Acinetobacter spp are Gram negative, coccobacillus and strict aerobes Munoz, Robert and Weinsten, (2007). They play significant role in the colonization and infection of patients admitted to the hospital Schr-eckenberger, Daneshvar and Weyant, (2007). It is an opportunistic pathogen found to be associated with a wide spectrum of infection including nosocomial pneu-monia, meningitis, endocarditis, skin and soft tissue infections. Others are Urinary tract infection, conjunct-tivitis, burns, wound infections and bacteraemia Gerner, Tjernberg and Ursing, (1991). Carbapenems have long been thought of as the agents of choice for serious A. baumannii infections Davis et al. (2004). However, the clinical utility of carbapenems is increasingly jeopar-dized by the production of carbapenemases. Outbreaks of infection caused by strains of A. baumannii resistant to multiple antibiotics classes including carbapenems, are a serious concern in many specialized hospitals units, including intensive care unit (ICUS). The fore-most implication of infection with carbapenem-resistant A. baumannii is the need to use “last-line” antibiotics such as colistin, polymyxin B, or Tigecycline David et al. (2012). Selection of empirical anti-biotic therapy when A. baumannii is suspected, it is challenging & must rely on knowledge of local epidemiology (Sarker et al., 2021; Shahen et al., 2019). The interval from onset of infection to initiation of effective empirical therapy clearly influences outcome. Given the diversity of resistance mechanisms in A. baumannii, definitive therapy should be based on the results of antimicrobial susceptibility testing.

This study was carried out collaborately at the Micro-biology laboratory department of the University of Ilorin Teaching Hospital (UITH) and Bangladesh; UITH is located in Ilorin which provides quality health care services to the neighbouring state such as Oyo, Kogi, Niger, Osun and Ekiti states. UITH has bed space of about four hundred and fifty (450) and ad-mission rate of about twelve thousand (12,000) pati-ents per annum. Ilorin is the capital of Kwara state. The study population includes patients admitted into medicals, surgical wards and intensive care unit (ICU) OF University of Ilorin Teaching Hospital, Ilorin, Nigeria during February to July, 2018 whose clinical samples were sent to the Medical microbiology labo-ratory for routine investigation.

study Design

This is a descriptive cross sectional study.

Sampling Method

Purposive sampling, a non probability method was employed for this study. All Acinetobacter spp isolates from clinical samples collected in a repetitive manner were used for this study. All patients data to each isolate available in the laboratory register were used for this study. The age, sex and unit/wards were noted in the proforma.

Ethical Clearance

Ethical approval was obtained from the Ethical Review committee of the University of Ilorin Teaching Hospital, Ilorin.

Sample Size

Sample size was determined using the sample size formula for estimating single proportion Lislie and Wiley, (2007).

N= z2pq

d2

Where,

N=Minimum sample size

Z=Standard normal deviation, usually set at 1.96 which corresponds to 95% confidence level

P=The best estimated prevalence of target population; 8% from a study, Odewale et al. (2016) = 0.08%

Q=I-p; and 1-0.08=0.92

d=minimum statistically significant difference to be measured at 0.05 precision.

Hence,

N= 1.96X0.08X0.92 =113

0.05X0.05

The minimum sample size is 113. Therefore, 113 clini-cal samples were collected for this study. However, they were some multiple samples collected from more than one patient which made it 150 clinical samples.

Specimen collection

Various clinical samples were collected through aseptic technique by medical practitioners to prevent conta-mination. For optimal results, specimen was collected in clean sterile, wide bore containers. The clinical samples include urine, pus, blood, fluid (pleural, peri-cardial, synovial and peritoneal), wound swab, cere-brospinal fluid (CSF), sputum, central venous pressure (CVP), catheter tip , stool, throat swab, ear swab, nasal swab, from the tip of  Foley catheter, tissue (wound and soft tissues), and bronchial washing samples. They were transported immediately to the Medical Micro-biology Laboratory of the University of Ilorin Teaching Hospital for microbiological analysis.

Characterization of bacterial isolates

Colonial morphology of suspected colonies from both blood agar and Macconkey agar plate was charac-terized based on their appearances. Gram staining was done on the isolates and biochemical testing such as oxidase, catalase and triple sugar iron was furtherly done on the gram negative, coccobacillus isolates to characterize it. Moreso, the identified Acinetobacter-spp was furtherly confirmed by API20NE multi test system. These tests were used according to manufac-turers protocol for Enterobacteriaceae and non-enteric bacteria.

Susceptibility Testing

Antimicrobial Susceptibility test was determined using disc diffusion method. The disc diffusion method is a modification of the Kirby Bauer technique that has been carefully standardized by CLSI as described by Lalitha M. K in Manual of Antimicrobial Suscepti-bility Testing. This is meant to designate isolates as either Carbapenem - resistant Acinetobacter. Baum-annii (CRAB) (with Imipenem MIC> 8ug/ml). The tested agents included Amoxicillin, Cefixime, Strepto-mycin, Amoxicillin-clavulanate, Perfloxacin, Genta-mycin, Imipenem, Nitrofurantoin and Ceftriaxone. Quality Control for the MIC analysis was performed with E. coli ATCC 25922 and P. aeruginosa ATCC 27853. 

Statistical analysis

Data obtained was fed into a computer and analyses were done using statistical package for the social sciences (SPSS) version 20.0. Data was presented in frequency tables, charts and prose. Cross tabulation of important table was done.    

Acinetobacter Speciation

Acinetobacter baumannii constituted 7(70%) of the species isolated followed by Acinetobacter iwoffi 2(20%) with least from A. haemolyticus 1 (10%) using API20NE which are majorly male prepondence as shown in Table 1. 

Antibiotics Susceptibility Testing

The Antimicrobial susceptibility pattern of Acineto-bacter spp isolated from this study as shown in Table 2. Overall, 11 different antibiotics were tested and the isolates were resistant to at least two or more anti-biotics. All the isolates were resistant to amoxicillin, amoxicillin clavulanic acid, gentamicin, nitro-furan-toin, cefixime, ceftriaxone and cefuroxime. Significant resistance is observed with Streptomycin 90%, per-floxacin 90% and least resistance is observed with imipenem 20%.

Table 3 below shows the resistance pattern of Multi-Drug Resistance (MDR) Acinetobacter spp which in-cludes seven antibiotics such as Amoxicillin, Cefixime and others. 

Antimicrobial resistance among   Acinetobacter species has increased significantly in the past decades Mara-gakis and Perl, (2008). The ability of Acinetobacter species to extensively resist antimicrobial agents may be explained in part by the organisms relatively impe-rmeable outer membrane, selective pressure & envi-ronmental exposure to a large reservoir of resistance genes (Bonomo & Szabo, 2006; Sarker et al., 2021). Definition of MDR Acinetobacter spp varies, referring to a wide array of genotypes and phenotypes Falagas et al. (2006). 

Two of the most common definitions of multidrug resistance are carbapenem resistance or resistance to >3 classes of antimicrobial agents investigated in this study. In this study all the strains exhibited resistance to >6 antimicrobial agents tested. All (100%) strains were resistant to amoxicillin, amoxicillin clavulanate, cefixime. Cefuroxime, ceftriaxome, nitrofurantoin and gentamicin used. In 1970s, Acinetobacter infections were treated with ampicillin second generation cepha-lospirins, minocycline, colistin, carbenicilin and genta-micin Iregbu et al. (2002). Today, most strains are resistant to ampicillin, cefotaxime and chlorampheni-col with reports of 84% resistant to gentamicin in some institutions Iregbu et al. (2002). This is consistent with the observation made in this study. Among the classes of penicillins used in this study, all the strains (100%) were resistance to amoxicillin-clavulanate and amoxi-cillin. The beta-lactamase inhibitors used, amoxicillin-clavulanate did not improve the antimicrobial activity with all the isolates showing resistance. This is in agreement with previous observation made by Higgins et al. (2004). For the antibiotic class cephalosporins, all the isolates were resistance to cefuroxime the only second generation subclass of cephalosporin investi-gated. Similarly zero susceptibility rates were also recorded against the third generation subclass of cep-halosporin, cefixime and ceftriaxone. These obser-vations were comparable to report made by Iregbu et al. (2002) against ceftriaxone and cefuroxime. Gene-rally, Cephalosporins are beta-lactam antibiotics with reportedly high antimicrobial activity and low toxicity. Increased resistance observed from this institution could partly be explained by high level production of extended-spectrum antimicrobial therapy and frequent prescription of the drugs. Carbapenems remain the anti-biotic of choice to treat   A. baumannii and other Gram-negative infections due to both a wider spectrum of antibacterial activity and less frequent side effects. The report of high susceptibility pattern to carbapenem in this study is similar to Farahani et al. 

However, there was high rate of resistance to carba-penem reported by Wang et al. (2013) in South Africa reported 63% resistance and Ramoul et al. (2013) reported 91.3% in Algeria health care centers. It is important to note that this wide differences associated with carbapenem sensitivity and Acinetobacter in-fection in this study may be due to the difference in the time of the study, the kind of antibiotics sensitivity disc used and can also be due to inappropriate use of this antibiotic in the hospital setting where this study was carried[out. Aminioglycosides are usually used in com-bination with another active anti-microbial agent. In this study, the only amino-glycoside used in gentamicin having 100% resistance rate, similar finding was reported by Nemecand Maixnerova, (2004) with gentamicin having similar trend of 87% resistance.

The prevalence rate of Acinetobacter spp in this study is high and they are generally Multi-Drug Resistant (MDR). However, Carbapenem, Streptomycin and Per-floxacin remain useful therapy for the infections caused by these organisms. As such, rational usage of Carba-penems, Streptomycin, Perfloxacin and functional anti-biotic prescription policy are desired for the man-agement of Acinetobacter infection to avoid treatment failures. Continuous surveillance through well-equip-ped laboratories for prompt accurate detection of Acinetobacter spp.

We acknowledge the effort of Dr (Mrs) Mohammed-Nasir Rahmatin getting some of the materials used for this work.

There are no conflicts of interest.