# Acute Otitis Media in Children--Challenges of Antibiotic Resistance in the Post-Vaccination Era
## 3 Results
### Antimicrobial Resistance Profile  
We focused on _Streptococcus pneumoniae_ and _Haemophilus influenzae_ (70/147, and 17/147, respectively), as these strains were isolated most frequently (89.68% of all positive \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Bacteria** & \
\begin{tabular}{c} **Number of Isolated Bacteria** \\ **(\% of Positive Cultures)** \\ \end{tabular} &
\begin{tabular}{c} **Age Group (Average Age,** \\ **Median Age) \({}^{*}\)** \\ \end{tabular} & **Male: Female Ratio \({}^{**}\)** \\ \hline _Streptococcus pneumoniae_ & 70 (72.16\%) & 2–48 (20, 20) & 39:31 (1.25) \\ \hline _Haemophilus influenzae_ & 17 (17.52\%) & 4–60 (30, 24) & 12:5 (2.4) \\ \hline _Moraxella catarthalis_ & 2 (2.06\%) & 21–72 (46, 46) & 2:0 \\ \hline MRSA & 2 (2.06\%) & 2–13 (7, 7) & 1:1 \\ \hline _Pseudomonas aeruginosa_ & 2 (2.06\%) & 14–24 (19, 19) & 1:1 \\ \hline _Escherichia coli_ & 1 (1.03\%) & 12 (12, 12) & - \\ \hline _Enterobacter aerogenes_ & 1 (1.03\%) & 6 (6, 6) & - \\ \hline _Streptococcus pyogenes_ & 1 (1.03\%) & 72 (72, 72) & - \\ \hline _Turicella otitis_ & 1 (1.03\%) & 12 (12, 12) & - \\ \hline Total strains & 97 (100\%) & 2–84 (22, 19) & 93:54 (1.72) \\ \hline \end{tabular}  
* The age is reported as months old. ** Not applicable in case of only one positive strain of that type.  
\end{table} 
Table 1: Bacteriological flora isolated from the middle ear fluid of children with AOM. cultures. The penicillin resistant strains of _Streptococcus pneumoniae_ accounted for 5.71% (4/70), whereas 10 strains (14.28%) had intermediate susceptibility to penicillin. We report the minimum inhibitory concentrations for _Streptococcus pneumoniae_ strains (Table 2). In vitro sensitivity for ceftaxone, mooxifloxacin and vancomycin was reported in all tested strains, whereas only 6/70 strains were susceptible to trimethoprim/sulfamethoxazole, and 9/70 strains to macrolides (Table 2). _Haemophilus influenzae_, the second most common bacteria found in the middle ear samples, accounted for 17 (17.52%) (Table 4). We noticed that all the strains were sensitive to a second-generation cephalospororin (cefuroxime) and to a third-generation cephalospororin (cefuroxone). Using the nitrocefin test to assess beta-lactamase production, we identified only 4 (23.5%) ampicillin-resistant strains. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & & \multicolumn{4}{c}{**MIC * (\(\mu\)g/mL)**} & \multicolumn{4}{c}{**Number of Strains**} \\ \cline{3-8}
**Antibiotic** & \multirow{2}{*}{\begin{tabular}{c} **S** \\ **(Sensitive)** \\ \end{tabular} } & **I** & **R** & \multirow{2}{*}{\begin{tabular}{c} **Number of** **O** \\ **(Resistant)** \\ \end{tabular} } \\  & & **(S)** & **I** & **R** & \multirow{2}{*}{\begin{tabular}{c} **R** \\ **(Resistant)** \\ \end{tabular} } \\  & & **(S)** & **(S)** & **I** & **R** \\ \hline \multirow{4}{*}{\
\begin{tabular}{c} Penicillins \\ \end{tabular} } & \multirow{4}{*}{
\begin{tabular}{c} Penicillin \\ 2 \\ \end{tabular} } & 0.25 & 4 & 8 & 15 & 10 & 4 \\  & Penicillin & 1 & - & - & 27 & - & - \\  & & 2 & - & - & 14 & - & - \\  & & 0.5-1 & - & - & 70 & - & - \\  & & 0.25–0.5 & 2 & - & 69 & 1 & - \\  & & 0.25 & 2 & 4 & 65 & 1 & 4 \\  & & 0.12 & - & \textgreater{}2 & 9 & - & 61 \\ Macrolides & Clarithromycin & \textless{}0.12 & - & \textgreater{}2 & 9 & - & 61 \\  & Erythromycin & \textless{}0.06 & - & \textgreater{}1 & 9 & - & 61 \\ Lincosamides & Clindamycin & \textless{}0.06 & - & \textgreater{}1 & 16 & - & 54 \\ Fluoroquinolones & Moxifloxacin & \textless{}0.25–0.5 & - & - & 70 & - & - \\  & Levofloxacin & \textless{}0.5 & 4 & - & 69 & 1 & - \\ Glycopeptide & Vancomycin & 0.5–1 & - & - & 70 & - & - \\ Trimethoprim/sulfamethoxazole & \textless{}2.5/4.7 & - & \textgreater{}2/38 & 6 & - & 64 \\ Chloraphenicol & \textless{}2 & - & \textgreater{}8 & 66 & - & 4 \\ \hline \end{tabular}
* MIC—minimum inhibitory concentration.  
\end{table} 
Table 2: Antibiotic resistance of _Streptococcus pneumoniae_ strains.