Prevalence and molecular analysis of multidrug-resistant Acinetobacter baumannii in the extra-hospital environment in Mthatha, South Africa

ABSTRACT Introduction: The presence of Acinetobacter baumannii outside hospitals remains unclear. This study aimed to determine the prevalence of multidrug-resistance (MDR) A. baumannii in the extra-hospital environment in Mthatha, South Africa and to investigate the frequency of carbapenemase-encoding genes. Material and Methods: From August 2016 to July 2017 a total of 598 abattoir samples and 689 aquatic samples were collected and analyzed presumptively by cultural methods for the presence of A. baumannii using CHROMagar™ Acinetobacter medium. Species identification was performed by autoSCAN-4 (Dade Behring Inc., IL) and confirmed by the detection of their intrinsic blaOXA-51 gene. Confirmed MDR A. baumannii isolates were screened for the presence of carbapenemase-encoding genes, ISAba1 insertion sequence and integrase intI1. Results: In total, 248 (19.3%) Acinetobacter species were isolated. Acinetobacter. baumannii was detected in 183 (73.8%) of which 85 (46.4%) and 98 (53.6%) were recovered from abattoir and aquatic respectively. MDR A. baumannii was detected in 56.5% (48/85) abattoir isolates and 53.1% (52/98) aquatic isolates. Isolates showed high resistance to antimicrobials most frequently used to treat Acinetobacter infections such as piperacillin/tazobactam; abattoir (98% of isolates resistant), aquatic (94% of isolates resistant), ceftazidime (84%, 83%), ciprofloxacin (71%, 70%), amikacin (41%, 42%), imipenem (75%, 73%), and meropenem (74%, 71%). All the isolates were susceptible to tigecycline and colistin. All the isolates carried blaOXA-51-like. The blaOXA-23 was detected in 32 (66.7%) abattoir isolates and 11 (21.2%) aquatic isolates. The blaOXA-58-like was positive in 7 (14.6%) and 4 (7.7%) abattoir and aquatic isolates, respectively. Both groups of isolates lacked blaOXA-24-like, blaIMP-type, blaVIM-type, blaNDM-1, blaSIM, blaAmpC, ISAba1 and inI1. Isolates showed high level of Multiple Antibiotic Resistance Index (MARI) ranging from 0.20-0.52. Conclusion: Extra-hospital sources such as abattoir and aquatic environments may be a vehicle of spread of MDR A. baumannii strains in the community and hospital settings.

Bacteriological Profile and Antibiogram of Aerobic Burn Wound Isolates in Mthatha; Eastern Cape; South Africa

Burn wound colonisation and infection is not only associated with delayed wound healing and scar formation; but may also lead to sepsisrelated mortality. A wide variety of microorganisms; like staphylococcus aureus; Pseudomonas aeruginosa; and Enterobacteriaceae-like Klebsiella pneumoniae and Escherichia coli; are involved. Resistance is generally increasing; with reports of multidrug-and pan-resistant isolates. This study was conducted to determine the common aerobic bacterial isolates in our setting and describe their antimicrobial susceptibility. This retrospective; descriptive study was carried out on 243 patients; from whom 312 burn wound specimens were received by the Nelson Mandela Academic Hospital microbiology laboratory of the National Health Laboratory Service; Mthatha. All samples were processed according to standard laboratory protocols; isolates were tabulated according to age and gender of the patients; and their percentage susceptibilities to relevant antibacterials were computed. A total of 229 patient specimens showed growth on culture. The total number of isolates was 629; out of which 269 were Gram-positive cocci and 360 were Gram-negative bacilli. The commonest organism was S. aureus (27.7); followed by K. pneumoniae (13.4); Proteus mirabilis (12.4); Group D streptococcus (9.4); P. aeruginosa (8.9) and E. coli (6.2). A generally high level of resistance was observed in many organisms. Methicillinresistant S. aureus accounted for 57.5 of the S. aureus. Resistance among the Gram-negative bacilli was; in general; least to imipenem; amikacin and ciprofloxacin. The common organisms causing burn wound infections in our setting include staphylococci; Klebsiella; Proteus and Pseudomonas and there is a high level of resistance against commonly used antimicrobials. Regular surveillance of burn wound organisms and their antimicrobial resistance patterns will help in determining empirical antibiotic therapy for subsequent related septic events