Infection with an Extended-Spectrum β-Lactamase-Producing Strain of Serratia marcescens following Tongue Reconstruction

Abstract

We report a case of postsurgical wound infection of polymicrobial etiology caused by Serratia marcescens and Pseudomonas aeruginosa following the use of a radial forearm free flap for oncological tongue reconstruction. S. marcescens was a producer of SHV-12 extended-spectrum ␤-lactamase (ESBL). This is the first report from India of this ESBL. S. marcescens and P. aeruginosa were resistant to the empirical perioperative antibiotics administered. Delay in the recognition of the type of infection and in the institution of appropriate therapy resulted in total loss of the free flap. CASE REPORTA 39-year-old man was admitted to the surgical oncology ward of the All India Institute of Medical Sciences (New Delhi, India) with a history of a nonhealing ulcer of 1-year duration on the left side of the tongue. An initial examination revealed a 0.5-by 1-cm indurate area on the left ventrolateral surface of the tongue. A biopsy was performed which showed a welldifferentiated squamous cell carcinoma of the left lateral border of the tongue. The tumor was classified as stages T1, N1, and M0.The patient underwent operative treatment consisting of left hemiglossectomy and unilateral supraomohyoid neck dissection. This was followed by reconstruction of the tongue with a radial forearm free flap. An initial regimen of metronidazole, amoxicillin, and clavulanic acid was started postoperatively.Ten days later, there were signs of collection of pus at the postoperative wound site. The pus was drained and sent for bacterial culture. Consecutive cultures obtained from the wound yielded growth of Serratia marcescens and Pseudomonas aeruginosa. S. marcescens is an opportunistic gram-negative bacterium that is associated with sporadic urinary tract infections and pneumonia in patients in intensive care units, although outbreaks can occur (1).Antibiotic susceptibility profiles were done by using a standard disk diffusion method recommended by the NCCLS (7). P. aeruginosa was susceptible to ciprofloxacin, ceftazidime, cefpirome, piperacillin-tazobactam, and cefoperazone-sulbactam. It was resistant to amoxicillin-clavulanic acid, piperacillin, cefotaxime, and amikacin. S. marcescens exhibited resistance to piperacillin, cefotaxime, ceftazidime, ceftriaxone, cefoperazone, cefpirome, amikacin, netilmicin, ciprofloxacin, and amoxicillin-clavulanic acid. It was sensitive to piperacillin-tazobactam and cefoperazone-sulbactam. The strain tested positive, by the method described by the NCCLS (7), for the production of extended-spectrum ␤-lactamase (ESBL).Isoelectric focusing and gene sequencing characterized the ESBL. Isoelectric focusing was performed with polyacrylamide gels containing Ampholine with a pH range of 3.5 to 10 as previously described (2). ␤-lactamases of known isoelectric points (pIs), TEM-1 (pI 5.4), TEM-2 (pI 5.6), TEM-24 (pI 6.5), SHV-5 (pI 8.2), and CTX-M-1 (pI 8.4), were used as standards. Isoelectric focusing showed that the ESBL focused at a pI of 8.4, suggesting that the ESBL of the S. marcescens strain was an SHV-type ␤-l...

Prediction of the Evolution of Ceftazidime Resistance in Extended-Spectrum β-Lactamase CTX-M-9

“…Thirty CTX-M mutants were recovered, and they harbored 38 distinct substitutions at 32 positions. Most positions were located in the vicinity of the binding site and can be categorized into three clusters: positions previously mutated among clinical CTX-M enzymes (positions 167 and 240) (4,8,16,31,33,38), mutated positions observed among ceftazidimase TEM/SHV-type ESBLs (positions 164 and 179) (21), and new mutated positions (Fig. 2).…”

“…However, seven CTX-M mutants harboring point mutations which improve enzymatic efficiency against ceftazidime have been reported recently, suggesting that CTX-Ms are altering their substrate specificity in response to continued antibiotic selective pressure. Five mutants harbor substitution Asp240Gly (4,5,16,29,31), and two mutants harbor substitutions Pro167Ser/Thr (33, 38). These substitutions have not been previously observed in natural TEM or SHV ESBLs, suggesting that CTX-M enzymes have a singular evolutionary potential.…”

Prevalence and clonality of extended-spectrum β-lactamases in Asia

“…Three hundred isolates were collected, 72 (24%) being ESBL producers, 50 being from patients in the community; significantly, 74% and 76% had a history of prior use, at some time, of a cephalosporin and quinolone, respectively [40]. There have been relatively few genotyping studies, but SHV‐12 in K. pneumoniae has been reported from Southern India to be linked to the qnrB plasmid‐mediated quinolone resistance determinant, the first report being from S. marcescens [41,42] There is a report of SHV‐5 produced by Salmonella senftenberg causing an outbreak on a burns ward in Delhi [43]. The only genotype of a TEM ESBL is TEM‐104, reported in ten isolates of K. pneumoniae from New Delhi in 2001–2002 [7].…”

Extended-spectrum beta-lactamase producers: Detection for the diagnostic laboratory

“…While some centers in India have reported a predominance of E. coli , others have reported primarily Klebsiella spp. [ 12 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 ]…”