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Now here is an interesting study where the aim of this double-blind, randomised cross-over study was to compare the antibacterial effect and the substantivity of two toothpaste formulations containing amine fluoride (AmF) or zinc chloride (ZnCl2).

After a professional tooth cleaning, 20 volunteers refrained from all oral mechanical hygiene measures for the subsequent 24 hours (day 0). Subsequently, a plaque sample was taken from three teeth and analysed for vitality of the plaque bacteria by means of the vital fluorescence technique (VF0; in %). After assessment of this baseline value the subjects had to brush their teeth for 2 minutes with 1.2 ml of the allocated toothpaste containing (a) 0.66% AmF or (b) 0.2% ZnCl2. For the following 8 hours no oral hygiene measures were allowed. After 4 and after 8 hours further plaque samples were analysed for biofilm vitality (VF4, VF8). During the following 3 days the volunteers had to brush twice daily for 2 minutes with the allocated toothpaste. On day 4, plaque index was assessed using the criteria of Quigley and Hein (Turesky modification). After a washout time of 9 days the next test cycle with the other toothpaste was started.

The results from both toothpastes reduced the biofilm vitality significantly at VF4 and VF8 compared with VF0 (p < or =0.001). While after 8 hours the vitality values for the ZnCl2-toothpaste obtained significantly higher reductions (53%) than for the AmF-toothpaste (44%), results for plaque index were not significantly different (0.98 and 1.04 respectively).

Finally both toothpastes showed a significant and prolonged anti-bacterial effect up to 8 hours with a benefit in favour of the ZnCl2 toothpaste.

Oral Health Prev Dent. 2007;5(1):25-32.
Auschill TM, Deimling D, Hellwig E, Arweiler NB
Department of Operative Dentistry and Periodontology, Albert-Ludwigs-University, Freiburg, Germany. thorsten.auschill@uniklinik-freiburg.de

Over the past twenty years, the rapid emergence and increased prevalence of opportunistic Gram-negative bacilli demonstrating resistance to the β-lactam class of antibiotics has become a major health care crisis.

The production of β-lactamases, the innate capabilities of these organisms to genetically adapt structural and regulatory genes and the ease with which resistance genes are transferred via plasmids, transposons and integrons between different species, have broadened the ability of Gram-negative bacteria to inactivate the β-lactam antibiotics. This diminishes the clinical utility of these key anti-microbial agents making them resistant.

Extended spectrum β-lactamases (ESβLs) hydrolyse the penicillins, first-, second- and third-generation cephalosporins, especially cefotaxime, ceftriaxone, ceftazidime and cefpodoxime, and the oxyimino-monobactam, aztreonam.

ESβLs are inhibited by β-lactamase inhibitors, such as clavulanic acid, and are susceptible to the carbapenems (imipenem, meropenem and ertapenem) and the cephamycins (cefoxitin and cefotetan), though there have been a number of reports stating that ESβL-producing organisms can become resistant to the cephamycins due to the loss of an outer membrane porin protein (Martinéz-Martinéz et al 1996).

Since their discovery following the clinical introduction of the third-generation oxyimino-cephalosporins in 1981, there are now approximately 160 Temoneira (TEM), 100 sulfhydryl-variable (SHV), 64 cefotaxime-hydrolysing (CTX-M) and 102 oxacillinase (OXA) variant enzymes, along with a number of minor ESβL variants (Jacoby and Bush 2007).

Extensive laboratory and clinical experience exists regarding the detection and treatment of ESβL-producing Gram-negative bacilli. This suggest that the knowledge of their existence via means of antibiotic selective pressure, adaption and dissemination, may have an impact on therapeutic choices and the health and well-being of patients via targeted pragmatic antimicrobial selection and infection control practices.

It is unclear; however, if ESβL-producing organisms are being accurately detected 100% of the time. Furthermore, with the recent emergence of metallo β-lactamase-producing Gram-negative bacilli, it is also unclear whether the same mandate exists for the accurate detection, treatment and control of metallo β-lactamases. Metallo β-lactamases (MβLs) are a therapeutic disaster.

These enzymes hydrolyse all β-lactam antibiotics (except the monobactams), including the “drugs of last resort” the carbapenems (imipenem and meropenem), thus requiring the use of alternative, potentially more toxic classes of antibiotics to circumvent the hydrolytic actions of these β-lactamases.

Metallo β-lactamases, which are found in organisms such as Pseudomonas aeruginosa, Acinetobacter specie and members of the Enterobactericeae group such as salmonella and especially Escherichia coli and Klebsiella pneumoniae. They all utilise metal ions (usually zinc) to coordinate water molecules that serve as nucleophiles and hydrolyse the amide bond of the β-lactam ring, rendering the β-lactam antibiotic inactive.

These enzymes are divided into four genetically mobile variants: the older imipenem-hydrolysing (IMP) and Verona integron-encoded metallo β-lactamase (VIM) enzymes; and the more recently described Sao Paolo metallo β-lactamase (SPM) and GIM types (Poirel et al 2004).

Gram-negative bacteria that produce extended-spectrum and metallo β-lactamases are being discovered and isolated at a significant rate worldwide, while the development of new synthetic and natural antimicrobial agents to combat and elude the hydrolytic actions of these β-lactamases has significantly decreased in recent years (Valenzuela et al 2004).

Clinicians prescribing antibiotics need to know, understand and appreciate the short and long term outcomes of the inappropriate use of antibiotics for their patients, which, if not controlled and decreased, will inevitably reduce or eliminate the therapeutic options available in the future.

References

Franklin, C., Liolios, L., Peleg, A.Y. (2006). Phenotypic detection of carbapenem-susceptible metallo β-lactamase-producing Gram-negative bacilli in the clinical laboratory. Journal of Clinical Microbiology, 44: 3139-3144.

Martinéz-Martinéz, L., Hernández-Allés, S., Albertí, S., Tomás, J., Benedi, V., Jacoby,G.A. (1996). In vivo selection of porin-deficient mutants of Klebsiella pneumoniae with increased resistance to cefoxitin and expanded-spectrum cephalosporins. Antimicrobial Agents and Chemotherapy, 40, pp. 342-348.

Poirel, L., Heritier, C., Spicq, C., Nordmann, P. (2004). In vivo acquisition of high-level resistance to imipenem in Escherichia coli. Journal of Clinical Microbiology, 42 (8), pp. 3831-3833.

Valenzuela, J., Thomas, L., Iredell, J. for Australian Society of Microbiology (ASM). (2004). Beta-lactam resistance in Gram-negative bacteria. Antimicrobial Susceptibility Testing: Methods and Practices with an Australian Perspective, 5, pp. 127-157.

Mycobacterium tuberculosis has thrived in South Asia for over 100 years, but until now no one had studied the diversity of the strains present. To do this, Niyaz Ahmed and his colleagues from the University of Hyderabad, India, analysed 91 samples of tuberculosis taken from all over the country, studying the number and type of short, repetitive DNA sequences within three key genes.

They discovered that the ancestral strain is widespread, suggesting that India is the ancient reservoir for tuberculosis, from which more recent strains evolved and spread to other countries.

This may have enabled the immune systems of people living there to adapt to it, providing some degree of protection. However, that might be about to change, because the Indian population is far less well adapted to a recent strain of tuberculosis known as Beijing strain, found in India only since 2002. This highly infectious strain is threatening to replace the ancestral one, says Ahmed, who presented his results at a conference in Bangkok, Thailand, last month. Coinciding with a surge in HIV cases, this could spell disaster for the 5.7 million Indians infected with the virus.

Source: 10 January 2007 From New Scientist Print Edition issue 2585, page 15

There have been increasing numbers of applications using oral fluids, saliva in particular, as the target substrate for performing clinical diagnostic tests. These have focused primarily on point of care (POC) testing.

These POC testing approaches range from, for example, currently available, highly specialized screening tests for the presence of antibodies recognizing HIV to the potential development of “lab-on-a-chip” platforms. Broad claims have been made that the latter will revolutionize clinical laboratory testing.

From the perspective of large centralized clinical laboratories, multiple issues must be considered before implementing individual tests using saliva as the target fluid in a POC format or using saliva as a universal test fluid for measuring multiple analytes in a centralized laboratory format.

The current scope of laboratory testing is large and comprehensive, involving both POC and centralized testing. Current academic laboratory programs have the ability to qualitatively identify and/or quantitatively measure several thousand analytes in various target matrices including blood, plasma, serum, urine, joint fluid, pleural fluid, peritoneal fluid, cerebrospinal fluid, and tissue. These tests fall into multiple clinical pathology disciplines, including clinical chemistry, hematology, coagulation, transfusion medicine, microbiology, cytogenetics, molecular diagnosis, and immunology.

In addition, before implementing a given test, multiple issues need to be evaluated to ensure the validity of the reported result; these include considerations involving the three major phases of testing: pre-analytical (e.g., patient identification and specimen collection, stability, and transport), analytical (e.g., sensitivity, specificity, accuracy, and precision), and post-analytical (e.g., reporting results, quality improvement, and turn-around-time).

Ann N Y Acad Sci. 2007 Mar;1098:192-9. Pesce MA, Spitalnik SL
Department of Pathology, College of Physicians

According to the Lancet, a new treatment for Candida species has been proven to be equally effective and with les side effects than the current treatment. Candida, especially Candia albicans is a yeast fungus that multiplies rapidly and cause thrush (infection of the vagina). Candida can also cause sepsis which is a life-threatening infection leading to fever, hypotension, and shock.

Researchers led by Oliver Cornely, from the University Hospital of Cologne, Germany, tested the effectiveness of two well known treatments, liposomal amphotericin B and micafungin, against the common infections candidaemia and invasive candidosis.

A total of 531 patients with these infections were split into two groups and given either micafungin 100mg per day or liposomal amphotericin B 3mg per kg body weight daily. The success rate of both drugs was almost exactly the same – 89.6% for micofungin versus 89.6% for liposomal amphotericin B.

The effectiveness of either treatment was independent of primary site of infection and the patient’s immune status, and whether or not a catheter had been fitted during treatment.

But micafungin produced fewer treatment related side effects than liposomal amphotericin B. Increased problems with kidney function, as well as higher occurrence of problems during drug administration, were observed in the patients receiving liposomal amphotericin B.

The authors conclude: “Our results establish micafungin as a treatment option for first-line therapy of candidaemia and invasive candidosis.”

They add: “Micafungin also has broad-spectrum activity against Aspergillosis species, thus to assess its efficacy in the treatment of invasive aspergillosis will be an important future goal.”

Source

A multiple antibiotic resistant strain of pseudomonas aeruginosa known as (Methicillin Resistant Pseudomonas Aeruginosa (MRPA) has forced the cancellation of some elective cardio thoracic and neurological surgery cases in the Royal North Shore (Australia).

Because of this outbreak, the intensive care unit remained closed this week until the bacteria is eliminated from the area.

The neurological surgery ward (6C) of the Intensive Care Unit within the hospital was closed prior to Easter and patients were moved to another section of intensive care while cleaning and sanitation of the area took place.

Environmental swabs are currently being tested for the suspect bacterium and the ward is expected to be re-opened this week once the area is confirmed free of this strain of bacterium.

MRPA was isolated and identified on 10 patients during the late March and this prompted the management of the hospital to take aggressive measures including isolating infected patients before closing the affected ward and basically bombing the area with super grade disinfectant.

Pseudomonas aeruginosa is commonly found in soil and water; however there are a few strains that have started to build up resistant against front line antibiotics. Once these strains multiply and become the dominant type within the environment, we have a real problem especially if patients using life-saving antibiotics are located in the same area.

According to a spokesperson within the hospital, they say that the hospital usually has about 30 to 40 cases of MRPA a year, mostly in intensive care wards.

Patients with confirmed MRPA were being cared for in isolation with treatment for their primary illness continuing without interruption. Their families were permitted to visit but had to follow infection control procedures such as washing hand before and leaving the hospital grounds.

Bird flu has again struck another victim in Egypt bringing the toll to 14. Marianna Kameel Mikhail who was 15 years old contracted the H5N1 bird flu virus last week.

She was admitted to hospital in Cairo on Thursday and died of respiratory failure on Tuesday evening. Although being treated in hospital with the antiviral Tamiflu, it was too late as she was admitted 7 – 10 days after developing advance symptoms. None of her family members were found to have the virus.

With a total of 34 humans who have caught bird flu in Egypt, 14 have died and 19 have recovered. A two-year-old girl from central Egypt is under treatment and is in good condition.

Egypt has the highest number of confirmed human bird flu cases outside Asia.

According to the Japanese Times, a 1 year old boy in the Kanto region of Japan died of severe pneumonia last year after being infected with a highly virulent strain of community-associated methicillin-resistant Staphylococcus aureus (MRSA), medical professionals said Sunday.

This was the first time that a fatal case was confirmed in Japan resulting from infection with community-associated MRSA, whose contagion within a community or a school has been feared, they said.

Community associated MRSA as opposed to the more common hospital associated MRSA has already become a big issue in Europe and the United States but has gained little public attention in Japan.

“We do not have to worry too much about it because a highly virulent strain is rare within community-associated types, but we need to strengthen monitoring activities to prepare for greater infection with the bacteria,” said Tatsuo Yamamoto, a professor of bacteriology at Niigata University.

According to Kitasato University Hospital in Sagamihara, Kanagawa Prefecture, where the boy was treated, he exhibited symptoms such as a fever and coughing and was diagnosed with pneumonia at a different general hospital. He was later admitted to Kitasato University Hospital and received treatment that included antibiotics, but he died about 10 days later. The antibiotics resistant staphylococcus was found in his blood sample.

While the boy had never been hospitalized before, a laboratory test showed that the genetic structure of the bacteria found in his blood matched that of community associated MRSA and that the strain was highly virulent, capable of producing a toxin that kills white blood cells, according to the hospital.

It is not clear how the bacteria got into him.

“It is known that MRSA has a community associated type, but this is the first time that I have encountered a strain as highly virulent as this,” said Yuki Bando, a lecturer at Kitasato University Hospital’s pediatric department. “The existence of a highly virulent strain has hardly been recognized in the medical field, so I would like to call attention to it.”

MRSA has been commonly known as the major bacteria which infects patients in hospitals around the world, but concerns have been expressed in recent years that infections could also occur outside hospitals.

It is believed that people could be infected with MRSA through skin contact during sports and communal life.

So far, the types of community-associated MRSA found in Japan are known to have caused rashes on the skin, but some cases have been reported in which people suffered seriously due to highly virulent strains of MRSA.

Worldwide, highly virulent strains have caused major infections. A series of fatal causes were reported in France and the United States in the late 1990s, prompting concerns about the spread of community-associated MRSA.

Source

A strain of bacterium could easily develop drug-resistance and become a major health threat, warn scientists.

A study, published on the 21 March 2007 in PLoS ONE, found that the drug-resistance genes in a plague bacterium from a 1995 case of the disease were the same as those in many common bacteria and are able to ‘jump’ from bacteria to bacteria.

The researchers say this illustrates how easily Yersinia pestis, the bacterium causing plague can develop resistance to antibiotics, which are vital in the treatment and prevention of the disease. There is no vaccine available for plague and this represents a significant public health concern.

A new multi-drug-resistant form of Yersinia pestis was found in a 16-year-old boy in Madagascar (1995). The strain had developed resistance against eight different groups of antibiotics including streptomycin and tetracycline.

Researchers discovered that the genes conferring this resistance are also in common food poisoning bacterium such as salmonella, E. coli, klebsiella, shigella and listeria from market samples of beef, pork, chicken and turkey in the United States.

As these genes are able to transmit themselves between bacteria, it raises the possibility of drug resistant Yersinia pestis emerging easily.

Lead author Jacques Ravel, of the US-based Institute for Genomic Research, says, “Our agricultural and medical use and abuse of antibiotics is generating a large reservoir of bacteria carrying resistance genes. These genes can transfer from bacteria to bacteria.”

The key to controlling any outbreak of plague lies in prompt treatment with common antibiotics such as tetracycline and streptomycin, which can reduce death rates from 60 to 15 per cent.

Kamal Krishna Datta, former director of India’s National Institute of Communicable Diseases who oversaw the 1994 plague outbreak in Surat, western India says the discovery “needs to be widely shared and discussed and the disease surveillance mechanism strengthened through a global network.”

In the past five years alone, plague has been reported in Algeria, India, Malawi and Zambia. The last reported case was in the Democratic Republic of Congo in 2006.

Although it has been suspected as being good for your health, probiotics may also protect against food poisoning.

Irish scientists report that a combination of five probiotic strains may reduce food poisoning by salmonella, if results of their pig study can be translated to humans.

“The administered strains of probiotic bacteria improved both the clinical and microbiological outcome of Salmonella infection in pigs,” wrote the researchers, led by Colin Hill from University College Cork. “Unlike the normal Lactobacillus acidophilus or bifidobacterium probiotic bacteria, these strains offer significant benefit for use in the food industry and may have potential in human applications.”

According to the European Commission, salmonella induced food poisoning costs the UK economy alone around €1.5 billion each year, with 160,000 cases reported annually Europe-wide. In addition about 1.4 million Americans are estimated to suffer annually from salmonella, according to the Centers for Disease Control and Prevention.

The new research divided 15 weaned pigs and fed them milk supplemented with a mixture of five Lactobacillus probiotic strains (two strains of Lactobacillus murinus and one strain each of Lactobacillus salivarius sub specie salivarius, Lactobacillus pentosus, and Pediococcus pentosaceous), or placebo (regular milk) for 30 days.

After six days of the probiotics, the pigs were given an oral dose of Salmonella enteritica serovar Typhimurium. The health and microbiology of the faeces were monitored for 23 days.

According to the researchers in the journal Applied and Environmental Microbiology, the pigs receiving probiotics showed reduced incidence, severity and duration of diarrhea. It was also significantly lower in numbers of Salmonella from faecal samples after 15 days post-infection.

The probiotic milk group also gained more weight than the control pigs, they said.

Probiotic products containing ‘friendly’ bacteria are now well accepted by consumers in many European countries, with putative benefits highlighted for gut and immune health.

The benefits for gut health have been reported to be due to the probiotic bacteria adhering to the walls of the intestine, which inhibits the ability of the pathogenic Salmonella to stick and colonise the gut, thereby reducing the infection.

Further research is needed, particularly on whether similar positive results are obtainable in human subjects.

Source: Applied and Environmental Microbiology
Volume 73, Issue 6, Pages 1858-1863
“A five-strain probiotic combination reduces pathogen shedding and alleviates disease signs in pigs challenged with Salmonella enterica serovar Typhimurium.”
Authors: P.G. Casey, G.E. Gardiner, G. Casey, B. Bradshaw, P.G. Lawlor, P.B. Lynch, F.C. Leonard, C. Stanton, R.P. Ross, G.F. Fitzgerald, C. Hill.