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.

In vitro activity of gemifloxacin (SB-265805) compared to eleven other antimicrobial agents against streptococcal isolates, excluding Streptococcus pneumoniae.

The purpose of the study presented here was to determine the in vitro activity of gemifloxacin compared with that of 11 other antimicrobial agents (5 of them quinolones) against 400 isolates of beta-haemolytic and viridans group streptococci. The minimum inhibitory concentration values for gemifloxacin against 90% of the streptococci tested were as follows: Lancefield groups A, C and G, 0.06 microg/ml; Lancefield group B, Streptococcus mitis, Streptococcus mutans and Streptococcus bovis, 0.125 microg/ml; and Streptococcus milleri, 0.03 microg/ml. Resistance to penicillin, ampicillin and erythromycin was found mainly in the Streptococcus mitis isolates; tetracycline showed variable results, and no vancomycin resistance was encountered. Higher rates of ciprofloxacin resistance were identified in the Streptococcus bovis, mitis and mutans isolates. In conclusion, gemifloxacin was the most active quinolone tested followed by trovafloxacin, sparfloxacin, grepafloxacin, ciprofloxacin and levofloxacin, especially against isolates resistant to beta-lactam agents, macrolides and tetracycline.

Mutator plasmid in a nalidixic acid-resistant strain of Shigella dysenteriae type 1.

A clinical isolate of Shigella dysenteriae from Kashmir, resistant to seven antibacterial agents including nalidixic acid, carried four plasmids, only one of which was transferable by conjugation. This plasmid, designated pYD1, conferred trimethoprim resistance and increased the frequency of mutation to nalidixic acid resistance in recipient strains. Thus, although nalidixic acid resistance was not carried on a transferable plasmid, the presence of pYD1 increased the frequency at which the strain mutated to nalidixic acid resistance.

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.

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.

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)