Ans. D. Plain catgut. (Ref. Bailey and Love 26th/pg. 36. Table 18.1).While plain Catgut or Chromic catgut often causes bacterial infection due to inflammatory tissue reaction. Reaction to catgut depends on the stage of absorption and is mainly histocytic in type. Nonabsorbable sutures are encapsulated by a rim of connective tissue, while near the suture histocytes, giant cells and lymphocytes are found. This is most marked with silk and cotton, less so with Dacron, and least with nylon and wire.# All the natural sutures, silk, cotton, linen and catgut, are being replaced by polymeric synthetic materials that cause minimal inflammatory reactions, are of predictable strength and absorb at an appropriate rate. They can be manufactured as monofilaments or braids, and can be coated with wax, silicone or polybutyrate to allow them to run smoothly through tissues and to knot securely. The absorbables cause a minimal tissue reaction as they are resorbed. To aid in the prevention of postoperative infection, particularly after prosthetic surgery, absorbable synthetic sutures may be impregnated with an antiseptic (Vicryl Plus, a polyglactin, is impregnated with triclosan).# The integrity of some synthetic non-absorbables in holding healing tissues together can last indefinitely, such as the use of polypropylene in arterial anastomosis. Polyamide (nylon) is slowly biodegradable and therefore not suitable for this purpose. Many nonabsorbables are presented as monofilaments, which eliminates interstices in the thread and makes knots less likely to be a nidus for infection by reducing the risk of bacterial biofilms and adherence, but requires more skill in tying secure knots# Polyglyconate is newest synthetic monofilament absorbable suture. It is sterile, noncollagenous, nonantigenic, nonpyrogenic. It elicits only slight tissue reaction during absorption, absorption is by nonenzymatic hydrolytic process.Absorbable suturesSutureTissue reactionHow suppliedCommon indicationsContraindicationsCatgut plainHigh6/0-1 with needles; 4/0-3 without needlesLigate superficial vessels, suture subcutaneous tissuesStomas and other tissues that heal rapidlyNot for use in tissues which heal slowly and require prolonged supportCatgut chromicModerate6/0-3 with needles;5/0-3 without needlesAs for plain catgut PolyglactinMild8/D--2 with needles;5/0-2 without needlesGeneral surgical use where absorbable sutures required, e.g. gut anastomoses, vascular ligatures. Has become the 'workhorse' suture for many applications in most general surgical practices, including undyed for subcuticular wound closures. Ophthalmic surgeryPopular in some centres as an alternative to Vicryl and PDS.Not advised for use in tissues which require prolonged approximation under stressPolyglyconateMild7/0-2 with needles Not advised for use in tissues which require prolonged approximation under stressPolyglycolic acidMinimal9/0-2 with needles;9/0-2 without needlesUses as for other absorbable sutures, in particular where slightly longer wound support is requiredNot advised for use in tissues which require prolonged approximation under stressPolydioxanone (PDS)MildPolydioxanone suture (PDS) 10/0-2 with needlesUses as for other absorbable sutures, in particular where slightly longer wound support is requiredNot for use in association with heart valves or synthetic grafts, or in situations in which prolonged tissue approximation under stress is requiredPolyglycaproneMild8/0-2 with needlesSubcuticular in skin, ligation, gastrointestinal and muscle surgeryNo use for extended suppNon-absorbable suturesSutureTissue reactionCommon usesContraindicationsSilkModerate to high.Not recommendedConsider suitable absorbable or non-absorbableLgation and suturing when long-term tissue support is necessary for securing drains externallyNot for use with vascular prostheses or in tissues requiring prolonged approximation under stress Risk of infection and tissue reaction makes silk unsuitable for routine skin closureLinenModerateLigation and suturing in gastrointestinal surgery. No longer in common use in most centresNot advised for use with vascular prosthesesSurgical steelMinimalClosure of sternotomy wounds, Previously found favour for tendon and hernia repairsShould not be used in conjunction with prosthesis of different metalNylonLowGeneral surgical use, e.g. skin closure, abdominal wall mass closure, hernia repair, plastic surgery, neurosurgery, microsurgery, ophthalmic surgeryNonePolyesterLowCardiovascular, ophthalmic, plastic and general surgeryNonePolybutesterLowExhibits a degree of elasticity. Particularly favoured for use in plastic surgeryNonePolypropyleneLowCardiovascular surgery, plastic surgery, ophthalmic surgery, general surgical subcuticular skin closureNone