Assessing the biological efficacy and rate of recontamination following hydrogen peroxide vapour decontamination.

The inanimate hospital environment can become contaminated with nosocomial pathogens. Hydrogen peroxide vapour (HPV) decontamination has proven effective for the eradication of persistent environmental contamination. We investigated the extent of meticillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE) and gentamicin-resistant Gram-negative rod (GNR) contamination in a ward side-room occupied by a patient with a history of MRSA, VRE and GNR infection and colonisation and investigated the impact of HPV decontamination. Fifteen standardised sites in the room were sampled using a selective broth enrichment protocol to culture MRSA, VRE and GNR. Sampling was performed before cleaning, after cleaning, after HPV decontamination and at intervals over the subsequent 19 days on two separate occasions. Environmental contamination was identified before cleaning on 60, 30 and 6.7% of sites for MRSA, GNR and VRE, respectively, and 40, 10 and 6.7% of sites after cleaning. Only one site (3.3%) was contaminated with MRSA after HPV decontamination. No recontamination with VRE was identified and no recontamination with MRSA and GNR was identified during the two days following HPV decontamination. Substantial recontamination was identified approximately one week after HPV decontamination towards post-cleaning levels for GNR and towards pre-cleaning levels for MRSA. HPV is more effective than standard terminal cleaning for the eradication of nosocomial pathogens. Recontamination was not immediate for MRSA and GNR but contamination returned within a week in a room occupied by a patient colonised with MRSA and GNR. This finding has important implications for the optimal deployment of HPV decontamination in hospitals.

Hospital hairdresser as a potential source of cross-infection with MRSA.

Following medical staff concerns about patients screening positive for methicillin-resistant Staphylococcus aureus (MRSA) from the hairline site only, it was suggested that the hospital hairdresser could be a possible source for cross-contamination. Analysis of her procedures and decontamination practices confirmed her to be a potential source. Swabbing of her equipment after a day's session with her normal cleansing practice revealed the presence of MRSA, confirmed by phage typing as an epidemic strain within the hospital. This provided putative evidence for a vehicle of transmission. A review of advice for hairdressers in hospitals was obtained from the literature and via a telephone survey of infection control nurses in London. A composite policy was produced for hairdressers attending MRSA-positive patients in hospital to minimize this potential risk.

The effect of handcream on the antibacterial activity of chlorhexidine gluconate.

A series of handwashing experiments compared the residual effect on Escherichia coli of non-medicated soap, chlorhexidine detergent followed by an anionic handcream, chlorhexidine detergent followed by a non-ionic handcream and chlorhexidine detergent alone. Handcreams containing an anionic emulsifying agent reduced the antibacterial effect of chlorhexidine.

Refrigerated food storage in hospital ward areas.

A survey of ward refrigerators was carried out in two hospitals, with reference to type and efficiency in maintaining cold storage temperatures. A total of 40 refrigerators were surveyed on two occasions. Only seven were found to maintain temperatures between 5 degrees C and 7 degrees C. Commercial larder type refrigerators are recommended for ward use. Training and updating of staff in policies and procedures is emphasized.

A multi-centre evaluation of two chlorhexidine-containing formulations for surgical hand disinfection.

Many experimental methods have been used to assess the efficacy of products intended for surgical hand disinfection. In this study, a modification of the Peterson glove juice method was used to compare two chlorhexidine-based surgical hand disinfectants, 'Hibiscrub' and an experimental formulation, F.6115. The study was performed by four independent laboratories and data merged for analysis. There was found to be no significant difference between the two formulations. The results illustrate that this modified Peterson glove juice method has the potential to form the basis of a standard method for testing surgical hand disinfectants which is both relevant to the practical situation and reproducible in different laboratories.

Comparative post-antibiotic effect of five antibiotics against ten aerobic gram-positive cocci.

The post-antibiotic effect (PAE) is the persistent suppression of bacterial growth after a short antibiotic exposure. It is well documented with a variety of antibiotics and micro-organisms and may have important therapeutic implications. The authors have evaluated the PAE produced by teicoplanin, fucidin, gentamicin, rifampicin and ciprofloxacin against a total of ten Gram-positive organisms (S. aureus (2), MRSA (2), S. epidermis (2) S. haemolyticus (2) and E. faecalis (2)). All the organisms were clinical isolates with variable sensitivity patterns confirmed by disc and MIC testing. MICs were performed by the broth dilution method using a final inoculum of 10 x 5 cfu/ml. The PAE was estimated by adding 5 x MIC of each antibiotic to a log phase of growth of approximately 10 x 7 cfu/ml, and incubating at 37 degrees C for 1 h. Antibiotic was removed by 1000-fold dilution in nutrient broth, and total viable counts were carried out hourly by the Miles and Misra method for a further 9 h. All the antibiotics tested showed a PAE against the organisms tested, except for fucidin and ciprofloxacin against the enterococci. Overall, teicoplanin showed a maximum PAE of 5 h against MSRA and a minimum of 0.6 h against E. faecalis. Gentamicin, rifampicin and ciprofloxacin also showed a variable range. Fucidin showed the least PAE against the ten organisms, ranging from 0-1.3 h, except for S. epidermidis (FUC-R) which had a PAE of up to 4.5 h. The duration of PAE of each antibiotic/organism combination varied and was associated with the sensitivity pattern of the organism.(ABSTRACT TRUNCATED AT 250 WORDS)

The in vitro activity of roxithromycin (RU 28965) compared with four oral antibiotics.

The in vitro activity of roxithromycin (RU 28965), a new semisynthetic macrolide, was compared with that of amoxycillin, cephradine, doxycycline and erythromycin against 160 respiratory and skin isolates including 10 methicillin-resistant Staph. aureus, 10 beta-lactamase-producing Haemophilus influenzae and 30 anaerobes. The MIC determinations were performed by an agar dilution method using a final inoculum of 10(4)-10(5) c.f.u./ml and results were recorded as the lowest concentration of the drug that inhibited visible growth (MIC). All organisms were incubated aerobically at 37 degrees C for 18 h, except anaerobes which were incubated in an anaerobic chamber at 37 degrees C for 48 h. The MICs of roxithromycin against staphylococci (30 strains, 10 of which were erythromycin-resistant, MIC greater than or equal to 2 mg/l) ranged from 0.03 to greater than or equal to 16 mg/l. The MIC90 against erythromycin-sensitive staphylococci was 1.0 mg/l. The MICs of roxithromycin ranged from 0.03-4 mg/l (MIC90 0.25 mg/l) against streptococci (50 strains), from 1 to 32 mg/l (MIC90 8 mg/l) against Haemophilus spp. (40), and from 0.06 to 0.25 mg/l (MIC90 0.125 mg/l) against B. catarrhalis (10). Roxithromycin was less active than erythromycin against fusobacteria (MIC 0.05 to greater than or equal to 128 mg/l) and against Veillonella spp. (MIC greater than 128 mg/l). Roxithromycin was more active than cephradine, doxycycline and amoxycillin against the aerobic organisms (except for amoxycillin against streptococci, where the activity was similar) but less active against the anaerobes examined. Taken together with reported kinetic advantages, these results suggest that roxithromycin may be a useful antibiotic in selected circumstances and studies to determine its efficacy seem indicated.

Clinical efficacy of carumonam.

Carumonam is a new N-sulfo-beta-lactam antibiotic active against aerobic Gram-negative bacteria. An open study was carried out to evaluate the efficacy, safety and tolerance of carumonam with either 1 g t.i.d. (group A) or 2 g t.i.d. (group B) in bacterial septicaemia or severe sepsis. A total of 24 patients (14 men and 10 women) were included in the study, their ages ranged from 48-87 years (mean age 59). Eighteen patients were treated for bacteraemia, three for bronchopneumonia, two for urinary tract infection and one for a subphrenic abscess; seven were in group A and fourteen in group B; three were treated with a variable regimen. The pathogens isolated included E. coli [10], Klebsiella aerogenes [9], Enterobacter cloacae [3], Citrobacter freundii [2], Pseudomonas spp. [4], Providence stuartii [2], Serratia marcescens [1] and Haemophilus influenzae [1]. Clinical improvement occurred in all patients in both groups. One patient in group A and four patients in group B required further antibiotic therapy. The overall clinical cure rate was 84% and the bacteriological cure rate was 72%. Supra-infection occurred in three patients and adverse reactions attributable to carumonam were seen in two patients: diarrhoea (in one), and aggravation of renal failure in the other. Carumonam is well tolerated at both the dosage regimens; it is effective in the treatment of aerobic Gram-negative sepsis.

Open study of teicoplanin in gram-positive infections.

Eighteen patients with documented Gram-positive infections which included osteomyelitis, prosthetic infections, endocarditis, skin and soft tissue, and urinary tract infections were treated with teicoplanin. The organisms involved included Staphylococcus aureus (15 isolates of which six were methicillin-resistant-MRSA), Staphylococcus epidermidis (two), Streptococcus faecalis (one) and Streptococcus milleri (one). Clinical success occurred in all seven patients with skin and soft tissue Streptococcus milleri (one). Clinical success occurred in all seven patients with skin and soft tissue infections (with bacterial persistence in three out of the seven), in three patients with bacteraemia endocarditis, and in one of the three patients with chronic osteomyelitis. In four patients with prosthetic bone and joint infections, clinical improvement followed removal of prostheses. Adverse effects occurred in two patients and these included one patient with a rise in serum aspartate aminotransferase and bilirubin and one patient with a rise in blood urea, both of which returned to within normal limits on discontinuing the drug. The study showed that teicoplanin is a safe and effective antistaphylococcal agent.

The post-antibiotic effect of teicoplanin: monotherapy and combination studies.

The post-antibiotic effect (PAE) of teicoplanin was measured alone and in combination with other antibiotics against Staphylococcus aureus. A total of five strains were used: the Oxford S. aureus and two clinical isolates each of methicillin sensitive and methicillin resistant strains. Fusidic acid had no or a small post-antibiotic influence (range 0-1.25 h) whereas a relatively higher PAE was seen for all other drugs against all strains: teicoplanin 2.4-4.1 h: gentamicin 3.1-5.2 h, rifampicin 3.0-3.95 h, and ciprofloxacin 1.6-3.4 h. Combination of teicoplanin with fusidic acid resulted in shorter PAEs than teicoplanin alone. In contrast, PAEs for all other combinations with teicoplanin were longer than PAE of teicoplanin, gentamicin, rifampicin or ciprofloxacin alone. Addition of teicoplanin during the post-antibiotic phase of the other antibiotics and vice versa showed that the only combination which was consistently bactericidal was that of teicoplanin with gentamicin. We conclude that these in-vitro results suggest that the combination of teicoplanin with gentamicin is likely to be the most effective of those tested and should be further evaluated in clinical trials.

The in-vitro activity of piperacillin/tazobactam, ciprofloxacin, ceftazidime and imipenem against multiple resistant gram-negative bacteria.

One hundred and fifty Gram-negative bacterial strains including respiratory pathogens, such as Haemophilus influenzae and Branhamella catarrhalis, and Enterobacteriaceae with known resistance to beta-lactam and other antibiotics were tested in vitro for sensitivity to piperacillin, piperacillin/tazobactam (ratio 8:1), ceftazidime, ciprofloxacin and imipenem. A 16-fold or greater reduction in the MIC90 of piperacillin was achieved by the addition of tazobactam, in the respiratory pathogens, thus bringing them within the susceptible range. Among the Enterobacteriaceae, a 32-fold or greater reduction in the MIC90 was found for Providencia stuartii, Proteus mirabilis and Aeromonas hydrophila. When compared with the other three antimicrobials, the combination was found to be active against fewer species of multiply resistant Enterobacteriaceae, but equally effective against H. influenzae and B. catarrhalis.

Audit of the detection and notification of meningococcal disease at a North London university district hospital.

The microbiology department at a North London hospital audited notifications of suspected meningococcal disease in response to a reported high rate, which it suspected was due to over-reporting out of hours to public health specialists. All cases notified over a 14-month period were assessed with regards to time of reporting and subsequent microbiological confirmation. Of 36 notifications, 18 were confirmed as bacterial, mostly meningococcal meningitis. Of the four types of sample readily obtainable on admission (blood culture, ethylene diamine tetra-acetic acid [EDTA] blood sample, throat swab and acute serum) all were obtained in only two cases. The reporting was considered appropriate, reflecting the relatively high incidence of meningococcal disease (MD) within the local population. Further cases might perhaps have been laboratory confirmed had all samples been sent on admission. A single form requesting all four samples in suspected meningococcal disease cases is recommended. Informing public health specialists out of hours could be rationalised.

Flavobacterium meningosepticum ventriculitis: in vivo and in vitro results with the combinations rifampicin-erythromycin and mezlocillin-cefoxitin.

A case of Flavobacterium meningosepticum ventriculitis is described in which the failure of therapy with a combination of rifampicin and erythromycin is attributed to inadequate antibiotic levels in cerebrospinal fluid. The successful eradication of the organism was achieved with the use of mezlocillin and cefoxitin given by the intravenous and intraventricular route. In vitro sensitivity tests of recently isolated strains of Flavobacterium meningosepticum suggested that the combination mezlocillin and cefoxitin is more often synergistic than rifampicin and erythromycin.