Michael R. Britt

Risk factors for postoperative pneumonia

Abstract Prospectively studied were 520 patients undergoing elective thoracic, upper abdominal and lower abdominal surgeries to analyze risk factors for postoperative pneumonias. Over-all, pneumonias developed in 91 of the 520 patients studied (17.5 percent). The acquisition of pneumonia was highly associated with preoperative markers of the severity of underlying diseases such as low serum albumin concentrations on admission (P We were able to identify risk factors for pneumonia and to define a subpopulation of patients in which the risk of pneumonia was negligible. The acquisition of pneumonia by a low-risk patient should alert the physician to the possibility of a potentially preventable nosocomial infection.

Prevention of catheter-associated urinary tract infections: Efficacy of daily meatal care regimens

To evaluate the efficacy of daily cleansing of the urethral meatus-catheter junction in preventing bacteriuria during closed urinary drainage, randomized, controlled trials of two widely recommended regimens for meatal care were completed. In 32 (16.0 percent) of 200 patients given twice daily applications of a povidone-iodine solution and ointment bacteriuria was acquired, as compared with 24 (12.4 percent) of 194 patients not given this treatment. In 28 (12.2 percent) of 229 patients given once daily meatal cleansing with a nonantiseptic solution of green soap and water bacteriuria was acquired, as compared with 18 (8.1 percent) of 23 patients not given special meatal care. There was no evidence in either trial of a beneficial effect of meatal care. Moreover, each of four different statistical methods indicated that the rates of bacteriuria were higher in the treated groups than in the untreated groups. In subsets of female patients at high risk in both studies significantly higher rates of bacteriuria were noted in the treated groups than in the untreated groups. Current methods of meatal care appear to be hazardous, as well as expensive, and cannot be recommended as measures to control infection.

An evaluation of daily bacteriologic monitoring to identify preventable episodes of catheter-associated urinary tract infection.

We evaluated the efficacy of a daily bacteriologic monitoring program for preventing symptomatic urinary tract infections (UTI) in hospitalized patients with temporary indwelling urethral catheters. We identified 99 instances in which bacteriuria was present at the time of catheter insertion among 1,140 catheterizations. Of those, 62 patients were asymptomatic and 37 patients had fever or symptoms attributable to UTI. Of the 37 symptomatic episodes, only 14 developed symptoms 24 hours or more after the first culture and might be considered potentially preventable. We also identified 76 episodes of acquired bacteriuria among 608 catheterizations that were initially nonbacteriuric in which at least two cultures were available. Of these 76 patients, 51 (67%) remained asymptomatic throughout their period of hospitalization. Of the 25 patients who developed symptomatic infections, only ten were potentially preventable. In all, only 24 symptomatic episodes among 1,140 catheterizations (2%) occurred 24 hours or more after colonization was first detected and might be considered potentially preventable. Our data suggest that routine daily bacteriologic monitoring of urine from all catheterized patients is not an efficient way to decrease the incidence of symptomatic, catheter-associated UTI.

Antimicrobial Prophylaxis for Catheter-Associated Bacteriuria

We evaluated short-term systemic antimicrobial prophylaxis for catheter-associated bacteriuria in women undergoing elective gynecological operations in a prospective, controlled, double-masked study. Nine of 100 placebo-treated patients acquired bacteriuria during catheterization compared with 3 of 96 of the drug-treated group. However, at the time of hospital discharge, clean-voided urine specimens were positive as frequently in the drug-treated group (8 of 82 patients cultured) as in the placebo group (8 of 75 patients cultured). No difference in febrile morbidity due to bacteriuria was noted between the prophylaxis and placebo groups. The incidence of catheter-associated bacteriuria may be reduced by antimicrobial prophylaxis. However, because the protective effect is transient and is associated with the selection of resistant organisms, prophylaxis is not indicated for patients at low risk for acquired bacteriuria and in whom the sequelae of catheter-associated infections are infrequent.

Failure of Bacterial Filters to Reduce the Incidence of Pneumonia after Inhalation Anesthesia

The authors prospectively studied 520 patients undergoing inhalation anesthesia to evaluate the efficacy of low resistance 0.22-micron bacterial filters in preventing postoperative pneumonias. Patients undergoing elective thoracic, upper abdominal and lower abdominal surgeries were randomly assigned preoperatively to filtered and nonfiltered anesthesia circuits by a study nurse. A second study nurse, who was unaware of patient assignments, followed each patient for five postoperative days to identify possible pulmonary complications. Both groups of patients were similar in age, sex distribution, smoking history, prior pulmonary disease, types and duration of surgery, ASA physical status classification, and receipt of intraoperative antibiotics. No differences in rates of postoperative pneumonia were observed between patients assigned to filtered and nonfiltered circuits (16.7 per cent vs. 18.3 per cent, respectively, P = 0.73). Also, no differences were observed when the incidences of other outcome criteria such as postoperative fever, abnormal chest x-ray, sputum production, or abnormal pulmonary physical exam findings were evaluated. The results suggest that bacterial gas filters do not influence the incidence of postoperative pneumonias and that routine use of these devices for this purpose is not cost-effective.

Sinus contamination with Pseudomonas paucimobilis: a pseudoepidemic due to contaminated irrigation fluid.

During a five-week period, Pseudomonas paucimobilis was isolated from maxillary sinus irrigation washes of four patients who attended an ear, nose and throat clinic. The saline irrigation solution was found to be contaminated with the same organism. Further investigation demonstrated the organism in a majority of hospital sinks surveyed. Although P. paucimobilis was isolated from clinical specimens, the presence of the organism did not appear to have clinical significance.

In Vitro Activity of Tobramycin and Gentamicin

The in vitro antimicrobial activity of tobramycin and gentamicin was compared against 362 bacterial isolates. The minimal inhibitory concentration (MIC) of tobramycin was fourfold less than the MIC of gentamicin against most of 119 Pseudomonas organisms. Gentamicin and tobramycin had similar in vitro activity against Enterobacteriaceae and Staphylococcus aureus. Proteus rettgeri were commonly resistant to both tobramycin and gentamicin. The 10-μg tobramycin disc separated resistant (MIC ≥5 μg/ml) and susceptible (MIC <5 μg/ml) organisms in 359 of 362 tested. In disc diffusion testing, the tobramycin and gentamicin zone diameters were found to vary significantly with concentrations of magnesium ions in the media employed. The MIC of tobramycin varied with the size of the inoculum, and tobramycin was most effective at a neutral pH.

Treatment of Acne-Reply

In Reply.— First, a comment on Dr Vorons initial statement concerning Table 2. The average for each degree of dryness is weighted in the statistical analysis according to the number of patients in that category. The dryness score of 3 contained only four subjects, which meant that the percent improvement of 49% weighted much less in the final statistical analysis than did the dryness score of 2 that contained 12 subjects with an average percent improvement of 41%. A superficial scan of this table clearly shows that dryness scores of 0 to 1 indicated that those subjects who had minimally dry skin showed improvement of 60+%, and those who had drier skin (with scores of 2 or 3) had only a 40+% improvement at 16 weeks. The most important argument against Dr Vorons first point, however, is that the statistical analysis showed an inverse correlation between dryness and clearing of