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Pathogenicity and Virulence
Published in Julius P. Kreier, Infection, Resistance, and Immunity, 2022
Bacteria and fungi make use of mechanisms other than surface structures to prevent phagocytosis. Many organisms secrete exotoxins that interfere with chemo-taxis (the attraction of phagocytes to the site of the invading microbe), impair phagocytosis, or kill the phagocyte. Pseudomonas aeruginosa secretes a protein that impairs chemotaxis and also inhibits lysosomal fusion once phagocytosis has occurred. Several strains of this bacterium also produce a leukocidin, a protein that damages the ceil membrane of leukocytes, resulting in leakage of essential nutrients and cell death. Exotoxin A, produced by most clinical isolates of P. aeruginosa, is similar in action to diphtheria toxin and is lethal to human macrophages.
Infection prevention and control
Published in Nicola Neale, Joanne Sale, Developing Practical Nursing Skills, 2022
Another important feature of S. aureus is its ability to produce toxins, which, in turn, can have the ability to cause significant tissue damage. One of the most significant of these are the Panton-Valentine Leukocidin (PVL) toxin-producing strains that can cause septic arthritis and necrotising pneumonia. These may also be MRSA but commonly meticillin-sensitive strains are also isolated. Due to the serious nature of these infections, specific guidance in relation to the identification and management of PVL S. aureus has been published (HPA 2008).
Acute erythematous rash on the trunk and limbs
Published in Richard Ashton, Barbara Leppard, Differential Diagnosis in Dermatology, 2021
Richard Ashton, Barbara Leppard
Recently, a new strain of Staph. aureus producing Panton-Valentine leukocidin (PVL) has been identified. PVL is a cytotoxin that can destroy white blood cells and cause extensive tissue necrosis. PVL+ve Staph. is usually methicillin -resistant but acquired in the community unlike MRSA. It causes recurrent skin abscesses and cellulitis, which do not respond to routine doses of flucloxacillin or erythromycin.
Novel strategies for rapid identification and susceptibility testing of MRSA
Published in Expert Review of Anti-infective Therapy, 2020
Masako Mizusawa, Karen C Carroll
Application of virulence prediction, for example, to manage patients suspected of having community-acquired pneumonia due to Panton-Valentine leukocidin positive strains, is feasible, but not yet widely applied in clinical practice [189]. Other studies have noted the value of WGS sequencing for predicting resistance. For example, as mentioned earlier in this review, a novel mecA homolog, mecALGA251 (now renamed mecC) was discovered by Garcia-Alvarez et al. when the investigators used WGS to study a bovine SCCmec type – XI MRSA strain that was resistant to methicillin but mecA and PBP2a negative [35]. However, challenges remain for resistance prediction due to loss of resistance determinants carried on mobile genetic elements such as SCCmec cassette in the case of S. aureus [189].
A porcine model of skin wound infected with a polybacterial biofilm
Published in Biofouling, 2018
Pavel Klein, Martin Sojka, Jan Kucera, Jana Matonohova, Vojtech Pavlik, Jan Nemec, Gabriela Kubickova, Rastislav Slavkovsky, Katarzyna Szuszkiewicz, Petr Danek, Miroslav Rozkot, Vladimir Velebny
These bacterial isolates were assessed for associated virulence factors (Table 1). The production of haemolysins was observed as a complete haemolysis zone on Columbia blood agar plates. Gelatinase activity was tested by the method described by Su et al. (1991), and hyaluronidase activity was proven by the method of Frank and Gerber (1981). The presence of leukocidins was tested on raw fraction of leukocytes isolated from fresh citrated porcine blood using a sucrose gradient (Cencic et al. 1998). The isolated cells were exposed to the media from a 24-h culture of a particular bacterial strain in tryptone soya broth (TSB) for 10 min, then stained with trypan blue and counted by a haemocytometer. In the presence of leukocidins, the cells were typically almost completely destroyed. Bacterial strains were maintained in glycerol cryoprotective medium (Test Cryobank B, Itest, Hradec Kralove, Czech Republic), resuscitated on Columbia agar plates supplemented with sheep blood (Oxoid, Wesel, Germany) and incubated at 37°C for 24 h. A sodium chloride peptone broth (buffered peptone bouillon, BPB; Merck, Darmstadt, Germany) was generally used for dilutions and for normalizing the optical density of the cultures.
Hand carriage, antimicrobial resistance and molecular characterisation of methicillin-resistant coagulase-negative staphylococci isolated from gynaecological surgical staff
Published in Journal of Obstetrics and Gynaecology, 2022
Panton–Valentine leukocidin (pvl) gene was amplified by primers: PVL-For, 5′-ACACACTATGGCAATAGTTATTT-3′and PVL-Rev, 5′-AAAGCAATGCAATTGATGTA-3′(Goryachev and Nikolaev 2005), and the mixture and conditions have followed the procedure that was reported by Lina et al. (1999). icaR gene was determined according to Cafiso et al. (2004), and primer icaR F (5′-TACTGTCCTCAATAATCCCGAA-3′) and icaR R (5′-GGTACGATGGTACTACACTTG ATG-3′) were used in this study (Cafiso et al.2004). ica gene detection was applied to all Staphylococcusepidermidis.