To determine the cause of acute illness on August 30, 2000, among patients at an outpatient dialysis center (center A).

We performed a cohort study of all patients receiving dialysis on August 30, 2000; reviewed dialysis procedures; and analyzed dialysis water samples using microbiologic and chemical assays.

Dialysis center (center A).

A case-patient was defined as a patient who developed chills within 5 hours after starting hemodialysis at center A on August 30, 2000.

Sixteen (36%) of 44 patients at center A met the case definition. All case-patients were hospitalized; 2 died. Besides chills, 15 (94%) of the case-patients experienced nausea; 12 (75%), vomiting; and 4 (25%), fever. Illness was more frequent on the second than the first dialysis shift (16 of 20 vs 0 of 24, P < .001); no other risk factors were identified. The center's water treatment system had received inadequate maintenance and disinfection and a sulfurous odor was noted during sampling of the water from the reverse osmosis (RO) unit. The water had elevated bacterial counts. Volatile sulfur-containing compounds (ie, methanethiol, carbon disulfide, dimethyldisulfide, and sulfur dioxide) were detected by gas chromatography and mass spectrometry in 8 of 12 water samples from the RO unit and in 0 of 28 samples from other areas (P < .001). Results of tests for heavy metals and chloramines were within normal limits.

Parenteral exposure to volatile sulfur-containing compounds, produced under anaerobic conditions in the RO unit, could have caused the outbreak. This investigation demonstrates the importance of appropriate disinfection and maintenance of water treatment systems in hemodialysis centers.

It remains unclear whether a follow-up blood culture (FUBC) for gram-negative bacilli (GNB) bacteremia should be routinely or selectively performed. To evaluate the value of the practice, we analyzed the association between current FUBC practices and length of stay, antibiotic treatment duration, and in-hospital mortality.

Retrospective cohort study.

The study was conducted in 4 acute-care hospitals in New York City.

The study included hospitalized adults with GNB bacteremia between 2017 and 2018.

An FUBC was defined as a blood culture performed between 24 hours and 7 days after an initial blood culture positive for GNB. Using propensity scores for FUBCs performed, patients were matched 1:1 for outcome comparison.

In total, 376 hospitalized adults with GNB bacteremia met eligibility criteria. Among them, FUBCs were performed in 271 patients (72%). After propensity score matching, we analyzed 87 pairs of patients with and without an FUBC to compare outcomes. The median length of stay was longer among patients with FUBCs than patients without FUBCs (9 days vs 7 days; P = .017). The median duration of antibiotic treatment was also longer among patients with FUBCs than patients without FUBCs (8 vs 6 days; P = .007). No statistically significant difference was observed in in-hospital mortality between patients with and without an FUBC (odds ratio, 0.37; 95% confidence interval, 0.08–1.36).

Current FUBC practices for GNB bacteremia were associated with prolonged length of stay and duration of antibiotic treatment. Further data to better inform selectivity criteria for FUBCs in GNB bacteremia are needed.

To compare practice patterns regarding the diagnosis and management of streptococcal pharyngitis across pediatric primary care practices.

Retrospective cohort study.

All encounters to 25 pediatric primary care practices sharing an electronic health record.

Streptococcal pharyngitis was defined by an International Classification of Diseases, Ninth Revision code for acute pharyngitis, positive laboratory test, antibiotic prescription, and absence of an alternative bacterial infection. Logistic regression models standardizing for patient-level characteristics were used to compare diagnosis, testing, and broad-spectrum antibiotic treatment for children with pharyngitis across practices. Fixed-effects models and likelihood ratio tests were conducted to analyze within-practice variation.

Of 399,793 acute encounters in 1 calendar year, there were 52,658 diagnoses of acute pharyngitis, including 12,445 diagnoses of streptococcal pharyngitis. After excluding encounters by patients with chronic conditions and standardizing for age, sex, insurance type, and race, there was significant variability across and within practices in the diagnosis and testing for streptococcal pharyngitis. Excluding patients with antibiotic allergies or prior antibiotic use, off-guideline antibiotic prescribing for confirmed group A streptococcal pharyngitis ranged from 1% to 33% across practices (P < .001). At the clinician level, 13 of 25 sites demonstrated significant within-practice variability in off-guideline antibiotic prescribing (P ≤ .05). Only 18 of the 222 clinicians in the network accounted for half of all off-guideline antibiotic prescribing.

Significant variability in the diagnosis and treatment of pharyngitis exists across and within pediatric practices, which cannot be explained by relevant clinical or demographic factors. Our data support clinician-targeted interventions to improve adherence to prescribing guidelines for this common condition.

Laboratory investigations were initiated with a povidone-iodine antiseptic solution that was intrinsically contaminated with Pseudomonas cepacia. These investigations were helpful in understanding the microbicidal and chemical properties of iodophor solutions and the mechanism by which P cepacia can survive in iodine-containing antiseptics.

Included in these studies were: prolonged survival of P cepacia; available and free iodine determinations; microbial challenge studies; and scanning electron microscopic examination of contaminated antiseptic.

P cepacia survived in this iodophor antiseptic up to 68 weeks from the date of manufacture. A uniform concentration of 1% available iodine was found in all lots of povidone-iodine tested as specified on the product label, but free iodine (I,) values varied greatly. Low free iodine levels of 0.23 to 0.46 ppm were associated with the contaminated lot of povidone-iodine. Solutions of povidone-iodine with varying levels of free iodine were rapidly microbicidal when challenged with cells of P cepacia derived from culture broth and washed or adapted to growth in water. P cepacia cells taken directly from contaminated povidone-iodine survived for significantly longer periods of time. Large numbers of P cepacia were found embedded in extracellular material and among strands of glycocalyx between cells as shown by scanning electron microscopy.

The physical thickness of cellular and extracellular material that forms on surfaces could protect embedded organisms from the microbicidal action of disinfectants and antiseptics and subsequently allow for extended microbial survival times. Manufacturers should be aware that distribution piping surfaces colonized with bacteria may be a source of product contamination and resistant organisms.

In 2007–2008, several US hospitals reported summertime increases in the number of clinical blood cultures positive for Bacillus species, which are common environmental bacteria.

To investigate increased rates of isolation of Bacillus species from blood cultures, identify risk factors, and recommend control strategies.

Survey and case-control study.

Multiple hospitals, including a cancer center.

We surveyed 24 facilities that reported increases. We also conducted a field investigation at a hospital with a high rate, reviewing charts, collecting clinical and environmental isolates, and observing infection control procedures. A case-control study compared inpatient case patients who had any blood culture positive for Bacillus with unmatched control patients who had a blood culture with no growth during June-August 2008.

Among surveyed facilities, mean monthly rates rose from 25 to a peak of 75 Bacillus-positive blood cultures per 10,000 blood cultures performed during the period June-August. At the hospital where the case-control investigation was conducted, for most case patients (75%), the Bacillus-positive blood cultures represented contamination or device colonization rather than infection. We enrolled 48 case patients and 48 control patients; in multivariate analysis, only central venous access device use was significantly associated with case status (odds ratio, 14.0; P < .01). Laboratory testing identified at least 12 different Bacillus species (non-anthracis) among the isolates. Observation of infection control procedures revealed variability in central line care and blood sample collection techniques.

Periodic increases in the environmental load of Bacillus species may occur in hospitals. Our investigation indicated that at one facility, these increases likely represented a pseudo-outbreak of Bacillus species colonizing central venous lines or their accessories, such as needleless connector devices. Vigilant attention should be paid to infection control practices when collecting blood samples for culture, to minimize the risk of contamination by environmental microorganisms.