Prevalence of AmpC β-Lactamase Production and Antimicrobial ResistancePatterns among Proteus spp. at a Tertiary Care Hospital in Lahore

Background

&

Objective

AmpC beta-lactamase production among Gram-negative bacteria is an emerging therapeutic challenge due to resistance to several beta-lactam antibiotics. Limited local data are available on AmpC production among Proteus species. The main objective of this study was to determine AmpC beta-lactamase production in Proteus species using phenotypic methods and assess their antibiotic resistance patterns. METHODOLOGY: This cross-sectional study was conducted at the Microbiology Laboratory, Department of Pathology, King Edward Medical University/Mayo Hospital, Lahore, Pakistan, during 01-02-2025 to 31-10-2025. Sixty nonduplicate clinical isolates of Proteus spp. were included. Identification was based on Gram staining, colony morphology, swarming motility, and biochemical testing. Antimicrobial susceptibility was determined by Kirby–Bauer disc diffusion according to CLSI guidelines (M100, 35th edition, 2025). Isolates with a cefoxitin zone <18 mm were screened for AmpC production and further evaluated using the AmpC disc test and Modified Hodge Test. Data were analyzed using SPSS version 27.

Results

Of 60 isolates, 41 (68.3%) were from males and 19 (31.7%) from females. AmpC production was detected in 7 (11.7%) isolates by the AmpC disc test and 6 (10.0%) by the Modified Hodge Test. Highest resistance was observed to amoxicillin-clavulanate (93.3%), cefotaxime (83.3%), ceftriaxone (85%), and ciprofloxacin (68.3%). Resistance to meropenem and piperacillin-tazobactam was 6.7% and 10.0%, respectively.

Conclusion

A significant number of AmpC beta lactamase proteus was found, which also showed MDR. Regular diagnostic labs should have no trouble incorporating these phenotypic detection techniques. KEY WORDS: AmpC Beta- lactamase, Antibiotic resistance, Cefoxitin Hodge test, Enterobacteriaceae, MDR, Proteus species.