|Year : 2012 | Volume
| Issue : 4 | Page : 476-479
Necrotizing fasciitis caused by a variant of epidemic methicillin resistant Staphylococcus aureus -15
S Govindan1, B Chakrakodi2, S Prabhakara2, G Arakere2, S Kumar3, I Bairy1
1 Department of Microbiology, Melaka Manipal Medical College, Manipal University, Manipal, India
2 Society for Innovation and Development, Indian Institute of Science, Bangalore, India
3 Department of Surgery, Kasturba Medical College, Manipal, Karnataka, India
|Date of Submission||30-May-2012|
|Date of Acceptance||14-Jun-2012|
|Date of Web Publication||24-Nov-2012|
Department of Microbiology, Melaka Manipal Medical College, Manipal University, Manipal
Source of Support: None, Conflict of Interest: None
We report a case of necrotizing fasciitis (NF), caused by community-acquired epidemic methicillin resistant Staphylococcus aureus 15 (EMRSA 15). The patient had a prolonged recovery period following treatment with antibiotics and surgical debridement of the infected part. Molecular characterization revealed that the isolate carried Staphylococcal Cassette Chromosome mec (SCC mec) type IV harboring Panton-Valentine Leucocidin (pvl) gene and having accessory gene regulator (agr) type I. The isolate was positive for enterotoxin gene cluster (egc). Pulsed field gel electrophoresis patterns revealed that the isolate belonged sequence type 22, which is an Indian variant of EMRSA 15, reported earlier.
Keywords: Epidemic methicillin resistant Staphylococcus aureus 15, necrotizing fasciitis, pulsed field gel electrophoresis
|How to cite this article:|
Govindan S, Chakrakodi B, Prabhakara S, Arakere G, Kumar S, Bairy I. Necrotizing fasciitis caused by a variant of epidemic methicillin resistant Staphylococcus aureus -15. Indian J Med Microbiol 2012;30:476-9
|How to cite this URL:|
Govindan S, Chakrakodi B, Prabhakara S, Arakere G, Kumar S, Bairy I. Necrotizing fasciitis caused by a variant of epidemic methicillin resistant Staphylococcus aureus -15. Indian J Med Microbiol [serial online] 2012 [cited 2020 Feb 20];30:476-9. Available from: http://www.ijmm.org/text.asp?2012/30/4/476/103778
| ~ Introduction|| |
Necrotizing fasciitis (NF) is a rapidly progressive life threatening infection of the skin and soft tissue including deep fascia, which leads to gross morbidity and mortality if left untreated. Most often, it is associated with polymicrobial etiology. Staphylococcus aureus (S. aureus) is one of the agents reported in monomicrobial type of NF especially when it is acquired from the community.  A retrospective study of NF cases conducted at Los Angeles reports that community associated methicillin resistant S. aureus (CA MRSA) was the pathogenic agent in one-third of their samples.  Epidemic methicillin resistant Staphylococcus aureus (EMRSA 15) originated as a hospital pathogen in United Kingdom in the early nineties which then disseminated throughout the world as CA MRSA. A variant of EMRSA- 15 has been reported from various carriers and disease isolates in India.  Here we report a case of NF caused by this Indian variant of EMRSA 15.
| ~ Case Report|| |
A 48-year-old laborer, who was previously healthy presented to surgery at the outpatient department (OPD) with complaints of severe pain and swelling on his right lower limb in the preceding week. There was no history of trauma or decreased sensation of the leg at the time of presentation and the patient was conscious. His heart rate was 130 beats per minute and blood pressure was 120/90 mmHg. At the time of hospitalization, he was febrile. His right lower limb was edematous, red, warm, and tender and it was discolored, initially reddish and became dark at the time of the visit. His right thigh had multiple blackish patches and blisters filled with turbid fluid. This was suggestive of necrotizing soft tissue infection. No inguinal lymphadenopathy was noticed. A peripheral pulse of the lower limb was palpable. The surgeon admitted the patient with a diagnosis of NF of right thigh. On laboratory diagnosis he was found to be diabetic with a fasting blood glucose level of 143 mg/dL and postprandial blood sugar of 267 mg/dL.
In addition to antibiotics, a surgical debridement of the wound was performed under spinal anesthesia on the day of admission. During this time a swab from the infected tissue was collected and sent for microbiological investigations. The sequence of events and treatments are presented in [Table 1]. There was a pus discharge from the gluteal region and anterior thigh, which were regularly irrigated. His blood glucose level was managed well during that time. Due to heavy loss of tissue at the infected area, a split skin graft (SSG) was done under spinal anesthesia almost a month later. The graft was taken up well except at knee joint and upper thigh where pus kept pouring for few more days. A second graft was done after a month during which a drain was put for the pus. A pus sample was cultured during this time. Patient also developed a foot right drop, indicating neurological manifestation.
Both specimens were processed by inoculating into 5% sheep blood agar (Fi Tech Biosciences, Bangalore) and Mac Conkey agar (in house preparation) and incubated at 37°C aerobically for overnight. A heavy growth of S. aureus was noticed in the sample obtained during the first wound debridement (laboratory code: Ro 1087) and a scanty growth of S. aureus was obtained from the second sample, which was collected just before the patient got discharged (laboratory code: Ro 370). The organism was identified based on the observation of gram positive cocci in clusters, catalase production, and positive tube coagulase test. It was further confirmed by S. aureus latex agglutination test (Hi Media, Mumbai). Kirby Bauer's disk diffusion test for antibiotic susceptibility showed resistance to 30 μg disc of cefoxitin, which was suggestive of methicillin resistance.  The strain showed resistance to all the beta-lactam antibiotics tested, which included amoxicillin-clavulanic acid, ampicillin and all generations of cephalosporins. It also showed resistance to ciprofloxacin, erythromycin and gentamicin. But the strain was susceptible to nonbeta-lactam antibiotics like amikacin, cotrimoxazole, tetracycline, clindamycin, linezolid, rifampicin, teicoplanin and vancomycin.
Molecular characterization of the isolate was carried out by determining the SCC mec element type, agr type, staphylococcal protein A (spa) type, and presence of Panton-Valentine Leucocidin (pvl) gene by using published procedures for polymerase chain reaction (PCR) and multiplex PCR. , The SCC mec element was determined as type IV by the presence of downstream constant region (dcs), cassette chromosome recombinase (ccr) B2 [Figure 1] by multiplex PCR and also the presence of IS1272. The isolate was pvl and enterotoxin gene cluster (egc) positive, and belonged to the agr type I and sequence type (ST) 22. ,, The spa type was t 852.  Pulsed field gel electrophoresis (PFGE) with Sma I restriction digestion of the isolate was performed as reported before.  [Figure 2] depicts the PFGE pattern of the isolate that resembles the variant EMRSA 15 isolates, which we have reported earlier.  The PFGE pattern of the Indian variants and the current strain differed from the classical EMRSA 15 by 3-4 bands and was closely related to it.
|Figure 1: Multiplex PCR for SCCmec typing of the isolate. Lanes: M. 50 bp ladder; (1.) USA 300 (Type IV); (2.) Ro 1087 (Type IV); (3.) Ro 370 (Type IV)|
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|Figure 2: PFGE pattern of the isolate Ro 1087 and Ro 370 after SmaI digestion. (Lane 1.) NCTC 13142 (classical EMRSA 15); (Lane 2.) Ro 1087; (Lane 3.) Ro 370; (Lane 4.) 113 (Indian variant of EMRSA15); (Lane 5.) NCTC 8325|
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In view of the prolonged course of disease and financial problem, the patient requested for discharge. At discharge his condition was improved and he was advised to take cotrimoxazole and required to revisit after a month. He returned to the OPD after a month and the wound was almost healed [Figure 3]. The sample collected at this time did not grow any bacteria indicating a complete recovery from the infection.
|Figure 3: Wound of the patient during the revisit to the hospital after 3 months|
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| ~ Discussion|| |
This patient was previously healthy, going to regular work as a laborer and had not needed any medical assistance in the past one year. This indicates that there were no predisposing conditions for MRSA infections in this patient pointing to perhaps community involvement. When the patient was screened for colonization of MRSA in anterior nares, gluteal area or axillary region no MRSA has been grown (not reported in this case report). NF is commonly associated with polymicrobial infections. Even though it is well known that S. aureus is the most common agent associated with NF of mono microbial type, the incidents are comparatively less. Repeated isolation of same epidemiological type of S. aureus substantiates the pathogenic role of the isolate with the presence of toxins like pvl and egc. EMRSA 15 has been reported earlier as being associated with infections of the skin and soft tissue but NF is not common.  The original EMRSA-15 reported from hospitals in the United Kingdom did not contain the pvl gene. Subsequently, pvl producing EMRSA 15 has been reported in hospital isolates from various countries. , The coexistence and circulation of CA MRSA and hospital associated EMRSA 15 with pvl and egc genes in Kuwait hospitals demonstrate the epidemic nature of EMRSA 15.  All these classical EMRSA 15 were existed in the hospital environment or causing infections in the hospitalized patients. Current report of NF is caused by a variant EMRSA 15, which was acquired from the community. The epidemiological significance of the current variant strain is its acquisition of pvl and egc toxins. The Indian variants also differ in PFGE patterns by 3-4 bands indicating the genetic changes they have undergone and the additions of toxins, which perhaps can increase the virulence of this bacterium. This case indicates that the same Indian variant of EMRSA 15 can cause NF. The signs of improvement shown by this patient convey that the treatment in infections caused by CA MRSA is not a major challenge rather the virulence of the organism is of major concern. Epidemiological typing of MRSA isolates associated with community acquired infections are very important due to their increased ability to cause severe infections like NF and necrotizing pneumonia. Early detection can prevent prolonged morbidity and better treatment options.
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[Figure 1], [Figure 2], [Figure 3]