The addition of a mobile ultra-clean exponential laminar airflow screen to conventional operating room ventilation reduces bacterial contamination to operating box levels.

A mobile screen producing ultra-clean exponential laminar airflow (LAF) was investigated as an addition to conventional turbulent/mixing operating room (OR) ventilation (16 air changes/h). The evaluation was performed in a small OR (50 m(3)) during 60 standardized operations for groin hernia including mesh implantation. The additional ventilation was used in 50 of the operations. The LAF passed from the foot-end of the OR table over the instrument and surgical area. Strict hygiene OR procedures including tightly woven and non-woven OR clothing were used. Sedimentation rates were recorded at the level of the patients' chests (N=60) (i.e. the air had passed the surgical team) and in the periphery of the OR. In addition bacterial air contamination was studied above the patients' chests in all 10 operations without the additional LAF and in 12 with the LAF. The screen reduced the mean counts of sedimenting bacteria (cfu/m(2)/h) on the patients' chests from 775 without the screen to 355 (P=0.0003). The screen also reduced the mean air counts of bacteria (cfu/m(3)) above the patients' chests from 27 to 9 (P=0.0001). No significant differences in mean sedimentation rates (cfu/m(2)/h) existed in the periphery of the OR where 628 without and 574 with screen were recorded. During the follow-up period of six months no surgical site infections were detected. In conclusion when the mobile LAF screen was added to conventional OR ventilation the counts of aerobic airborne and sedimenting bacteria-carrying particles downstream of the surgical team were reduced to the levels achieved with complete ultra-clean LAF OR ventilation (operating box).

Inefficiency of upward displacement operating theatre ventilation.

A new thermally based ventilation system ('Floormaster') with inlet of cool clean air at floor level, and evacuation at the ceiling of the air warmed by activity in the room (upward displacement ventilation, 17 air changes/h) was compared with a standard positive pressure (plenum) ventilation system with air supply through an inclined perforated screen along one wall at the ceiling and evacuation at floor level (conventional turbulent or mixing system, 16 air changes/h). The study was made during rigidly standardized sham operations (N = 20) performed in the same operating room by a six-member team wearing non-woven disposable or cotton clothing. In general the upward displacement system removed dust particles too small to carry bacteria (0.16-<0.3 microm, 0.001

Assessment of horizontal laminar air flow instrument table for additional ultraclean space during surgery.

The area in a vertical ultraclean laminar air flow (LAF) theatre is usually too small to accommodate all the equipment needed for major surgery. We investigated the addition of an instrument table supplied with fixed ultraclean LAF and placed alongside the existing main LAF unit, to determine its physical and bacteriological effect on the main unit. In phase 1, with two investigators but without a patient, smoke tests showed no intrusion of air from the table into the main unit and particle counts did not show any adverse effect on the main LAF unit. In phase 2, during patients undergoing two total knee replacements, the LAF table and a table without LAF were placed alongside the main LAF unit. The tables were subjected to the activity of an extra operating room (OR) nurse working from inside the main LAF vigorously simulating handling of instruments. During this activity, the >5µm particle counts were 275/m(3) at the instrument table with LAF and 8550/m(3) at the table without LAF (P<0.0001). Also, without the OR nurse activity, the particle counts, just inside the main unit and adjacent to the LAF table, were significantly reduced (P<0.03-0.003). Sedimentation plates on the LAF table and in the main unit registered 22 and 25cfu/m(2)/h respectively compared with 45cfu/m(2)/h at the instrument table without LAF. In conclusion, the results from the smoke tests, particle counts and bacteriological evaluation showed that the additional instrument table supplied with LAF is efficient and can be safely used as an extension additional to a main OR LAF unit.

Norfloxacin versus placebo for prophylaxis against travellers' diarrhoea.

In a randomized, double blind study, 127 subjects travelling to countries outside Northern Europe were given norfloxacin 200 mg or placebo bid as prophylaxis against diarrhoea. Fifty-six subjects randomized to norfloxacin and 59 to placebo fulfilled criteria for evaluation of efficacy and of those, respectively six and 20 (P = 0.0006) developed diarrhoea. The mean duration of symptoms in the placebo group was 3.6 days, while all subjects on norfloxacin had symptoms for one day only. In travellers to Mediterranean Europe or the Canary Islands, no significant differences were seen between norfloxacin and placebo. Among subjects going to Africa, Asia or Latin America, 4/32 subjects on norfloxacin and 16/30 on placebo developed diarrhoea (P = 0.0004). Adverse effects were few and mild. Faeces for aerobic cultures was obtained before travelling and three weeks and then three months post-treatment. Treatment with norfloxacin resulted in a significant reduction of samples yielding aerobic Gram-negative rods but did not affect enterococci. In the placebo group, Gram-negative organisms other than Escherichia coli were increased on return to Sweden and the subjects frequently acquired Gram-negative organisms resistant to antibiotics. In none of the groups was there a tendency towards increased norfloxacin resistance. Biotyping of E. coli showed that in both groups the subjects changed their E. coli strains frequently during and after travelling. This trial showed that norfloxacin is a safe and effective prophylactic agent with no adverse effect on bacterial flora, but that its use should be restricted to travellers to non-European countries.

Efficacy and safety of cefpirome (HR810).

Sixty adult patients with suspected systemic bacterial infections were treated with cefpirome 1 g or 2 g twice daily for 5-22 days. Forty-seven patients were evaluable for clinical efficacy. Diagnoses in evaluable patients were urinary tract infections (20), pneumonia (10), soft tissue infections (17), and bone and joint infections (4); four patients had two infections each. Nine patients were bacteraemic and all were cured; the responsible bacteria were Escherichia coli (6), Streptococcus pneumoniae (1), Pseudomonas aeruginosa (1), and Haemophilus influenzae (1). One patient with a soft tissue infection failed to respond clinically to cefpirome. Bacteriologically, 41 of 48 isolated pathogens (85%) were eradicated. In wound cultures, three strains of Staphylococcus aureus and one each of Ps. aeruginosa and Str. faecalis persisted. One Enterobacter sp. relapsed in urine. Of isolated strains, only Str. faecalis and methicillin resistant Staph, epidermidis were resistant to cefpirome. Staph, aureus strains were inhibited in vitro by 0.25 to 2 mg/l of cefpirome in agar dilution. Adverse effects, probably or possibly related to cefpirome, were skin reactions (3), fever (1), Clostridium difficile diarrhoea (2), and disturbed taste sensation (1). Tolerance was good. Cefpirome is suitable for large-scale comparative trials.

Empiric treatment of acute diarrheal disease with norfloxacin. A randomized, placebo-controlled study. Swedish Study Group.

OBJECTIVE: To evaluate the clinical and microbiologic efficacy and safety of norfloxacin for acute diarrhea. DESIGN: Double-blind, placebo-controlled, randomized clinical multicenter trial. SETTING: Six departments of infectious disease. PARTICIPANTS: Patients 12 years of age or older with a history of acute diarrhea lasting 5 or fewer days. Eighty-five percent of patients (511/598) were evaluable for efficacy. Of these evaluable patients, 70% had traveled abroad within the previous 6 weeks. INTERVENTIONS: Patients received either norfloxacin, 400 mg, or placebo twice daily for 5 days. MEASUREMENTS: Enteric pathogens were isolated in 51% of the evaluable patients: Campylobacter species in 29%, Salmonella species in 16%, Shigella species in 3.5%, and other pathogens in 2.6%. RESULTS: Norfloxacin had a favorable overall effect compared with placebo (cure rate, 63% compared with 51%; P = 0.003). There were statistically favorable effects in culture-positive patients, patients with salmonellosis, and severely ill patients but not in culture-negative patients or patients with campylobacteriosis or shigellosis. A significant difference was noted between norfloxacin and placebo in median time to cure among all evaluable patients (3 compared with 4 days, P = 0.02) and in patients with campylobacteriosis (3 compared with 5 days, P = 0.05) but not in patients. Culture-positive, but not culture-negative patients, in the norfloxacin group had significantly fewer loose stools per day compared with patients in the placebo group from day 2 onward (P less than or equal to 0.01). Norfloxacin was significantly less effective than placebo in eliminating Salmonella species on days 12 to 17 (18% compared with 49%, P = 0.006), whereas the opposite was true for Campylobacter species (70% compared with 50%, P = 0.03). In six of nine patients tested, norfloxacin-resistant Campylobacter species (MIC, greater than or equal to 32 micrograms/mL) appeared after norfloxacin treatment. CONCLUSION: Empiric treatment reduced the intensity and, to some extent, the duration of symptoms of acute diarrhea. The effect was restricted to patients who had bacterial enteropathogens or who were severely ill. The clinical usefulness of this treatment is limited by the fact that norfloxacin seems to delay the elimination of salmonella and to induce resistance in campylobacter.