rectal carriage was rare. A pulmonary therapist with chronic dermatitis had persistent hand colonization with the epidemic strain, and he contaminated respiratory therapy equipment. Cross contamination of respiratory therapy equipment occurred while in use, but no other inanimate reservoir was demonstrated. Although previous studies have implied that the inanimate hospital environment has unique reservoirs of A. calcoaceticus, these reservoirs were not implicated in this outbreak. Human skin must be considered an important reservoir of A. calcoaceticus.

Indwelling arterial catheters as a source of nosocomial bacteremia. An outbreak caused by Flavobacterium Species.

Between mid-May and mid-October, 1973, 49 blood cultures from 14 patients in an intensive care unit were positive for flavobacterium species, Group II-b. We conducted an investigation to determine how patients were being infected with this unusual organism. Comparison of the 14 infected patients with 37 controls associated indwelling arterial catheters with subsequent flavobacterium bacteremia (p = 0.005). Risk of infection was greatest during the period in which blood gas determinations were done most frequently (the first three days of catheterization) and in which infected patients had more blood gas determinations than control patients with arterial catheters (p less than 0.05). Flavobacterium species was cultured from in-use arterial catheters, from stopcocks, and from ice in the intensive-care units ice machine; the catheters were probably contaminated by syringes that were cooled in ice before being used to obtain arterial specimens for blood gas determination. This outbreak calls attention to arterial monitoring systems as a potential source of nosocomial infection.

Nosocomial fungemia in neonates associated with intravascular pressure-monitoring devices

In the period from January, 1982, to March, 1983, eight infants in the neonatal intensive care unit at one hospital had blood cultures positive for Candida parapsilosis; six cases had occurred after December, 1982. Epidemiologic investigation included a case-control study comparing the 8 cases with 29 birth weight-matched controls. Logistic regression analysis indicated that the model that best fit the observed data included the following risk factors for fungemia: duration of umbilical artery catheterization; duration of receipt of parenteral nutrition; and estimated gestational age. Parenteral nutrition therapy was often administered through the umbilical artery catheters, which were also used for monitoring arterial pressure; transducer domes thus contained parenteral nutrition fluid. Transducers were usually disinfected with alcohol. Laboratory investigation showed that the heads of 6 of 11 in-use blood pressure transducers and 1 of 4 transducers in storage after cleaning were culture-positive for C. parapsilosis. After control measures were instituted no further cases occurred.

Epidemic neonatal gentamicin-methicillin-resistant Staphylococcus aureus infection associated with nonspecific topical use of genetamicin

One hundred sixteen infants in an intensive care nursery acquired Staphylococcus aureus resistant to gentamicin and methicillin; 54 patients acquired S. aureus sensitive to gentamicin and methicillin. Topical application of gentamicin ointment was significantly associated with acquisition of GMRS. Of 78 infants who acquired GMRS, 38 had received GmO before GMRS was first cultured, whereas only one of 49 infants with GMSS had previously received GmO (P = 8.6 X 10(-8)). Infants with GMRS were also more likely than patients with GMSS to have had a lower mean birth weight, Apgar score, and gestational age; systemic antibiotic therapy and incubator care were significantly prolonged for patients with GMRS, but these factors did not explain susceptibility to GMRS infection. Multivariate logistic regression analysis showed that use of GmO was the single most important risk factor.

Nosocomial Bacteriuria: A Prospective Study of Case Clustering and Antimicrobial Resistance

To investigate the role of cross-infection in nonepidemic nosocomial bacteriuria in a large, university-affiliated hospital, we identified in adult patients admitted over an 11-week period all cases caused by organisms of the same genus, species, and antimicrobial susceptibility and clustered by date of onset and hospital ward. Further laboratory studies were conducted to verify clustering. Among the 3452 patients studied, 194 cases of nosocomial bacteriuria were identified; 49 appeared clustered by epidemiologic evidence. Additional laboratory tests verified clustering in 30 cases (15.5%). We found that 90% of clustered and 76% of nonclustered cases had had previous urinary catheterization; Pseudomonas aeruginosa, Serratia marcescens, and Citrobacter freundii often caused clustered infection while Escherichia coli predominated in nonclustered cases; and resistance to gentamicin, sulfathiazole, and carbenicillin was significantly greater for pathogens from clustered cases than for nonclustered ones. This increased resistance emphasizes the need to prevent cross-infection, even in the absence of epidemics.

Vaginal Colonization with Staphylococcus aureus in Healthy Women: A Review of Four Studies

Four studies assessed the frequency of vaginal Staphylococcus aureus colonization in healthy women and associated risk factors. An association was found between S. aureus vaginal colonization and colonization at the labia minora and the anterior nares. Significant risk factors associated with an increased risk of vaginal S. aureus in at least one study were a history of genital herpes simplex infection, insertion of tampons without an applicator, and the use of Rely (Procter & Gamble) tampons. The use of systemic antibiotics within 2 weeks of the vaginal culture decreased the risk of recovery of S. aureus. The overall frequency of vaginal S. aureus in the 808 women in the four studies was 9.2%.

Gram-negative bacteremia in open-heart-surgery patients traced to probable tap-water contamination of pressure-monitoring equipment.

OBJECTIVE To determine the cause(s) of an outbreak of gram-negative bacteremia (GNB) in open-heart-surgery (OHS) patients at hospital A. DESIGN Case-control and cohort studies and an environmental survey. RESULTS Nine patients developed GNB with Enterobacter cloacae (6), Pseudomonas aeruginosa (5), Klebsiella pneumoniae (3), Serratia marcescens (2), or Klebsiella oxytoca (1) following OHS; five of nine patients had polymicrobial bacteremia. When the GNB patients were compared with randomly selected OHS patients, having had the first procedure of the day (8 of 9 versus 12 of 27, P = .02), longer cardiopulmonary bypass (median, 122 versus 83 minutes, P = .01) or cross-clamp times (median, 75 versus 42 minutes, P = .008), intraoperative dopamine infusion (9 of 9 versus 15 of 27, P = .01), or exposure to scrub nurse 6 (6 of 9 versus 4 of 27, P = .001) were identified as risk factors. When stratified by length of the procedure, only being the first procedure of the day and exposure to scrub nurse 6 remained significant. First procedures used pressure-monitoring equipment that was assembled before surgery and left open and uncovered overnight in the operating room, whereas other procedures used pressure-monitoring equipment assembled immediately before the procedure. At night, operating rooms were cleaned by maintenance personnel who used a disinfectant-water solution sprayed through a hose connected to an automatic diluting system. Observation of the use of this hose documented that this solution could have contacted and entered uncovered pressure-monitoring equipment left in the operating room. Water samples from the hose revealed no disinfectant, but grew P aeruginosa. The outbreak was terminated by setting up pressure-monitoring equipment immediately before the procedure and discontinuing use of the hose-disinfectant system. CONCLUSIONS This outbreak most likely resulted from contamination of uncovered preassembled pressure-monitoring equipment by water from a malfunctioning spray disinfectant device. Pressure-monitoring equipment should be assembled immediately before use and protected from possible environmental contamination.

Epidemic gram-negative bacteremia in a neonatal intensive care unit in Guatemala.

BACKGROUND Nosocomial bloodstream infection is an important cause of morbidity and mortality among neonates. From September 1 through December 5, 1990 (epidemic period), gram-negative bacteremia developed in 26 neonates after their admission to the neonatal intensive care unit (NICU) of Hospital General, a 1000-bed public teaching hospital in Guatemala with a 16-bed NICU. Twenty-three of the 26 patients (88%) died. METHODS To determine risk factors for and modes of transmission of gram-negative bacteremia in the NICU, we conducted a cohort study of NICU patients who had at least one blood culture drawn at least 24 hours after admission to the NICU and performed a microbiologic investigation in the NICU. RESULTS The rate of gram-negative bacteremia was significantly higher among patients born at Hospital General, delivered by cesarian section, and exposed to selected intravenous medications and invasive procedures in the NICU during the 3 days before the referent blood culture was obtained. During the epidemic period, the hospitals chlorinated well-water system malfunctioned; chlorine levels were undetectable and tap water samples contained elevated microbial levels, including total and fecal coliform bacteria. Serratia marcescens was identified in 81% of case-patient blood cultures (13/16) available for testing and from 57% of NICU personnel handwashings (4/7). Most S. marcescens blood isolates were serotype O3:H12 (46%) or O14:H12 (31%) and were resistant to ampicillin (100%) and gentamicin (77%), the antimicrobials used routinely in the NICU. CONCLUSIONS We hypothesize that gram-negative bacteremia occurred after invasive procedures were performed on neonates whose skin became colonized through bathing or from hands of NICU personnel.

Pseudomonas cepacia Peritonitis Associated with Contamination of Automatic Peritoneal Dialysis Machines

During a 3-month period, Pseudomonas cepacia was recovered from the peritoneal fluid of 10 patients having chronic dialysis therapy at a peritoneal dialysis center. Six patients developed clinical evidence of peritonitis; one patient developed septicemia. Epidemiologic studies showed that dialysis on specific peritoneal dialysis machines was associated with an increased risk of infection. Laboratory investigation showed contamination of two machines with P. cepacia. Inadequacies in the cleaning and disinfection practices of the automatic peritoneal dialysis machines were identified. Cross-contamination between machines probably occurred through the peritoneal fluid discharge from infected patients during dialysis. Also, the intermittent 2-hour exposure of the machine to 2% formaldehyde may have been inadequate. P. cepacia has not been isolated from the peritoneal fluid of any peritoneal dialysis patient after machine cleaning and disinfection practices were altered.