Bacteriological Safety Research Articles

Bacteriological safety and cost-effectiveness of a non-refluxing valve in the irrigation system during outpatient flexible cystoscopy.

Bacteriological safety and cost-effectiveness of a non-refluxing valve in the irrigation system during outpatient flexible cystoscopy.

Removal kinetics of Bacillus cereus spores from a stainless steel surface exposed to constant shear stress 2. Removal kinetics modelling: Influence of adhesion conditions

In the food industries, the efficiency of food‐contact surface cleaning and disinfection procedures is of prime importance to ensure the bacteriological quality and safety of the products. Hydrodynamic removal kinetics of Bacillus cereus spores adhering to a stainless steel surface was studied as a function of attachment medium and surface hydrophobicity. The method was based on the use of a controlled shear rate viscometer. The well‐known enhancing effect of hydrophobic surfaces on soil adhesion was clearly observed. Conversely, the presence of macromolecules in the attachment medium was found to favor spore detachment. Spore removal kinetics were modelled by a simple three‐parameter hyperbolic tangent model. The influence of both the adhesion medium and surface hydrophobicity on the predicted values of spore spontaneous detachment, residual adhering spores and relaxation time, a parameter directly linked to the removal rate, were assessed by analysis of variance. Experimental spore removal kinetics were then predicted as functions of attachment medium and surface hydrophobicity, with a 15% relative error. In the conditions tested, lowering the adhesion forces between spores and surface was found to be necessary to remove more than 1 log within 1.5 h shearing at 28 Pa under a laminar flow regime. A clear definition of the “acceptable cleanliness level”; concept appears to be necessary prior to any attempt at CIP procedure optimization.

Clinical and Bacteriologic Efficacy of Amoxycillin b.d. (45 mg/kg/day) Versus Amoxycillin t.d.s (40 mg/kg/day) in Children with Group A b-hemolytic Streptococcal Tonsillopharyngitis

This randomized, observer-blind, multicenter, parallel-group study compared the clinical and bacteriologic efficacy and safety of amoxycillin, 45 mg/kg/day b.d. and amoxycillin, 40 mg/kg/day t.d.s. after 7 days of treatment in 517 children with acute bacterial tonsillopharyngitis. At the end of treatment, a successful clinical response was recorded in more than 96% of patients in each of the treatment groups. A similar result was obtained at follow-up. Among those patients who were bacteriologically evaluable at the end of treatment, a successful bacteriologic response was achieved in more than 94% in each treatment group. Both treatments were well tolerated. Drug-related adverse events were recorded in just 12 patients (4.6%) in the b.d. group and six (2.4%) in the t.d.s. group. The study demonstrated that a twice-daily regimen of amoxycillin, 45 mg/kg/day, was as effective and as well tolerated as the standard three-times-daily regimen of amoxycillin, 40 mg/kg/day, in the treatment of acute bacterial tonsillopharyngitis in children.

Analysis of Clarithromycin and Propicillin in the Management of Streptococcal Pharyngotonsillitis in Children

Objective: To compare the clinical and bacteriological efficacy and safety of clarithromycin and propicillin in the treatment of streptococcal pharyngotonsillitis in children.

Comparison of the Efficacy and Tolerability of Short-Course Cefuroxime Axetil and Amoxicillin/Clavulanic Acid in the Treatment of Secondary Bacterial Infections of Acute Bronchitis A Multicentre, Randomised, Double-Blind Clinical Trial

Objective and Study Design: This multicentre, randomised, double-blind clinical trial compared the clinical and bacteriological efficacy and safety of cefuroxime axetil and amoxicillin/clavulanic acid in the treatment of secondary bacterial infections of acute bronchitis (SBIAB).

Is it safe to use preprepared endotracheal tubes in the resuscitation room?

To investigate the bacteriological safety of preprepared endotracheal tubes in accident and emergency departments. Swabs were taken and cultured from luminal and exterior surfaces of every preprepared exposed endotracheal tube in a hospital resuscitation room. Coagulase negative staphylococci (common skin commensals) were isolated from 50% of the tubes. No other bacteria were isolated. The practice of leaving preprepared airway equipment exposed in the resuscitation room is unlikely to contribute to the development of nosocomial pneumonia, provided the equipment is kept dry and that personnel minimize handling.

Zoned vertical ultraclean operating room ventilation: A novel concept making long side walls unnecessary

We evaluated a novel concept of High Efficiency Particulate Air (HEPA)-filtered vertical Laminar Air Flow (LAF) for operating room ventilation, designed to be used without side-walls. The LAF-unit has a central zone with an airflow of 0.4 m/s and a peripheral zone with an airflow of 0.2 m/s. The design provides an exponential downflow of air resembling an upside-down trumpet mouth and it was claimed to prevent entrainment of peripheral contaminated air. The unit was evaluated with regard to elimination of particles with focus on bacteria-carrying particles (colony-forming units = cfu) during rigidly standardized sham operations. Three different lengths of walls/enclosures (short-ending 2.0 m, medium 1.0 m and long 0.2 m above the floor) were tested. It provided a high degree of bacteriological cleanliness (0.05-4 cfu/m3 of air and 7-64 cfu/m2/h surface contamination) and its efficiency was proved to be independent of the length of the enclosures. We conclude that the novel zoned ultraclean vertical LAF unit is versatile, as it allows for omitting long side-walls, without compromising bacteriological safety.

Bacteriological Safety of Swine Carcasses Treated with Reconditioned Water

ABSTRACTSwine carcass microflora were evaluated for selected foodborne pathogens after exposure to reconditioned water during scalding, dehairing, and polishing operations. Reused water had been reconditioned and chlorinated. Rodac plates applied to hams were used to assess carcass microflora. Water samples were enumerated using membrane filtration or spiral plating. Sampling was at mid‐week throughout the year. Total aerobic plate counts on hams were unaffected by treating with potable or reconditioned waters. No differences were observed for staphylococci, enterics, fecal streptococci, Listeria monocytogenes, coliforms, and Aeromonas levels. A preevisceration potable water carcass wash reduced the bacterial load, regardless of initial treatment. Bacterial counts on carcasses paralleled those in water. Reuse is an alternative to potable water for initial slaughter operations without diminishing bacteriologic safety.

Piperacillin/Tazobactam in the Treatment of Lower Respiratory Tract Infections: an Open Non-Comparative and Multicentered Trial

The aim of this study was to determine the clinical and bacteriological efficacy and safety of piperacillin-tazobactam (PT) (4g/500 mg IV tid) in the treatment of 107 adult patients with lower respiratory tract infections (LRTI) requiring hospitalization. Patients included were 66 men and 41 women with a mean age of 55.2 years (range 18-89), enrolled from Mexican (6) and Argentinean (5) hospitals. Ninety-nine clinically evaluable patients (92.5%), 87 with pneumonia and 12 with bronchitis, were treated for a mean period of 9.3 and 7.3 days, respectively. Response to treatment was favorable in 94.3% cases with pneumonia and 100% of cases with bronchitis; 86 cases (80.3%) were bacteriologically evaluable, 77 with pneumonia (eradication 74, persistence 1, superinfection 2), and 9 with bronchitis (eradication in all). Streptococcus pneumoniae was recovered in 24, Klebsiella pneumoniae in 21, Staphylococcus aureus in 8, Haemophilus influenzae in 7, Pseudomonas aeruginosa in 5, Enterobacter spp. in 6, Escherichia coli in 6 and other organisms in 12. Toxicity or intolerance were not observed. Our data suggest that PT is a reliable therapy for severe LRTI.

Bacteriological safety and low-air-loss beds.

The distribution of bacteria into the environment while managing a simulated 1 0% body surface area burn on either a standard hospital bed or a low-air-loss bed was examined in this study. The extent of contamination was similar for both types of bed but operating the bed head/foot mechanism of the low-air-loss bed might be a hazard in certain circumstances. The investigation demonstrated the insidious build up of bacteria within a patient treatment cubicle. Means for eliminating possible contamination of the low-air-loss bed were investigated and an effective method devised. It was also found that commonly employed topical therapeutic agents for burns did not affect the air sac fabric of the low-air-loss bed, but a standard phenolic disinfectant was deleterious. The cleaning and disinfecting procedures were found to be effective in clinical practice.

The Incidence of Listeria spp. in Commercial Raw Hamburgers and their Bacteriological Safety Following Cooking

The Incidence of Listeria spp. in Commercial Raw Hamburgers and their Bacteriological Safety Following Cooking

Bacteriological Safety of a Fermented Weaning Food Containing L-lactate and Nisin

Using a rice-based model weaning food, the effect of Lactococcus lactis on the growth and survival of a range of enteric pathogens has been investigated. The starter organism used produces the bacteriocin nisin and the physiological L-lactate isomer, thus avoiding the risk of D-lactate acidosis when consumed by infants. L. lactis was a less effective antagonist than stronger acid producers such as the DL lactate producer, Lactobacillus plantarum, and only produced a potentially useful inhibition of pathogens when present in a large numerical superiority (>105:1). Prefermentation of the weaning food with L. lactis for 24 h produced a product with a pH of 3.7–3.8 containing ≈ 0.25% lactate (>96% L-lactate). The prefermented product was bactericidal for pathogens introduced subsequently. Despite the production of 100–150 international units nisin per g during fermentation, the inhibition of pathogens could be ascribed to acid production alone.

Water sanitation practices on the Texas-Mexico border: implications for physicians on both sides.

With the epidemic of cholera in South and Central America and reports of cholera in the Northern Hemisphere in Mexico, increasing concern focuses on sanitation problems along the border between the United States and Mexico. It is feared that binationally shared water supplies are threatened or contaminated by sewage and other wastes. Although much anecdotal information exists, surprisingly few hard data are available in the United States (or in Mexico, for that matter) regarding water quality on the Mexican side of the border. This shortage of data is felt most acutely in the semiarid portions of the border, where water is extraordinarily scarce. In 1987, researchers at the University of Texas School of Public Health (UTSPH) began gathering data on the availability, accessibility, and bacteriologic and chemical safety of raw and finished drinking water in Mexico at its border with Texas. In view of their timely significance, we wish to share pertinent data. This particular study was carried out in Ciudad Juarez, a city of more than 1 million people, situated just across the Rio Grande from the Texas city of El Paso. The investigation was conducted at the invitation and with the assistance of municipal authorities of Cd. Juarez. As far as we know, this was the first time the water in Cd. Juarez had been tested for indicator fecal bacteria and other selected contaminants.

A 2-year survey of the prevalence of enteric viral infections in children compared with contamination in locally-harvested oysters.

We studied, for two years, the prevalence of indigenous human enteric viruses in wild oysters gathered each month from the bottom of Mikawa Bay, Aichi Prefecture, Japan. Viruses were detected periodically in 9 out of 54 oyster pools prepared by the acid or polyethylene glycol precipitation method although all these 9 pools met current national bacteriological safety standards. Since most of the serotypes of the enteric viruses detected in the oysters were identical with those of viruses isolated from sick children living in the area, it is suggested that contamination of enteric viruses in the oysters would depend on the prevalence of enteric viral infections in the local inhabitants.

Bacteriological safety of cook-chill food at the Royal Free Hospital, with particular reference to Listeria

Cook-chill food prepared by the Catering Department of the Royal Free Hospital was examined over an 8-month period commencing October 1989. Total aerobic viable counts (TAVCs) were performed on 200 food specimens which were also examined for Listeria using selective enrichment culture. Ten of 200 food samples tested had TAVCs > 10 5 colony forming units (cfu) g −1, and nine of these were from non-vegetarian (meat) dishes. Although most of the food prepared by cook-chill had microbial loads within the limits recommended by current Department of Health guidelines (i.e. <10 5 cfu g −1), our findings for the non-vegetarian dishes suggest that extra caution is required when preparing such food. Listeria were not isolated from any food sample. In a survey of listeria faecal carriage, Listeria monocytogenes was isolated from only two of 100 faeces specimens obtained from patients.

Some aspects of the gastrointestinal microflora of veal calves fed different rations: A pilot study

The gastrointestinal microflora of veal calves reared on different diets was studied because the nature of this microflora affects the quality of veal as a result of contamination of carcass surfaces with intestinal contents during slaughter. Diet A consisted of a milk substitute, diet B of milk substitute + straw pellets and diet C of milk substitute + straw pellets + concentrates. In the rumen fluid of calves reared on diet A significantly higher counts of Gram-negative bacteria but lower counts of thermotrophic enterobacteriaceae were found than in calves reared on diets B or C. As for the faecal flora, diets B and C seem to result in significantly lower counts of Gram-negative bacteria and thermotrophic enterobacteriaceae. In 46% of the faecal specimens and 62% of the specimens of rumen fluid from calves fed on milk substitute only, Pseudomonas aeruginosa was isolated in mean counts of 4.1 log cfu/g and 5.2 log cfu/g respectively. P. aeruginosa could not be isolated from any specimen from calves receiving straw pellets. These results indicate that the inclusion of straw pellets in the diet of veal calves may increase the bacteriological safety and keeping quality of veal.

Vérification de l'inocuité bactériologique du climatiseur PCM 40

This study assessed the bacteriological safety of the bedside air conditioner PCM 40 (Howorth Airtech), used for prevention of intraoperative hypothermia, by blowing filtered warm air through a special mattress. The 3 μm bacterial filter of the device released 2,968 ± 5,618 particles of diameter < 3 μm per m 3 of room air, containing 78,798 ± 37,243 of such particles per m 3. The amount of bacteries in the air pulsed from the mattress was 30 ± 41 cfu/m 3 vs 120 cfu/m 3 in the ambient air and in the hot air supply tubing it reached 6 ± 5 cfu/m 3 vs 175 ± 77 cfu/m 3. It is concluded that bacteriological data do not contra-indicate the use of this air conditioner in the operating theater. The only limitations for use are the position (prone or lateral position) and type of surgery (neurosurgery).

Préparation de concentrés de plaquettes humaines déleucocytés par centrifugation et filtration d'un pool de buffy-coats connectés stérilement

We describe a new method for the preparation of standardised therapeutic doses of leukocyte depleted platelets. The first step is to remove the buffy-coat from whole blood units drawn on triple Siamese ACD/SAGM bags (Maco-Pharma) by means of a Compomat (NPBI). The second step is to connect (SCD Haemonetics) six buffy-coats and one plasma to a special kit (Maco-Pharma) including a PALL PL 100 filter; after centrifugation, the supernatant platelet concentrate is extracted, filtered and recovered in a 2 litre TOTM PVC bag. The volume, the number of platelets and leukocytes of these pools are measured. A comparison of these parameters is made with therapeutic doses prepared in the same way without filtration. Besides, pH measurements up to the 6th day of storage and bacteriological checks are carried out. The results show: no platelet loss related to filtration; a synergy between the preparation process out of buffy-coats and the filtration: so each dose contains less than 10(6) leukocytes; a good pH level allowing the storage for five days as it is associated to the bacteriological safety of the functionally closed system. This technique makes it possible to transfuse only leukocyte depleted platelet concentrates. In addition, it offers new prospects for standardisation and quality improvement.

Fermented sausages

Abstract The fermentation processing of raw sausages controlled by metabolic activity of added microorganisms (starter cultures) has been known for several decades and is widespread in countries with developed meat industries. Its success is due to several factors, like rapid turnover, pleasant aroma and taste, and good safety record, to name just a few. The basic process is the bacterial breakdown of added carbohydrate, mostly dextrose and/or sucrose or any other mono‐ or disaccharides, as a result of which lactic acid is formed. In the presence of lactic acid the pH drops to a value close to the isoelectric point of muscle protein, in this way reducing water‐holding capacity and making rapid drying possible. By doing so, growth of undesirable microorganisms is inhibited, salmonellae and staphylococci being most important in this respect, and firm consistency is formed in a very short time. In addition to these basic processes other biochemical changes also take place, of which changes in N‐compounds and in lipids seem to be important in formation of aroma compounds. These changes thus play a definite role in the special palatability feature of raw fermented sausages, which is completely different from any other types of meat products. An interesting activity of starter cultures is their antagonism against undesirable (i.e., pathogenic and spoilage) microorganisms. It seems probable that in addition to acidity (presence of lactic acid formed) exhibiting a nonspecific inhibitive effect, undesirable bacteria are inhibited also specifically by, for example, antibiotics; but formation of hydrogen peroxide, depletion of nutrients, etc., may play a role too. The bacteriological safety of these products is provided by the combined effect of low pH (below 5.3) and low water activity (0.95 or below), which makes it possible to store them even at room temperature without health risk or spoilage.

Positive tip cultures and related risk factors associated with intravascular catheterization in pediatric cardiac patients.

The incidence and risk factors of positive catheter tip cultures were studied prospectively in 392 consecutive children undergoing cardiac surgery under cover of cephalothin prophylaxis. A total of 1649 catheter tips were cultured and 58 (3.5%) yielded positive cultures. Specifically, the incidence of positive catheter tip cultures for iv, central venous, arterial and pulmonary arterial (PA) catheters was 0.9%, 5.9%, 3.9% and 10.6%, respectively, whereas one of the six surgically placed venous and arterial catheters had a positive tip culture and none of the 279 transthoracic catheters. Staphylococcus epidermidis was isolated from 79% of the positive tip cultures. Ten percent of the children had one or more positive tip cultures but none developed catheter-related septicemia or endocarditis. Stepwise logistic regression analysis revealed that longer in situ time (p less than .001), younger age (p less than .001), and inotropic support (p = .003) were significant independent predictors of risk for children developing positive catheter tip cultures. The safe in situ period for arterial, central venous, and PA catheters is 3 days in infants under 1 yr and 4 and 6 days for arterial and central venous catheters, respectively, in older children, if 0.95 cumulative probability of remaining free of a positive tip culture is accepted. The data generally support the bacteriologic safety of invasive hemodynamic monitoring in infants and children undergoing cardiac surgery.